JP2016029361A - Tire air pressure monitoring device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a tire air pressure monitoring device whose tire-side device has a simple configuration.SOLUTION: A tire air pressure monitoring device 1 for monitoring an air pressure of a tire mounted in a vehicle includes: at least one power generation section 20 for generating power by using a vibration associated with rotation motion of the tire; and a calculation section 42 for calculating the air pressure of the tire. The power generation section 20 generates at least two electric signals each of which corresponds to different vibration states of the tire. The calculation section 42 calculates the air pressure of the tire on the basis of at least the two electric signals.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a tire air pressure monitoring device, and more particularly, to a tire air pressure monitoring device including a power generation unit that generates electric power using vibration accompanying rotation of a tire.

  In recent years, a tire pressure monitoring system called TPMS (Tire Pressure Monitoring System) for monitoring the air pressure of tires mounted on vehicles and tire pressure monitoring devices corresponding to the tire pressure monitoring system have become widespread. The tire pressure monitoring device is generally composed of a sensor terminal that is a tire-side device and a control unit that is called an ECU (Engine Control Unit) that is a vehicle-side device. The sensor terminal usually has a sensor element such as a pressure sensor for detecting the air pressure of the tire, a transmission circuit (transmitter) for wirelessly transmitting information detected using the sensor element, and various types of sensors on the sensor terminal side. It has a control circuit for performing control, calculation, and the like, and a storage element for stably supplying power to each circuit on the sensor terminal side.

  Normally, a battery is used as a power storage element on the sensor terminal side, but the battery life is limited, and it is necessary to replace the battery in accordance with the battery life. Therefore, in recent years, in order to eliminate the troublesome battery replacement on the sensor terminal side, the sensor terminal has a power generation unit that generates power using vibration accompanying rotation of the tire, and the power obtained by the power generation of the power generation unit is Tire pressure monitoring devices that can be supplied to each circuit on the terminal side have been developed.

  Patent document 1 etc. are disclosed regarding the conventional tire pressure monitoring apparatus provided with such a power generation part. FIG. 11 is an explanatory diagram showing a configuration of a conventional tire pressure monitoring device, and shows a configuration of a tire pressure monitoring device 301 according to Patent Document 1. As shown in FIG.

  As shown in FIG. 11, the tire pressure monitoring device 301 according to Patent Document 1 includes a sensor terminal 361 and a vehicle-side controller 371 (control unit). The sensor terminal 361 is disposed at a predetermined position on the tire side (such as the inner wall of the tire) and rotates with the rotation of the tire. The vehicle-side controller 371 is disposed at a predetermined position on the vehicle side and monitors tire air pressure based on information from the sensor terminal 361.

  The sensor terminal 361 includes a vibration detection unit 302, various sensor elements such as an air pressure sensor 362 and a temperature sensor 363, a control circuit 364, and a transmission circuit 366 (transmission unit). The vibration detection unit 302 includes a vibration power generator 304 (power generation unit), a counter circuit 307, a DC-AC conversion circuit 309, and a storage element 310. The air pressure sensor 362 detects the tire air pressure. The transmission circuit 366 wirelessly transmits information such as tire air pressure to the vehicle-side controller 371. The control circuit 364 performs various controls and calculations on the sensor terminal 361 side.

  The vibration power generator 304 generates power using vibration energy associated with the rotation of the tire. The counter circuit 307 counts the frequency of the output voltage in the power generation by the vibration power generator 304. The DC-AC conversion circuit 309 converts an AC current generated by the power generation of the vibration power generator 304 into a DC signal that can be stored. The power storage element 310 stores the power obtained by the power generation of the vibration power generator 304 and supplies the stored power to each circuit of the sensor terminal 361. Then, by supplying the power obtained by the power generation of the vibration power generator 304 to each circuit of the sensor terminal 361, battery replacement on the sensor terminal 361 side is unnecessary.

  The vehicle-side controller 371 includes a not-shown receiving circuit (receiving unit) for receiving a radio signal transmitted from the transmitting circuit 366, a not-shown control circuit for performing various controls and calculations on the vehicle side, and the like. doing. The vehicle-side controller 371 operates by being supplied with electric power from a vehicle-side power supply device (not shown), and monitors tire air pressure based on information wirelessly transmitted from the sensor terminal 361.

JP 2011-221002 A

  In the tire pressure monitoring device, it is desirable that the configuration of the tire-side device is simple from the viewpoint of size reduction, weight reduction, cost reduction, and the like. However, in the tire pressure monitoring device 301 according to Patent Document 1, a sensor terminal 361 that is a tire-side device includes a vibration generator 304, a storage element 310, various sensor elements such as a pneumatic sensor 362, a control circuit 364, Therefore, the sensor terminal 361 has a complicated configuration because it has many elements and circuits such as the transmission circuit 366.

  The present invention has been made in view of the actual situation of the prior art, and an object of the present invention is to provide a tire pressure monitoring device with a simple configuration of a tire-side device.

  In order to solve this problem, a tire air pressure monitoring device according to claim 1 is a tire air pressure monitoring device that monitors the air pressure of a tire mounted on a vehicle, and uses vibration associated with the rotation operation of the tire. At least one power generation unit for generating power and a calculation unit for calculating the tire air pressure, wherein the power generation unit generates at least two electrical signals respectively corresponding to different vibration states of the tire, The unit calculates tire air pressure based on the at least two electrical signals.

  In the tire pressure monitoring apparatus with this configuration, the power generation unit generates at least two electrical signals corresponding to the different vibration states of the tire, and the calculation unit calculates the tire pressure based on the at least two electrical signals. ing. Therefore, the power generation unit can be used as a sensor element for detecting the tire air pressure. Then, by using the power generation unit as a sensor element, the number of elements used in the tire-side device can be reduced. As a result, the configuration of the tire side device can be simplified.

  The tire pressure monitoring device according to claim 2, wherein the power generation unit is configured to detect ground vibration that occurs when a predetermined position of the tire contacts the ground with rotation of the tire, and rotation operation of the tire. Accordingly, the electric signal is generated corresponding to the separation vibration generated when the predetermined position of the tire is separated from the ground, and the calculation unit is configured to generate the electric signal corresponding to the ground vibration. The tire air pressure is calculated based on an interval from the generation timing of the electrical signal corresponding to the separation vibration.

  When a tire rotates in a vehicle, an impact occurs when the predetermined position of the tire touches the ground with the rotation operation of the tire, or an impact when the predetermined position of the tire moves away from the ground with the rotation operation of the tire. In response to this, a large vibration such as a ground vibration or a separation vibration occurs. On the other hand, in the tire pressure monitoring device with this configuration, the power generation unit generates power using vibrations associated with the rotation operation of the tire, and thus easily generates electrical signals in response to such ground vibrations and separation vibrations. Can be made. In addition, since the interval between the generation timing of the ground vibration and the generation timing of the separation vibration changes corresponding to the tire air pressure, the calculation unit generates the electrical signal corresponding to the ground vibration and the electrical timing corresponding to the separation vibration. By calculating the tire air pressure based on the interval from the signal generation timing, the tire air pressure can be easily calculated.

  The tire pressure monitoring device according to claim 3, wherein the electrical signal generated by the power generation unit is wirelessly transmitted, and the electrical signal wirelessly transmitted by the transmission unit is received and transmitted to the arithmetic unit. A receiving unit; and the transmitting unit is disposed at a predetermined position on the tire side together with the power generation unit, and the receiving unit is disposed at a predetermined position on the vehicle side together with the calculating unit. Features.

  The tire pressure monitoring apparatus having this configuration further includes a transmission unit that wirelessly transmits an electrical signal generated by the power generation unit, and a reception unit that receives the electrical signal wirelessly transmitted by the transmission unit and transmits the electrical signal to the calculation unit. . For this reason, the power generation unit is arranged on the tire side together with the transmission unit, and the calculation unit is arranged on the vehicle side together with the reception unit. Thus, an electric signal can be transmitted. And by arrange | positioning a calculating part with the receiving part on the vehicle side, the control circuit for controlling a calculating part, the electrical storage element for operating a calculating part stably, etc. can also be arrange | positioned on the vehicle side. As a result, the configuration of the tire side device can be further simplified.

  The tire pressure monitoring device according to claim 4, wherein the power generation unit is disposed so as to be close to a ground contact surface of the tire, and corresponds to the ground vibration and the separation vibration along the circumferential direction of the tire. Power generation is performed using vibration of the ground contact surface of the tire.

  When a predetermined position of a tire ground contact surface contacts the ground in a vehicle, the ground contact vibration of the tire along the circumferential direction of the tire occurs as the tire ground contact surface is pushed from the ground. Occur. Further, when the predetermined position of the tire ground contact surface is separated from the ground, the tire ground contact surface vibrates along the circumferential direction of the tire as the tire ground contact surface is released from the pressed state by the ground. Separation vibration occurs. In the tire pressure monitoring apparatus having this configuration, the power generation unit is disposed at a position close to the tire ground contact surface, and generates power using vibrations of the tire ground contact surface along the tire circumferential direction. Therefore, it is possible to efficiently generate power corresponding to ground contact vibration and separation vibration, and to stably generate an electric signal corresponding to ground vibration and separation vibration.

  The tire pressure monitoring device according to claim 5, wherein the power generation unit is disposed so as to be close to a ground contact surface of the tire, and corresponds to the ground vibration and the separation vibration along the radial direction of the tire. Power generation is performed using vibration of the ground contact surface of the tire.

  When a predetermined position of the tire ground contact surface contacts the ground in the vehicle, the ground contact vibration of the tire along the radial direction of the tire occurs as the tire ground contact surface is pushed from the ground. Occur. Further, when the predetermined position of the tire ground contact surface is separated from the ground, the tire ground contact surface vibrates along the tire radial direction as the tire ground contact surface is released from the pressed state by the ground. Separation vibration occurs. In the tire pressure monitoring apparatus having this configuration, the power generation unit is disposed at a position close to the tire ground contact surface, and generates power using vibration of the tire ground contact surface along the tire radial direction. Therefore, it is possible to efficiently generate power corresponding to ground contact vibration and separation vibration, and to stably generate an electric signal corresponding to ground vibration and separation vibration.

  The tire pressure monitoring device according to claim 6, wherein the power generation unit is disposed on a side surface of the tire or an inner wall of the tire facing the side surface of the tire, and corresponds to the ground vibration and the separation vibration, Electricity is generated by utilizing vibration of the side surface of the tire along the width direction of the tire.

  When a predetermined position of the tire ground contact surface contacts the ground in the vehicle, a ground vibration occurs in which the tire side surface vibrates along the tire width direction as the tire ground contact surface is pushed from the ground. To do. Further, when the predetermined position of the tire ground contact surface is separated from the ground, the tire side surface vibrates along the tire width direction as the tire ground contact surface is released from the pressed state by the ground. Separation vibration occurs. In the tire pressure monitoring device having this configuration, the power generation unit is disposed on the side surface of the tire or the inner wall of the tire facing the side surface of the tire, and generates power using vibrations on the side surface of the tire along the tire width direction. Therefore, it is possible to efficiently generate power corresponding to such ground vibration and separation vibration, and to stably generate an electric signal corresponding to ground vibration and separation vibration. In addition, since the power generation unit is disposed on the tire side surface or the tire inner wall facing the tire side surface together with the transmission unit, the transmission unit is located away from snow or rainwater on the ground even when it is snowing or raining. Can be arranged. As a result, an electric signal can be stably transmitted from the power generation unit to the calculation unit even during snowfall or rain.

  The tire pressure monitoring device according to claim 7, wherein the power generation unit includes a housing attached to the tire side and a movable unit housed inside the housing so as to be movable with respect to the housing. The power generation is performed by utilizing a collision between the casing and the movable part accompanying the movement of the movable part.

  In the tire pressure monitoring device having this configuration, the power generation unit generates power using a collision between the casing and the movable unit accompanying the movement of the movable unit, thereby generating an electrical signal generated by the power generation unit with a pulse having a short generation time. The electrical signal generation timing can be easily specified. As a result, the detection accuracy of the tire air pressure can be increased.

  The tire pressure monitoring device according to claim 8 is characterized in that the casing is attached to the tire via an elastic member.

  In the tire pressure monitoring apparatus having this configuration, the elastic member can absorb the vibration of the tire having a small amplitude, which is a noise component, and can selectively transmit the vibration of the tire having a large amplitude to the housing. As a result, it is possible to reduce the influence of tire vibration, which becomes a noise component, and to further increase the accuracy of detection of tire air pressure.

  ADVANTAGE OF THE INVENTION According to this invention, the tire pressure monitoring apparatus with the simple structure of the apparatus by the side of a tire can be provided.

It is explanatory drawing which shows the structure of the tire pressure monitoring apparatus which concerns on 1st Embodiment of this invention. It is explanatory drawing which shows arrangement | positioning of the electric power generation unit and control part which concern on 1st Embodiment of this invention. It is explanatory drawing which shows the structure of the electric power generation part which concerns on 1st Embodiment of this invention. It is explanatory drawing regarding rotation operation | movement of the tire which concerns on 1st Embodiment of this invention. It is explanatory drawing which shows the electrical signal which concerns on 1st Embodiment of this invention. It is explanatory drawing which shows the structure of the tire pressure monitoring apparatus which concerns on 2nd Embodiment of this invention. It is explanatory drawing regarding rotation operation | movement of the tire which concerns on 2nd Embodiment of this invention. It is explanatory drawing which shows the structure of the tire pressure monitoring apparatus which concerns on 3rd Embodiment of this invention. It is explanatory drawing regarding rotation operation | movement of the tire which concerns on 3rd Embodiment of this invention. It is explanatory drawing which shows the structure of the electric power generation part which concerns on the modification of this invention. It is explanatory drawing which shows the structure of the conventional tire pressure monitoring apparatus.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the directions in each figure will be described with X1 on the left, X2 on the right, Y1 on the front, Y2 on the back, Z1 on the top, and Z2 on the bottom.

[First Embodiment]
A tire pressure monitoring apparatus according to a first embodiment of the present invention will be described with reference to FIGS. 1 to 5. FIG. 1 is an explanatory diagram showing the configuration of the tire pressure monitoring device according to the first embodiment of the present invention. FIG. 1A shows the overall configuration of the tire pressure monitoring device 1, and FIG. 1B shows the configuration of the power generation unit 10. FIG. 2 is an explanatory diagram showing the arrangement of the power generation unit and the control unit according to the first embodiment of the present invention. FIG. 2A shows the arrangement of the power generation unit 10 and the control unit 40 in the vehicle 50 when viewed from the right, and FIG. 2B shows the configuration of the power generation unit 10 in the tire 60 when viewed from the front. The arrangement is shown.

  FIG. 3 is an explanatory diagram showing the structure of the power generation unit according to the first embodiment of the present invention. 3A schematically illustrates a cross-sectional structure when viewed from the right, and FIG. 3B schematically illustrates a method for attaching the power generation unit 20 to the tire 60 when viewed from the right. Yes. In FIG. 3, Ps1 is a detection position in the present embodiment, and L1 is an imaginary line that passes through the detection position Ps1 and extends along the circumferential direction of the tire 60 at the detection position Ps1. A solid line arrow indicates the moving direction of the movable portion 22. Hereinafter, the circumferential direction of the tire 60 at the detection position Ps <b> 1 is abbreviated as the circumferential direction of the tire 60, and the description proceeds.

  FIG. 4 is an explanatory diagram relating to the rotation operation of the tire according to the first embodiment of the present invention. FIG. 4A shows a state of the tire 60 when the detection position Ps1 contacts the ground 70 when viewed from the right, and FIG. 4B shows the detection position Ps1 when viewed from the right. The state of the tire 60 when separated from the ground 70 is shown. In FIG. 4, Po is the rotation axis of the tire 60. The dotted arrow indicates the rotation direction of the tire 60, and the solid arrow indicates the direction of the force acting on the ground contact surface 61 of the tire 60 in the vicinity of the detection position Ps1. The tire 60 is assumed to rotate counterclockwise about the rotation axis Po as viewed from the right.

  FIG. 5 is an explanatory diagram showing an electrical signal according to the first embodiment of the present invention. 5A shows the first detection signal Sa1 and the second detection signal Sa2 that are electrical signals generated by the power generation unit 20, and FIG. 5B shows the electrical signal output from the constant voltage circuit 31. A certain first output signal Sb1 and a second output signal Sb2 are shown, and FIG. 5C shows a first radio signal RF1 and a second radio signal RF2 which are electric signals (radio signals) wirelessly transmitted from the transmission circuit 32. It shows. In each diagram of FIG. 5, the horizontal axis represents time, and the vertical axis represents voltage.

  First, the configuration of the tire pressure monitoring apparatus according to the first embodiment of the present invention will be described with reference to FIGS. 1 to 3. The tire pressure monitoring device 1 according to the first embodiment of the present invention is a device corresponding to a tire pressure monitoring system called TPMS (Tire Pressure Monitoring System) that monitors a tire state such as a pressure of a tire mounted on a vehicle. . As shown in FIG. 1, the tire air pressure monitoring device 1 includes a power generation unit 10 and a control unit 40. As shown in FIG. 2, the power generation units 10 are respectively disposed on tires 60 attached to the vehicle 50. As shown in FIG. 2, the control unit 40 is disposed at a predetermined position near the front panel of the vehicle 50.

  The power generation unit 10 is a device on the tire 60 side having a function as a sensor terminal in a conventional tire pressure monitoring device. As illustrated in FIG. 1, the power generation unit 10 includes a power generation unit 20 and a transmission unit 30.

  The power generation unit 20 is a magnetostrictive vibration power generation apparatus. As illustrated in FIG. 3, the power generation unit 20 includes a housing 21, a movable unit 22, and an elastic member 23. The casing 21 is made of a material such as metal, and a space capable of accommodating the movable portion 22 is formed therein. The movable part 22 has a core member 22a composed of a magnet and a magnetostrictive element, and a coil part 22b wound around the core member 22a. The movable portion 22 is accommodated in a space inside the casing 21 so as to be capable of reciprocating with respect to the casing 21.

  Since the principle of power generation in the magnetostrictive vibration power generation apparatus is well known, detailed description is omitted, but the power generation unit 20 reciprocates the movable unit 22 inside the casing 21 by using vibration associated with the rotation operation of the tire 60. Electric power is generated by utilizing the change in the magnetic field caused by the collision between the inner wall 21b of the casing 21 and the movable part 22 as the movable part 22 moves. And the electric power generation part 20 is generating the electric signal corresponding to the vibration of the tire 60 by own electric power generation.

  The elastic member 23 is a plate-like member made of a material such as rubber. As shown in FIG. 3, one plate surface of the elastic member 23 is fixed to the outer wall of the casing 21 by a method such as adhesion, and the other plate surface of the elastic member 23 is the inner wall of the tire 60 by a method such as adhesion. 62 is fixed at a predetermined position. The elastic member 23 absorbs the vibration of the tire 60 having a small amplitude that becomes a noise component. In this way, the power generation unit 20 is disposed at a predetermined position on the inner wall 62 of the tire 60 via the elastic member 23.

  As shown in FIG. 1, the transmission unit 30 includes a constant voltage circuit 31, a transmission circuit 32, and a transmission antenna 33. The constant voltage circuit 31 converts the electrical signal generated by the power generation unit 20 into an electrical signal having a predetermined voltage. The transmission circuit 32 is activated using the electric signal output from the constant voltage circuit 31 as a power source, and converts the electric signal generated by the power generation unit 20 into a radio signal having a predetermined frequency. The transmission circuit 32 wirelessly transmits the electrical signal converted into the wireless signal to the control unit 40 side via the transmission antenna 33. As a radio signal for radio transmission, a high-frequency signal having a frequency in the UHF band (ultra-high frequency band: 300 MHz to 3 GHz) is used. Hereinafter, the transmission unit 30 converts the electric signal generated by the power generation unit 20 into a radio signal and wirelessly transmits the signal via the transmission antenna 33. The transmission unit 30 transmits the electric signal generated by the power generation unit 20 by radio. This is abbreviated.

  In the present embodiment, as shown in FIG. 3, the power generation unit 20 is disposed on the inner wall 62 of the tire 60 so as to be close to the detection position Ps <b> 1 that is a predetermined position of the ground contact surface 61 of the tire 60. The mounting direction of the power generation unit 20 is set so that the movable unit 22 reciprocates along the circumferential direction of the tire 60. Therefore, the power generation unit 20 can efficiently generate power with respect to vibration along the circumferential direction of the tire 60. Although not shown, the transmission unit 30 is disposed on the inner wall 62 of the tire 60 so as to be close to the detection position Ps <b> 1 of the ground contact surface 61 of the tire 60 together with the power generation unit 20.

  The control unit 40 is an on-vehicle electronic module for control called ECU (Engine Control Unit). As illustrated in FIG. 1, the control unit 40 includes a reception unit 41, a calculation unit 42, a data communication unit 43, and a control circuit unit 44.

  The receiving unit 41 receives the electric signal wirelessly transmitted from the transmitting unit 30 using a receiving antenna (not shown) disposed near the tire 60. Then, the information on the electrical signal received by the receiving unit 41 is transmitted to the calculation unit 42 via the control circuit unit 44. In the present embodiment, the information transmitted from the reception unit 41 to the calculation unit 42 is the reception timing of the electrical signal received by the reception unit 41. Hereinafter, transmitting the electrical signal information received by the receiving unit 41 to the computing unit 42 via the control circuit unit 44 is abbreviated as transmitting the electrical signal received by the receiving unit 41 to the computing unit 42.

  The calculation unit 42 calculates the air pressure of the tire 60 based on the information transmitted from the reception unit 41. The data communication unit 43 is connected to various electronic devices of the vehicle 50 (not shown) via an in-vehicle network (not shown), and obtains various information from the various electronic devices of the vehicle 50 and various types of the vehicle 50. Various information such as control information is transmitted to the electronic device. The control circuit unit 44 controls the reception unit 41, the calculation unit 42, and the data communication unit 43 in an integrated manner.

  The tire pressure monitoring device 1 has such a configuration. In the power generation unit 10, the power generation unit 20 generates power using vibrations associated with the rotation operation of the tire 60 and generates an electrical signal corresponding to the vibrations of the tire 60. The electric signal generated by the power generation unit 20 is transmitted to the calculation unit 42 via the transmission unit 30 and the reception unit 41. In the control unit 40, the calculation unit 42 calculates the air pressure of the tire 60 based on the electrical signal transmitted from the power generation unit 20.

  Next, a method for calculating the air pressure of the tire 60 will be described with reference to FIGS. 4 and 5. As shown in FIG. 4, when the ground contact surface 61 of the tire 60 is in contact with the ground 70 in the vehicle 50, the ground contact surface 61 of the tire 60 is pushed from the ground 70 and is deformed to the rotation axis Po side of the tire 60. The amount of deformation of the ground contact surface 61 of the tire 60 is smaller as the air pressure of the tire 60 is higher and larger as the air pressure of the tire 60 is lower. As described above, since the deformation amount of the ground contact surface 61 of the tire 60 changes corresponding to the air pressure of the tire 60, the air pressure of the tire 60 can be calculated based on the deformation amount of the ground contact surface 61 of the tire 60.

  Further, the time during which the tire 60 rotates once is defined as the rotation period T0 of the tire 60, and the time from when the predetermined position of the ground contact surface 61 of the tire 60 contacts the ground 70 to when the tire 60 moves away is the ground contact time T1 of the tire 60. Then, the ratio (T1 / T0) of the contact time T1 of the tire 60 to the rotation period T0 of the tire 60 is smaller as the deformation amount of the contact surface 61 of the tire 60 is smaller, and the deformation amount of the contact surface 61 of the tire 60 is larger. It gets bigger. As described above, the ratio of the contact time T1 of the tire 60 to the rotation period T0 of the tire 60 changes in accordance with the deformation amount of the ground contact surface 61 of the tire 60. Can be used. As a result, the air pressure of the tire 60 can be calculated based on the ratio of the contact time T1 of the tire 60 to the rotation period T0 of the tire 60.

  Next, a method for calculating the rotation period T0 of the tire 60 will be described. The rotation period T0 of the tire 60 is, for example, a value obtained by dividing a value obtained by multiplying the diameter D by the circumference ratio π by the speed V (π * D / V) where D is the diameter of the tire 60 and V is the speed of the vehicle 50. ). Further, the rotation period T0 of the tire 60 may be calculated from the rotation period of a shaft member (not shown) connected to the tire 60. Information such as the speed of the vehicle 50 and the rotation cycle of the shaft member can be obtained from the vehicle 50 side using the data communication unit 43. Further, dimensional information such as the diameter of the tire 60 is known in advance when the tire 60 is mounted.

  Next, a method for calculating the contact time T1 of the tire 60 and the air pressure of the tire 60 will be described. When the tire 60 rotates in the vehicle 50, an impact when a predetermined position of the ground contact surface 61 of the tire 60 contacts the ground 70 with the rotation operation of the tire 60, or the tire 60 rotates with the rotation operation of the tire 60. In response to an impact when the predetermined position of the ground surface 61 is separated from the ground 70, a large vibration such as a ground vibration or a separation vibration is generated.

  For example, when the ground contact surface 61 of the tire 60 near the detection position Ps1 contacts the ground 70, the ground contact surface 61 of the tire 60 is pushed from the ground 70. Accordingly, a force acts on the ground contact surface 61 of the tire 60 near the detection position Ps1 in the direction opposite to the rotation direction of the tire 60 along the circumferential direction of the tire 60 as shown in FIG. And the ground vibration which the ground contact surface 61 of the tire 60 of the detection position Ps1 vicinity vibrates along the circumferential direction of the tire 60 generate | occur | produces. In the present embodiment, since the power generation unit 20 is disposed on the inner wall 62 of the tire 60 so as to be close to the detection position Ps1, such a ground vibration generated near the detection position Ps1 is transmitted to the power generation unit 20. The

  In the power generation unit 10, the power generation unit 20 generates power corresponding to the ground vibration along the circumferential direction of the tire 60 as described above, and as illustrated in FIG. 5, the first electric signal corresponding to the ground vibration is the first signal. A detection signal Sa1 is generated. The first detection signal Sa1 is converted by the constant voltage circuit 31 into a first output signal Sb1 that is an electric signal having a predetermined voltage, and is converted by the transmission circuit 32 into a first radio signal RF1 that is a radio signal having a predetermined frequency. . Then, the first detection signal Sa1 is wirelessly transmitted from the transmission unit 30 of the power generation unit 10 to the reception unit 41 of the control unit 40 as the first wireless signal RF1.

  Further, when the ground contact surface 61 of the tire 60 near the detection position Ps1 is separated from the ground 70, the ground contact surface 61 of the tire 60 is released from the pressed state by the ground 70. Accordingly, a force acts on the ground contact surface 61 of the tire 60 near the detection position Ps1 in the same direction as the rotation direction of the tire 60 along the circumferential direction of the tire 60 as shown in FIG. Then, a separation vibration is generated in which the ground contact surface 61 of the tire 60 near the detection position Ps <b> 1 vibrates along the circumferential direction of the tire 60. In the present embodiment, since the power generation unit 20 is disposed on the inner wall 62 of the tire 60 so as to be close to the detection position Ps1, such separation vibration generated in the vicinity of the detection position Ps1 is transmitted to the power generation unit 20. The

  In the power generation unit 10, the power generation unit 20 generates power corresponding to such a separation vibration along the circumferential direction of the tire 60 and, as shown in FIG. 5, a second electric signal corresponding to the separation vibration. A detection signal Sa2 is generated. The second detection signal Sa2 is converted by the constant voltage circuit 31 into a second output signal Sb2 that is an electric signal having a predetermined voltage, and is converted by the transmission circuit 32 into a second radio signal RF2 that is a radio signal having a predetermined frequency. . The second detection signal Sa2 is wirelessly transmitted from the transmission unit 30 to the reception unit 41 of the control unit 40 as the second wireless signal RF2.

  In the control unit 40, the reception unit 41 receives the first radio signal RF1 and the second radio signal RF2 that are wirelessly transmitted from the transmission unit 30 of the power generation unit 10. Information such as the reception timing of the first radio signal RF1 and the reception timing of the second radio signal RF2 is transmitted to the calculation unit 42 via the control circuit unit 44. The computing unit 42 calculates the interval between the generation timing ts1 of the first detection signal Sa1 and the generation timing ts2 of the second detection signal Sa2 based on the reception timing of the first radio signal RF1 and the reception timing of the second radio signal RF2. Then, the contact time T1 is calculated based on the interval between the generation timing ts1 of the first detection signal Sa1 and the generation timing ts2 of the second detection signal Sa2. And the calculating part 42 is calculating the air pressure of the tire 60 based on the ratio with respect to the rotation period T0 of the tire 60 of the contact time T1 of the tire 60 calculated in this way.

  In the present embodiment, as described above, the power generation unit 20 generates power by using the collision between the inner wall 21b of the housing 21 and the movable unit 22 as the movable unit 22 moves. Therefore, the first detection signal Sa1 and the second detection signal Sa2 generated by the power generation unit 20 in response to the ground vibration and the separation vibration are in a pulse form having a shorter generation time than the grounding time T1, as shown in FIG. It becomes the electric signal. In the present embodiment, the first detection signal Sa1, the second detection signal Sa2, the first radio signal RF1, and the second radio signal RF2 are converted into pulse signals having a short generation time, thereby generating the first detection signal Sa1. The generation timing ts1 and the generation timing ts2 of the second detection signal Sa2 are easily specified.

  In the present embodiment, the deviation of the generation timing of the first detection signal Sa1 with respect to the generation timing of the ground vibration, and the deviation of the transmission timing and reception timing of the first radio signal RF1 with respect to the generation timing of the first detection signal Sa1 It is assumed to be negligibly small with respect to 60 contact time T1. Further, the deviation of the generation timing of the second detection signal Sa2 with respect to the generation timing of the separation vibration, and the deviation of the transmission timing and reception timing of the second radio signal RF2 with respect to the generation timing of the second detection signal Sa2 are also caused by the contact time T1 of the tire 60. Is negligibly small. In such a case, the grounding time T1 is equal to the interval between the reception timing of the first radio signal RF1 and the reception timing of the second radio signal RF2.

  Next, the effect of this embodiment will be described. In the tire pressure monitoring apparatus 1 of the present embodiment, the power generation unit 20 generates a first detection signal Sa1 and a second detection signal Sa2 that are two electrical signals corresponding to different vibration states of the tire 60, and a calculation unit. 42 calculates the air pressure of the tire 60 based on the first detection signal Sa1 and the second detection signal Sa2. Therefore, the power generation unit 20 can be used as a sensor element for detecting the air pressure of the tire 60. And the number of the elements used with the apparatus by the side of the tire 60 can be reduced by utilizing the electric power generation part 20 as a sensor element. As a result, the configuration of the device on the tire 60 side can be simplified.

  In addition, since such an effect is an effect obtained by using the power generation unit 20 as a sensor element, for example, the calculation unit 42 is not provided in the control unit 40 which is a device on the vehicle 50 side, but on the tire 60 side. Even when the power generation unit 10 as a device is provided, the same effect can be obtained.

  Further, in the vehicle 50 in which the tire pressure monitoring device 1 of the present embodiment is used, when the tire 60 rotates, a predetermined position of the ground contact surface 61 of the tire 60 contacts the ground 70 as the tire 60 rotates. Large vibrations such as grounding vibrations and separation vibrations are generated in response to the impacts when the predetermined position of the ground contact surface 61 of the tire 60 is separated from the ground 70 with the rotation of the tire 60 and the rotation of the tire 60. . On the other hand, in the tire pressure monitoring device 1 of the present embodiment, the power generation unit 20 generates power using vibrations associated with the rotation operation of the tire 60. Therefore, the first corresponding to such ground vibration and separation vibration is used. The detection signal Sa1 and the second detection signal Sa2 can be easily generated. In addition, since the interval between the generation timing of the ground vibration and the generation timing of the separation vibration changes corresponding to the air pressure of the tire 60, the calculation unit 42 generates the first detection signal Sa1 corresponding to the ground vibration with the generation timing ts1. By calculating the air pressure of the tire 60 based on the interval from the generation timing ts2 of the second detection signal Sa2 corresponding to the separation signal, the air pressure of the tire 60 can be easily calculated.

  In addition, the tire pressure monitoring device 1 according to the present embodiment receives the electrical signal generated by the power generation unit 20 by wireless transmission and the electrical signal wirelessly transmitted by the transmission unit 30 and transmits the electrical signal to the calculation unit 42. A receiving unit 41. Therefore, even if the distance between the power generation unit 20 and the calculation unit 42 is increased by arranging the transmission unit 30 on the tire 60 side together with the power generation unit 20 and the reception unit 41 on the vehicle 50 side together with the calculation unit 42. The electric signal can be stably transmitted from the power generation unit 20 to the calculation unit 42. By arranging the receiving unit 41 on the vehicle 50 side together with the calculating unit 42, a control circuit for controlling the calculating unit 42, a storage element for stably operating the calculating unit 42, and the like are also provided on the vehicle 50 side. Can be arranged. As a result, the configuration of the device on the tire 60 side can be further simplified.

  Further, in the vehicle 50 in which the tire pressure monitoring device 1 of the present embodiment is used, when the ground contact surface 61 of the tire 60 contacts the ground 70, the ground contact surface 61 of the tire 60 is pushed from the ground 70. Thus, a ground vibration is generated in which the ground contact surface 61 of the tire 60 vibrates along the circumferential direction of the tire 60. Further, when the ground contact surface 61 of the tire 60 is separated from the ground 70, the ground contact surface 61 of the tire 60 is released from the pressed state by the ground 70 so that the ground contact surface 61 of the tire 60 is A separation vibration that vibrates along the circumferential direction is generated. In the tire pressure monitoring apparatus 1 of the present embodiment, the power generation unit 20 is disposed on the inner wall 62 of the tire 60 so as to be close to the ground contact surface 61 of the tire 60, and the tire 60 corresponding to the ground vibration and the separation vibration is disposed. Since power generation is performed using the vibration of the ground contact surface 61 of the tire 60 along the circumferential direction, it is possible to efficiently generate power in response to such ground vibration and separation vibration, and to deal with ground vibration and separation vibration. Thus, the first detection signal Sa1 and the second detection signal Sa2 can be generated stably.

  Further, in the tire pressure monitoring device 1 of the present embodiment, the power generation unit 20 performs power generation using the collision between the inner wall 21b of the housing 21 and the movable unit 22 accompanying the movement of the movable unit 22, thereby causing ground vibration. The first detection signal Sa1 and the second detection signal Sa2 that are generated by the power generation unit 20 in response to the separation vibration and the first detection signal Sa2 can be made into a pulsed electric signal having a generation time shorter than the grounding time T1. It is possible to easily specify the generation timing of the detection signal Sa1 and the second detection signal Sa2. As a result, the air pressure detection accuracy of the tire 60 can be further increased.

  Further, in the tire pressure monitoring device 1 of the present embodiment, the elastic member 23 absorbs the vibration of the tire 60 having a small amplitude that becomes a noise component, and the vibration of the tire 60 having a large amplitude such as a ground vibration or a separation vibration is selectively selected. Can be transmitted to the housing 21. As a result, the influence of the vibration of the tire 60 that becomes a noise component can be reduced, and the accuracy of detecting the air pressure of the tire 60 can be further increased.

[Second Embodiment]
Next, a tire pressure monitoring apparatus according to a second embodiment of the present invention will be described with reference to FIGS. In addition, in this embodiment, when it is the same structure as 1st Embodiment mentioned above, the same code | symbol is attached | subjected and detailed description is abbreviate | omitted.

  FIG. 6 is an explanatory diagram showing the configuration of the tire pressure monitoring apparatus according to the second embodiment of the present invention. FIG. 6A shows the overall configuration of the tire pressure monitoring apparatus 101. FIG. 6B schematically shows a method of attaching the power generation unit 20 to the tire 60 when viewed from the right. In FIG. 6B, Ps2 is a detection position in the present embodiment. L2 is an imaginary line extending along the radial direction of the tire 60 at the detection position Ps2 through the detection position Ps2. A solid line arrow indicates the moving direction of the movable portion 22. Hereinafter, the radial direction of the tire 60 at the detection position Ps <b> 2 is abbreviated as the radial direction of the tire 60, and the description proceeds.

  FIG. 7 is an explanatory diagram relating to the rotation operation of the tire according to the second embodiment of the present invention. FIG. 7A shows the state of the tire 60 when the detection position Ps2 contacts the ground 70 when viewed from the right, and FIG. 7B shows the detection position Ps2 when viewed from the right. The state of the tire 60 when separated from the ground 70 is shown. In FIG. 7, the dotted arrow indicates the rotation direction of the tire 60, and the solid arrow indicates the direction of the force acting on the ground contact surface 61 of the tire 60 in the vicinity of the detection position Ps <b> 2.

  First, the structure of the tire pressure monitoring apparatus according to the second embodiment of the present invention will be described with reference to FIG. The configuration of the tire pressure monitoring apparatus 101 according to the second embodiment of the present invention is the same as the configuration of the tire pressure monitoring apparatus 1 according to the first embodiment, as shown in FIG. However, in this embodiment, the attachment method to the tire 60 of the electric power generation part 20 differs from 1st Embodiment.

  In the present embodiment, as shown in FIG. 6B, the power generation unit 20 is disposed on the inner wall 62 of the tire 60 so as to be close to the detection position Ps <b> 2 that is a predetermined position of the ground contact surface 61 of the tire 60. . The mounting direction of the power generation unit 20 is set so that the movable unit 22 reciprocates along the radial direction of the tire 60. Therefore, the power generation unit 20 can efficiently generate power with respect to the vibration of the ground contact surface 61 of the tire 60 along the radial direction of the tire 60. Although not shown, the transmission unit 30 is disposed on the inner wall 62 of the tire 60 so as to be close to the detection position Ps2 of the ground contact surface 61 of the tire 60 together with the power generation unit 20.

  Next, a method for calculating the air pressure of the tire 60 will be described with reference to FIG. When the ground contact surface 61 of the tire 60 near the detection position Ps2 contacts the ground 70, the ground contact surface 61 of the tire 60 is pushed from the ground 70. Along with this, as shown in FIG. 7A, a force directed from the ground contact surface 61 side toward the rotation axis Po along the radial direction of the tire 60 acts on the ground contact surface 61 of the tire 60 near the detection position Ps2. . And the ground vibration which the ground contact surface 61 of the tire 60 of the detection position Ps2 vicinity vibrates along the radial direction of the tire 60 generate | occur | produces.

  Further, when the ground contact surface 61 of the tire 60 near the detection position Ps2 is separated from the ground 70, the ground contact surface 61 of the tire 60 is released from the pressed state by the ground 70. Along with this, on the ground contact surface 61 of the tire 60 in the vicinity of the detection position Ps2, a force acting from the rotation axis Po side to the ground contact surface 61 side acts along the radial direction of the tire 60 as shown in FIG. . Then, a separation vibration in which the ground contact surface 61 of the tire 60 near the detection position Ps2 vibrates along the radial direction of the tire 60 is generated.

  In the present embodiment, since the power generation unit 20 is disposed on the inner wall 62 of the tire 60 so as to be close to the detection position Ps2, such a ground vibration or separation vibration generated near the detection position Ps2 is generated by the power generation unit 20. Is transmitted to. The power generation unit 20 generates power using such ground vibration and separation vibration and generates the first detection signal Sa1 and the second detection signal Sa2 corresponding to the ground vibration and separation vibration. In addition, 1st detection signal Sa1 and 2nd detection signal Sa2 are transmitted to the calculating part 42 from the electric power generation part 20 by the method similar to 1st Embodiment. Moreover, the calculating part 42 calculates the air pressure of the tire 60 based on the first detection signal Sa1 and the second detection signal Sa2 by the same method as in the first embodiment.

  Next, the effect of this embodiment will be described. In the present embodiment, only effects different from those of the first embodiment will be described. In the vehicle 50 in which the tire pressure monitoring apparatus 101 according to the present embodiment is used, when the ground contact surface 61 of the tire 60 contacts the ground 70, the ground contact surface 61 of the tire 60 is pushed from the ground 70. Ground contact vibration is generated in which the ground contact surface 61 of the tire 60 vibrates along the radial direction of the tire 60. Further, when the ground contact surface 61 of the tire 60 is separated from the ground 70, the ground contact surface 61 of the tire 60 is released from the pressed state by the ground 70, so that the ground contact surface 61 of the tire 60 has a diameter of the tire 60. A separation vibration that vibrates along the direction is generated. In the tire pressure monitoring apparatus 101 of the present embodiment, the power generation unit 20 is disposed on the inner wall 62 of the tire 60 so as to be close to the ground contact surface 61 of the tire 60, and the tire 60 corresponding to the ground vibration and the separation vibration. Since power generation is performed using the vibration of the ground contact surface 61 of the tire 60 along the radial direction, it is possible to efficiently generate power corresponding to such ground vibration and separation vibration, and to cope with ground vibration and separation vibration. The first detection signal Sa1 and the second detection signal Sa2 can be generated stably.

[Third Embodiment]
Next, a tire pressure monitoring apparatus according to a third embodiment of the present invention will be described with reference to FIGS. In addition, in this embodiment, when it is the same structure as 1st Embodiment mentioned above or 2nd Embodiment, the same code | symbol is attached | subjected and detailed description is abbreviate | omitted.

  FIG. 8 is an explanatory diagram showing the configuration of the tire pressure monitoring apparatus according to the third embodiment of the present invention. FIG. 8A shows the overall configuration of the tire pressure monitoring device 201. FIG. 8B schematically shows a method of attaching the power generation unit 20 to the tire 60. In FIG. 8B, Ps3 is a detection position in the present embodiment. L3 is an imaginary line passing through the detection position Ps3 and extending along the width direction of the tire 60 at the detection position Ps3. A solid line arrow indicates the moving direction of the movable portion 22. Hereinafter, the width direction of the tire 60 at the detection position Ps <b> 3 is abbreviated as the width direction of the tire 60, and the description proceeds.

  FIG. 9 is an explanatory diagram relating to the rotation operation of the tire according to the third embodiment of the present invention. FIG. 9A shows a state of the tire 60 when the ground contact surface 61 of the tire 60 adjacent to the detection position Ps3 comes in contact with the ground 70 when viewed from the front, and FIG. The state of the tire 60 when the ground contact surface 61 of the tire 60 adjacent to the detection position Ps3 is separated from the ground 70 when viewed is shown. In FIG. 9, the dotted arrow indicates the direction of movement of the front end of the tire 60 as the tire 60 rotates, and the solid arrow indicates the direction of the force acting on the side surface 63 of the tire 60 in the vicinity of the detection position Ps3.

  The configuration of the tire pressure monitoring device 201 according to the third embodiment of the present invention is the same as the configuration of the tire pressure monitoring device 1 according to the first embodiment, as shown in FIG. However, in this embodiment, the attachment method to the tire 60 of the electric power generation part 20 differs from 1st Embodiment.

  In the present embodiment, as shown in FIG. 8B, the power generation unit 20 is disposed on the inner wall 62 of the tire 60 so as to face the detection position Ps3 that is a predetermined position on the side surface 63 of the tire 60. The mounting direction of the power generation unit 20 is set so that the movable unit 22 reciprocates along the width direction of the tire 60. Therefore, the power generation unit 20 can efficiently generate power with respect to the vibration of the ground contact surface 61 of the tire 60 along the width direction of the tire 60. Although not shown, the transmission unit 30 is disposed on the inner wall 62 of the tire 60 so as to face the detection position Ps3 on the side surface 63 of the tire 60 together with the power generation unit 20.

  Next, a method for calculating the air pressure of the tire 60 will be described with reference to FIG. When the ground contact surface 61 of the tire 60 adjacent to the detection position Ps3 contacts the ground 70, the ground contact surface 61 of the tire 60 is pushed from the ground 70. Accordingly, a force acts on the side surface 63 of the tire 60 near the detection position Ps3 so that the width W of the tire 60 increases along the width direction of the tire 60 as shown in FIG. Therefore, a ground vibration is generated in which the side surface 63 of the tire 60 near the detection position Ps3 vibrates along the width direction of the tire 60.

  Further, when the ground contact surface 61 of the tire 60 adjacent to the detection position Ps3 is separated from the ground 70, the ground contact surface 61 of the tire 60 is released from the pressed state by the ground 70. Accordingly, a force acts on the side surface 63 of the tire 60 near the detection position Ps3 so that the width W of the tire 60 becomes narrower along the width direction of the tire 60, as shown in FIG. Therefore, a separation vibration is generated in which the side surface 63 of the tire 60 near the detection position Ps3 vibrates along the width direction of the tire 60.

  In the present embodiment, since the power generation unit 20 is disposed on the inner wall 62 of the tire 60 so as to face the detection position Ps3 on the side surface 63 of the tire 60, The separation vibration is transmitted to the power generation unit 20. The power generation unit 20 generates power using such ground vibration and separation vibration and generates the first detection signal Sa1 and the second detection signal Sa2 corresponding to the ground vibration and separation vibration. In addition, 1st detection signal Sa1 and 2nd detection signal Sa2 are transmitted to the calculating part 42 from the electric power generation part 20 by the method similar to 1st Embodiment. Moreover, the calculating part 42 calculates the air pressure of the tire 60 based on the first detection signal Sa1 and the second detection signal Sa2 by the same method as in the first embodiment.

  Next, the effect of this embodiment will be described. In the present embodiment, only effects different from those of the first embodiment will be described. In the vehicle 50 in which the tire pressure monitoring device 201 of the present embodiment is used, when the ground contact surface 61 of the tire 60 contacts the ground 70, the ground contact surface 61 of the tire 60 is pushed from the ground 70. A ground vibration is generated in which the side surface 63 of the tire 60 vibrates along the width direction of the tire 60. Further, when the ground contact surface 61 of the tire 60 is separated from the ground 70, the side surface 63 of the tire 60 extends in the width direction of the tire 60 as the ground contact surface 61 of the tire 60 is released from the pressed state by the ground 70. A separation vibration that vibrates along the axis is generated. In the tire pressure monitoring device 201 of the present embodiment, the power generation unit 20 is disposed on the inner wall 62 of the tire 60 facing the side surface 63 of the tire 60, and in the width direction of the tire 60 corresponding to ground vibration and separation vibration. Since the power generation is performed using the vibration of the side surface 63 of the tire 60 along, the first detection corresponding to the ground vibration and the separation vibration can be performed efficiently in response to the ground vibration and the separation vibration. The signal Sa1 and the second detection signal Sa2 can be generated stably.

  Moreover, in the tire pressure monitoring device 201 of the present embodiment, the transmitter 30 is disposed on the inner wall 62 of the tire 60 that faces the side surface 63 of the tire 60 together with the power generation unit 20, so that it is during snowfall or rain. In addition, the transmission unit 30 can be arranged at a position away from snow or rainwater on the ground 70. Therefore, even when it is snowing or raining, an electrical signal can be wirelessly transmitted from the transmitting unit 30 to the receiving unit 41 without being interrupted by snow or rainwater. As a result, the electric signal can be stably transmitted from the power generation unit 20 to the calculation unit 42 even during snowfall or rain.

  In the tire pressure monitoring device 201 of the present embodiment, the air pressure of the tire 60 is calculated based on the deformation amount of the tire 60 instead of directly detecting the air pressure of the tire 60 using an air pressure sensor or the like. The power generation unit 20 and the transmission unit 30 of the power generation unit 10 may not be disposed inside the tire 60. For example, even when the power generation unit 20 and the transmission unit 30 are arranged on the side surface of the tire 60 that is the outer surface of the tire 60, the same effect as in the present embodiment can be obtained.

  As mentioned above, although embodiment of this invention has been described, this invention is not limited to said embodiment, In the range which does not deviate from the objective of this invention, it can change suitably. Hereinafter, a modification of the present invention will be described with reference to FIG. FIG. 10 is an explanatory diagram showing the structure of the power generation unit according to a modification of the present invention. FIG. 10A is an explanatory diagram illustrating a first modification example regarding the power generation unit 20, and FIG. 10B is an explanatory diagram illustrating a second modification example regarding the power generation unit 20.

  In the embodiment of the present invention, the power generation unit 20 may have a structure other than that described above. For example, as shown in 10 (a), the power generation unit 20 may be directly attached to the inner wall 62 of the tire 60 without using the elastic member 23. Also, as shown in FIG. 10B, the casing 21 is wound around the core member 21c, with a core member 21c configured by a magnet and a magnetostrictive element and attached to the inner wall 21b of the casing 21. The coil unit 21d may be used, and power generation may be performed using a change in the magnetic field caused by the collision between the movable member 22 and the core member 21c on the housing 21 side as the movable unit 22 moves.

  In the embodiment of the present invention, a piezoelectric element may be attached to the inner wall 21b of the casing 21 instead of the core member 21c and the coil portion 21d. Further, when sufficient detection accuracy is obtained, power generation may be performed without causing the movable portion 22 and the end portion of the housing 21 to collide by a method such as electromagnetic induction. Further, the power generation unit 20 may be disposed at a position away from the transmission unit 30. Further, the power generation unit 20 may be disposed at a plurality of locations of one tire 60.

  In the embodiment of the present invention, the radio signal for radio transmission used in the transmission unit 30 may be a radio signal having a frequency other than those described above. For example, the radio signal for radio transmission may be a radio signal having a frequency of LF band (long wave band: 30 kHz to 300 kHz), a radio signal having a frequency of 2.4 GHz band, or the like.

  In the embodiment of the present invention, the calculation unit 42 may calculate the air pressure of the tire 60 using a calculation method other than that described above. For example, the calculation unit 42 may calculate the rotation period T0 of the tire 60 based on the repetition time of the first detection signal Sa1, and may calculate the air pressure of the tire 60 using the calculated rotation period T0 of the tire 60. . Further, the power generation unit 20 generates an electrical signal corresponding to a plurality of vibration states other than the ground vibration and the separation vibration, and the calculation unit 42 generates an electric signal corresponding to a plurality of vibration states other than the ground vibration and the separation vibration. Based on this, the air pressure of the tire 60 may be calculated.

  In the embodiment of the present invention, the calculation unit 42 is not included in the control unit 40 disposed on the vehicle 50 side, but may be disposed on the tire 60 side together with the power generation unit 10. In addition, the calculation unit 42 may be incorporated in an electronic device such as a smartphone owned by the user of the vehicle 50. Even if the tire pressure monitoring device has such a configuration, the configuration of the device on the tire 60 side can be simplified by using the power generation unit 20 as a sensor element.

DESCRIPTION OF SYMBOLS 1 Tire pressure monitoring apparatus 10 Electric power generation unit 20 Electric power generation part 21 Case 21a Outer wall 21b Inner wall 21c Core member 21d Coil part 22 Movable part 22a Core member 22b Coil part 23 Elastic member 30 Transmission part 31 Constant voltage circuit 32 Transmission circuit 33 Transmission antenna 40 Control unit 41 Reception unit 42 Calculation unit 43 Data communication unit 44 Control circuit unit 50 Vehicle 60 Tire 61 Ground surface 62 Inner wall 63 Side surface 70 Ground 101 Tire pressure monitoring device 201 Tire pressure monitoring device

Claims (8)

A tire pressure monitoring device for monitoring the pressure of a tire mounted on a vehicle,
At least one power generation unit that generates power using vibration associated with the rotational operation of the tire;
A calculation unit for calculating the tire pressure,
The power generation unit generates at least two electrical signals respectively corresponding to different vibration states of the tire;
The tire pressure monitoring device, wherein the calculation unit calculates tire pressure based on the at least two electrical signals. The power generation unit includes a ground vibration that occurs when the predetermined position of the tire contacts the ground with the rotation operation of the tire, and the predetermined position of the tire moves away from the ground with the rotation operation of the tire. Generating the electrical signal corresponding to the separation vibration generated when
2. The tire calculating unit according to claim 1, wherein the calculation unit calculates tire air pressure based on an interval between the generation timing of the electrical signal corresponding to the ground vibration and the generation timing of the electrical signal corresponding to the separation vibration. The tire pressure monitoring device described in 1. A transmitter that wirelessly transmits the electrical signal generated by the power generation unit;
A receiver that receives the electrical signal wirelessly transmitted by the transmitter and transmits the electrical signal to the calculator;
The transmission unit is arranged at a predetermined position on the tire side together with the power generation unit,
The tire pressure monitoring device according to claim 2, wherein the receiving unit is arranged at a predetermined position on the vehicle side together with the calculating unit. The power generation unit is disposed so as to be close to the ground contact surface of the tire,
The tire pressure monitoring device according to claim 3, wherein power generation is performed using vibration of a ground contact surface of the tire along a circumferential direction of the tire corresponding to the ground vibration and the separation vibration. The power generation unit is disposed so as to be close to the ground contact surface of the tire,
The tire pressure monitoring device according to claim 3, wherein power generation is performed using vibration of a ground contact surface of the tire along a radial direction of the tire corresponding to the ground vibration and the separation vibration. The power generation unit is disposed on a side surface of the tire or an inner wall of the tire facing a side surface of the tire,
The tire pressure monitoring device according to claim 3, wherein power generation is performed using vibration of a side surface of the tire along a width direction of the tire corresponding to the ground vibration and the separation vibration. The power generation unit includes a housing attached to the tire side, and a movable unit housed inside the housing so as to be movable with respect to the housing.
The tire pressure monitoring device according to any one of claims 1 to 6, wherein power generation is performed by utilizing a collision between the casing and the movable portion accompanying the movement of the movable portion. The tire pressure monitoring apparatus according to claim 7, wherein the casing is attached to the tire via an elastic member.