Tire information acquisition device

A tire information acquisition device includes: a sensor unit mountable on a tire inner surface and including a sensor configured to acquire tire information; and a power supply unit mountable on a wheel. The power supply unit includes a power supply mechanism configured to supply power to the sensor unit in a non-contact manner. The sensor unit includes: a power reception mechanism configured to receive power from the power supply unit in a non-contact manner; and an information transmission unit configured to wirelessly transmit acquired tire information.

TECHNICAL FIELD

The present technology relates to a tire information acquisition device, and particularly relates to a tire information acquisition device that can provide the weight of a sensor unit reduced as much as possible and that can also provide the suppressed effect on the weight balance of a tire.

BACKGROUND ART

To acquire tire internal information such as internal pressure or temperature, various sensors are installed in a tire cavity. In such sensors, abundant power supplies are required to continually acquire advanced tire information.

In a case where a battery is used as a power supply, there is a problem of being unable to continuously supply power for a long period of time. In addition, in a case where energy harvesting technology that generates power by using rotation energy of a tire is used as a power supply, a device having relatively large size and weight is required to increase power generation efficiency. Thus, when such a device is installed in a tire, there is a problem of the significant effect on the weight balance of the tire. Further, in a case where to supply power to a sensor, a power supply device is installed in a tire inner surface (for example, see Japan Unexamined Patent Publication Nos. 2005-525265 and 2005-335692), there is a problem of the effect on the weight balance of a tire, and thus deterioration of uniformity.

SUMMARY

The present technology provides a tire information acquisition device that can provide the weight of a sensor unit reduced as much as possible and that can also provide the suppressed effect on the weight balance of a tire.

A tire information acquisition device for achieving the above-described object includes: a sensor unit mountable on a tire inner surface and including a sensor configured to acquire tire information; and a power supply unit mountable on a wheel. The power supply unit includes a power supply mechanism configured to supply power to the sensor unit in a non-contact manner. The sensor unit includes: a power reception mechanism configured to receive power from the power supply unit in a non-contact manner; and an information transmission unit configured to wirelessly transmit acquired tire information.

According to an embodiment of the present technology, the sensor unit mountable on the tire inner surface and including the sensor configured to acquire tire information, and the power supply unit mountable on the wheel are provided. The power supply unit includes the power supply mechanism configured to supply power to the sensor unit in a non-contact manner. The sensor unit includes: the power reception mechanism configured to receive power from the power supply unit in a non-contact manner; and the information transmission unit configured to wirelessly transmit acquired tire information. Thus, the power supply unit is configured separately from the sensor unit. Thus, the weight of the sensor unit can be reduced as much as possible. In addition, since the power supply unit having a large weight is disposed in a wheel without being disposed in the tire inner surface, the effect on the weight balance of a tire can be suppressed.

According to an embodiment of the present technology, the power supply unit preferably includes, as the power supply mechanism, a power generation unit configured to generate electrical energy by rotation or vibration of a tire during traveling, an electrical storage unit configured to store electrical energy generated by the power generation unit, and a power transmission unit configured to transmit electrical energy stored in the electrical storage unit to the outside. Accordingly, the power supply unit can efficiently supply power by using rotation or vibration of a tire during traveling.

According to an embodiment of the present technology, the power generation unit preferably includes an electret configured to generate power by a positional change of an electrode made by rotational movement or reciprocating movement. Accordingly, the power generation unit can efficiently generate power by a power generation system including the electret.

According to an embodiment of the present technology, the sensor unit preferably includes, as the power reception mechanism, an antenna configured to receive power supplied from the power supply unit. Preferably, the antenna is radially disposed in a surface of an innerliner layer constituting the tire inner surface and receives power in a non-contact manner by radio waves, electromagnetic induction, or magnetic resonance. Accordingly, the durability of the antenna constituting the sensor unit can be improved.

According to an embodiment of the present technology, the sensor unit is preferably driven directly by power supplied from the power supply unit. Accordingly, the sensor unit can be driven efficiently.

According to an embodiment of the present technology, the sensor unit is preferably bonded by vulcanization to an innerliner layer constituting the tire inner surface. The sensor unit is subjected to a vulcanization process together with a tire component and thus can be installed efficiently in the tire inner surface.

According to an embodiment of the present technology, the power supply unit preferably includes an information reception unit configured to receive tire information transmitted from the sensor unit, and an information retransmission unit configured to retransmit the received tire information.

Accordingly, when the power supply unit receives the tire information transmitted from the sensor unit and retransmits the tire information, the power supply unit can amplify transmission output, and this leads to a reduction in the required power of the sensor unit.

According to an embodiment of the present technology, the sensor unit is preferably disposed in the tire inner surface in the range from −90° to 90° with respect to a tire circumferential direction from a position of the power supply unit in the tire circumferential direction. Accordingly, the power supply unit and the sensor unit are disposed close to each other, and thus power supply efficiency can be improved.

According to an embodiment of the present technology, the power supply unit is preferably installed in a valve of the wheel. Accordingly, the power supply unit can be installed very easily. In particular, in a case where an air pressure measurement function is added to the power supply unit, the weight of the sensor unit can be reduced, and thus this leads to further weight reduction.

DETAILED DESCRIPTION

Configurations of embodiments of the present technology will be described in detail below with reference to the accompanying drawings.FIGS.1and2illustrate a pneumatic tire in which a tire information acquisition device according to an embodiment of the present technology is mounted.FIG.3illustrates a configuration of a tire information acquisition device according to an embodiment of the present technology.

As illustrated inFIGS.1and2, a tire cavity is formed between a pneumatic tire1and a wheel3, and a tire information acquisition device10is mounted in the tire cavity. The tire information acquisition device10includes a sensor unit20mountable on a tire inner surface2and a power supply unit30mountable on the wheel3. The tire inner surface2includes an innerliner layer that is a tire component. A cylindrical valve4configured to inject pressure from the outside to the inside of the tire is provided in the wheel3.

InFIG.1, the sensor unit20is provided at a position corresponding to the center of a tread portion of the pneumatic tire1in the tire lateral direction. As illustrated inFIG.3, the sensor unit20includes a sensor21, a power reception mechanism22, and an information transmission unit23. The sensor21is a sensor configured to measure tire information such as an internal temperature or internal pressure of the pneumatic tire1, and the amount of wear of the tread portion. The power reception mechanism22receives power from the power supply unit30in a non-contact manner. An example of a non-contact power reception system includes radio waves, electromagnetic induction, or magnetic resonance. The information transmission unit23wirelessly transmits various kinds of tire information acquired by the sensor21to the outside of the tire or to the power supply unit30.

In addition, the sensor unit20includes an antenna24as the power reception mechanism22, and the antenna24receives power supplied from the power supply unit30. The antenna24is radially disposed in the tire inner surface2(a surface of the innerliner layer). Such an antenna24preferably receives power in a non-contact manner by radio waves, electromagnetic induction, or magnetic resonance.

The power supply unit30includes a power supply mechanism31configured to supply power to the sensor unit20in a non-contact manner. An example of a non-contact power supply system includes radio waves, electromagnetic induction, or magnetic resonance. The power supply unit30is preferably disposed, in particular, in a well that is a flat portion of a rim of the wheel3.

In addition, the power supply unit30includes, as the power supply mechanism31, a power generation unit32configured to generate electrical energy by rotation or vibration of the pneumatic tire1during traveling, an electrical storage unit33configured to store electrical energy generated by the power generation unit32, and a power transmission unit34configured to transmit electrical energy stored in the electrical storage unit33to the outside. In particular, the power generation unit32preferably includes a structure that generates electrical energy by rotation of the pneumatic tire1.

The tire information acquisition device described above includes: the sensor unit20mountable on the tire inner surface2and including the sensor21configured to acquire tire information; and the power supply unit30mountable on the wheel3. The power supply unit30includes the power supply mechanism31configured to supply power to the sensor unit20in a non-contact manner, and the sensor unit20includes: the power reception mechanism22configured to receive power from the power supply unit30in a non-contact manner; and the information transmission unit23configured to wirelessly transmit acquired tire information. Thus, the power supply unit30is configured separately from the sensor unit20. Thus, the weight of the sensor unit20can be reduced as much as possible. In addition, since the power supply unit30having a large weight is disposed in the wheel3without being disposed in the tire inner surface2, the effect on the weight balance of the pneumatic tire1can be suppressed.

FIG.4illustrates a modified example of a configuration of a tire information acquisition device according to an embodiment of the present technology. InFIG.4, a power supply unit30includes an information reception unit35configured to receive tire information transmitted from a sensor unit20, and an information retransmission unit36configured to retransmit the received tire information. That is, a tire information acquisition device10illustrated inFIG.4includes a configuration in which the information reception unit35and the information retransmission unit36are added to the tire information acquisition device10illustrated inFIG.3. The power supply unit30is configured in this manner. Thus, when the power supply unit30receives tire information transmitted from the sensor unit20and retransmits the tire information, the power supply unit30can amplify transmission output, and this leads to a reduction in the required power of the sensor unit20.

In the tire information acquisition device described above, the sensor unit20may be driven directly by power supplied from the power supply unit30. That is, the sensor unit20is driven by an RF tag system. The sensor unit20is directly driven by power supplied from the power supply unit30in this manner, and thus the sensor unit20can be driven efficiently.

In addition, the sensor unit20is preferably bonded by vulcanization to the innerliner layer constituting the tire inner surface2. Since the sensor unit20receives power from the power supply unit30, the sensor unit20itself has no power supply device. Thus, the sensor unit20can be subjected to a vulcanization process together with a tire component. Consequently, the sensor unit20can be installed efficiently in the tire inner surface2.

In the tire information acquisition device described above, a power generation unit32constituting the power supply unit30preferably includes an electret configured to generate power by a positional change of an electrode, made by rotational movement or reciprocating movement, and the power generation unit32further preferably generates power by using a positional change of the electrode made by rotational movement. The power generation unit32includes the electret in this manner, and thus the power generation unit32can efficiently generate power.

In addition, the power supply unit30is preferably fixed to a valve4of a wheel3. The power supply unit30is installed in this manner, and thus the power supply unit30can be installed very easily. In particular, in a case where an air pressure measurement function is added to the power supply unit30, the weight of the sensor unit20can be reduced, and thus this leads to further weight reduction.

InFIG.2, a position of the sensor unit20in the tire circumferential direction in the tire inner surface2is defined as a position L1, and a position of the power supply unit30in the tire circumferential direction in the wheel3is defined as a position L2. In addition, an angle formed between the position L1of the sensor unit20and the position L2of the power supply unit30is defined as an angle θ. In this case, the angle θ is preferably in the range of from −90° to 90°, and more preferably in the range from −45° to 45°. The angle θ is appropriately set in this manner, and thus the power supply unit30and the sensor unit20are disposed close to each other. Thus, power supply efficiency can be improved. Note that any of the positions L1and L2is based on the center position of the sensor unit20or the power supply unit30in the tire circumferential direction.

In the above-described embodiment ofFIG.2, the example in which the antenna24is disposed in a region from the tread portion to a sidewall portion of the pneumatic tire1and is formed in a shape repeatedly bent in the sidewall portion is described; however, the shape of the antenna24is not limited to this shape. The antenna24may be formed in a shape including a radially elongated portion. In a case where the antenna24includes a portion elongated in the tire circumferential direction, the antenna24may be damaged due to distortion of the pneumatic tire1. Thus, the antenna24includes the radially elongated portion, and thus durability can be enhanced.

In addition, in the embodiments ofFIGS.3and4, the example in which the power supply mechanism31includes the power generation unit32and the electrical storage unit33is described; however, the power supply mechanism31can include a battery instead of the power generation unit32and the electrical storage unit33. In particular, in a case where the power supply mechanism31includes the power generation unit32and the electrical storage unit33, the power supply mechanism31can efficiently supply power by using rotation and vibration of the pneumatic tire1during traveling.