JP2007237827A - Tire air pressure monitoring device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a tire air pressure monitoring device capable of further promptly and correctly distinguishing a tire position. <P>SOLUTION: An ASIC10d detecting the speed reduction of a vehicle on the basis of the rotation speed of a wheel detected by a rotation speed sensor 10c is provided. A tire air pressure sensor 10 transmits a radio signal every fixed time at least during the traveling of the vehicle, on the other hand, immediately outputs the radio signal when the speed reduction of the vehicle is detected regardless of transmitting timing corresponding to the fixed time. A tire air pressure alarm controller 12 distinguishes fore-and-aft positions of each tire on the basis of changes in each tire air pressure generated at the time of reducing the speed of the vehicle, and registers that by storing the positions to an EEPROM12g and updating them. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention belongs to the technical field of a tire pressure monitoring device that monitors tire pressure.

In the conventional tire pressure monitoring device, when each tire position changes due to tire rotation exchange etc., the vehicle deceleration is detected from the brake signal, and the tire longitudinal position is detected based on the wheel load change generated on the front and rear wheels. Yes. Similarly, the turning state of the vehicle is detected from the steering state, and the left and right positions of the tire are detected based on the wheel load change generated on the left and right wheels (see, for example, Patent Document 1).
JP 2003-159920 A

  However, in the above-described prior art, the tire air pressure transmitted from each tire during traveling is always at a constant interval, so that the brake signal or the timing of steering and the timing of transmitting the tire air pressure coincide with each other by chance. During this time, changes in air pressure caused by wheel load are not measured. Therefore, there is a possibility that it takes a long time from the replacement of the rotation of the tire to the detection of the tire position.

  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 device capable of determining a tire position more quickly and accurately.

In order to achieve the above object, in the present invention,
A pressure sensor that is attached to each of a plurality of tires mounted on a vehicle and detects each tire air pressure, and a transmitter that transmits at least the detected tire air pressure together with a tire identification code for each tire by a radio signal. Tire pressure detecting means;
A receiver attached to the vehicle side for receiving a radio signal transmitted from the tire pressure detecting means;
Tire identification code registration means for registering the tire identification code of each tire by storage update to a memory;
In a tire pressure monitoring device equipped with
Traveling state detecting means for detecting the traveling state of the vehicle;
Provide wheel load change detection means for detecting wheel load change of each tire,
The tire air pressure detecting means transmits the wireless signal at regular intervals at least during traveling of the vehicle, while when a wheel load change occurs in each tire, regardless of the transmission timing according to the regular time, Immediately output a radio signal,

  The tire identification code registration means determines the position of each tire based on the running state of the vehicle and the wheel load change of each tire, and registers it by storing and updating the memory.

  In the tire pressure monitoring device of the present invention, when a wheel load change of each tire is detected, the tire air pressure is immediately output regardless of a preset transmission timing every predetermined time, and the vehicle running state and wheel load change Each tire position is determined based on the above, and the front and rear positions of each tire are re-registered in the memory. In other words, the tire pressure transmission timing can be made to coincide with the timing of the air pressure fluctuation accompanying the change in the wheel load of each tire, so that it is faster and more accurate than the conventional technology that always transmits the tire air pressure at a constant timing. The tire position can be detected.

  Hereinafter, an embodiment for realizing a tire pressure monitoring device of the present invention will be described based on Example 1.

First, the configuration will be described.
[overall structure]
FIG. 1 is an overall view showing a vehicle to which the tire pressure monitoring device of the first embodiment is applied. The tire pressure monitoring device of the first embodiment includes a right front wheel tire 1, a left front wheel tire 2, a right rear wheel tire 3, and a left side. Rear wheel tire 4, spare tire 5, right front wheel speed sensor 6, left front wheel speed sensor 7, right rear wheel speed sensor 8, left rear wheel speed sensor 9, tire air pressure sensor (tire air pressure detecting means) 10, ABS controller 11, A tire pressure warning controller (tire identification code registering means) 12 and a pressure drop warning lamp 13 are provided.

  The right front wheel speed sensor 6, the left front wheel speed sensor 7, the right rear wheel speed sensor 8, and the left rear wheel speed sensor 9 detect the wheel speeds of the front and rear wheels 1, 2, 3, and 4, and the wheel speed sensor signals are ABS. Input to the controller 11.

  The tire pressure sensor 10 is attached to the road wheels of the front and rear wheel tires 1, 2, 3, 4 and the spare tire 5, respectively, and detects the tire pressure of each tire, and the ID (tire identification code) of each tire. The detected tire pressure and the centrifugal force switch signal are transmitted to the tire pressure alarm controller 12 by radio signals.

  The ABS controller 11 inputs wheel speed sensor signals from the wheel speed sensors 6, 7, 8, 9 and outputs vehicle speed information (vehicle speed, vehicle acceleration / deceleration, wheel speed) to the tire air pressure alarm controller 12.

  When the tire pressure alarm controller 12 performs ID registration for each tire and determines that at least one of the front and rear wheel tires 1, 2, 3, and 4 specified by the ID registration has decreased, A lamp lighting command is output to the air pressure reduction warning lamp 13.

FIG. 2 is a detailed view showing the tire pressure sensor 10 and the tire pressure alarm controller 12 of the tire pressure monitoring device of the first embodiment.
[Configuration of tire pressure sensor]
The tire pressure sensor 10 includes a pressure sensor 10a that detects tire pressure, a centrifugal force switch 10b that is open (OFF) in a region where the acting centrifugal force is small and is closed (ON) in a region where the centrifugal force is large, and wheel rotation. Rotation speed sensor 10c for detecting speed, ASIC (running state detection means, wheel load change detection means) 10d which is an application specific integrated circuit, transmitter 10e and transmission antenna (transmitter) 10f Is done.

  The ASIC 10d is triggered by the opening / closing of a centrifugal switch 10b installed to ensure battery life, and has a long transmission interval (1 hour) in an extremely low vehicle speed range including a stop, and a short transmission in a region where the vehicle speed is higher than that. The transmission cycle is changed into two stages such as an interval (1 minute), and modulated pressure value information from the pressure sensor 10a, individual tire ID information, and a centrifugal force switch signal are used as radio signals (electromagnetic waves). To send.

  The ASIC 10d calculates the vehicle deceleration from the wheel rotation speed detected by the rotation speed sensor 10c. If the deceleration exceeds a predetermined deceleration determination threshold value, the ASIC 10d responds to the transmission interval (1 minute). Regardless of the transmission timing, the wireless signal is transmitted immediately. Here, the deceleration threshold value is set based on the deceleration when stopping at an intersection or the like from the vehicle speed while traveling in an urban area.

  FIG. 3 shows an output waveform of the rotation speed sensor 10c. As shown in FIG. 3, when the vehicle is traveling at a constant speed, the rotational speed sensor 10c outputs a limit wave having a substantially constant period (frequency), and the period is long (frequency is low) during deceleration. . The ASIC 10d uses this period or frequency change as a trigger. When the frequency change amount is small, the ASIC 10d transmits air pressure information at regular intervals, and when the frequency greatly decreases, the air pressure information is immediately transmitted.

[Configuration of tire pressure alarm controller]
The tire pressure alarm controller 12 receives 5V power supply circuit 12a, a receiving antenna 12b and a receiving circuit (receiver) 12c for receiving transmission data from the transmitting antenna 10f of the tire pressure sensor 10, and vehicle speed information from the ABS controller 11. The vehicle speed information input circuit 12d, the reception data from the reception circuit 12c and the input information from the vehicle speed information input circuit 12d are inputted, and the microcomputer 12f that performs arithmetic processing according to a predetermined control law, and the electrical that performs ID registration EEPROM (memory) 12g, which is a read-only memory capable of erasing stored information, and a warning lamp output for judging the pressure value of the attached tire from the received data and outputting a tire pressure warning command to the low pressure warning lamp 13 when the pressure drops And a circuit 12h.

  The tire air pressure alarm controller 12 discriminates the front / rear position of each tire based on the air pressure information transmitted from the tire air pressure sensor 10 when the vehicle decelerates, associates the ID of each tire with the front / rear position of the tire, and stores data in the EEPROM 12g. Update. Here, the method described in JP-A-2003-159920 can be used for the front-rear position of each tire. That is, when the vehicle decelerates, the center of gravity moves to the front side of the vehicle, so that the wheel load on the front wheels increases and the wheel load on the rear wheels decreases as compared to during steady running. Therefore, the tire front-rear position can be determined by comparing the tire air pressure received during steady running immediately before deceleration with the tire air pressure received during deceleration.

[Transmission timing change control processing]
FIG. 4 is a flowchart showing the flow of the transmission timing change control process executed by the ASIC 10d of the tire pressure sensor 10 of the first embodiment. Each step will be described below. This control process is repeatedly executed every predetermined control 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, the rotational speed of the wheel is read from the rotational speed sensor 10c, and it is determined whether or not the vehicle speed is constant based on the rotational speed of the wheel. If YES, the process proceeds to step S3. If NO, the process proceeds to step S4. Here, the constant vehicle speed means a state in which the amount of change in the rotation speed of the wheel per time is within a predetermined range.

  In step S3, transmission of air pressure information is continued every certain time (one hour when the vehicle speed is in the extremely low vehicle speed range, one minute when the vehicle speed is higher), and the process proceeds to step S6.

  In step S4, it is determined whether or not the vehicle is decelerated from the rotational speed of the wheel read in step S2. If YES, the process proceeds to step S5. If NO, the process proceeds to step S2. Here, the deceleration of the vehicle refers to a state in which the amount of speed reduction per hour of the vehicle calculated from the rotational speed of the wheels exceeds the deceleration determination threshold value.

  In step S5, the air pressure information is immediately transmitted, and the process proceeds to step S6.

  In step S6, 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.

Next, the operation will be described.
[Transmission timing change effect during deceleration]
In the vehicle tire pressure detecting device disclosed in Japanese Patent Application Laid-Open No. 2003-159920, when each tire position changes due to tire rotation exchange or the like, the vehicle deceleration is detected from the brake signal, and based on the wheel load change that occurs during deceleration. By detecting the tire front-rear position, the correspondence between the ID and the tire front-rear position is re-registered in the memory.

  However, in this prior art, the tire air pressure transmitted from each tire during traveling is always at a constant interval (for example, 1 minute), so that the timing of the brake signal coincides with the timing of transmitting the tire air pressure by chance. During this period, the tire air pressure during deceleration is not measured, and it may take a long time from the replacement of the rotation of the tire to the detection of the front-rear position of the tire.

  On the other hand, it is possible to increase the probability that the brake signal coincides with the transmission timing of the pneumatic information by increasing the transmission frequency of the pneumatic information (for example, about several seconds), but the problem is that the battery life of the transmitter is shortened. There is. Moreover, the front and rear positions of the tires can be determined by installing the receivers at different positions in the vehicle longitudinal direction, for example, between the left and right front wheels and between the left and right rear wheels. Increased costs will increase.

  On the other hand, in the tire pressure monitoring device of the first embodiment, when the deceleration of the vehicle is detected, the tire pressure is immediately output regardless of the transmission timing at a predetermined interval (1 minute) set in advance, and the vehicle deceleration The front / rear position of each tire is determined on the basis of the variation in the tire air pressure caused by the above, and the front / rear position of each tire is re-registered in the EEPROM 12g.

  That is, since the tire air pressure transmission timing can be made to coincide with the air pressure fluctuation timing associated with the change in the wheel load of each tire, the receiving circuit 12c is compared with the prior art that always transmits the tire air pressure at a constant timing. The tire position can be detected more quickly and accurately without increasing the number and without shortening the battery life by reducing the transmission interval of the air pressure information.

  Further, in the first embodiment, since the deceleration of the vehicle is detected on the tire pressure sensor 10 side mounted on each tire, for example, compared with the case where the deceleration of the vehicle is detected on the tire pressure alarm controller 12 side, The transmission timing of air pressure information can be changed more quickly.

[Transmission timing change control action]
FIG. 5 is a time chart of tire air pressure information showing the transmission timing change control operation of the first embodiment.
In the vehicle tire pressure detecting device disclosed in Japanese Patent Application Laid-Open No. 2003-159920, since air pressure information is always transmitted at regular intervals (time points t1, t3, and t6), a brake signal is output due to vehicle deceleration at time points t2 and t5. In spite of this, the transmission of air pressure information is at times t3 and t6 when the vehicle is not decelerating, and the air pressure information during deceleration cannot be referred to.

  On the other hand, in the tire pressure monitoring apparatus of the first embodiment, until the time point t2 is reached, the flow from step S2 to step S3 to step S6 is repeated in the flowchart of FIG. Air pressure information is transmitted at 1-minute intervals. Thereby, each tire air pressure can be monitored for every fixed time like the prior art.

  At time t2, since deceleration is detected, the process proceeds from step S2 to step S4 to step S5, and the air pressure information is immediately transmitted. The tire pressure alarm controller 12 determines the front / rear position of each tire based on the change in each tire pressure generated during vehicle deceleration, and updates the registration information in the EEPROM 12g based on the determination result.

At time t4, since 1 minute has elapsed from time t2, air pressure information is transmitted.
At time t5, as with time t2, air pressure information is immediately transmitted upon detection of deceleration, the front and rear positions of each tire are determined, and the registration information in the EEPROM 12g is updated.

Next, the effect will be described.
In the tire pressure monitoring apparatus according to the first embodiment, a pressure sensor 10a that is attached to each of a plurality of tires 1, 2, 3, and 4 mounted on a vehicle and detects each tire pressure, and at least the detected tire pressure. A tire pressure sensor 10 having a transmitting antenna 10f that transmits a wireless signal together with an individual ID of each tire; a receiving circuit 12c that is attached to the vehicle and receives a wireless signal transmitted from the tire pressure sensor 10; In a tire pressure monitoring device comprising a tire pressure alarm controller 12 for registering the ID of each tire 1, 2, 3, 4 by storing and updating the EEPROM 12g, an ASIC 10d for detecting deceleration of the vehicle is provided. Transmits a radio signal at regular intervals, at least when the vehicle is running, When the vehicle deceleration is detected, a wireless signal is immediately output regardless of the transmission timing corresponding to a certain time, and the tire pressure alarm controller 12 determines whether each tire pressure is based on a change in each tire pressure that occurs during vehicle deceleration. Are registered by updating the stored data in the EEPROM 12g. Thereby, compared with the prior art which always transmits tire pressure at a constant timing, it is possible to detect the front and rear positions of the tire more quickly and accurately.

(Other examples)
As described above, the tire pressure monitoring device of the present invention has been described based on the first embodiment. However, the specific configuration is not limited to the first embodiment, and is described in each claim of the claims. Design changes and additions are allowed without departing from the scope of the present invention.

For example, in Example 1, although the example which detects only the front-back position of each tire was shown, the structure which detects the wheel load change of right-and-left wheels, such as turning of a vehicle, and detects the left-right position of each tire based on this It is good.
In the first embodiment, the vehicle speed information is obtained from the ABS controller 11. However, the vehicle speed information may be obtained from a vehicle speed sensor.

1 is an overall view showing a vehicle to which a tire pressure monitoring device according to a first embodiment is applied. It is detail drawing which shows the tire pressure sensor of the tire pressure monitoring apparatus of Example 1, and a tire pressure warning controller. It is a figure which shows the output waveform of the rotational speed sensor at the time of constant speed driving | running | working and deceleration of Example 1. FIG. It is a flowchart which shows the flow of the transmission timing change control process performed by ASIC10d of the tire pressure sensor 10 of Example 1. FIG. 3 is a time chart of tire air pressure information showing a transmission timing change control operation of the first embodiment.

Explanation of symbols

1 right front wheel tire 2 left front wheel tire 3 right rear wheel tire 4 left rear wheel tire 5 spare tire 6 right front wheel speed sensor 7 left front wheel speed sensor 8 right rear wheel speed sensor 9 left rear wheel speed sensor 10 tire pressure sensor 10a pressure sensor 10b Centrifugal force switch 10c Rotational speed sensor 10d ASIC
10e Transmitter 10f Transmitting antenna 11 Controller 12 Tire pressure alarm controller 12a Power supply circuit 12b Receiving antenna 12c Receiving circuit 12d Vehicle speed information input circuit 12f Microcomputer 12g EEPROM
12h Warning lamp output circuit 13 Low air pressure warning lamp

Claims (1)

A pressure sensor that is attached to each of a plurality of tires mounted on a vehicle and detects each tire air pressure, and a transmitter that transmits at least the detected tire air pressure together with a tire identification code for each tire by a radio signal. Tire pressure detecting means;
A receiver attached to the vehicle side for receiving a radio signal transmitted from the tire pressure detecting means;
Tire identification code registration means for registering the tire identification code of each tire by storage update to a memory;
In a tire pressure monitoring device equipped with
Traveling state detecting means for detecting the traveling state of the vehicle;
Provide wheel load change detection means for detecting wheel load change of each tire,
The tire air pressure detecting means transmits the wireless signal at regular intervals at least during traveling of the vehicle, while when a wheel load change occurs in each tire, regardless of the transmission timing according to the regular time, Immediately output a radio signal,
The tire identification code registration means discriminates the position of each tire based on the running state of the vehicle and the wheel load change of each tire, and registers it by storing and updating the memory. .

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