Hybrid resonant structure to verify parameters of a tire
Control of running conditions, and particularly physical parameters of tires are recommended to increase automobile safety. A sensor according to the invention is used to determine various factors such as the temperature or pressure of tires. The sensor is a hybrid resonant passive structure that may be integrated in the vehicle ground connection, and particularly in the rubber of the tire when it is manufactured.
1. An element of a vehicle-to-ground connection, comprising:
at least one hybrid resonant acoustic structure acting as a sensor, wherein the resonant acoustic structure includes:
(1) a support; and
(2) a piezoelectric transducer, wherein the transducer includes:
(a) a first conducting electrode supported by the support,
(b) a second conducting electrode,
(c) a film of piezoelectric material separating the first and second conducting electrodes, the film of piezoelectric material being positioned adjacent a first surface of the second conducting electrode, and
(d) an additional layer positioned adjacent a second surface of the second electrode, wherein the additional layer causes a maximum stress to be located within the film of piezoelectric material,
wherein a working frequency of the resonant acoustic structure is in a radiofrequency spectrum from about 300 MHz to about 3000 MHz.
2. The element of the vehicle-to-ground connection according to claim 1 , wherein the working frequency of the resonant acoustic structure in the radiofrequency spectrum is a harmonic with rank N≠1 of a natural frequency (F 0 ) of the resonant acoustic structure.
3. The element of the vehicle-to-ground connection according to claim 1 or 2 , wherein the support is a silicon monocrystal substrate blade.
4. The element of the vehicle-to-ground connection according to claim 1 , wherein the film of piezoelectric material is an aluminum nitride layer.
5. The element of the vehicle-to-ground connection according to claim 1 , wherein the additional layer concentrates an acousto-electric density to cause the maximum stress to be located within the film of piezoelectric material.
6. The element of the vehicle-to-ground connection according to claim 1 , wherein the additional layer is formed of a same material as the support.
7. The element of the vehicle-to-ground connection according to claim 1 ,
wherein the resonant acoustic structure further includes at least one Bragg mirror, the at least one Bragg mirror being positioned on the additional layer, between the support and the transducer, or both,
wherein each of the at least one Bragg mirror includes an alternation of layers of materials with different reflection coefficients, and
wherein a reflection coefficient of each of the at least one Bragg mirror is maximum close to a resonant frequency of the resonant acoustic structure.
8. The element of the vehicle-to-ground connection according to claim 7 , wherein the resonant acoustic structure further includes a coating layer on at least one of the at least one Bragg mirror.
9. The element of the vehicle-to-ground connection according to claim 1 , further comprising an antenna connected to the resonant acoustic structure.
10. The element of the vehicle-to-ground connection according to claim 9 , further comprising at least one other resonant acoustic structure, wherein characteristics of each resonant acoustic structure enable differential measurement of a temperature.
11. The element of the vehicle-to-ground connection according to claim 1 , wherein the resonant acoustic structure is integrated in tire rubber.
12. The element of the vehicle-to-ground connection according to claim 1 , wherein the resonant acoustic structure is used to measure a running parameter of a vehicle.
13. The element of the vehicle-to-ground connection according to claim 12 , wherein the running parameter is a temperature of a tire.