Tire pressure detecting apparatus for vehicle
First Claim
1. A tire pressure detecting apparatus for detecting a tire pressure of a tire of a vehicle, comprising:
- pressure-impedance transforming means, provided within said tire, for transforming a change in tire pressure into a change of capacitance indicative of said change in pressure, said pressure-impedance transforming means including;
a housing which is provided within said tire;
a first chamber provided within said housing, a pressure of said first chamber being maintained at a predetermined value;
a second chamber provided within said housing including means for introducing said tire pressure into said second chamber; and
a piezoelectric element provided within said housing so as to be deformed by a pressure difference between the predetermined pressure of said first chamber and the tire pressure of said second chamber, whereby a capacitance of said piezoelectric element is changed in accordance with its deformation;
resonant signal producing means, electrically connected with said pressure-impedance transforming means within said tire, for producing a resonant electric signal having a resonant frequency in accordance with the capacitance change generated from said pressure-impedance transforming means;
voltage supplying means, provided in said vehicle, for supplying said resonant signal producing means with an alternating voltage whose frequency is changed within a predetermined range including said resonant frequency;
resonant signal receiving means, provided in said vehicle, for receiving said resonant electric signal produced from said resonant signal producing means; and
pressure detecting means, provided in said vehicle, for detecting the tire pressure based on said received resonant electric signal.
1 Assignment
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Accused Products
Abstract
A tire pressure detecting portion includes a housing, provided within the tire, within which a piezoelectric element is provided so as to be deformed by the tire pressure. The capacitance of said piezoelectric element is changed in accordance with its deformation. The piezoelectric element is electrically connected with a first coil diposed within said tire. The first coil is electromagnetically coupled with an excitation coil and a receiving coil, both of which are provided in the vehicle. The excitation coil provides an excitation voltage whole frequency is changed within a predetermined range including a resonant frequency. When the received voltage has the resonant frequency, a correspondinq tire pressure is determined based on a data map showing the relationship between said resonant frequency and the tire pressure.
53 Citations
28 Claims
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1. A tire pressure detecting apparatus for detecting a tire pressure of a tire of a vehicle, comprising:
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pressure-impedance transforming means, provided within said tire, for transforming a change in tire pressure into a change of capacitance indicative of said change in pressure, said pressure-impedance transforming means including; a housing which is provided within said tire; a first chamber provided within said housing, a pressure of said first chamber being maintained at a predetermined value; a second chamber provided within said housing including means for introducing said tire pressure into said second chamber; and a piezoelectric element provided within said housing so as to be deformed by a pressure difference between the predetermined pressure of said first chamber and the tire pressure of said second chamber, whereby a capacitance of said piezoelectric element is changed in accordance with its deformation; resonant signal producing means, electrically connected with said pressure-impedance transforming means within said tire, for producing a resonant electric signal having a resonant frequency in accordance with the capacitance change generated from said pressure-impedance transforming means; voltage supplying means, provided in said vehicle, for supplying said resonant signal producing means with an alternating voltage whose frequency is changed within a predetermined range including said resonant frequency; resonant signal receiving means, provided in said vehicle, for receiving said resonant electric signal produced from said resonant signal producing means; and pressure detecting means, provided in said vehicle, for detecting the tire pressure based on said received resonant electric signal. - View Dependent Claims (2, 3, 4, 5)
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6. A tire pressure detecting apparatus for detecting a tire pressure of a tire of a vehicle, comprising:
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pressure-impedance transforming means, provided within said tire, for transforming a change in tire pressure into a change of capacitance indicative of said change in pressure; resonant signal producing means, electrically connected with said pressure-impedance transforming means within said tire, for producing a resonant electric signal having a resonant frequency in accordance with the capacitance change generated from said pressure-impedance transforming means; voltage supplying means, provided in said vehicle, for supplying said resonant signal producing means with an alternating voltage whose frequency is changed within a predetermined range including said resonant frequency; resonant signal receiving means, provided in said vehicle, for receiving said resonant electric signal produced from said resonant signal producing means; and pressure detecting means, provided in said vehicle, for detecting the tire pressure based on said received resonant electric signal, said pressure detecting means including; resonant frequency determining means for determining that said received resonant electric signal has said resonant frequency; and tire pressure determining means for determining a corresponding tire pressure by using a determination result of said resonant frequency determining means and a data map which stores a relationship between said resonant frequency and said tire pressure; and wherein said resonant frequency determining means determines that said received resonant electric signal has said resonant frequency when a phase difference between said alternating voltage and said received resonant electric signal becomes π
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7. A tire pressure detecting apparatus for detecting a tire pressure of a tire of a vehicle, comprising:
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a housing provided within said tire; a first chamber provided within said housing, a pressure of said first chamber being maintained at a predetermined value; a second chamber, provided within said housing, including means for introducing the tire pressure into said second chamber; a piezoelectric element provided within said housing so as to be deformed by a pressure difference between the predetermined pressure in said first chamber and the tire pressure in said second chamber, whereby an impedance of said piezoelectric element is changed in accordance with its deformation; a first coil electrically connected with said piezoelectric element within said tire; an excitation coil, provided in the vehicle, which is electromagnetically coupled with said first coil, for exciting said first coil with an excitation voltage whose frequency is changed within a predetermined range including a resonant frequency; a receiving coil, provided in the vehicle, which is electromagnetically coupled with said first coil for receiving an induced voltage from said first coil; resonant frequency determining means for determining that said induced voltage has said resonant frequency; and tire pressure determining means for determining a corresponding tire pressure by using a determination result of said resonant frequency determining means and a data map storing a relationship between said resonant frequency and said tire pressure. - View Dependent Claims (8, 9, 10)
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11. A tire pressure detecting apparatus for detecting a tire pressure of a tire of a vehicle, comprising:
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first transforming means, provided within said tire, for transforming a change in tire pressure into a capacitance change; second transforming means, provided within said tire, for transforming a tire temperature into a capacitance change; first resonant signal producing means, electrically connected with said first transforming means within said tire, for producing a first resonant electric signal having a first resonant frequency in accordance with the capacitance change generated from said first transforming means; second resonant signal producing means, electrically connected with said second transforming means within said tire, for producing a second resonant electric signal having a second resonant frequency in accordance with the capacitance change generated from said second transforming means; first voltage supplying means, provided in said vehicle, for supplying said first resonant signal producing means with a first alternating voltage having at least said first resonant frequency; second voltage supplying means, provided in said vehicle, for supplying said second resonant signal producing means with a second alternating voltage having at least said second resonant frequency; first resonant signal receiving means, provided in said vehicle, for receiving said first resonant electric signal produced from said first resonant signal producing means; second resonant signal receiving means, provided in said vehicle, for receiving said second resonant electric signal produced from said second resonant signal producing means; pressure detecting means, provided in said vehicle, for detecting the tire pressure based on said first received resonant electric signal; temperature detecting means, provided in said vehicle, for detecting the tire temperature based on said second received resonant electric signal; and compensating means for compensating said tire pressure detecting by said pressure detecting means, based on said tire temperature. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19)
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20. A tire pressure detecting apparatus for detecting a tire pressure of a tire of a vehicle, comprising:
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first transforming means, provided within said tire, for transforming a pressure change of said tire into a capacitance change; second transforming means, provided within said tire, for transforming a tire temperature into a capacitance change; first resonant signal producing means, electrically connected with said first transforming means within said tire, for producing a first resonant electric signal having a first resonant frequency in accordance with the capacitance change generated from said first transforming means; second resonant signal producing means, electrically connected with said second transforming means within said tire, for producing a second resonant electric signal having a second resonant frequency in accordance with the capacitance change generated from said second transforming means; voltage supplying means, provided in said vehicle, for supplying said first resonant signal producing means with a first alternating voltage having at least said first and second resonant frequencies; first resonant signal receiving means, provided in said vehicle, for receiving said first resonant electric signal produced from said first resonant signal producing means; second resonant signal receiving means, provided in said vehicle, for receiving said second resonant electric signal produced from said second resonant signal producing means; pressure detecting means, provided in said vehicle, for detecting the tire pressure based on said first received resonant electric signal; temperature detecting means, provided in said vehicle, for detecting the tire temperature based on said second received resonant electric signal; and compensating means for compensating said tire pressure detecting by said pressure detecting means, based on said tire temperature. - View Dependent Claims (21, 22, 23, 24, 25, 26, 27, 28)
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Specification