Tire pressure warning system
First Claim
1. Apparatus for detecting changes in inflation pressure of a tire on a vehicle, said apparatus comprising:
- means for generating an electric signal indicative of vertical accelerations experienced by said tire, said accelerations exhibiting a resonant frequency dependent upon inflation pressure of said tire;
means for determining a first value of the resonant frequency experienced by said tire at a first time and for determining a second value of the resonant frequency experienced by said tire at a second time, both determined from said generated electric signal indicative of the vertical accelerations experienced by said tire;
means for storing said determined first value of the resonant frequency experienced by said tire;
comparing means for comparing said determined second value of the resonant frequency experienced by said tire with said stored determined first value of the resonant frequency experienced by said tire and for generating a signal indicative of a difference therebetween; and
alarm means responsive to said comparing means for providing an alarm to a driver when said signal generated by said comparing means indicates there is a difference between said stored determined first value of the resonant frequency and said determined second value of the resonant frequency greater than a predetermined amount.
2 Assignments
0 Petitions
Accused Products
Abstract
A tire inflation pressure detector which senses changes in tire pressure by detecting the changes in the spring rate of the tire which result from changes in tire pressure. An accelerometer (40) is mounted on a vehicle suspension component adjacent the tire. The accelerometer is sensitive to vertical accelerations experienced by the tire and provides a signal indicative thereof. A filter bank (64) processes the accelerometer signal so as to define the frequency distribution of the accelerometer output signal. A microcomputer (100) responds to the signals provided by the filters and locates the low frequency resonance peak whose position is influenced by the tire spring rate. The microcomputer determines whether tire pressure is low in accordance with the frequency of the resonance peak.
106 Citations
15 Claims
-
1. Apparatus for detecting changes in inflation pressure of a tire on a vehicle, said apparatus comprising:
-
means for generating an electric signal indicative of vertical accelerations experienced by said tire, said accelerations exhibiting a resonant frequency dependent upon inflation pressure of said tire; means for determining a first value of the resonant frequency experienced by said tire at a first time and for determining a second value of the resonant frequency experienced by said tire at a second time, both determined from said generated electric signal indicative of the vertical accelerations experienced by said tire; means for storing said determined first value of the resonant frequency experienced by said tire; comparing means for comparing said determined second value of the resonant frequency experienced by said tire with said stored determined first value of the resonant frequency experienced by said tire and for generating a signal indicative of a difference therebetween; and alarm means responsive to said comparing means for providing an alarm to a driver when said signal generated by said comparing means indicates there is a difference between said stored determined first value of the resonant frequency and said determined second value of the resonant frequency greater than a predetermined amount. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
-
-
9. Apparatus for detecting changes in inflation pressure of at least two tires on a vehicle, said apparatus comprising:
-
plurality of signal generating means, each tire of said at least two tires having an associated signal generating means for generating an electric signal indicative of vertical accelerations experienced by its associated tire, said accelerations exhibiting a resonant frequency dependent upon inflation pressure of its associated tire; means for determining a value of the resonant frequency experienced by each tire of said at least two tires at a first time and at a second time; means for determining the driving time of the vehicle; first means for comparing, when said determined driving time is not greater than a predetermined value, the determined value of the resonant frequency experienced by a selected tire of said at least two tires at said first time with the determined value of the resonant frequency experienced by said selected tire at said second time and for generating a signal indicative of the difference therebetween; second means for comparing, when said determined driving time is greater than said predetermined value, the determined value of the resonant frequency experienced by said selected tire with the determined value of the resonant frequency experienced by another of said at least two tires and for generating a signal indicative of the difference therebetween; and indicator means responsive to said first means and to said second means for providing an alarm to a driver when said signal generated by said first means indicates a difference between the determined value of the resonant frequency experienced by said selected tire at said first time and the determined value of the resonant frequency experienced by said selected tire at said second time is greater than a predetermined value, or when said signal generated by said second means indicates a difference between the determined value of the resonant frequency experienced by said selected tire and the determined value of the resonant frequency experienced by said another tire is greater than a predetermined value. - View Dependent Claims (10, 11, 12, 13, 14, 15)
-
Specification