JP6027043B2 - Tire condition monitoring device - Google Patents

Description

  The present invention relates to a tire condition monitoring device including a tire sensor unit provided on each wheel and a receiver unit installed on a vehicle body of the vehicle in order to monitor the condition of tires of a plurality of wheels provided on the vehicle.

  As a device for enabling a driver to check the state of a plurality of tires provided in a vehicle in a passenger compartment, a wireless tire state monitoring device has been proposed. In general, a tire condition monitoring device includes a plurality of tire sensor units mounted on each wheel of a vehicle and a receiver unit mounted on a vehicle body of the vehicle. Each tire sensor unit includes a battery as a power source, and a pressure sensor or the like operates by supplying power from the battery to detect a pressure in the tire or the like. Further, each tire sensor unit wirelessly transmits a data signal indicating the detected tire state to the receiver unit by supplying power from the battery. On the other hand, the receiver unit receives the data signal transmitted from each tire sensor unit, and displays information related to the tire pressure and the like on a display provided in the vehicle compartment as necessary.

  Further, in the tire condition monitoring device, the received data signal indicates from which tire sensor unit provided in which tire of the plurality of tire sensor units, in other words, the received data signal. The position of the associated wheel is specified in the receiver unit.

  As this type of tire condition monitoring device, for example, Patent Document 1 can be cited. In Patent Document 1, each wheel of the wheel is provided with a first sensor (tire sensor unit). A second sensor (ABS) is provided corresponding to the wheel. In Patent Document 1, a measurement system provided in a vehicle includes a receiver that detects a signal from a first sensor, an input-side module for detecting a signal from a second sensor, and a microcontroller and a memory. Prepare.

  And in patent document 1, although a 1st sensor transmits the signal which shows the position regarding the position of a wheel and the information regarding a tire at the preset angle, this transmission operation is performed by the electric power supply from a battery. . The position at which the first sensor transmits a signal is detected by an acceleration sensor that is provided in the first sensor and that operates by supplying power from the battery (position detection). The receiver receives the signal transmitted by the first sensor. Further, the input side module receives the signal of the second sensor. Then, the microcontroller determines the phase position of the signal of the first sensor, and when the phase position remains within a predetermined allowable range in a predetermined monitoring engine, the position of the wheel provided with the first sensor. Is to identify.

Special table 2011-527971 gazette

  By the way, in Patent Document 1, in a tire sensor unit that operates by supplying power from a battery, when the battery power consumption proceeds and the battery voltage decreases, a signal indicating information about the tire is transmitted from the tire sensor unit. It becomes impossible to transmit, and the tire condition cannot be grasped by the receiver unit.

  An object of the present invention is to provide a tire sensor unit having a position detection function that can maintain a state detection value transmission operation for a longer time compared to a case in which position detection is continued when a battery voltage decreases. It is to provide a state monitoring device.

  A tire condition monitoring device for solving the above problems is installed in a tire sensor unit provided in each wheel and in a vehicle body of the vehicle in order to monitor the condition of tires of a plurality of wheels provided in the vehicle. A receiver unit, the tire sensor unit having a battery, an acceleration sensor that rotates together with a wheel to detect acceleration, a state detector that detects the state of the tire, and a control unit; and an acceleration sensor Position detection for detecting the angle of the tire sensor unit at the wheel based on the acceleration obtained by the above-mentioned operation, and receiving a state detection value when the position detection detects that the tire sensor unit is positioned at a preset angle. In the tire condition monitoring device that performs a transmission operation to be transmitted to the machine unit, the tire sensor unit includes a monitoring unit that monitors the battery voltage. The control unit stops the position detection when the battery voltage monitored by the monitoring unit falls below a preset threshold during the transmission operation after the position detection, and performs only the transmission operation. The gist.

  According to this, position detection is stopped when the battery voltage monitored by the monitoring unit falls below a preset threshold value. For this reason, the battery voltage drop caused by the position detection is eliminated. As a result, during the transmission operation, the state detection value detected by the state detector can be transmitted to the receiver unit without the battery voltage falling below the minimum operation voltage, and the transmission operation of the state detection value can be maintained. In addition, since there is no power consumption for position detection, battery power consumption can be suppressed in a tire sensor unit having a position detection function.

In the tire condition monitoring device, the control unit may restart the position detection when the battery voltage exceeds a preset value after stopping the position detection.
The tire condition monitoring device according to claim 3 is a tire sensor unit provided on each wheel and a receiver installed on the vehicle body of the vehicle in order to monitor the condition of tires of a plurality of wheels provided on the vehicle. The tire sensor unit includes a battery, an acceleration sensor that rotates together with the wheel to detect acceleration, a state detector that detects the state of the tire, and a control unit, and is obtained by the acceleration sensor. Position detection for detecting the angle of the tire sensor unit at the wheel based on the acceleration that has been detected, and when the position detection detects that the tire sensor unit is positioned at a preset angle, a status detection value is received. In the tire condition monitoring device that performs a transmission operation to transmit to the unit, the tire sensor unit includes a temperature detector that measures the ambient temperature of the battery. The control unit is configured to stop the position detecting ambient temperature is lower than the preset temperature of the battery is summarized in that to perform the transmission operation only.

  According to this, when the ambient temperature of a battery becomes low, it becomes difficult to ensure the minimum operating voltage of the battery. In this case, since position detection is not performed, a decrease in battery voltage caused by performing position detection is eliminated. Accordingly, the state detection value detected by the state detector can be transmitted to the receiver unit without the battery voltage falling below the minimum operating voltage, and the transmission operation of the state detection value can be maintained. In addition, since there is no power consumption for position detection, battery power consumption can be suppressed in a tire sensor unit having a position detection function.

  Moreover, about a tire condition monitoring apparatus, the said control part may restart the said position detection, if the ambient temperature of the said battery exceeds the preset temperature after stopping the said position detection.

  According to the present invention, in the tire sensor unit having a position detection function, the transmission operation of the state detection value can be maintained for a longer time than in the case where the position detection is continued when the battery voltage decreases.

The schematic block diagram which shows the vehicle by which the tire condition monitoring apparatus is mounted. The block diagram which shows the circuit structure of a tire sensor unit. The graph which shows the relationship between the voltage of a battery, and time. The graph which shows the relationship between battery capacity and time.

Hereinafter, an embodiment in which the tire condition monitoring device is embodied will be described with reference to FIGS.
As shown in FIG. 1, the tire condition monitoring apparatus includes four tire sensor units 3 that are respectively attached to four wheels 2 of the vehicle 1 and a receiver unit 4 that is installed on the vehicle body of the vehicle 1. Each wheel 2 includes a wheel portion 5 and a tire 6 attached to the wheel portion 5.

  Each tire sensor unit 3 is attached to the wheel portion 5 to which the tire 6 is mounted so as to be disposed in the internal space of the tire 6. Each tire sensor unit 3 detects the state of the corresponding tire 6 (in-tire pressure, in-tire temperature), and wirelessly transmits a signal including data indicating the detected tire state. Each tire sensor unit 3 is attached to the wheel portion 5 so as to be positioned on the outer surface side of the vehicle 1.

  As shown in FIG. 2, each tire sensor unit 3 includes a pressure sensor 11 as a state detector, a temperature sensor 12 as a state detector and a temperature detector, an acceleration sensor 13, a voltage sensor 17 as a monitoring unit, and a control unit. As a sensor unit controller 14 and an RF transmitter circuit 16 as a transmitter. The pressure sensor 11, the temperature sensor 12, the acceleration sensor 13, the sensor unit controller 14, the voltage sensor 17, and the RF transmission circuit 16 are each operated by supplying power from the battery 15. The pressure sensor 11 detects a pressure in the corresponding tire 6 (in-tire pressure), and outputs tire pressure data as a state detection value obtained by the detection to the sensor unit controller 14. The temperature sensor 12 detects the temperature in the corresponding tire 6 (in-tire temperature), and outputs the in-tire temperature data as the state detection value obtained by the detection to the sensor unit controller 14.

  The acceleration sensor 13 is a uniaxial acceleration sensor, and is well known as, for example, a piezoresistive type or a capacitance type acceleration sensor. The acceleration sensor 13 outputs acceleration data as acceleration obtained by the detection to the sensor unit controller 14. As the acceleration sensor 13, an acceleration sensor capable of detecting an acceleration component in a direction along one detection axis is used. The voltage sensor 17 detects the voltage of the battery 15 at regular time intervals, and outputs a detection value (voltage data) obtained by the detection to the sensor unit controller 14.

  The sensor unit controller 14 includes a microcomputer including a CPU and a storage unit 14a (RAM, ROM, etc.), and an ID code that is identification information unique to each tire sensor unit 3 is registered in the storage unit 14a. This ID code is information used to identify each tire sensor unit 3 in the receiver unit 4 and is included in a signal transmitted from the sensor unit controller 14. The sensor unit controller 14 outputs a signal including tire pressure data, tire temperature data, acceleration data, and an ID code to the RF transmission circuit 16. The RF transmission circuit 16 generates a modulation signal obtained by modulating the signal from the sensor unit controller 14 and wirelessly transmits the modulation signal from the transmission antenna 18.

  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 a receiving antenna 32 disposed at an arbitrary position on the vehicle body, receives signals from the tire sensor units 3 through the receiving antennas 32, and processes the received signals.

  The receiver unit 4 includes a receiver unit controller 33, an RF receiving circuit 35 as a receiving unit, and a display 38. The receiver unit controller 33 is composed of a microcomputer including a CPU and a storage unit 33a (ROM, RAM, etc.), and comprehensively controls the operation of the receiver unit 4. The RF receiving circuit 35 demodulates a signal (modulated signal) received from each tire sensor unit 3 through the receiving antenna 32 and sends the demodulated signal to the receiver unit controller 33. Based on the signal from the RF receiving circuit 35, the receiver unit controller 33 grasps the tire pressure and the tire temperature of the tire 6 corresponding to the tire sensor unit 3 that is the transmission source.

  Furthermore, the receiver unit controller 33 determines which wheel 2 of the vehicle 1 the tire sensor unit 3 of the transmission source is based on the ID code included in the signal from the RF reception circuit 35. judge. Then, the receiver unit controller 33 causes the indicator 38 to display the tire pressure and the tire temperature related to the determined wheel 2. The indicator 38 is arranged in the visible range of the passenger of the vehicle 1 such as the passenger compartment.

Next, a configuration for suppressing power consumption of the battery 15 in the tire sensor unit 3 will be described.
First, the transmission operation by the tire sensor unit 3 will be described.

  In the four tire sensor units 3, the acceleration sensor 13 detects acceleration at regular time intervals and outputs the detected acceleration data to the sensor unit controller 14. The sensor unit controller 14 detects the angle of the tire sensor unit 3 at the wheel 2 based on the acceleration detected by the acceleration sensor 13 (position detection). The reason for detecting the angle of the tire sensor unit 3 is to transmit a signal from the RF transmission circuit 16 when the tire sensor unit 3 is positioned at a preset angle. In the four tire sensor units 3, angles at which signals are transmitted from the RF transmission circuit 16 are set in advance, and the angles differ among the four tire sensor units 3.

  When the sensor unit controller 14 determines that the tire sensor unit 3 is located at a preset angle based on the detected acceleration, the sensor unit controller 14 uses the RF transmission circuit 16 to transmit the tire pressure data, A signal including temperature data, acceleration data, and an ID code is transmitted to the receiver unit 4. This transmission operation is performed a plurality of times with respect to data transmitted in one transmission operation in order to increase the reception rate at the receiver unit 4.

  As shown in FIG. 3, every time position detection using the acceleration sensor 13 is performed, the battery voltage is lowered in the battery 15. In addition, the battery voltage of the battery 15 is lowered every time the RF transmitter circuit 16 performs a transmission operation. In addition, compared with the detection of the acceleration by the acceleration sensor 13, the battery voltage decreases more during the transmission operation by the RF transmission circuit 16. When the battery voltage decreases, the electromotive force of the battery 15 decreases and the voltage of the battery 15 also decreases.

  In the storage unit 14 a of the sensor unit controller 14, a voltage threshold 1 that is required in the transmission operation from the RF transmission circuit 16 is stored in advance. This voltage threshold 1 is set with a margin for the voltage at which the transmission operation by the RF transmission circuit 16 becomes unstable.

  Further, the voltage threshold 2 is stored in the storage unit 14 a of the sensor unit controller 14, and the voltage threshold 2 is set higher than the minimum operating voltage and the voltage threshold 1 of the battery 15. Furthermore, the storage unit 14 a of the sensor unit controller 14 stores in advance a temperature threshold value that makes it difficult to ensure the minimum operating voltage of the battery 15. This temperature threshold is a temperature at which the electromotive force of the battery 15 is increased and the minimum operating voltage can be secured when the ambient temperature of the battery 15 exceeds the temperature threshold. The storage unit 14a of the sensor unit controller 14 stores a program executed by the sensor unit controller 14 when the voltage of the battery 15 falls below the voltage threshold value 1.

Next, the control executed by the sensor unit controller 14 when the voltage of the battery 15 falls below the voltage threshold 1 will be described together with the operation.
In each tire sensor unit 3, in a state where the voltage of the battery 15 is detected by the voltage sensor 17, the acceleration is detected by the acceleration sensor 13 a plurality of times, and the position of the tire sensor unit 3 is detected. At this time, the battery voltage does not fall below the voltage threshold value 1. When it is determined that the tire sensor unit 3 is located at a preset angle based on the acceleration detected by the acceleration sensor 13, the sensor unit controller 14 directs the signal to the receiver unit 4 by the RF transmission circuit 16. To send multiple times. That is, a signal transmission operation is performed.

  When the battery voltage detected during this transmission operation falls below the voltage threshold 1, the sensor unit controller 14 stops position detection for the next transmission operation performed after the current (three times) transmission operation. . Therefore, in the next transmission operation, the battery voltage does not decrease due to position detection. As a result, in the next transmission operation, the battery voltage decreases from the voltage restored after the previous transmission operation, and there is no voltage decrease corresponding to position detection. Absent.

  After the battery voltage falls below the voltage threshold 1 and position detection by the acceleration sensor 13 is stopped, when the voltage of the battery 15 detected by the voltage sensor 17 exceeds the voltage threshold 2, the sensor unit controller 14 performs the next transmission operation. In this case, position detection is resumed.

  As shown in FIG. 4, the change in battery capacity when the transmission operation is continued without stopping the position detection is shown by a solid line. On the other hand, a change in battery capacity when control for stopping position detection is performed is shown by a one-dot chain line. As indicated by the alternate long and short dash line, when position detection is stopped, power consumption associated with position detection disappears after the stop, and only power consumption associated with transmission operation occurs. For this reason, when the position detection is stopped, the speed of power consumption of the battery 15 becomes slower than when the position detection is continued, and it is possible to prolong the time until the limit of the battery capacity is reached. .

According to the above embodiment, the following effects can be obtained.
(1) Based on the acceleration detected by the acceleration sensor 13, the angle of the tire sensor unit 3 at the wheel 2 is detected (position detection), and the tire sensor unit 3 that performs the transmission operation at the set angle performs the transmission operation. When the battery voltage of the battery 15 falls below the preset voltage threshold 1, the position detection is stopped. Therefore, since the battery voltage drop due to position detection is eliminated, the transmission operation of tire pressure data and tire temperature data is maintained for a longer time than when position detection is continued when the battery voltage drops. can do.

  (2) In the transmission operation, a signal is transmitted a plurality of times in order to ensure the reception rate at the receiver unit 4. When the battery voltage falls below the voltage threshold value 1, the position detection is only stopped and the number of transmissions is not reduced. Therefore, the reception rate of each data in the receiver unit 4 does not decrease.

In addition, you may change this embodiment as follows.
○ Although the voltage sensor 17 is used as the monitoring unit for monitoring the battery voltage, a current sensor is provided instead of the voltage sensor 17 as the monitoring unit, and the battery voltage is monitored by detecting the current of the battery 15. Also good. The threshold value in this case depends on the current.

  In the embodiment, the voltage sensor 17 is not provided, and the position detection may be stopped when the ambient temperature of the battery 15 falls below a preset temperature threshold based on the detection result of the temperature sensor 12. Note that the temperature threshold for stopping position detection may be higher than the minimum operating temperature.

  When the ambient temperature decreases, the battery voltage decreases, and it is difficult to ensure the minimum operating voltage of the battery 15. In this case, by stopping the position detection, the battery voltage drop due to the position detection is eliminated, and therefore, compared with the case where the position detection is continued when the battery voltage is lowered, the tire pressure data for a longer time, and Transmission operation of tire temperature data can be maintained.

Then, when the ambient temperature of the battery 15 detected by the temperature sensor 12 exceeds a preset temperature, the position detection by the acceleration sensor 13 may be resumed.
A position when the battery voltage detected by the voltage sensor 17 exceeds the preset voltage threshold 2 and the ambient temperature detected by the temperature sensor 12 exceeds the preset temperature in a state where the position detection is stopped. Detection may be resumed.

  In the embodiment, if the battery voltage falls below the preset voltage threshold 1, the position detection may not be resumed after the next transmission operation. In this case, compared with the case where position detection is restarted, the time until the battery capacity limit is reached can be further prolonged.

  In the embodiment, if the voltage sensor 17 is not provided, the battery voltage becomes lower than the minimum operating voltage, the RF transmission circuit 16 cannot transmit, and the tire sensor unit 3 is reset, the sensor unit controller 14 The position detection may be stopped.

In the transmission operation, the number of signal transmissions by the RF transmission circuit 16 may be one.
In the embodiment, the transmission operation is based on the acceleration detected by the acceleration sensor 13 and transmits a state detection value at a preset angle. However, the transmission operation is performed with the acceleration information detected by the acceleration sensor 13. The detection value may be transmitted, and the position detection may be performed by the receiver unit 4.

  In the embodiment, the state detection value is the tire pressure data and the tire temperature data, but not limited thereto, the state detection value may be only the tire pressure. Alternatively, the state detection value may be tire pressure data and other data.

In the embodiment, the acceleration sensor 13 is a uniaxial acceleration sensor, but may be a biaxial or triaxial acceleration sensor.
The transmission unit may be an LF transmission circuit instead of the RF transmission circuit 16.

The tire condition monitoring device may be applied not to the vehicle 1 having four wheels 2 but to a vehicle having two or three wheels 2.
Next, the technical idea that can be grasped from the above embodiment and other examples will be described below.

  (B) A tire condition monitoring device in which the signal is transmitted a plurality of times.

  DESCRIPTION OF SYMBOLS 1 ... Vehicle, 2 ... Wheel, 3 ... Tire sensor unit, 4 ... Receiver unit, 6 ... Tire, 11 ... Pressure sensor as state detector, 12 ... Temperature sensor as state detector and temperature detector, 13 ... Accelerometer, 14... Sensor unit controller as control unit, 15... Battery, 17.

Claims (4)

In order to monitor the state of tires of a plurality of wheels provided on a vehicle, the vehicle includes a tire sensor unit provided on each wheel, and a receiver unit installed on a vehicle body of the vehicle, the tire sensor unit including a battery An acceleration sensor that rotates together with the wheel to detect acceleration, a state detector that detects the state of the tire, and a control unit, and the wheel of the tire sensor unit based on the acceleration obtained by the acceleration sensor A tire state that performs position detection for detecting the angle of the vehicle and a transmission operation for transmitting the state detection value to the receiver unit when the position detection detects that the tire sensor unit is positioned at a preset angle. In the monitoring device,
The tire sensor unit includes a monitoring unit that monitors a battery voltage, and the control unit detects that the battery voltage monitored by the monitoring unit is lower than a preset threshold during a transmission operation after the position detection. A tire condition monitoring device that stops position detection and performs only a transmission operation.   The tire condition monitoring device according to claim 1, wherein after the position detection is stopped, the control unit restarts the position detection when the battery voltage exceeds a preset value. In order to monitor the state of tires of a plurality of wheels provided on a vehicle, the vehicle includes a tire sensor unit provided on each wheel, and a receiver unit installed on a vehicle body of the vehicle, the tire sensor unit including a battery An acceleration sensor that rotates together with the wheel to detect acceleration, a state detector that detects the state of the tire, and a control unit, and the wheel of the tire sensor unit based on the acceleration obtained by the acceleration sensor Tire condition monitoring that performs position detection for detecting the angle of the vehicle and transmission operation for transmitting the state detection value to the receiver unit when the position detection detects that the tire sensor unit is positioned at a preset angle. In the device
The tire sensor unit includes a temperature detector that measures the ambient temperature of the battery, and the control unit stops position detection and performs only a transmission operation when the ambient temperature of the battery becomes lower than a preset temperature. The tire condition monitoring apparatus characterized by the above-mentioned.   The tire state monitoring device according to claim 3, wherein after the position detection is stopped, the control unit restarts the position detection when an ambient temperature of the battery exceeds a preset temperature.