JP2007253847A - Tire pneumatic pressure monitoring system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a tire pneumatic pressure monitoring system capable of promoting the adjustment of the optimum pneumatic pressure to a driver irrespective of the change of the tire pneumatic pressure as a vehicle travels. <P>SOLUTION: The tire pneumatic pressure monitoring system for monitoring the tire pneumatic pressure of each tire fitted to a vehicle and presenting the tire pneumatic pressure to a driver comprises a tire pneumatic pressure change detection means (Step S14) for detecting the change of the tire pneumatic pressure from the time immediately after the traveling is started to the present time, a recommended pneumatic pressure correction means (Step S15) for performing the correction by adding the change of the tire pneumatic pressure to the recommended pneumatic pressure specific to the tire, and a display device for presenting the corrected recommended pneumatic pressure to the driver together with the present tire pneumatic pressure. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention belongs to a technical field of a tire pressure monitoring system that monitors tire pressure information of each tire.

In a conventional tire pressure monitoring system, the tire pressure of each tire is monitored, and the tire pressure is presented to the driver using a method such as screen display. The driver compares the presented tire pressure with the recommended tire-specific air pressure to adjust the tire air pressure (see, for example, Patent Document 1).
JP 2005-145113 A

However, in the above-described prior art, there is a possibility that the driver may erroneously adjust the tire pressure.
For example, even if the recommended air pressure is used at the start of traveling, when the tire air pressure is measured again after traveling for a predetermined time, the tire air pressure is high due to the traveling environment such as road surface friction and outside air temperature. At this time, since the recommended air pressure according to the tire temperature is unknown, the driver compares the current tire air pressure with the recommended air pressure when the tire is cold, and decreases the tire air pressure. There is a risk of lower than air pressure.

  The present invention has been made paying attention to the above problems, and an object of the present invention is to provide a tire pressure monitoring system capable of prompting a driver to adjust an optimum air pressure regardless of a change in tire pressure accompanying traveling. It is to provide.

In order to achieve the above object, in the present invention,
In the tire pressure monitoring system that monitors the tire pressure of each tire mounted on the vehicle and presents it to the driver,
Tire pressure change amount detecting means for detecting a change amount of tire air pressure immediately after the start of running until the present time;
Recommended air pressure correcting means for correcting the tire air pressure change amount by adding to the recommended air pressure specific to the tire;
Presenting means for presenting the corrected recommended air pressure along with the current tire pressure to the driver;
A tire comprising:

In the tire pressure monitoring system according to the present invention, the tire pressure change amount from immediately after the start of traveling to the present time is added to the recommended tire-specific air pressure to be corrected and presented to the driver together with the current tire air pressure. Therefore, for example, when adjusting the air pressure at a gas station after traveling for a predetermined time from home, even if the tire pressure is higher than immediately after the start of traveling, the driver changes the current tire pressure and the tire pressure change. The tire pressure can be set to an optimum value by adjusting the air pressure by comparing the recommended air pressure corrected by adding the amount.
As a result, the driver can be urged to adjust the air pressure optimally regardless of changes in tire air pressure associated with traveling.

  Hereinafter, the best mode for realizing the tire pressure monitoring system of the present invention will be described based on the first embodiment.

First, the configuration will be described.
FIG. 1 is a configuration diagram of a tire air pressure monitoring system according to the first embodiment. The tire pressure monitoring system TPMS includes sensor units 10a, 10b, 10c, 10d installed on the tires 2a, 2b, 2c, 2d of the vehicle 1, a receiving antenna 20a disposed on the front side of the vehicle 1, The receiving antenna 20b arrange | positioned at the back side of the vehicle 1, the control apparatus 30, and the display apparatus (presentation means) 40 are provided.

  FIG. 2 is a block diagram of the sensor unit according to the first embodiment. The sensor unit 10 (10a to 10d) includes a tire pressure sensor 11 that detects tire pressure, a rotation sensor 12 that detects the rotation and rotation direction of the tire, a CPU unit 13, an RF unit 14, a transmission antenna 15, And a battery 16 for supplying power to each part.

The rotation sensor 12 is configured using, for example, an acceleration sensor.
The CPU unit 13 is configured using a one-chip microcomputer or the like that incorporates a CPU, ROM, RAM, EEPROM, A / D converter, and the like. The CPU unit 13 captures the output of the tire pressure sensor 11 at predetermined time intervals.

  The CPU unit 13 detects the tire rotation direction based on the output of the rotation sensor 12, and determines that the vehicle is in a stopped state when the output of the rotation sensor 12 does not change. Here, the CPU unit 13 can also be configured to measure the time for one tire rotation (tire rotation speed) based on the output of the rotation sensor 12. The CPU unit 13 holds identification information (ID information) unique to each sensor unit 10 in, for example, an EEPROM or the like.

  FIG. 3 is a diagram illustrating an example of a format of data wirelessly transmitted from the sensor unit according to the first embodiment. As shown in FIG. 3, the CPU unit 13 generates a series of transmission data including a header, a function, identification information (ID), tire pressure information, tire rotation direction information, an error correction code, and the like, and supplies the transmission data to the RF unit 14. To do.

  The RF unit 14 generates a signal obtained by modulating a carrier wave having a predetermined carrier frequency by a predetermined modulation method based on the transmission data, and wirelessly transmits the signal from the transmission antenna 15. If the CPU 13 determines that the vehicle is in a stopped state based on the output of the rotation sensor 12, the CPU 13 performs data transmission, for example, every hour. If the CPU 13 determines that the vehicle is in a traveling state, the CPU 13 transmits data at intervals of several seconds to several minutes.

FIG. 4 is a block configuration diagram of the control device 30 according to the first embodiment.
The control device 30 includes a CPU, ROM, RAM, EEPROM, a one-chip microcomputer 31 having an interface for serial data communication with an in-vehicle LAN communication system, an antenna switching means 32, and a tuner 33.

  The antenna switching means 32 connects the tuner 33 and the receiving antenna 20a when the control device 30 detects the tire pressure of the left and right front wheels 2a and 2b, and detects the tire pressure of the left and right rear wheels 2c and 2d. The tuner 33 and the receiving antenna 20b are connected. The tuner 33 converts the high frequency signal received by the receiving antennas 20 a and 20 b into a voltage signal in a format that can be read by the microcomputer 31, and outputs the voltage signal to the microcomputer 31.

  The microcomputer 31 includes tire low pressure determination means 31a, warning output means 31b, hazard output means 31c, air pressure adjustment support means 31d, air check SW detection means 31e, and recommended air pressure change means 31f. Based on the rotation direction and ID, the received tire pressure and the tire position are associated with each other and monitored, and the air pressure is presented to the driver on the display screen of the display device 40.

The tire low pressure determination means 31a determines whether any one of the tire air pressures input via the tuner 33 is below a preset tire low pressure threshold.
When it is determined that any one of the tire pressures is lower than the tire low pressure threshold, the warning output means 31b turns on or blinks a warning lamp installed in the meter to reduce the tire pressure to the driver. Warning.

When it is determined that any one of the tire air pressures is lower than the threshold value, the hazard output means 31c blinks the hazard lamp with the hazard output.
When an input to the air check SW is performed by the driver, the air pressure adjustment support means 31d displays each current tire pressure and a recommended air pressure that is a tire-specific recommended air pressure on the display device 40.

  The air check SW detection unit 31e detects an input to the air check SW. The recommended air pressure changing means 31f sets an initial air pressure value for setting a recommended air pressure specific to the tire depending on whether or not the host vehicle has just started running, and an input to the air check SW is performed by the driver. At this time, the tire pressure change amount from immediately after the start of traveling to the present time is calculated from the set initial pressure value and the current tire pressure, and the calculated tire air pressure change amount is added to the recommended air pressure for correction.

  The display device 40 is configured using a plurality of lamps, light emitting diodes, or the like that visually display the tire position and abnormality of the tire pressure. The display device 40 may be provided in the instrument panel. The display device 40 may be configured using a display device that can display characters, images, and the like. Furthermore, instead of providing a dedicated display device, a tire status may be displayed using a display device such as a navigation system.

[Pneumatic initial value setting control processing]
FIG. 5 is a flowchart showing the flow of the initial air pressure setting control process executed by the recommended air pressure changing means 31f of the control device 30 of the first embodiment. Each step will be described below. This control process is repeatedly executed every predetermined calculation cycle.

  In step S1, it is determined whether or not the ignition key switch is ON. If yes, then go to step S2, if no, go to return.

  In step S2, it is determined whether or not the previous air pressure initial value is stored in the ROM. If YES, the process proceeds to step S3. If NO, the process proceeds to step S6.

  In step S3, it is determined whether or not the temperature inside the tire of each tire exceeds the outside air temperature. If YES, the process proceeds to step S4. If NO, the process proceeds to step S6.

  In step S4, it is determined whether or not the current vehicle position is a place other than the vicinity of the home. If YES, the process proceeds to step S5. If NO, the process proceeds to step S6.

  In step S5, the previous air pressure initial value is held, and the process proceeds to step S9.

  In step S6, the apparatus waits for air pressure data reception from the transmitting antenna 15, and proceeds to step S7.

  In step S7, it is determined whether or not air pressure data from the transmission antenna 15 has been received. If yes, then continue with step S8, otherwise repeat step S7.

  In step S8, the air pressure initial value is rewritten and updated with the received air pressure data, and the process proceeds to step S9.

  In step S9, it is determined whether or not the ignition key switch is OFF. If YES, the process proceeds to return, and if NO, the process proceeds to step S2.

  That is, the start time of travel is determined by comparing the outside air temperature with the temperature inside the tire in step S3 or by detecting the position of the host vehicle in step S4. The tire pressure is used as the initial pressure value and stored in the ROM. On the other hand, if it is determined that it is not at the start of travel, the air pressure at the previous start of travel recorded in the ROM (previous air pressure initial value) is used as the air pressure initial value in step S5.

[Recommended air pressure setting control process]
FIG. 6 is a flowchart showing a flow of recommended air pressure setting control processing executed by the recommended air pressure changing means 31f of the control device 30 of the first embodiment. Each step will be described below. This control process is repeatedly executed every predetermined calculation cycle.

  In step S11, it is determined whether or not there is an input to the air check SW. If YES, the process proceeds to step S12. If NO, the process proceeds to return.

  In step S12, the apparatus waits for air pressure data reception from the transmitting antenna 15, and proceeds to step S13.

  In step S13, it is determined whether or not air pressure data from the transmission antenna 15 has been received. If yes, then continue with step S14, otherwise repeat step S13.

  In step S14, the tire air pressure change amount is calculated from the difference between the tire air pressure received in step S13 and the initial air pressure value, and the process proceeds to step S15 (tire air pressure change amount detecting means).

  In step S15, the amount of change in air pressure calculated in step S14 is corrected by adding it to the recommended air pressure unique to the tire, and the flow proceeds to return (recommended air pressure correcting means).

Next, the operation of the first embodiment will be described.
[Initial pressure rewriting action according to change in tire pressure]
Normally, the tire pressure changes at the start of running and after 30 minutes from running (measured 2 psi = 13.8 kPa = 0.14 kgf / cm 2). After 30 minutes, the air pressure is almost stable and then fluctuates due to changes in atmospheric pressure. Therefore, it is recommended that the inspection of the tire and adjustment to the recommended air pressure be performed while the tire is cold. After refilling the air pressure at a gas station or the like, the expanded air pressure is measured, the driver compares the measured value with the recommended air pressure, and decides whether to refill or bleed air.

In the technique described in Japanese Patent Laid-Open No. 2000-145113, the tire air pressure of each tire is monitored, and the tire air pressure is presented to the driver using a method such as screen display. The driver compares the presented tire pressure with the recommended tire-specific air pressure, and adjusts the tire pressure. However, in the above-described conventional technology, the driver uses the current tire air pressure when the tire is cold. Compared to the recommended air pressure at the airport, it is more likely that the recommended air pressure will be compared, so if you drive from your home to a gas station and the tire pressure is high due to road conditions such as road surface friction and outside temperature, start running There is a possibility that the tire pressure may be reduced by comparing the tire pressure higher than that immediately after and the recommended pressure, and the tire pressure will be lower than the recommended pressure.

  On the other hand, in the tire pressure monitoring system of the first embodiment, when an input to the air check SW is performed, the amount of change in the tire pressure from immediately after the start of running to the present is added to the recommended air pressure to correct the current tire. Present to the driver along with the air pressure. That is, in the flowchart of FIG. 6, the tire air pressure change amount is calculated based on the initial air pressure value and the current tire air pressure in step S14, and the tire air pressure change amount is added to the recommended air pressure specific to the tire in step S15. Air pressure is corrected.

  FIG. 7A shows an example of each tire air pressure displayed on the display device 40 immediately after the start of traveling. When the recommended air pressure immediately after the start of traveling is set to 220 kPa for each wheel, in the example of FIG. For tires only, the tire pressure does not match the recommended pressure. Therefore, when the driver presses the air check SW, as shown in FIG. 7B, “OK” indicating that the tire pressure is appropriate above the tire pressure display positions of the right front tire and the left and right rear tires. Is displayed, and the recommended air pressure immediately after the start of traveling is displayed above the tire air pressure display position of the left front tire.

  After that, when the driver travels from the home to the gas station for 30 minutes to adjust the air pressure of the front left tire, each tire air pressure depends on the traveling environment such as road surface friction and outside air temperature as shown in FIG. Thus, it is 14 kPa higher than immediately after the start of running.

  In the first embodiment, when the driver presses the air check SW immediately after arrival at the gas station, as shown in FIG. 8 (b), the display device 40 is corrected by adding the amount of air pressure change immediately after the start of traveling. The recommended air pressure of 234 kPa (220 kPa + 14 kPa) is displayed, so the driver can adjust the air pressure only for the front left tire where the tire air pressure is insufficient with respect to the recommended air pressure, regardless of the tire air pressure change during driving. The air pressure can be easily adjusted to match the recommended air pressure.

  In the first embodiment, the amount of change in air pressure from immediately after the start of travel to the present is added to the recommended air pressure. For example, Japanese Patent Publication No. 2005-519274 discloses a technique for correcting the recommended air pressure by measuring the air temperature of a tire. However, a heat generation source such as a brake or an in-wheel motor is located near the tire. In some cases, it is necessary to correct the air temperature in consideration of them.

  On the other hand, in Example 1, the tire air temperature is not used, and the amount of change in tire air pressure is corrected by adding to the recommended air pressure, so that it is appropriate regardless of the influence of heat sources near the tire. Recommended air pressure can be presented.

Next, the effect will be described.
In the tire pressure monitoring system according to the first embodiment, the tire pressure change amount detecting means (step S14) for detecting the change amount of the tire air pressure from immediately after the start of traveling to the present time, and the tire air pressure change amount is used as a recommended air pressure specific to the tire. The recommended air pressure correcting means (step S15) that corrects the air pressure by adding to the display, and the display device 40 that presents the corrected recommended air pressure to the driver together with the current tire air pressure. For this reason, the driver can be urged to adjust the air pressure optimally regardless of changes in tire air pressure associated with traveling.

(Other examples)
The best mode for carrying out the present invention has been described based on the first embodiment. However, the specific configuration of the present invention is not limited to the first embodiment and does not depart from the gist of the present invention. A range design change and the like are also included in the invention.

  For example, in the first embodiment, the change amount of the tire air pressure from the start of running to the present is described as being constant. However, when the tire air pressure varies depending on the tire, a configuration in which the tire air pressure is increased may be adopted.

It is a block diagram of the tire pressure monitoring system of Example 1. FIG. 2 is a block configuration diagram of a sensor unit according to the first embodiment. It is a figure which shows an example of the format of the data transmitted by radio | wireless from the sensor unit of Example 1. FIG. FIG. 2 is a block configuration diagram of a control device 30 according to the first embodiment. It is a flowchart which shows the flow of the pneumatic pressure initial value setting control processing performed with the recommended pneumatic pressure change means 31f of the control apparatus 30 of Example 1. FIG. It is a flowchart which shows the flow of the recommended air pressure setting control processing performed with the recommended air pressure change means 31f of the control apparatus 30 of Example 1. FIG. (a) A display example of the display device 40 indicating each tire air pressure immediately after the start of traveling, and (b) a recommended air pressure display example on the display device 40 when the air check SW is pressed immediately after the start of traveling. (a) Display example of the display device 40 indicating each tire air pressure after 30 minutes has elapsed since the start of travel, (b) Recommendation to the display device 40 when the air check SW is pressed after 30 minutes have elapsed since the start of travel It is an example of a pneumatic pressure display.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Vehicle 2a, 2b Left-right front wheel 2c, 2d Left-right rear wheel 10 Sensor unit 11 Tire pressure sensor 12 Rotation sensor 13 CPU part 14 RF part 15 Transmission antenna 16 Battery 20a, 20b Reception antenna 30 Control apparatus 31 Microcomputer 31a Tire low pressure judgment means 31b Warning output means 31c Hazard output means 31d Air pressure adjustment support means 31e Detection means 31f Recommended air pressure change means 32 Antenna switching means 33 Tuner 40 Display device

Claims (1)

In the tire pressure monitoring system that monitors the tire pressure of each tire mounted on the vehicle and presents it to the driver,
Tire pressure change amount detecting means for detecting a change amount of tire air pressure immediately after the start of running until the present time;
Recommended air pressure correcting means for correcting the tire air pressure change amount by adding to the recommended air pressure specific to the tire;
Presenting means for presenting the corrected recommended air pressure along with the current tire pressure to the driver;
A tire pressure monitoring system comprising:

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