TIRE COMPRISING AN ELECTRONIC CIRCUIT FOR MEASURING TREAD DEPTH, AN ASSEMBLY AND A VEHICLE

Abstract

A tire comprising an electronic circuit for measuring tread depth of a tread of the tire, wherein a groove is associated with the tread, the electronic circuit comprising a first conductive portion embedded in the tire and comprising a first conductive wire portion which extends in the tread and terminates open at an outer peripheral portion of the tread, a second conductive portion embedded in the tire and comprising a second conductive wire portion which extends in the tire and terminates open at an outer peripheral portion of the groove, and an electronic connection portion, wherein the first and second conductive portions are electrically connected via the electronic connection portion and extend from the electronic connection portion to the outer peripheral portions of the tread and groove, respectively.

Claims

1. A tire comprising an electronic circuit for measuring tread depth of a tread of the tire, wherein a groove is associated with the tread, the electronic circuit comprising: a first conductive portion embedded in the tire and comprising a first conductive wire portion which extends in the tread and terminates open at an outer peripheral portion of the tread, a second conductive portion embedded in the tire and comprising a second conductive wire portion which extends in the tire and terminates open at an outer peripheral portion of the groove, and an electronic connection portion, wherein the first and second conductive portions are electrically connected via the electronic connection portion and extend from the electronic connection portion to the outer peripheral portions of the tread and groove, respectively, wherein the first conductive portion has a first electrical length, as measured from the electronic connection portion to the outer peripheral portion of the tread, and wherein the second conductive portion has a second electrical length, as measured from the electronic connection portion to the outer peripheral portion of the groove, and wherein the first electrical length and the second electrical length only differ by a difference in height between the outer peripheral portion of the tread and the outer peripheral portion of the groove.

2. The tire of claim 1, wherein the electronic circuit further comprises a signal obtaining portion for obtaining a waveform signal, wherein the signal obtaining portion is electrically connected to the electronic connection portion such that an obtained waveform signal is transmitted to each one of the first and the second conductive portions.

3. The tire of claim 2, wherein the first conductive portion comprises a first transmitting portion for transmitting a reflected waveform signal which has been reflected in the first conductive wire portion at the outer peripheral portion of the tread.

4. The tire of claim 3, wherein the first conductive portion comprises a first directional coupler device, wherein: the first conductive portion is coupled to the electronic connection portion via an input port of the first directional coupler device, the first transmitting portion is coupled to an isolated port of the first directional coupler device, and the first conductive wire portion is coupled to an output port of the first directional coupler device.

5. The tire of claim 2, wherein the second conductive portion comprises a second transmitting portion for transmitting a reflected waveform signal which has been reflected in the second conductive wire portion at the outer peripheral portion of the groove.

6. The tire of claim 5, wherein: the second conductive portion comprises a second directional coupler device, the second conductive portion is coupled to the electronic connection portion via an input port of the second directional coupler device, the second transmitting portion is coupled to an isolated port of the second directional coupler device, and the second conductive wire portion is coupled to an output port of the second directional coupler device.

7. The tire of claim 2, wherein at least one of the signal obtaining portion, the first transmitting portion, and the second transmitting portion comprises an antenna.

8. The tire of claim 7, wherein at least two of the signal obtaining portion, the first transmitting portion, and the second transmitting portion comprises a respective antenna, wherein the respective antennas are configured such that they have different polarization.

9. The tire of claim 8, wherein at least one of the respective antennas with different polarization is a linearly polarized antenna, such as a vertically polarized antenna or a horizontally polarized antenna.

10. The tire of claim 8, wherein one of the respective antennas with different polarization is a circularly polarized antenna.

11. The tire of claim 1, wherein the electronic circuit is a passive circuit.

12. An assembly for measuring tread depth of a tread of a tire, the assembly comprising the tire of claim 1 and a receiving device which is configured to receive waveform signals which have been reflected in each one of the first and the second conductive wire portions at the outer peripheral portions of the tread and the groove, respectively.

13. The assembly of claim 12, wherein the assembly is configured to measure the tread depth by comparing the received waveform signals.

14. The assembly of claim 13, wherein comparing the received waveform signals comprises determining a physical difference in height between the tread and the groove using phase shift and/or time domain reflectometry.

15. A vehicle comprising the tire of claim 1.

16. A vehicle comprising the assembly of claim 12.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0040] With reference to the appended drawings, below follows a more detailed description of embodiments of the invention cited as examples.

[0041] In the drawings:

[0042] FIG. 1 is a schematic sectional view of a tire according to an embodiment of the present invention;

[0043] FIGS. 2a-b are schematic views of directional couplers of an electronic circuit according to an embodiment of the present invention; and

[0044] FIG. 3 is a perspective view of a vehicle in the form of a bus according to an embodiment of the present invention.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS OF THE INVENTION

[0045] FIG. 1 depicts a tire 1 according to an example embodiment of the first aspect of the invention and also an assembly 1′ according to an example embodiment of the second aspect of the invention. The schematic view of the tire 1 is a sectional view of a plane which is defined by a rotational axis A of the tire 1.

[0046] The tire 1 comprises an electronic circuit 10 for measuring tread depth h of a tread t of the tire 1, wherein a groove g is associated with the tread t. In this example, the groove g is provided adjacent to the tread t. The electronic circuit 10 comprises: [0047] a first conductive portion 20 embedded in the tire 1 and comprising a first conductive wire portion 21 which extends in the tread t and terminates open at an outer peripheral portion t.sub.1 of the tread t. The first conductive wire portion 21 is configured such that it will wear down with the tread t as the treads t wears down during use of the tire 1. For example, the first conductive wire portion 21 should have a diameter which is small enough so that it will wear down with the tread t during use of the tire 1. The first conductive wire portion 21 may for example have a diameter of about 1 millimetre or less.

[0048] The electronic circuit 10 further comprises: [0049] a second conductive portion 30 embedded in the tire and comprising a second conductive wire portion 31 which extends in the tire and terminates open at an outer peripheral portion g.sub.1 of the groove g, [0050] an electronic connection portion 40, wherein the first and second conductive portions 0, 30 are electrically connected via the electronic connection portion 40 and extend from the electronic connection portion 40 to the outer peripheral portions t.sub.1, g.sub.1 of the tread and groove t, g, respectively. The electronic connection portion 40 may for example be a radio frequency filtering power divider.

[0051] Furthermore, the first conductive portion 20 has a first electrical length, as measured from the electronic connection portion 40 to the outer peripheral portion t.sub.1 of the tread t, and the second conductive portion 30 has a second electrical length, as measured from the electronic connection portion 40 to the outer peripheral portion g1 of the groove g. The first electrical length and the second electrical length only differ by a difference in height h between the outer peripheral portion t.sub.1 of the tread t and the outer peripheral portion g.sub.1 of the groove g. Thereby, the difference in height h between the tread t and the groove g can be determined by comparing waveform signals which have been reflected at the respective outer peripheral portions t.sub.1, g.sub.1 of the tread t and the groove g, respectively.

[0052] As shown in FIG. 1, the electronic circuit 10 may further comprise a signal obtaining portion 50 for obtaining a waveform signal, wherein the signal obtaining portion 50 is electrically connected to the electronic connection portion 40 such that an obtained waveform signal is transmitted to each one of the first and second conductive portions 20, 30.

[0053] Further in this embodiment, the first conductive portion 20 comprises a first transmitting portion 22 for transmitting a reflected waveform signal which has been reflected in the first conductive wire portion 21 at the outer peripheral portion of the tread t.sub.1. As shown, the first conductive portion 20 may also comprise a first directional coupler device 23, which is shown in further detail in FIG. 2b. The first conductive portion 20 is coupled to the electronic connection portion 40 via an input port 231 of the first directional coupler device 23, the first transmitting portion 22 is coupled to an isolated port 232 of the first directional coupler device 23 and the first conductive wire portion 21 is coupled to an output port 233 of the first directional coupler device 23.

[0054] As further shown in FIG. 1, the second conductive portion 30 may comprise a second transmitting portion 32 for transmitting a reflected waveform signal which has been reflected in the second conductive wire portion 31 at the outer peripheral portion of the groove g.sub.1.

[0055] Similar to the above, and detailed in FIG. 2a, the second conductive portion 30 comprises a second directional coupler device 33, wherein the second conductive portion 30 is coupled to the electronic connection portion 40 via an input port 331 of the second directional coupler device 33, the second transmitting portion 32 is coupled to an isolated port 332 of the second directional coupler device 33 and the second conductive wire portion 31 is coupled to an output port 333 of the second directional coupler device 33.

[0056] In each one of FIG. 1 and FIGS. 2a-2b, arrows are shown which represent the waveform signal and its direction in the different conductive portions.

[0057] In the shown embodiment, each one of the signal obtaining portion 50, the first transmitting portion 22 and the second transmitting portion 32 comprises an antenna 50, 22, 32. It shall however be noted that it is not a requisite to have three antennas as in the shown embodiment, also other configurations are possible. For example, instead of antennas, wired connections for obtaining and transmitting waveform signals are feasible.

[0058] As such, the signal obtaining portion 50, the first transmitting portion 22 and the second transmitting portion 32 comprises a respective antenna, and the respective antennas are configured such that they have different polarization. Thereby it will be easier to differentiate between the different waveform signals which are obtained and transmitted to/from the electronic circuit 10. In the shown embodiment, the first transmitting portion 22 comprises a vertically polarized antenna, the second transmitting portion 32 comprises a horizontally polarized antenna and the signal obtaining portion 50 comprises a circularly polarized antenna.

[0059] The electronic circuit 10 as shown is a passive circuit. However, it may also be an active circuit comprising e.g. a battery for powering the electronic circuit. An active electronic circuit may for example comprise a signal generation device for generating a waveform signal which is obtained by a signal obtaining device of the electronic circuit.

[0060] FIG. 1 further depicts an assembly 1′ for measuring tread depth h of a tread t of a tire 1 according to the second aspect of the invention. The assembly 1′ comprises the tire 1 and a receiving device 60, indicated by a box with dashed lines, which is configured to receive waveform signals which have been reflected in each one of the first and second conductive wire portions 21, 31 at the outer peripheral portions t.sub.1, g.sub.1 of the tread and groove t, g, respectively. Accordingly, the receiving device 60 is configured to receive waveform signals from the antennas of the first and second transmitting portions 22 and 32. According to an example embodiment, the receiving device 60 may be in the form of an electronic control unit which comprises means for receiving the wireless waveform signals from the antennas. Additionally, the receiving device 60 may also be configured to transmit a wireless waveform signal to the signal obtaining portion 50, and/or it may be connected to the signal obtaining portion via a wired connection (not shown). The wired connection may be configured to transmit a waveform signal. Further, the wired connection may also be configured to power the electronic circuit 10, thereby resulting in an active circuit.

[0061] The receiving device 60 may be integrated in the tire 1, in a wheel on which the tire 1 is mounted or in a vehicle, such as the vehicle 100 shown in FIG. 3. For example, the receiving device 60 may be provided in a wheel rim (not shown). Thereby, the waveform signals may not need to travel a too long distance between the receiving device 60 and the electronic circuit 10, implying increased reliability.

[0062] The assembly 1′ is configured to measure the tread depth h by comparing the received waveform signals. For example, comparing the received waveform signals comprises determining a physical difference in height h between the tread t and the groove g using phase shift and/or time domain reflectometry.

[0063] For example, the tread depth h may be determined by using phase shift distance measurement for determining physical distance, and to compare a difference in physical distance between the tread t and the groove g. For example, a distance between a source of a waveform signal and a reflection point, i.e. in this case the open ends of the wires portions 21, 31, can be calculated by:

[00001]$L=\frac{\Delta \Phi }{180^{\circ }}\times \lambda$

where L is the physical length, λ is the wavelength, ΔΦ is the difference in phase between the transmitted and the reflected waveform signal and can be found by:

[00002]$\Delta \Phi =\frac{\Delta t}{T}\times 180^{\circ }$

where T is the period of the waveform signal and Δt=t.sub.peakB−t.sub.peakA, where t.sub.peakA is the peak of the transmitted wave and t.sub.peakB is the peak of the received wave.

[0064] Each wire portion 21, 31 should be configured such that it is able to reflect back a significant portion of the energy of the transmitted waveform signal where it terminates open at the respective outer peripheral portions. This is possible as long as the length of each conductive portion 20, 30 is not a harmonic of the source waveform signal. In such a case the waveform signal would instead radiate as an antenna where the wire portion 21, 31 terminates open.

[0065] With respect to FIG. 3, an embodiment of a vehicle 100 according to the third aspect of the invention is shown. The vehicle 100 is here a bus with a tire 1 and an assembly 1′ according to the invention. Alternatively, the vehicle may be a truck or construction equipment, such as a wheel loader. Still further, the vehicle may be a passenger car, a motorcycle, or any other vehicle using a tire with a tread and groove.

[0066] It is to be understood that the present invention is not limited to the embodiments described above and illustrated in the drawings; rather, the skilled person will recognize that many changes and modifications may be made within the scope of the appended claims.