Communications: electrical – Land vehicle alarms or indicators – Internal alarm or indicator responsive to a condition of the...
Reexamination Certificate
2001-07-06
2004-07-06
Wu, Daniel J. (Department: 2632)
Communications: electrical
Land vehicle alarms or indicators
Internal alarm or indicator responsive to a condition of the...
C340S438000, C340S440000, C340S445000, C152S152000, C301S005210
Reexamination Certificate
active
06759952
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a tire and suspension warning and monitoring system that is composed of a set of sensors. These sensors monitor and measure current tire and suspension performance and periodically warn the driver when the tires or the suspension system needs servicing. There is one sensor for each tire on the vehicle. Each sensor measures the following tire and suspension performance (a) tire imbalance of each tire of a vehicle, (b) tire tread wear of each tire of a vehicle, and (c) shock absorber performance for each tire of a vehicle.
The handling performance of a motor vehicle, e.g., vehicle steering and braking, as well as fuel consumption, is affected by the condition of the tires and the suspension. Handling performance can be affected by improper tire inflation, abnormal tire tread wear, out of balance conditions, as well as by poorly performing shock absorbers.
It is estimated that ten percent of tires that would normally wear out at 40,000 miles actually wear out at 30,000 miles due to abnormal tire tread wear. As a result, over the course of vehicle life of 120,000 miles, the vehicle would need an additional set of tires, at an average cost of $300. Thus, it is desirable to alert the driver of abnormal tire imbalance.
A tire monitoring system currently available from SmarTire Systems, Inc. uses wireless technology to monitor the air pressure and temperature in vehicle, tires using wireless wheel-mounted sensors and a display receiver mounted within sight and reach of the driver. One sensor is mounted on each wheel and the tire mounted over the sensor, each sensor containing a pressure transducer, a temperature transducer, a centrifugal switch, a radio transmitter and a lithium battery. The display module shows required pressure, actual pressure, pressure status and temperature. While this system provides temperature and pressure information, it does not provide information about tread wear, balance and shock absorber performance.
In addition, anti-lock braking systems (ABS) and integrated vehicle controllers (IVC) require the input of information indicating the wheel rotational speed for each wheel. Currently, a separate wheel speed sensor is provided for each wheel. It typically consists of a toothed wheel made of a magnetic disk attached co-axially to a corresponding axle rotatably supporting a tire and a pick-up coil arranged adjacent each toothed wheel with an interval therebetween to provide an alternating sensor signal having a frequency indicative of speed of each tire. It would be desirable to eliminate the need for this type of sensor by using a sensor, which also provides additional functions.
U.S. Pat. No. 6,278,361, discloses a system and method for monitoring vehicle conditions affecting tires including tire tread wear, shock absorber performance, balance condition of the vehicle tire, and rotational speed of vehicle wheel.
While the above-noted co-pending application includes many features in common with those of the present invention, it does not include salient features of the present invention including informing a driver of the vehicle when various vehicle components will fail and informing the driver as to how much time until a component failure.
SUMMARY OF THE INVENTION
The present invention relates to tire and suspension monitoring and warning system for (a) tire imbalance on a tire of a vehicle, (b) tire tread wear on a tire of a vehicle, and (c) shock absorber performance of a vehicle. Here, a change in match-filtered vibration signal from a single or multiple vibration sensors from its baseline value is used to determine the condition of a vehicle parameter of interest.
According to the present invention, a sensor measures the tire imbalance by sensing at least one acceleration of a tire, such as the radial acceleration of the tire, to provide acceleration signals. The signals are provided to at least one processor which processes the signals. A single processor or multiple processors can be used. The sensor and at least one processor can be mounted on the wheel, e.g., on the rim either inside the tire at the wheel well or near the valve stem or outside the tire in a protective casing. The at least one processor is responsive to acceleration signals from the sensor and processes these signals and determines the tire imbalance on the basis of a comparison of the processed signals with a previously stored threshold value, and provides an information signal indicative of tire imbalance which is transmitted to a driver information display. The signal can be either an alarm signal or a quantitative indication of tread imbalance.
According to the present invention, at least one acceleration of the wheel is sensed before computing tire imbalance. A predetermined number of acceleration signal samples are collected and then transformed and normalized. The rotational frequency of the wheel is then computed from the transformed and normalized samples and the second harmonic of the rotational frequency is then computed. All of the frequency components are then summed around the computed second harmonic frequency including a predetermined standard deviation on either side of the computed second harmonic frequency. The results may then be weighted by a power of the fundamental rotational frequency. The result may then also be low pass filtered to eliminate higher order frequencies including spurious noise. The filtered result is then compared with a predetermined threshold value. A signal is then outputted which is indicative of the comparison result.
According to the present invention, a sensor measures the tire tread wear by sensing at least one acceleration of a tire, such as the axial acceleration of the tire, to provide acceleration signals. The signals are provided to at least one processor which processes the signals. A single processor or multiple processors can be used. The sensor and at least one processor can be mounted on the wheel, e.g., on the rim either inside the tire at the wheel well or near the valve stem or outside the tire in a protective casing. At least one processor is responsive to acceleration signals from the sensor and processes these signals and determines the tire tread wear on the basis of a comparison of the processed signals with a previously stored baseline value, and provides an information signal indicative of tire tread wear which is transmitted to a driver information display. The signal can be either an alarm signal or a quantitative indication of tread wear.
According to the present invention, at least one acceleration of the wheel is sensed before computing tire tread wear. A predetermined number of acceleration signal samples are collected and then transformed and normalized within a first predetermined frequency range. The transformed and normalized samples are then averaged within a second predetermined frequency range around the lateral resonance frequency of a tire shell, and the equivalent or average frequency from within in that second range is then compared with a previously stored baseline value for an unworn tire. A signal indicative of shift in equivalent or average frequency in a second predetermined range is then outputted, which is indicative of the comparison result for a worn tire.
According to one aspect of the invention, a technique for monitoring the shock absorber performance of a shock absorber attached to a vehicle wheel is provided. The technique uses a sensor which senses at least one acceleration of a tire, such as the radial acceleration of the tire, to provide acceleration signals. The signals are provided to at least one processor which processes the signals. A single processor or multiple processors can be used. The sensor and the at least one processor can be mounted on the wheel, e.g., on the rim either inside the tire (at the wheel well or near the valve stem) or outside the tire in a protective casing. The at least one processor is responsive to acceleration signals from the sensor and collects a predetermined number of acceleration sample
Brown Kenneth L.
Chilcott Kelley D.
Dunbridge Barry
Magiawala Kiran R.
McIver George W.
Tang Son
Tarolli, Sundheim Covell & Tummino L.L.P.
TRW Inc.
Wu Daniel J.
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