Measuring and testing – Frictional resistance – coefficient or characteristics
Reexamination Certificate
2001-08-17
2004-03-30
Noland, Thomas P. (Department: 2856)
Measuring and testing
Frictional resistance, coefficient or characteristics
Reexamination Certificate
active
06711935
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to monitoring a road surface condition on which a vehicle is travelling, and more particularly to a method and apparatus for continuously determining a slip condition of a vehicle which is directly related to the coefficient of friction of the road surface.
The invention also relates to a method and apparatus for applying a controlled vertical (i.e., normal) force to a test wheel of a friction monitor and to a friction monitor using such a vertical force monitor in combination with an electromagnetic torque motor for producing slippage of a test wheel.
The invention further relates to a device for monitoring a surface (e.g., road, runway, rail line etc.) condition on which a monitor (e.g., vehicle, airplane, train etc.) is travelling, and more particularly to a method and apparatus for determining a slip condition of a vehicle which is directly related to the coefficient of friction of the road surface while utilizing an electromagnetically controlled vertical force applied to the test wheel.
BACKGROUND OF THE INVENTION
The availability of quantitative information representative of the coeficient of friction of the road surface is very beneficial to drivers of moving vehicles, including planes. An exact knowledge of how slippery the surface is, continuously provided, gives the driver significant advantages in determining safe speeds, distances from other automobiles, acceleration and braking patterns etc. so as to permit a safer operation of the vehicle, plane or apparatus being driven.
Previous devices for monitoring the coefficient of friction had significant disadvantages such as, for example: a failure to provide continuous road friction data over long distances; the use of complex electro-mechanical-hydraulic mechanisms with unfavorable wear characteristics; limited, specificity, variability and responsiveness of test wheel(s) braking force; the use of only indirectly measured values of the force (torque) required to produce slippage; employment of equipment which was unsuited for continuous use close to the ground and in inclement conditions; the use of a cumbersome test wheel suspension and carriage; employment of equipment which produced adverse affect on normal drive operation; and the use of relatively complex designs which produces an expensive apparatus of only limited use.
When measuring the coefficient of friction, various means of applying vertical force have been employed, such as: springs, coils, rubber, compressed air bags, pistons containing air, gases, oil. The foregoing vertical force applying devices have significant limitations. The vertical force tends to increase as tensioning means are compressed and decrease when decompressed. The vertical force is difficult to measure, especially if continuous or frequent measurements are desirable. Further, one is generally not able to standardize the force from one system to another. The vertical force tends to change with use/wear due to deterioration of compressed materials/mechanisms, and to vary with change in temperature and/or moisture.
REVIEW OF PRIOR ART
Several patents are directed to devices which do not employ a separate test wheel but rather employ one of the usual drive or driven wheels of the vehicle. Among these patents are U.S. Pat. No. 4,882,693 to Yopp and U.S. Pat. No. 4,545,240 to Leiber. These devices necessarily adversely effect the driving characteristics of the vehicle.
The Yopp patent measures forces acting on a steering column, such as the steering angle combined with other data.
Other patents teach the use of a test wheel or probe which is lowered into contact with the road surface to perform the desired measurement. Among these patents are U.S. Pat. Nos. 4,098,111 and 4,212,063 to Hardmark; U.S. Pat. No. 4,958,512 to Johnson; U.S. Pat. No. 3,893,330 to Shute; U.S. Pat. No. 4,315,426 to Brandon; U.S. Pat. No. 4,662,211 to Strong; and U.S. Pat. No. 4,909,073 to Takahashi. These patents employ complex devices which are not adapted for continuous operation and wear and which are bulky and complicated in their operation.
OBJECTS OF THE INVENTION
One object of an aspect of the invention is to continuously monitor road surface friction characteristics under a wide variety of road conditions and vehicle velocities.
Another object of the invention is to provide a slippage indication by simulating the actual physical circumstances of slippage of a braked or accelerated wheel of a vehicle.
A further object of the invention is to monitor road surface friction without interfering with the movement of the vehicle wheels or braking system such as would affect the directional path or speed of the vehicle, and in particular, not to affect the freedom of the drive wheels or other wheels of the vehicle or interfere with the braking system, thereby potentially throwing the car off its directional path or causing acceleration or deceleration of the vehicle.
Yet another object of an aspect of the invention is to provide a lightweight, comparatively small monitoring device of suitable weight and size for mounting on an automobile or plane that operates independently of any other system in a moving vehicle, that is comparatively inexpensive to manufacture, and that does not require much maintenance.
Another object of an aspect of the invention is to provide a simple, easily retractable, and easily detachable slip detection device which does not constitute a significant obstacle to the movement of the vehicle.
Another object of an aspect of the invention is to continuously provide near instantaneous, widely variable, highly specific, easily directly measurable, braking or accelerative force; which does not vary, fade, or fail, at any vehicular speed.
Another object of an aspect of the invention is to measure friction conditions without utilizing cumbersome direct mechanical friction devices with their attendant mechanical wear.
Yet another object is to provide a slip detection device suitable for after market mounting on existing vehicles.
It is a further object of an aspect of the invention to provide a compact suspension mechanism for applying and maintaining a controlled, accurately measurable vertical force to the test wheel of a friction monitor, which vertical force is unaffected by variations in temperature, moisture, or atmospheric pressure; remains constant as the test wheel moves up and down with reference to its point of support due to variations in the contour of the measured surfaces; and counters the tendency of the test wheel to move upwards and lose contact with the measured surface. The vertical force may be varied in a controlled manner during use.
SUMMARY OF THE INVENTION
The emphasis with the present invention, in accordance with an aspect thereof, is on the continuous determination of road surface friction characteristics for automobile drivers or pilots, so as to facilitate decision-making with regard to safe travelling speed, braking distance, cornering speed, acceleration speed and the like in various road conditions; wet (hydroplaning), snow, slush, ice, oily surface, etc. Data on varying road coefficient of friction characteristics is continuously presented to the driver as a visual and/or auditory signal.
An embodiment of the present invention provides a means for continuously evaluating the coefficient of friction of the road by providing a relative quantification of the coefficient of friction. The device is comparatively compact and relays to the driver a visual and/or auditory signal indicating relative slipperiness of the road. For example, a suitably placed, non-distracting flashing light could be used; the flashing light can be designed to flash more frequently and more brightly as the slipperiness of the road increases. An audio signal can also be used to inform the driver about road conditions: again, the frequency and intensity of the audio signal can be increased in relation to the slipperiness of the road.
An embodiment of the present invention mimics the strategy commonly used by drivers to evaluate road conditions: pressing o
Foley & Lardner
Noland Thomas P.
LandOfFree
Method and apparatus for continuous monitoring of road... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method and apparatus for continuous monitoring of road..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method and apparatus for continuous monitoring of road... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3224143