JP2012051429A - Tire sensor and tire state monitoring device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a tire sensor that can detect rotation of a tire and change the radio transmission frequency of the tire state according to rotation of the detected tire, while suppressing increase of the number of members, and to provide a tire condition monitoring device using the tire sensor.SOLUTION: A sensor unit 3 as a tire sensor includes: a sensor unit controller 13 which measures a state of a tire loaded to a wheel of a vehicle; a transmission circuit 14 which performs radio transmission of the data which shows the state of the tire which the sensor unit controller 13 has measured; and generating equipment 16 which generates power in response to wheel movement accompanying traveling of a vehicle, and loaded in the wheel. The sensor unit 3 detect rotation of a wheel based on change at least either voltage or current of power generated by the generating equipment 16, and changes frequency of radio transmission based on detected rotation of the wheel.

Description

  The present invention relates to a tire sensor mounted on a vehicle wheel for measuring a tire condition, and a tire condition monitoring apparatus using the tire sensor.

  2. Description of the Related Art Conventionally, a wireless tire condition monitoring device has been used in order to check the condition of a tire mounted on a vehicle in a passenger compartment. Such a wireless tire condition monitoring device includes a tire sensor having a transmitter mounted on a wheel of each tire and a receiver mounted on a vehicle body of the vehicle. The tire sensor measures values such as tire pressure and tire temperature corresponding to the tire sensor, and wirelessly transmits data indicating the measured value from the transmitter. On the other hand, the receiver receives the data from the transmitter with an antenna and displays the state of each tire on a display provided in the driver's seat of the vehicle, for example.

  By the way, although it is necessary to grasp | ascertain the state of the tire mentioned above normally at the time of driving | running | working of the vehicle which the driver is driving the vehicle, it is not necessary to grasp | ascertain when the driver | operator who is not boarding the vehicle stops. Therefore, the transmitter of the monitoring device described above periodically transmits data indicating the state of the tire while the vehicle is running, but does not transmit the data while the vehicle is stopped.

  For example, a tire condition monitoring device described in Patent Literature 1 includes a tire sensor provided on a wheel of a wheel (tire), and a ground contact state detection unit provided on the tire. The contact state detection unit detects whether or not the tire is rotating based on whether or not the contact force from the ground acts on a predetermined part. When the ground contact force is detected by the ground contact state detection unit, the tire sensor transmits data indicating the tire state from the transmitter. Thereby, when the tire is not rotating, data indicating the tire state is not transmitted from the transmitter.

  As another tire condition monitoring device, as shown in FIG. 9, a tire sensor 50 provided on a tire wheel detects the rotation of the tire by an acceleration sensor 51. The tire sensor 50 is driven when electric power charged in the secondary battery 15 from the power generation device 16 is supplied from the secondary battery 15. The sensor unit controller 13 transmits data indicating the measurement values measured by the pressure sensor 11 and the temperature sensor 12 from the transmission circuit 14 at a predetermined frequency based on the rotation of the tire detected by the acceleration sensor 51. Thereby, the data transmission frequency is adjusted according to the rotation state of the tire.

JP 2005-186749 A

  According to the transmitter in each tire condition monitoring device described above, the frequency of transmitting data can be changed according to the rotation of the tire. Therefore, it is possible to prevent data from being transmitted from the transmitter when the tire is not rotating.

However, in the apparatus described in Patent Document 1, since the ground contact state detection unit, which is a separate member from the transmitter, is added as a new constituent member, the number of members constituting the tire state monitoring device is naturally increased. Therefore, the trouble of installing the ground contact state detection unit on the tire is separately required. Similarly, in the other devices shown in FIG. 9, the number of members increases by the amount corresponding to the acceleration sensor. In addition, since the acceleration sensor is a sensor that is relatively vulnerable to impact, the accuracy of the measurement result is low, and the operation test of the acceleration sensor in a finished product takes time.

  The present invention has been made in view of such circumstances, and its purpose is to detect the rotation of the tire while suppressing the increase in the number of members, and to detect the tire condition according to the detected rotation of the tire. A tire sensor capable of changing the wireless transmission frequency of the tire and a tire condition monitoring device using the tire sensor are provided.

  In order to solve the above-mentioned problem, the invention according to claim 1 is a transmission unit that wirelessly transmits data indicating a state of a tire measured by the measurement unit and a measurement unit that measures a state of a tire mounted on a vehicle wheel. And a power generation unit that generates electric power in response to movement of the wheel as the vehicle travels, and is a tire sensor attached to the wheel, wherein at least one of voltage and current of the electric power generated by the power generation unit The present invention includes a control unit that detects the rotation of the wheel based on the change in the frequency and changes the frequency of the wireless transmission based on the detected rotation of the wheel.

  According to such a configuration, the rotation of the wheel is detected based on a change in at least one of the voltage and current of the power generated by the power generation unit provided in advance in the tire sensor. Therefore, the tire sensor can detect the rotation of the wheel without providing a dedicated sensor for detecting the rotation of the wheel. This eliminates the need for a sensor to detect wheel rotation even when changing the frequency of wireless transmission from the transmitter, thereby reducing the number of components that make up the tire sensor and the installation effort. In addition, reliability is maintained.

  In addition, since the power generation unit provided in advance in the tire sensor is used for detecting the rotation of the wheel, the structure of the tire sensor is maintained in the same manner as in the prior art, and there is no further complexity. That is, the configuration for detecting the rotation of the wheel in the tire sensor can be simplified.

  According to a second aspect of the present invention, in the tire sensor according to the first aspect, the tire sensor stores a power generated by the power generation unit, and supplies the stored power to the tire sensor. The gist is that is provided.

  According to such a configuration, since power is stably supplied from the secondary battery to the tire sensor, the operation of the tire sensor is stabilized and the rotation of the wheel can be detected more suitably. .

  According to a third aspect of the present invention, in the tire sensor according to the first or second aspect, the power generation unit has a predetermined change in at least one of a voltage and a current of electric power generated when the wheel is rotating. The control unit detects that the wheel is not rotating based on the fact that the predetermined change has not occurred in at least one of the voltage and current of the generated power. Is the gist.

  According to such a configuration, since it is suitably detected that the wheel is not rotating, for example, the frequency of wireless transmission in the tire sensor can be suitably changed based on the detection result. . In addition, if the frequency of wireless transmission is reduced based on the fact that the wheel is not rotating, the power consumption can be reduced.

  Invention of Claim 4 is a tire sensor as described in any one of Claims 1-3. WHEREIN: The said control part rotated the change of the voltage of the electric power generated by the said electric power generation part, and the said wheel rotated. The gist of the invention is to detect rotation of the wheel based on comparison with a change in voltage set in advance as a change in voltage of power generated by the power generation unit.

  According to such a configuration, since the rotation of the wheel can be detected by comparing the voltage of the electric power generated by the power generation unit with a change in a preset voltage, it is easy to detect the rotation of the wheel. Thereby, the tire sensor can appropriately perform wireless transmission of data based on the rotation of the wheel.

  According to a fifth aspect of the present invention, in the tire sensor according to the fourth aspect, the change in the preset voltage of the electric power is associated with a vibration state of the wheel that changes based on a traveling environment of the vehicle. The change in the voltage set by the power generation unit is detected by comparing the change in the voltage of the electric power generated by the power generation unit with the change in the preset voltage. Further, the gist is to wirelessly transmit data indicating the vibration state of the wheel together with data indicating the state of the tire.

  According to such a configuration, the traveling environment of the vehicle can be detected based on a change in the voltage of the generated power. As a result, the tire sensor can perform appropriate processing according to the traveling environment. In addition, in a device that acquires a tire state from a tire sensor, for example, a tire state monitoring device, it is possible to grasp the traveling environment of the vehicle together with the tire state and perform vehicle control according to the traveling environment. Become.

  A sixth aspect of the present invention is the tire sensor according to any one of the first to fifth aspects, wherein when the rotation of the wheel is not detected, the frequency of the wireless transmission is reduced. To do.

  According to such a configuration, when the rotation of the wheel is not detected, the frequency of wireless transmission from the transmission unit is reduced, so that the power consumption of the tire sensor is reduced. Thereby, the usable period of the power supply provided in the tire sensor can be extended.

  A seventh aspect of the present invention is the tire sensor according to any one of the first to sixth aspects, wherein when the rotation of the wheel is detected, the frequency of the wireless transmission is increased. And

  According to such a configuration, when the rotation of the wheel is detected, the frequency of wireless transmission from the transmission unit increases, so the tire state measured by the tire sensor is provided with higher frequency and accuracy, for example, to a monitoring device or the like Will be able to.

  In order to solve the above-described problem, an invention according to claim 8 is provided with a tire sensor that is provided in a tire of a vehicle and wirelessly transmits data indicating the state of the tire acquired by acquiring the state of the tire, A tire condition monitoring device provided on a vehicle body of a vehicle and including a receiving device that receives the data transmitted from the tire sensor, wherein the tire sensor is a tire according to any one of claims 1 to 7. The gist is that it consists of sensors.

According to such a configuration, data indicating the state of the tire can be transmitted according to the rotation of the wheel, so that the tire state monitoring accuracy is maintained at an appropriate level according to the rotation state of the wheel. Will be able to. That is, for example, unnecessary wireless communication can be suppressed. As a result, the tire sensor can suppress unnecessary wireless communication and extend the life of the power source, and the tire condition can also be suitably monitored as a tire condition monitoring device using the tire sensor. Since the period in which the data can be created is extended, the convenience is improved.

  In particular, when the data indicating the tire state is received together with the data indicating the tire state from the tire sensor, the tire state monitoring device can acquire the traveling environment of the vehicle from the received wheel vibration state. Thereby, the tire condition monitoring device can provide the vehicle traveling environment to the vehicle, and the vehicle can perform suspension control according to the provided traveling environment.

  Therefore, according to the above-described invention, a tire that can detect the rotation of the tire and suppress the wireless transmission frequency of the tire state according to the detected rotation of the tire while suppressing an increase in the number of members. A sensor and a tire condition monitoring device using the tire sensor can be provided.

1 is a schematic configuration diagram showing a vehicle equipped with a tire condition monitoring device according to an embodiment of the present invention. Sectional drawing of the wheel and tire with which the sensor unit used for the tire condition monitoring apparatus of the embodiment was provided. The block diagram which shows the circuit structure of the sensor unit of the embodiment. The block diagram which shows schematic structure of the sensor unit controller of the embodiment. The graph which shows an example of the state of the voltage of the electric power which the electric power generating apparatus of the embodiment is generating. (A) (b) The graph which shows an example of the generated voltage data based on the generated electric power of the electric power generating apparatus of the embodiment. (A)-(c) The graph which shows the example in which generated voltage data changes in the embodiment. (A)-(c) The graph which shows the example in which generated voltage data change a lot in the embodiment. The block diagram which shows the circuit structure of the conventional tire condition monitoring apparatus.

Hereinafter, an embodiment embodying the present invention will be described with reference to the drawings.
FIG. 1 shows a vehicle 1 equipped with a tire condition monitoring device. The tire condition monitoring device includes four sensor units 3 as tire sensors that are respectively attached to four wheels 5 of the vehicle 1 and a receiver unit 4 as a receiving device installed on the vehicle body of the vehicle 1. The sensor unit 3 and the receiver unit 4 constitute a tire pressure monitoring device as a tire condition monitoring device.

  As shown in FIGS. 1 and 2, each sensor unit 3 is fixed to the wheel 5 on which the tire 6 is mounted so as to be disposed in the internal space of the tire 6. The sensor unit 3 integrally includes a tire valve 3 a that penetrates the wheel 5. Each sensor unit 3 detects the state (internal air pressure, internal temperature, etc.) of the corresponding tire 6 and wirelessly transmits a signal including data indicating the detected tire state, that is, a tire state data signal.

As shown in FIG. 3, each sensor unit 3 includes a pressure sensor 11 constituting a measurement unit, a temperature sensor 12 constituting a measurement unit, a sensor unit controller 13 constituting a measurement unit and a control unit, and a transmission circuit as a transmission unit. 14 and an antenna 18. Each sensor unit 3 includes a secondary battery 15 for storing electric power necessary for the operation of the sensor unit 3, a power generation device 16 as a power generation unit for generating electric power necessary for the operation of the sensor unit 3, and A charge / discharge circuit 17 is provided.

  The secondary battery 15 is a known secondary battery that can repeatedly charge and discharge electric power, and includes, for example, a nickel-cadmium battery, a nickel-hydrogen battery, a lithium ion battery, or the like.

  The power generation device 16 generates electric power in response to the movement of the wheel 5 and outputs the generated power to the charge / discharge circuit 17. The power generation device 16 is, for example, a device that generates power by a piezoelectric element (piezo element) according to a change in applied force, a device that generates power by induced electromotive force by electromagnetic induction, a device that generates power by electrostatic induction by an electret, or the like. is there. The power generation device 16 supplies the generated power to the secondary battery 15 and the sensor unit controller 13 via the charge / discharge circuit 17.

  A sensor unit controller 13, a secondary battery 15, and a power generation device 16 are connected to the charge / discharge circuit 17. The charge / discharge circuit 17 supplies power generated by the power generation device 16 to the sensor unit controller 13 and, when there is surplus in generated power, causes the secondary battery 15 to charge the surplus power, while there is a shortage in generated power. The insufficient power is discharged from the secondary battery 15. As described above, since the secondary battery 15 is sequentially charged with the surplus power of the power generation device 16, the charge amount of the secondary battery 15 is suitably maintained.

  That is, each sensor unit 3 is supplied with electric power from the secondary battery 15 or the power generation device 16 that is a power source built in the sensor unit 3, and operates with the supplied electric power.

  The pressure sensor 11 measures the internal air pressure of the corresponding tire 6 and outputs an electric signal Sp corresponding to the air pressure obtained by the measurement to the sensor unit controller 13. The temperature sensor 12 measures the internal temperature of the corresponding tire 6 and outputs an electric signal St corresponding to the temperature obtained by the measurement to the sensor unit controller 13. In this embodiment, since the output of the power generation device 16 is connected to the sensor unit controller 13, the generated power of the power generation device 16 is input to the sensor unit controller 13 as an electric signal Sg corresponding to the state of the generated power. The

  The sensor unit controller 13 includes a microcomputer including a CPU, a RAM, and a ROM, and an ID code (identification code) that is unique identification information is registered in the ROM. This ID code is information used to identify the sensor unit 3 in the receiver unit 4 installed on the vehicle body.

  The sensor unit controller 13 generates a tire condition data signal including air pressure data, temperature data, and an ID code, and outputs the tire condition data signal to the transmission circuit 14. The transmission circuit 14 modulates the tire condition data signal from the sensor unit controller 13 into an RF signal (high frequency signal) having a predetermined carrier frequency, and causes the antenna 18 to wirelessly transmit the RF signal.

As shown in FIG. 4, the sensor unit controller 13 includes a sensor interface 20, a rotation detection unit 21, and a transmission controller 22. The sensor interface 20 converts various electric signals including voltages and capacitances input from various sensors and measurement objects into data suitable for processing by the sensor unit controller 13 as necessary. It is. For example, the sensor interface 20 receives an electrical signal (analog) from a sensor or the like, and performs digital processing suitable for processing by the sensor unit controller 13 by performing waveform shaping (for example, pal shaping) on the received electrical signal (analog). Convert to signal. Since the sensor interface 20 receives the electrical signal Sp corresponding to the air pressure from the pressure sensor 11, the sensor interface 20 generates air pressure data based on the received electrical signal Sp as necessary. Further, since the sensor interface 20 receives the electrical signal St corresponding to the temperature from the temperature sensor 12, the sensor interface 20 generates temperature data based on the received electrical signal St as necessary. The air pressure data and temperature data generated by the sensor interface 20 are input to the transmission controller 22.

  Furthermore, since the sensor interface 20 receives the electrical signal Sg corresponding to the voltage state of the generated power of the power generation device 16, the sensor interface 20 generates generated voltage data based on the received electrical signal Sg as necessary. The generated voltage data generated by the sensor interface 20 is input to the rotation detection unit 21. The generated voltage data is generated as data indicating changes in the voltage of the generated power that changes based on the force received by the power generation device 16 due to the vibration of the vehicle 1 or the force acting on the power generation device 16 as the wheel 5 rotates. The For example, when the power generation device 16 receives relatively small vibrations and pressures at a constant cycle, the generated voltage data has a substantially constant cycle and a constant amplitude as shown in each period excluding the time t1 and its vicinity in FIG. Obtained as data. On the other hand, when the power generation device 16 receives vibration with a relatively large amplitude or cycle, the generated voltage data is data having a relatively large cycle and a relatively large amplitude as shown at time t1 and its vicinity in FIG. can get.

  By the way, the voltage of the electric power generated by the power generation device 16 is defined according to the power generation principle of the power generation device 16, the installation state with respect to the wheel 5, the road surface condition, the direction and the magnitude of the centrifugal force acting by the rotation of the tire 6, and the like. The The voltage of the electric power generated by the power generation device 16 shows a predetermined change according to the movement of the wheel 5. Therefore, in the present embodiment, the configuration of the power generation device 16 and the installation state of the power generation device 16 on the wheel 5 are selected so that a change that can determine the rotation of the wheel 5 occurs in the power generation voltage data.

  Note that the configuration of the power generation device 16 that can acquire suitable power generation voltage data in this embodiment and the installation state of the power generation device 16 on the wheel 5 are determined by experiments, simulations, and mounting in an actual vehicle. ing.

  Since the rotation detection unit 21 performs a process of detecting the rotation of the tire 6 (wheel 5) based on the generated voltage data, the tire 6 (wheel 5) is determined based on the generated voltage data input from the sensor interface 20. Detects rotation. In the rotation detection unit 21, the rotation detection program stored in the ROM or the like of the sensor unit controller 13 is executed by the CPU of the sensor unit controller 13, whereby the rotation detection process of the tire 6 is performed. In the rotation detection process, it is detected whether or not the tire 6 is rotating based on, for example, comparing a change generated in the generated voltage data with a preset rotation detection condition. When the tire 6 is rotating, the rotation detection unit 21 may further detect the rotation speed. Information on whether or not the tire 6 obtained as a result of the rotation detection process by the rotation detection unit 21 is rotating is input to the transmission controller 22.

Note that the rotation detection condition in the present embodiment is set as follows. That is, with respect to the power generation device 16 mounted on the wheel 5, comparison data is generated as power generation voltage data for setting rotation detection conditions based on experiments and simulations in advance and measurement of the voltage of generated power in an actual vehicle. And various conditions necessary for detecting the rotation of the wheel 5, for example, characteristic values and changes indicating that the wheel 5 is not rotating, or characteristic values indicating that the wheel 5 is rotating And changes are extracted from the comparison data. The extracted condition is set as the rotation detection condition. Such a rotation detection condition may be one or a plurality of threshold values, map data, an arithmetic expression, or the like as long as the rotation of the wheel 5 can be detected.

  The transmission controller 22 generates a tire condition data signal including air pressure data, temperature data, and an ID code to be output to the transmission circuit 14 and adjusts (controls) the frequency of wireless transmission of the tire condition data signal by the transmission circuit 14. . While the pneumatic pressure data and the temperature data are input to the sensor interface 20, the rotation detection processing result is input from the rotation detection unit 21. Thus, the transmission controller 22 generates a tire condition data signal including air pressure data and temperature data, and causes the transmission circuit 14 to perform wireless transmission based on the result of the rotation detection process. For example, when a result that the tire 6 is not rotating is obtained by the rotation detection process, the transmission controller 22 reduces the frequency of wireless transmission by preventing the transmission circuit 14 from wirelessly transmitting the tire state data signal. . On the other hand, when the result that the tire 6 is rotating is obtained by the rotation detection process, the transmission controller 22 increases the frequency of wireless transmission by causing the transmission circuit 14 to wirelessly transmit the tire condition data signal. . In this case, the tire condition data signal is periodically transmitted at a predetermined time interval, for example, every one minute interval. Thereby, when the tire 6 is not rotating and the monitoring of the tire condition is unnecessary, the transmission controller 22 suppresses the wireless transmission with a large amount of power consumption, thereby suppressing the consumption of the secondary battery 15. The usable period of the power (remaining capacity) charged in the battery is extended. On the other hand, when the tire 6 is rotating and the tire condition needs to be monitored, the transmission controller 22 appropriately transmits the tire condition data signal wirelessly so that the tire condition monitoring device can suitably monitor the tire condition. To be done.

  As shown in FIG. 1, the receiver unit 4 is installed at a predetermined location of the vehicle body, and operates by power from a battery (not shown) of the vehicle 1, for example. The receiver unit 4 includes at least one antenna 32, a receiver unit controller 33, a receiving circuit 35, an alarm device 37, and a display 38. The receiver unit controller 33 includes a microcomputer including a CPU, a ROM, and a RAM.

  The receiving circuit 35 demodulates a signal (tire condition data signal) received from each sensor unit 3 through the antenna 32 and sends the demodulated signal to the receiver unit controller 33. The receiver unit controller 33 grasps the internal air pressure and the internal temperature of the tire 6 corresponding to the transmission source sensor unit 3 based on the tire condition data signal from the receiving circuit 35.

  The receiver unit controller 33 also causes the display 38 to display information relating to the internal air pressure and internal temperature of the tire 6. The indicator 38 is arranged in the visible range of the passenger of the vehicle 1 such as the passenger compartment. Further, the receiver unit controller 33 notifies an alarm (notifier) 37 of an abnormality in the internal air pressure and internal temperature of the tire 6. As the alarm device 37, for example, a device for notifying abnormality by sound or a device for notifying abnormality by light is applied. In addition, you may display the abnormality of internal air pressure and internal temperature on the indicator 38 as an alarm.

  Next, an example of rotation detection processing of the tire 6 (wheel 5) performed by the sensor unit 3 of the present embodiment will be described with reference to FIG. FIG. 6 is a graph showing an example of the generated voltage data, where (a) is a graph when the wheel 5 is not rotating, and (b) is a graph when the wheel 5 is rotating at a constant speed. is there.

As shown in FIG. 6A, when the wheel 5 is not rotating, the sensor interface 20 maintains the magnitude L0, which is a value indicating that the generated voltage is “0”, as the generated voltage data. Generate data. On the other hand, as shown in FIG. 6B, when the wheel 5 is rotating, the sensor interface 20 generates data whose value vibrates with respect to the magnitude L0 as the generated voltage data. Therefore, the rotation detection unit 21 can detect the rotation of the wheel 5 by detecting that the generated voltage data is oscillating with respect to the magnitude L0. It is to be noted that the oscillation of the generated voltage data is detected based on whether the value of the generated voltage data exceeds a threshold set in advance to a magnitude different from the magnitude L0, or the absolute value of the generated voltage data It is possible to detect by using various known calculation methods, such as detecting when the integrated value exceeds a predetermined value. The threshold value and the predetermined value used in such various calculation methods can be obtained from the above-described comparison data, and the obtained value is set in the ROM of the sensor unit controller 13 as the threshold value or the predetermined value. Is done.

  For this reason, the rotation detection unit 21 of the sensor unit controller 13 can detect that the wheel 5 (tire 6) is rotating based on the change in the voltage of the generated power of the power generation device 16.

  In the present embodiment, since the traveling environment (road surface state) of the vehicle 1 can be estimated, the estimation of the traveling environment will be described with reference to FIGS. 7 and 8. FIGS. 7A to 7C are graphs showing an example in which the generated voltage data changes in the rotating wheel 5. FIGS. 8A to 8C are graphs showing an example in which the generated voltage data changes relatively greatly in the rotating wheel 5.

  While the vehicle 1 is traveling, the generated voltage data changes depending on the traveling environment due to the vibration of the tire 6 caused by the traveling environment of the vehicle 1. For example, when the tire 6 vibrates in accordance with the unevenness of the driving environment, as shown in FIG. 7A, the generated voltage data changes gradually so that the magnitude of the value exceeds L1 at time t1, for example. Is detected as the first data. Further, for example, when the tire 6 vibrates in accordance with the larger unevenness of the driving environment, as shown in FIG. 7B, the generated voltage data has a value that exceeds L1 at time t1, for example. It is detected as second data that changes sharply. Further, for example, when the tire 6 vibrates according to a plurality of large irregularities in the driving environment, as shown in FIG. 7C, the generated voltage data has a value L1 at the time t1 and the time t2, for example. Is detected as third data that sharply changes to exceed. Each piece of data thus detected is compared with comparison data detected from a tire 6 that has been vibrated under a predetermined condition in advance, and similar comparison data is specified, so that the vehicle 1 travels from the generated voltage data. The environment can be estimated.

  In general, it can be estimated that the road environment in which the first data is detected is gentler (flat) on the road surface than the road environment in which the second data is detected. Further, it can be estimated that the driving environment in which the second data is detected has less road surface unevenness than the driving environment in which the third data is detected. On the other hand, if it is due to the influence of the difference in travel speed, it is usually estimated that the speed is high when the vibration is large or the frequency is high. Can be estimated to be faster than the first data. Similarly, the speed of the vehicle 1 can be estimated to be faster than the second data in the case of the third data. That is, it is possible to estimate these traveling environments by comparing the first to third data with the comparison data in the sensor unit 3.

Further, when the tire 6 vibrates in accordance with the unevenness of the driving environment, as shown in FIG. 8A, the generated voltage data has a value larger than the previous L1, for example, at time t1. It is detected as fourth data that gradually changes so as to exceed a certain L2. For example, when the tire 6 vibrates according to the large unevenness of the driving environment, as shown in FIG. 8B, the generated voltage data changes drastically so that the magnitude of the value exceeds L2, for example, at time t1. Is detected as fifth data. For example, when the tire 6 vibrates in accordance with a plurality of large irregularities in the driving environment, as shown in FIG. 8C, the generated voltage data has a value of L2 at time t1 and time t2, for example. It is detected as sixth data that changes drastically so as to exceed. In this case as well, similar to the case of FIG. 7 described above, the data detected in this way is compared with comparison data detected in advance from the tire 6 that has been vibrated under a predetermined condition. Thus, the traveling environment of the vehicle 1 can be estimated from the generated voltage data.

  Normally, when the fourth to fifth data as shown in FIG. 8 is detected, the data value is larger than the first to third data as shown in FIG. Thus, as the traveling environment of the vehicle 1, it can be estimated that the unevenness of the road surface is more severe than when the first to third data are detected. On the other hand, when such a difference in the value of the data is due to a difference in traveling speed, it is usually estimated that the speed is high when the vibration is large. Therefore, the traveling speed is determined from the fourth to fifth data. It can be estimated to be high. That is, the estimation relating to the travel environment can be performed by comparing the fourth to sixth data with the comparison data in the sensor unit 3.

  In addition, as in the case of FIG. 7, it is estimated that the driving environment in which the fourth data is detected has a gentle (flat) road surface unevenness compared to the driving environment in which the fifth data is detected. Can do. In addition, it can be estimated that the driving environment in which the fifth data is detected has less road surface unevenness than the driving environment in which the sixth data is detected. That is, it is possible to estimate the travel environment by comparing the fourth to sixth data with the comparison data in the sensor unit 3.

  The traveling environment of the vehicle 1 estimated in this way can be transmitted to the vehicle 1 via the receiver unit 4 by wireless transmission from the transmission circuit 14 as traveling environment data. According to this, the vehicle 1 can use the traveling environment data for various controls such as suspension control of the vehicle 1.

  As shown in the present embodiment, the rotation detection unit 21 of the sensor unit controller 13 detects the rotation of the wheel 5 (tire 6) based on the change in the voltage of the generated power of the power generation device 16, and therefore the rotation of the wheel 5 is detected. It is not necessary to install a dedicated sensor for detection. In addition, the frequency of wireless transmission can be changed according to the rotation of the wheel 5. Further, since the power generation device 16 provided in advance in the sensor unit 3 is used, an increase in the number of parts and installation work as the sensor unit 3 are suppressed, reliability is maintained, and the structure is further complicated. There is no such thing as. That is, the configuration for detecting the rotation of the wheel 5 in the sensor unit 3 can be simplified with a reduced number of members.

As described above, according to the tire valve unit of the present embodiment, the effects listed below can be obtained.
(1) The rotation of the wheel 5 is detected based on a change in the voltage of the electric power generated by the power generation device 16 provided in the sensor unit 3 in advance. Therefore, the sensor unit 3 can detect the rotation of the wheel 5 without providing a dedicated sensor for detecting the rotation of the wheel 5. Thus, even if the frequency of wireless transmission from the transmission circuit 14 is changed, the sensor unit 3 does not require a sensor for detecting the rotation of the wheel 5, and the number of components constituting the sensor unit 3 is increased or the number of installations is reduced. This saves time and effort while maintaining reliability.

  (2) Since the power generation device 16 provided in advance in the sensor unit 3 is used for detecting the rotation of the wheel 5, the structure of the sensor unit 3 is maintained in the same manner as in the prior art, and there is no further complexity. That is, the configuration for detecting the rotation of the wheel 5 in the sensor unit 3 can be simplified.

  (3) Since power is stably supplied from the secondary battery 15 to the sensor unit 3, the operation of the sensor unit 3 is stabilized and the rotation of the wheel can be detected more suitably.

  (4) Since it is suitably detected that the wheel 5 is not rotating, for example, the frequency of wireless transmission in the sensor unit 3 can be suitably changed based on the detection result. In addition, if the frequency of wireless transmission is reduced based on the fact that the wheel 5 is not rotating, the power consumption can be reduced.

  (5) Since the rotation of the wheel 5 can be detected by comparing the voltage of the electric power generated by the power generation device 16 with a change in voltage set in advance, the rotation of the wheel 5 can be easily detected. Accordingly, the sensor unit 3 can appropriately perform wireless transmission of data based on the rotation of the wheel 5.

  (6) The traveling environment of the vehicle 1 can be detected based on the change in the voltage of the generated power. As a result, the sensor unit 3 can perform appropriate processing according to the traveling environment. In addition, in a device that acquires a tire state from the sensor unit 3, such as a tire state monitoring device, it is possible to grasp the traveling environment of the vehicle 1 together with the tire state and perform vehicle control or the like according to the traveling environment. It also becomes.

  (7) Since the frequency of wireless transmission from the transmission circuit 14 is decreased when the rotation of the wheel 5 is not detected, the power consumption of the sensor unit 3 is decreased. Thereby, the usable period of the charge capacity of the secondary battery 15 provided in the sensor unit 3 can be extended.

  (8) Since the frequency of wireless transmission from the transmission circuit 14 is increased when rotation of the wheel 5 is detected, the tire state measured by the sensor unit 3 is provided with higher frequency and accuracy, for example, to a tire pressure monitoring device or the like Will be able to.

  (9) Since unnecessary wireless communication of the sensor unit 3 can be suppressed and the life of the power source can be extended, the tire condition monitoring device using the sensor unit 3 also has a period during which the tire condition can be suitably monitored. Since it extends, the convenience improves.

  (10) Since the tire condition monitoring device can receive the data indicating the tire condition from the sensor unit 3 and the data indicating the vibration condition of the wheel 5, the traveling environment of the vehicle 1 can be determined from the received vibration condition of the wheel 5. You can get it. Thereby, the tire condition monitoring device can provide the traveling environment of the vehicle 1 to the vehicle 1, and the vehicle 1 can perform suspension control according to the provided traveling environment.

In addition, the said embodiment can also be implemented in the following aspects, for example.
-In the said embodiment, when rotation of the wheel 5 is not detected, the frequency of radio transmission becomes low. Not limited to this, a configuration in which the frequency of previous wireless transmission is maintained may be maintained for a predetermined period after the rotation of the wheel 5 is not detected. Moreover, in the said embodiment, when rotation of the wheel 5 is detected, the frequency of radio transmission becomes high. Not only this but the structure where the frequency of the previous radio | wireless transmission is maintained for a predetermined period after the rotation of the wheel 5 is detected may be sufficient.

In the above embodiment, the case where the sensor unit 3 is provided with the pressure sensor 11 and the temperature sensor 12 is illustrated. However, the present invention is not limited to this, and the sensor unit may be provided with a sensor other than the pressure sensor and the temperature sensor, for example, a sensor for measuring the tire condition. Thereby, the performance as a sensor unit comes to improve.

  In the above embodiment, the case where the secondary battery 15 is provided in the sensor unit 3 is illustrated. However, the present invention is not limited to this, and the primary battery may be provided together with the secondary battery, or the secondary battery may not be provided. Even when the secondary battery is not provided, the sensor unit is driven based on the power generation of the power generation device when the tire rotates.

  In the above embodiment, the case where the secondary battery 15 is provided in the sensor unit 3 is illustrated. However, the present invention is not limited to this, and a battery other than what is generally referred to as a secondary battery, such as a capacitor, may be used as long as it can be charged and discharged like a secondary battery. Thereby, the design freedom of a sensor unit comes to improve.

  In each of the above embodiments, the case where the rotation of the wheel 5 is detected based on the change in the voltage of the power generated by the power generation device 16 has been illustrated. However, the present invention is not limited to this, and the rotation of the wheel may be detected based on the change in the current of the power generated by the power generation device, or based on the change in the voltage and current of the power generated by the power generation device. You may make it detect. Thereby, the design freedom of a sensor unit comes to improve.

  DESCRIPTION OF SYMBOLS 1 ... Vehicle, 3 ... Sensor unit, 3a ... Tire valve, 4 ... Receiver unit, 5 ... Wheel, 6 ... Tire, 11 ... Pressure sensor, 12 ... Temperature sensor, 13 ... Sensor unit controller, 14 ... Transmission circuit, 15 ... Secondary battery, 16 ... Power generation device, 17 ... Charge / discharge circuit, 18 ... Antenna, 20 ... Sensor interface, 21 ... Rotation detector, 22 ... Transmission controller, 32 ... Antenna, 33 ... Receiver unit controller, 35 ... Reception Circuit 37 ... alarm device 38 ... display device 50 ... tire sensor 51 ... acceleration sensor

Claims (8)

A measurement unit that measures the state of the tire mounted on the wheel of the vehicle;
A transmission unit that wirelessly transmits data indicating the state of the tire measured by the measurement unit;
A power generation unit that generates electric power in response to the movement of the wheel as the vehicle travels,
A tire sensor mounted on the wheel,
A control unit configured to detect rotation of the wheel based on a change in at least one of a voltage and a current of electric power generated by the power generation unit, and to change the frequency of the wireless transmission based on the detected rotation of the wheel; A tire sensor. The tire sensor according to claim 1, wherein the tire sensor is provided with a secondary battery that stores electric power generated by the power generation unit and supplies the stored electric power to the tire sensor. The power generation unit
A predetermined change in at least one of the voltage and current of the electric power generated when the wheel is rotating,
The controller is
The tire sensor according to claim 1 or 2, wherein it is detected that the wheel is not rotating based on the fact that the predetermined change has not occurred in at least one of the voltage and current of the generated electric power. The controller is
Based on comparing the change in voltage of the power generated by the power generation unit with a change in voltage preset as a change in voltage of power generated by the power generation unit when the wheel rotates, the wheel The tire sensor according to any one of claims 1 to 3. The change in the voltage of the preset power is a change in the voltage set in association with the vibration state of the wheel that changes based on the driving environment of the vehicle,
By comparing the change in the voltage of the power generated by the power generation unit with the change in the preset voltage, the vibration state of the wheel is detected, and data indicating the detected vibration state of the wheel is obtained. The tire sensor according to claim 4, wherein the tire sensor is wirelessly transmitted together with data indicating the state of the tire. The tire sensor according to any one of claims 1 to 5, wherein when the rotation of the wheel is not detected, the frequency of the wireless transmission is decreased. The tire sensor according to any one of claims 1 to 6, wherein when the rotation of the wheel is detected, the frequency of the wireless transmission is increased. A tire sensor that is provided in a vehicle tire and wirelessly transmits data indicating the tire state acquired by acquiring the tire state; and the data that is provided in the vehicle body of the vehicle and transmitted by the tire sensor. A tire condition monitoring device comprising a receiving device for receiving,
The tire sensor comprises the tire sensor according to any one of claims 1 to 7. A tire condition monitoring device, characterized in that:

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