JP2015136945A - Tire pneumatic pressure monitoring device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a tire pneumatic pressure monitoring device that can accurately monitor pneumatic pressure of a tire.SOLUTION: A tire sensor unit 13 is installed in each of a plurality of wheels. The tire sensor unit 13 detects a distance D between a wheel portion 5 and a tread portion 7 of a tire 6, and detects acceleration of the wheel. When the wheel has a specific angle on the basis of the acceleration of the vehicle, normal time processing for monitoring the pneumatic pressure of the tire 6 on the basis of the distance D is executed. In contrast, when a specific condition where the acceleration of the wheel exceeds an upper limit or lower limit threshold value is satisfied, the normal time processing is not executed.

Description

  The present invention relates to a tire pressure monitoring device that monitors tire pressure.

  When the air pressure of the tire provided in the vehicle is reduced, there is a risk of causing a reduction in fuel consumption or uneven wear in which a part of the tire is worn unevenly. For this reason, a tire pressure monitoring device is provided in the vehicle, and the tire pressure is monitored.

  There is a wireless tire pressure monitoring device as a device in which a plurality of wheels with tires mounted on a wheel portion are provided in a vehicle and the tire pressure can be monitored. Such an apparatus is configured to include a tire sensor unit (wheel side unit) provided in a tire of each wheel of the vehicle and a receiver (receiver unit) provided in a vehicle body of the vehicle. The tire sensor unit for each wheel includes a detection unit that detects tire air pressure and a transmission unit that wirelessly transmits a signal related to the detection result.

  In addition, for example, the device started in Patent Document 1 includes a detection unit that detects the distance between the wheel unit and the tread portion of the tire, the tire distortion is specified based on the distance, and the tire air pressure is reduced. An apparatus is disclosed in which a warning is shown.

Japanese Patent Laid-Open No. 7-81337

  However, in such a tire pressure monitoring device, since the ground contact state of the tire changes while the vehicle is running, for example, the wheel portion and the tread portion of the tire when the tire is grounded or not. The tire pressure could not be monitored accurately, such as the distance to

  The present invention has been made in view of the above-described conventional problems, and an object of the present invention is to provide a tire pressure monitoring device capable of accurately monitoring the tire pressure.

  A tire air pressure monitoring device that solves the above problems is a tire air pressure monitoring device that is provided in a vehicle including a plurality of wheels with tires mounted on a wheel portion and monitors the air pressure of the tire, and is provided for each of the plurality of wheels. Includes a distance detection unit that detects a distance between the wheel unit and the tread portion of the tire, and an acceleration detection unit that detects acceleration of the wheel, and the acceleration of the wheel detected by the acceleration detection unit When the wheel is at a specific angle, the normal time processing for monitoring the tire air pressure based on the distance between the wheel portion and the tread portion of the tire is executed, while the acceleration detecting portion A control unit is provided that does not execute the normal processing when a special condition exceeding an upper limit or lower limit threshold is established for the detected acceleration of the wheel. The gist of the door.

  According to this, when the wheel is at a specific angle based on the acceleration of the wheel, the normal time process for monitoring the tire air pressure based on the distance between the wheel portion and the tire tread portion is executed. The distance between the wheel portion and the tread portion of the tire can be detected in such a ground contact state of the wheel, and a decrease in tire air pressure can be accurately monitored. On the other hand, if a special condition exceeding the upper limit or lower limit threshold is satisfied for the acceleration of the wheel, the normal process is not executed. For this reason, an upper limit or a lower limit threshold can be set for the acceleration of the wheel, and when the acceleration of the wheel exceeds the upper limit or the lower limit threshold, execution of the normal time process can be restricted.

The tire pressure monitoring device may be configured such that the control unit does not monitor the tire pressure when the special condition is satisfied.
According to this, when the special condition is satisfied, for example, even when the distance between the wheel portion and the tread portion of the tire becomes an excessive distance, the tire air pressure is not monitored based on the distance, and the tire The air pressure drop can be monitored accurately.

  In the tire pressure monitoring device, when the special condition is satisfied, the control unit, when the wheel is at a specific angle based on the acceleration of the wheel detected by the acceleration detection unit, It is good also as a structure which performs the special time process which correct | amends the distance with the tread part of a tire, and monitors the air pressure of the said tire.

  According to this, when the special condition is satisfied, even if the distance between the wheel portion and the tread portion of the tire becomes an excessive distance, for example, based on the corrected distance by correcting the distance. Tire pressure is monitored, and a decrease in tire pressure can be accurately monitored.

About the said tire pressure monitoring apparatus, the said distance detection part is good also as a structure which detects the distance of the said wheel part and the tread part of the said tire by transmission and reception of an electromagnetic wave.
About the said tire pressure monitoring apparatus, the said specific angle is good also as a structure which is an angle by which the distance of the said wheel part detected by the said distance detection part and the tread part of the said tire is shortened.

  According to this, in a specific angle where the distance between the wheel portion and the tread portion of the tire is shortened, the distance is easily changed by the tire air pressure, and the decrease in the tire air pressure is accurately monitored. be able to.

  According to the present invention, it is possible to accurately monitor a decrease in tire air pressure.

The schematic block diagram which shows the vehicle by which the tire condition monitoring apparatus of embodiment is mounted. Sectional drawing which shows a tire, a wheel part, and a tire sensor unit. The figure which shows the circuit structure of a tire sensor unit. The figure which shows the relationship between the position of a tire sensor unit, and the distance measured. Sectional drawing which shows a tire, a wheel part, and a tire sensor unit.

Hereinafter, an embodiment in which the tire pressure monitoring device is embodied will be described with reference to FIGS.
As shown in FIG. 1, the vehicle 10 is equipped with a tire condition monitoring device 30. The four wheels 1 to 4 of the vehicle 10 are composed of a wheel portion 5 and a tire 6 attached to the wheel portion 5.

Next, the tire condition monitoring device 30 will be described.
The tire condition monitoring device 30 includes a tire sensor unit 13 that is attached to each of the four wheels 1 to 4 of the vehicle 10, and a receiver unit 31 that is installed on the vehicle body of the vehicle 10.

  As shown in FIG. 2, a tire sensor unit 13 is disposed in the wheel portion 5 integrally with the tire valve 8. The tire sensor unit 13 detects the distance D between the wheel rim 5a of the wheel portion 5 and the tread portion 7 of the tire 6 and wirelessly transmits a transmission signal (detection result information) including information on various detection results. Specifically, the tire sensor unit 13 detects a linear distance between the wheel rim 5 a of the wheel portion 5 and the tread portion 7 of the tire 6 along the radial direction of the tire 6. In the present embodiment, in order to facilitate understanding of the invention, the description of the error in the distance D due to the thickness of the tire sensor unit 13 and the tread portion 7 is omitted.

  As shown in FIG. 3, each tire sensor unit 13 includes a sensor unit controller 14, an RF sensor 15, an acceleration sensor 16, and a battery 20. The tire sensor unit 13 operates by supplying power from the battery 20. In the present embodiment, the tire sensor unit 13 is not provided with a pressure sensor or a temperature sensor, and is a sealed sensor that does not need to take in air in the tire 6.

  The RF sensor 15 serving as a distance detection unit is a sensor that combines various functions using radio waves in the same frequency band (in this embodiment, 2.4 GHz). The RF sensor 15 outputs a transmission signal (transmission data) to the receiver unit 31 and a distance detection function 15a that detects the distance from the object based on the phase difference between the radio wave radiated into the space and the radio wave reflected by the object. The sensor also has a data communication function 15b.

  The acceleration sensor 16 serving as an acceleration detection unit is a sensor that rotates together with the wheels 1 to 4 and detects acceleration in the centrifugal direction of the wheels 1 to 4, and outputs detected acceleration data to the sensor unit controller 14.

  The sensor unit controller 14 includes a microcomputer including a CPU 14a and a storage unit 14b (RAM, ROM, etc.). The storage unit 14 b of the sensor unit controller 14 stores an overall program that comprehensively controls the operation of the tire sensor unit 13.

  The acceleration sensor 16 rotates with the wheels 1 to 4 to detect the acceleration of the wheels 1 to 4 at predetermined intervals and outputs a signal indicating the acceleration to the sensor unit controller 14. Therefore, a plurality of acceleration data are input to the sensor unit controller 14 during a certain period, and the plurality of acceleration data are stored in the storage unit 14b.

  The sensor unit controller 14 as the control unit determines whether or not the stored acceleration data is within an effective range. In the present embodiment, the effective range is larger than a lower threshold that is detected as the vehicle 10 is traveling, and smaller than an upper threshold that is not affected by stepping, sudden braking, or sudden turning. It is specified in the range. When it is determined that the acceleration data is within the valid period, the sensor unit controller 14 identifies the acceleration data as valid data, and determines whether or not the wheels 1 to 4 are at a specific angle from the acceleration data. .

  When it is determined that the wheels 1 to 4 are at a specific angle, the sensor unit controller 14 causes the RF sensor 15 to output a detection signal, and causes the RF sensor 15 to output the wheel rim 5a of the wheel portion 5 and the tread portion of the tire 6. 7 is detected. Therefore, distance data is input to the sensor unit controller 14 for a fixed period, and the distance data is stored in the storage unit 14b.

  The RF sensor 15 detects a radio wave reflected by a steel wire embedded in the tread portion 7 of the tire 6 while emitting a radio wave in response to a signal input from the sensor unit controller 14. The RF sensor 15 detects the distance D between the wheel rim 5a of the wheel portion 5 and the tread portion 7 of the tire 6 from the phase difference between the radio waves, and outputs the distance data obtained by the detection to the sensor unit controller 14. To do. In the present embodiment, a portion where the distance D is detected by the tire sensor unit 13 in the tread portion 7 is referred to as a measurement portion 7a.

  As shown in FIG. 4, the specific angle is an angle at which the measurement unit 7 a is positioned below and is in contact with the ground. The tire 6 is most heavily loaded, and the wheel rim 5 a of the wheel unit 5 and the tire 6 are loaded. This is the angle at which the distance D to the tread portion 7 is minimized.

  A threshold for comparison with distance data detected by the RF sensor 15 is stored in advance in the storage unit 14b of the sensor unit controller 14 shown in FIG. The threshold value is information unique to the tire 6 and is set with a margin more than the distance data detected when the air pressure of the tire 6 enclosed by the wheel portion 5 and the tire 6 becomes excessively low. When the distance data detected by the RF sensor 15 exceeds the threshold value, the sensor unit controller 14 generates a transmission signal indicating a warning and causes the RF sensor 15 to transmit it. On the other hand, when the distance data detected by the RF sensor 15 does not exceed the threshold value, the sensor unit controller 14 does not generate a transmission signal indicating a warning. In addition, such processing in the present embodiment is referred to as normal processing.

  In the present embodiment, when the sensor unit controller 14 determines that the stored acceleration data is not within the effective range, the distance D between the wheel rim 5a of the wheel portion 5 and the tread portion 7 of the tire 6 is detected by the RF sensor 15. Do not detect itself. That is, if a special condition is established that the acceleration data is not within the effective range, such normal processing is not executed, and the air pressure of the tire 6 is not monitored.

  As shown in FIG. 1, the receiver unit 31 as a receiver includes a receiver unit controller 33 and an RF receiving circuit 35 as a receiving circuit. A display unit 38 is connected to the receiver unit controller 33 of the receiver unit 31. The receiver unit controller 33 is composed of a microcomputer including a CPU and a storage unit (ROM, RAM, etc.), and a program for comprehensively controlling the operation of the receiver unit 31 is stored in the storage unit. The RF reception circuit 35 demodulates the RF signal (transmission signal) received from each tire sensor unit 13 through the RF reception antenna 32 and sends it to the receiver unit controller 33.

  Based on the RF signal from the RF receiving circuit 35, the receiver unit controller 33 specifies that the state (air pressure) of the tire 6 corresponding to the tire sensor unit 13 of the transmission source has exceeded a threshold value. The receiver unit controller 33 causes the display 38 to display information related to the air pressure of the tire 6. The indicator 38 is disposed in the visible range of the passenger of the vehicle 10 such as the passenger compartment, and displays (notifies) an abnormality in the air pressure of the tire 6 specified by the receiver unit controller 33.

Next, the operation of the tire pressure monitoring device of this embodiment will be described.
In the present embodiment, the tire sensor unit 13 detects the acceleration of the wheels 1 to 4, the acceleration of the wheels 1 to 4 is within the effective range, and the wheels 1 to 4 are based on the acceleration of the wheels 1 to 4. When it is determined that the angle is a specific angle, the distance D between the wheel rim 5a of the wheel portion 5 and the tread portion 7 of the tire 6 is detected. The wheel rim 5a of the wheel portion 5 and the tread of the tire 6 are determined when it is determined that the acceleration of the wheels 1 to 4 is not within the effective range or the wheels 1 to 4 are not at a specific angle based on the acceleration. The distance D with the part 7 is not detected. When the detected distance D is equal to or less than the threshold value, it is determined that the tire 6 has a reduced air pressure, and a transmission signal indicating a warning is output to the receiver unit 31. In the receiver unit 31, a state based on an input of a transmission signal indicating a warning is displayed on the display unit 38. On the other hand, when the distance D is not less than or equal to the threshold value, it is determined that the tire 6 does not have a reduced air pressure, and the tire sensor unit 13 does not generate a transmission signal indicating a warning.

Therefore, according to the above embodiment, the following effects can be obtained.
(1) Normally, when the wheels 1 to 4 are at a specific angle based on the acceleration of the wheels 1 to 4, the air pressure of the tire 6 is monitored based on the distance D between the wheel portion 5 and the tread portion 7 of the tire 6. Since the time process is executed, the distance D can be detected in the ground contact state of the wheels 1 to 4 and the decrease in the air pressure of the tire 6 can be accurately monitored.

  (2) On the other hand, if a special condition exceeding the upper limit or lower limit threshold is satisfied for the acceleration of the wheels 1 to 4, the normal process is not executed. For this reason, it becomes possible to set an upper limit or a lower limit threshold for the acceleration of the wheels 1 to 4, and when the acceleration of the wheel exceeds the upper limit or the lower limit threshold, the execution of the normal process can be restricted.

  (3) Further, when the special condition is satisfied, for example, even when the distance D between the wheel portion 5 and the tread portion 7 of the tire 6 becomes an excessive distance, the air pressure of the tire 6 is determined based on the distance D. Monitoring is not performed, and a decrease in the air pressure of the tire 6 can be accurately monitored.

  (4) When the acceleration of the wheels 1 to 4 is equal to or lower than the lower limit threshold value, the normal time process is not executed. For this reason, for example, a lower limit threshold is set for the acceleration of the wheels 1 to 4 so that the vehicle 10 does not travel, and when the air pressure of the tire 6 is monitored, the vehicle 10 is not traveling. For example, power saving can be achieved without performing normal processing.

  (5) At a specific angle where the distance D between the wheel portion 5 and the tread portion 7 of the tire 6 is shortened, the distance D is easily changed by the air pressure of the tire 6, and the air pressure of the tire 6 decreases. Can be accurately monitored.

  (6) Each of the plurality of wheels 1 to 4 is provided with an RF sensor 15, and a function 15 a for detecting the distance D between the wheel portion 5 and the tread portion 7 of the tire 6 by transmitting and receiving radio waves, and the detection thereof. And a function 15b for transmitting detection result information based on the detection result by transmission of radio waves. For this reason, while being able to monitor the air pressure of the tire 6 by the distance D between the wheel part 5 and the tread part 7 of the tire 6, for example, a detection part for detecting the air pressure of the tire 6 and a transmission part for transmitting detection result information There is no need to provide both. Therefore, the air pressure of the tire 6 can be monitored without increasing the size.

  (7) Further, it is possible to determine a decrease in the air pressure of the tire 6 based on the detected distance D. For this reason, it is not necessary to form the air hole which takes in the air for detecting the air pressure of the tire 6 in the tire sensor unit 13, and it is possible to suppress the entry of foreign matter due to dew condensation or tire puncture repair agent.

(8) The tire sensor unit 13 is disposed on the wheel portion 5 side. For this reason, the tire sensor unit 13 can be integrated with the tire valve 8.
In addition, you may change embodiment as follows.

  When the special condition that the acceleration exceeds the upper limit or lower limit threshold is satisfied, the distance D between the wheel portion 5 and the tread portion 7 of the tire 6 when the wheels 1 to 4 are at a specific angle based on the acceleration of the wheel. And a special time process for monitoring the air pressure of the tire 6 may be executed. According to this, even if the distance D is an excessive distance, for example, by correcting the distance D, the tire air pressure is monitored based on the corrected distance, and the tire air pressure is monitored. The decrease can be monitored with high accuracy.

  As shown in FIG. 5, for example, the tire sensor unit 13 may be attached to the inner peripheral surface 7 b of the tread portion 7 of the tire 6. As a result, the RF sensor 15 built in the tire sensor unit 13 is disposed on the tread portion 7 side of the tire 6, and the RF rim 5a of the wheel portion 5 formed of a metal plate having a high radio wave reflectance is an RF sensor. The radio wave transmitted from 15 is reflected, and the detection accuracy of the reflected radio wave can be improved. Further, since the identification information unique to the tire 6 is stored in the tire sensor unit 13, for example, when changing the combination of the wheel unit 5 and the tire 6, it is possible to save the trouble of inputting identification information unique to the tire 6. For example, convenience can be improved.

  -The threshold value is not prescribed | regulated about the acceleration itself of the wheels 1-4, the threshold value may be prescribed | regulated about the variation | change_quantity with the previous acceleration and the present acceleration, and these combination may be sufficient. In particular, when the traveling speed of the vehicle 10 is high, the angular speed of the wheels 1 to 4 increases, so that a large centrifugal force is applied to the acceleration sensor 16 of the tire sensor unit 13 and a large acceleration may be detected. In this way, it is sufficient to determine at least one of the acceleration itself (absolute value) of the wheels 1 to 4 or the amount of change in the acceleration of the wheels 1 to 4, and control is performed so as to be switchable. Also good. For example, when it is determined that the acceleration of the wheels 1 to 4 has increased, both determinations such as determining the amount of change in the acceleration of the wheels 1 to 4 may be performed in duplicate. Further, for example, the determination target may be switched by further combining the speed and acceleration of the vehicle by the speed measurement unit and the acceleration measurement unit provided on the vehicle body of the vehicle 10. Further, for example, when determining the lower limit threshold value of the acceleration of the wheels 1 to 4, when determining the absolute value of the acceleration of the wheels 1 to 4, and when determining the upper limit threshold value of the acceleration of the wheels 1 to 4, the wheels 1 to 4 are determined. Different control may be performed in the determination of the upper limit threshold and the determination of the lower limit threshold, such as determining the amount of change in acceleration of No. 4.

  -No threshold is defined for the air pressure of the tire 6 itself or the distance D itself between the wheel portion 5 and the tread portion 7 of the tire 6, and the amount of change between the previous air pressure and the current air pressure, A threshold value may be defined for the amount of change from the current distance, or a combination thereof.

  A transmission signal indicating distance data and acceleration data may be output from the tire sensor unit 13 to the receiver unit 31, and the receiver unit 31 may monitor the air pressure of the tire 6. Further, the control unit for monitoring the air pressure of the tire 6 may be included in the tire sensor unit 13, the receiver unit 31, or a combination thereof. In this case, specific information that can specify the type of tire, a threshold value corresponding to the specific information, a determination table, or the like may be stored in the storage unit of the receiver unit 31 or stored in the sensor unit controller 14. May be output from the tire sensor unit 13 to the receiver unit 31.

-It is not restricted to the apparatus which monitors the fall of the air pressure of the tire 6, For example, the apparatus which measures the present air pressure of a tire may be used.
-You may control a specific angle so that a certain range may be taken. Further, the angle may be an angle at which the measuring unit 7a is positioned above, instead of the angle at which the measuring unit 7a is positioned below and grounded.

Although both the upper limit threshold and the lower limit threshold of acceleration are set, for example, either one may be set or none may be set.
The tire sensor unit 13 may include a pressure sensor and a temperature sensor in addition to the RF sensor 15 and the acceleration sensor 16.

  The tire condition monitoring device 30 is not limited to being applied to the tire 6 in the four-wheel vehicle 10, and may be applied to tires in vehicles other than four wheels such as two wheels, three wheels, four wheels or more. .

  The transmitter of the tire sensor unit 13 may be a transmission circuit that generates an LF signal instead of the RF sensor 15 that generates an RF signal. Further, for example, the RF sensor 15 may not have both the function of measuring the distance D and the function of outputting a transmission signal. Further, the distance detection unit may use a measurement unit that measures other elements such as infrared rays, ultrasonic waves, and capacitance without using radio waves.

  The tire sensor unit 13 may include a circuit (for example, an LF trigger circuit) that can communicate with the operation device in addition to the communication with the receiver unit 31. For example, various types of information such as information indicating the type of tire, information indicating a cycle for monitoring the tire state, and information for starting monitoring of the tire state may be input through such communication. Further, it may be an RF signal or a low frequency signal.

The receiving circuit of the receiver unit 31 may be a low-frequency LF receiving circuit instead of the RF receiving circuit 35.
Next, a technical idea that can be grasped from the above embodiment and other examples will be described below.

  (A) The distance detection unit transmits a detection result information based on the detected detection result by transmitting a radio wave and a function of detecting a distance between the wheel unit and the tread portion of the tire by transmitting and receiving the radio wave. It also has the function to perform.

(B) The distance detection unit is provided on the wheel unit side.
(C) The distance detector is provided on the tread portion side of the tire.
(D) A tire air pressure monitoring device that is provided in a vehicle having a plurality of wheels with tires mounted on the wheel portion and monitors the air pressure of the tire, wherein each of the plurality of wheels includes the wheel portion and the tire. A distance detection unit that detects a distance from the tread unit; and an acceleration detection unit that detects an acceleration of the wheel. The wheel is at a specific angle based on the acceleration of the wheel detected by the acceleration detection unit. In this case, the tire air pressure is monitored based on the distance between the wheel portion and the tread portion of the tire.

  DESCRIPTION OF SYMBOLS 1-4 ... Wheel, 5 ... Wheel part, 6 ... Tire, 7 ... Tread part, 10 ... Vehicle, 13 ... Tire sensor unit, 14 ... Sensor unit controller, 15 ... RF sensor, 16 ... Acceleration sensor, 20 ... Battery, 30 ... Tire condition monitoring device, 33 ... Receiver unit controller, 35 ... RF receiving circuit.

Claims (5)

A tire pressure monitoring device that is provided in a vehicle including a plurality of wheels with tires mounted on a wheel portion and monitors tire pressure,
Each of the plurality of wheels includes a distance detection unit that detects a distance between the wheel unit and the tread portion of the tire, and an acceleration detection unit that detects acceleration of the wheel.
Normal time when the tire pressure is monitored based on the distance between the wheel portion and the tread portion of the tire when the wheel is at a specific angle based on the acceleration of the wheel detected by the acceleration detection portion. A tire pressure monitoring apparatus comprising a control unit that does not execute the normal process when a special condition that exceeds an upper limit or lower limit threshold is satisfied for the acceleration of the wheel detected by the acceleration detection unit while executing the process.   The tire pressure monitoring device according to claim 1, wherein the control unit does not monitor the tire air pressure when the special condition is satisfied.   The control unit, when the special condition is satisfied, when the wheel is at a specific angle based on the acceleration of the wheel detected by the acceleration detection unit, the distance between the wheel unit and the tread portion of the tire The tire pressure monitoring apparatus according to claim 1, wherein a special time process for correcting the tire pressure and monitoring the tire pressure is executed.   The tire pressure monitoring device according to any one of claims 1 to 3, wherein the distance detection unit detects a distance between the wheel unit and the tread portion of the tire by transmitting and receiving radio waves.   The said specific angle is an angle by which the distance of the said wheel part detected by the said distance detection part and the tread part of the said tire is shortened, It is any one of Claims 1-4. Tire pressure monitoring device.