The present application relates generally to vehicle sensors, and more particularly, to apparatus for carrying a sensor in operable position on a vehicle.
Anti-lock braking systems (ABS) have become common safety equipment on every type of vehicle ranging from cars to trailers. A typical ABS includes a central electronic control unit (ECU), two or more hydraulic valves within the brake system, and wheel speed sensors—one for each wheel. The wheel speed sensors provide information to the ECU, which constantly monitors the wheel speed, and upon detecting a wheel rotating significantly slower than the others—a condition indicative of impending wheel lock—it actuates the valves to reduce hydraulic pressure to the brake at the affected wheel, thus reducing the braking force on that wheel.
The wheel sensors are typically located on the axle adjacent to the inboard-facing side of a wheel hub, the wheel hub incorporating a tone ring. The tone ring includes a series of teeth, which project from a surface of the tone ring. The wheel sensors detect movement of the tone ring teeth, and send corresponding signals to the ECU, enabling braking control. The position and location of the sensors with respect to the tone ring is crucial to the operation of the ABS, as any incorrect movement detection sends fallacious signals to the ECU, which in turn wrongly actuates the braking valves, causing undesired results.
Sensors are typically mounted on a backing plate near a tone ring, or a similar device. In a three channel (wheel) ABS system, wheel speed is detected through a single sensor placed on an axle near the tone ring in a ring and pinion assembly. In certain applications, space available for mounting the speed sensor becomes a constraint. While designing a four-channel (wheel) ABS system, for example, in Dual Rear Wheel (DRW) vehicles, very limited axle space is available between the wheels, and in these applications, typical mounting techniques cannot be used. Further, in modern day motor vehicle design, efficiency of packaging, lightweight, and ease of assembly are of paramount importance. Although prior art sensors mounts have been implemented, designers of such systems are constantly striving to increase their reliability, reduce packaging space requirements, and facilitate production, assembly, and calibration, all the while seeking to reduce their cost.
As a result, there exists a need for an improved sensor mounting system configured to reduce the effects of variations in the air gap between the rotor and stator, which is easier and less expensive to produce, and meets minimum packaging space requirements.
One embodiment of the present application describes a device for mounting a sensor assembly on a vehicle axle. The device comprises a substantially circular ring that circumferentially engages the vehicle axle tube. Further, the device includes a support block including a clamp-engaging segment that engages at least a portion of the ring circumference, a sensor-engaging segment that is adapted to engage the sensor assembly, and an axle-engaging segment adapted for engaging at least a portion of the axle to position the sensor assembly with relation to the axle.
Embodiments of the present disclosure provide many advantages. For example, the sensor-mounting device is very compact and can be easily fit into vehicles with space constraints near the tone ring, such as dual rear wheel vehicles. Further, due to the symmetrical structure of the sensor-mounting device, it can be fit adjacent any vehicle wheel without any modifications. Moreover, the device is inexpensive and can be formed of any suitable material with departing from the scope of the present disclosure.
These and other advantages, features, and objects of the present application will become apparent upon review of the following detailed description of the preferred embodiments when taken in conjunction with the drawings and the appended claims.
The drawings,
The support block 104 includes a clamp-engaging portion 106, a sensor-engaging portion 108, and an axle-engaging portion 110. The clamp-engaging portion 106 may be the bottom surface of the support block 104 and may be molded over the ring 102. Alternatively, the clamp-engaging portion 106 may be a snap-fit assembly. In the latter scenario, the clamp-engaging portion 106 includes two parallel surfaces, substantially arcuate, separated by a distance comparable to the ring's thickness. These two parallel surfaces engage the ring 102, one surface engaging the outer surface of ring 102, and the other surface engaging the ring's inner surface, thereby snapping onto the ring circumference.
The sensor-engaging portion 108 may include one or more recesses, protrusions, bolts, nuts, locks, or latches. These features engage corresponding features that may be present on the sensor. For example, if the sensor includes one protrusion and one recess, the sensor-engaging portion 108 may include one recess and one protrusion engaging with the protrusion and recess of the sensor assembly respectively. Other engaging features include slide-fits, rabbet fits, and so on. It will be appreciated by a person skilled in the art that the sensor-engaging portion 108 may include one or more fits, depending on the sensor assembly, without departing from the scope of the present disclosure.
The structure of the axle-engaging portion 110 may again vary depending on the application. In one embodiment of the present disclosure, the axle-engaging portion 110 may be a locator pin, of any shape, that can engage a corresponding locator aperture present on the axle tube. Alternatively, the axle-engaging portion 110 may be a locator aperture that may engage a corresponding locator pin present on the axle tube. It will be understood that the axle-engaging portion 110 secures the sensor position with relation to the axle tube and the tone ring. Any means for fixing this position can be contemplated and those means will not fall outside the scope of the present disclosure. For example, the axle-engaging portion 110 may include latches, nuts, bolts, apertures, pins, blocks, rabbet fits, slide fits, and so on.
In one embodiment of the present disclosure, the support block 104 is symmetrical about a central axis. Symmetry allows the same sensor-mounting device 100 to be fitted in any orientation on any wheel of the vehicle without modifications or alterations.
The sensor-mounting device 100 as described with reference to
The axle tube 204 further includes a locator aperture 206. The corresponding axle-engaging portion 110, such as a locator, engages this locator aperture 206 to position a vehicle speed sensor, such as sensor 208 accurately with respect to the tone ring 204. The accurate placement of the sensor 208 is required for correctly sensing the tone ring 204 speed. Any movement in the sensor 208 with respect to the tone ring 204 can result in erroneous data. Therefore, the axle-engaging portion 110 and the locator aperture 206 provide position locking, such that the sensor-mounting device 100 can withstand motional vibrations and tolerances without affecting the sensor 208 position.
Once the sensor-mounting device 100 is placed near the tone ring 204, and the axle-engaging portion 110 is properly engaged with the locator aperture 206, the ring 102 may be welded or bolted onto the axle tube 202. In another implementation, the ring 102 may be a tension clamp, and is slipped onto the axle tube 202 in its open position. When the sensor-mounting device 100 is properly positioned, the tension clamp is released or closed, such that the tension clamp clutches the axle tube 202 asserting constant tension on the axle tube 202. Different types of tension clamps may be used and
The tone ring 204 is mechanically coupled to the hub and drive assembly 210 of the vehicle. This is a standard hub-and-drive assembly, and will not be described in detail here.
The embodiments of the present disclosure described herein provide a sensor-mounting device 100 capable of positioning a wheel speed sensor accurately adjacent to a vehicle tone ring, in limited space applications. The sensor-mounting device 100 is low cost, light, easy to manufacture and maintain, and simple to construct. Furthermore, the sensor-mounting device 100 is robust to tolerance stack-ups and can be assembled with minimum or no change to the existing vehicle axle and wheel structure.
While the best mode for carrying out the invention has been described in detail, those familiar with the art to which this invention relates will recognize various alternative designs and embodiments for practicing the invention as described by the claims.