Communications: electrical – Land vehicle alarms or indicators – Internal alarm or indicator responsive to a condition of the...
Reexamination Certificate
1999-12-03
2001-08-21
Mullen, Thomas (Department: 2632)
Communications: electrical
Land vehicle alarms or indicators
Internal alarm or indicator responsive to a condition of the...
C073S011040, C340S440000, C701S029000, C702S183000
Reexamination Certificate
active
06278361
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a system and method for monitoring tread wear, shock absorber performance, balance condition of a vehicle tire, and/or rotational speed of a vehicle wheel.
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. Handling performance can be affected by improper tire inflation, abnormal tire wear, out of balance conditions, as well as by poorly performing shock absorbers.
It is estimated that a significant percentage of tires wear out due to abnormal tire tread wear. As a result, over the course of vehicle life, the vehicle would need an additional set of tires, costing additional money. Thus, to save this cost it is desired to alert the driver of abnormal tire wear and other conditions affecting the tires, including improper balance, poorly functioning shock absorbers and improper inflation pressure.
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 and typically consists of a toothed wheel made of a magnetic disk attached coaxially 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.
SUMMARY OF THE INVENTION
The present invention relates to a system and method for monitoring at least one of tire tread wear, shock absorber performance, balance condition of a vehicle tire, and wheel rotational speed.
According to the present invention, a system and method for monitoring at least tire tread wear of a vehicle tire are provided. The system and method use a sensor which senses at least one of radial and lateral acceleration of a 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 or outside the tire in a protective casing. The at least one processor is responsive to acceleration signals from the sensor and determines at least one resonance frequency of at least one of the radial and lateral acceleration of the tire, compares the determined at least one resonance frequency to at least one stored frequency, determines the tire tread wear on the basis of the comparison, 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.
More particularly, the at least one processor calculates a Discrete Fourier Transform (DFT) of the acceleration signals, e.g., by taking a Fast Fourier Transform (FFT) of the acceleration signals, to determine the at least one resonance frequency of at least one of the radial and lateral acceleration of the tire measured over a time duration longer than a vehicle suspension time constant. For example, the at least one processor may take a Fast Fourier Transform (FFT) of the radial and/or lateral acceleration signals to determine a resonance frequency in the range of 30-60 Hz of the radial and/or lateral acceleration of the tire, compare the resonance frequency to a stored resonance frequency in the range of 30-60 Hz indicative of no tire wear to determine a frequency shift, and determine tire tread wear on the basis of the frequency shift.
Preferably, a transmitter provided on a rim on which the tire is mounted or inside the tire wirelessly transmits the information signal to a receiver provided onboard the vehicle for receiving the wirelessly transmitted information signal.
According to another aspect of the invention, a system and method for monitoring at least shock absorber performance of a shock absorber attached to a vehicle wheel are provided. The system and method use a sensor which senses at least the radial acceleration of a 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 or outside the tire in a protective casing. The at least one processor is responsive to acceleration signals from the sensor and calculates a Discrete Fourier Transform (DFT) of the acceleration signals, e.g., by taking a Fast Fourier Transform (FFT) of the acceleration signals, measured over a time duration longer than a vehicle suspension time constant, determines an amplitude of the Fourier component of the radial acceleration, e.g., in the range of 0.5-2.0 Hz, compares the amplitude profiles to a stored amplitude profile, e.g., in the range of 0.5-2.0 Hz indicative of a new shock absorber for the vehicle, and determines shock absorber performance on the basis of any change in the amplitude profile over the stored amplitude, and provides an information signal indicative of shock absorber performance which is transmitted to the driver information display.
According to another aspect of the invention, a system and method for monitoring at least a balance condition of a vehicle tire are provided. The system and method use a sensor which senses at least the radial acceleration of a 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 or outside the tire in a protective casing. The at least one processor is responsive to acceleration signals from the sensor and calculates a Discrete Fourier Transform (DFT) of the acceleration signals, e.g., by taking a Fast Fourier Transform (FFT) of the acceleration signals, measured over a time duration longer than a vehicle suspension time constant, determines an amplitude of the Fourier component of the radial acceleration, e.g., in the range of 5-14 Hz, compares the amplitude to a stored amplitude, e.g., in the range of 5-14 Hz indicative of a specification predetermined balanced tire for the vehicle, and determines any out of specification predetermined balance condition of the tire on the basis of any increase in the amplitude over the stored amplitude.
According to another aspect of the invention, a system and method for monitoring at least wheel rotational speed of a vehicle wheel are provided. The system and method use a sensor which senses at least the radial acceleration of a tire to provide acceleration signals. A transceiver then transmits a radial signal frequency, e.g., in the range of 0-25 Hz indicative of wheel rotational speed to a vehicle controller such as an antilock braking system or an integrated vehicle controller. This system can be used to replace the wheel speed sensors currently being used.
REFERENCES:
patent: 5525960 (1996-06-01), McCall et
Dunbridge Barry
Eberhard Carol A.
Magiawala Kiran R.
McIver George W.
Zimmerman Thomas A.
Keller Robert W.
Mullen Thomas
TRW Inc.
LandOfFree
System and method for monitoring vehicle conditions... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with System and method for monitoring vehicle conditions..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and System and method for monitoring vehicle conditions... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2508590