JP2000203218A - Tire condition monitoring unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To extend battery life, and to make change in a tire condition at the time of stop informed of in advance to start of drive. SOLUTION: This monitoring unit is provided with a sensor 1 for measuring a physical quantity in a tire, a transmitter 2 for transmitting a data from the sensor 1, a control circuit 3 for controlling actions for the sensor 1 and the transmitter 2, a power source 4 for supplying an electric power to the control circuit 3, a switch 5 for sensing a traveling condition of a vehicle, and a receiver 6 for receiving the data transmitted from the transmitter 2. The control circuit 3 switches an operation interval of the sensor 1 based on the traveling condition of the vehicle to set the operation interval at the time of stop longer than the operation interval at the time of traveling, and the data is transmitted from the transmitter 2 at the time of stop only when a variation of the data exceeds a prescribed threshold value.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for monitoring the condition of tire pressure and the like, and more particularly, to extending battery life and warning a change in tire condition when the vehicle is stopped prior to starting operation. The present invention relates to a tire condition monitoring device that enables the above.

[0002]

2. Description of the Related Art Conventionally, a sensor module having a pressure sensor, a transmitter, and a battery is mounted on a wheel as a device for constantly monitoring the tire pressure, and data of the pressure sensor is transmitted from a transmitter. A system is used in which data is received by a receiver attached to a vehicle and is displayed on an appropriate display device.

[0003] In the tire pressure monitoring device, current control is performed by a centrifugal switch in order to extend the battery life of the sensor module. That is, the centrifugal switch is set to be turned off when the vehicle is stopped, and while the vehicle is stopped, the sensor module circuit does not operate and no data is transmitted, so that it is possible to reduce battery consumption. .

However, in the tire pressure monitoring device in which current control is performed by the centrifugal switch, data is not transmitted until the speed at which the centrifugal switch operates is reached. There is a problem that the driver is not warned until a while after traveling. It is desirable that such abnormal data be warned to the driver before or immediately after the start of traveling.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide a tire condition monitoring device which can extend the battery life and can warn of a change in tire condition when the vehicle is stopped prior to starting operation. It is in.

[0006]

According to the present invention, there is provided a tire condition monitoring apparatus comprising: a sensor for measuring a physical quantity in a tire; a transmitter for transmitting data from the sensor; A control circuit that controls the operation of the transmitter, a power supply that supplies power to the control circuit, a switch that detects a running state of the vehicle, and a receiver that receives data transmitted from the transmitter, The control circuit switches the operation interval of the sensor based on the traveling state of the vehicle, sets the operation interval at the time of stopping longer than the operation interval at the time of stopping, and when the change amount of the data is larger than a predetermined threshold value at the time of stopping. Only the transmitter transmits data.

As described above, in the device for constantly monitoring the physical quantities (air pressure, temperature, etc.) in the tire, the operation interval of the sensor when the vehicle is stopped is set longer than the operation interval when the vehicle is traveling. Since the data transmission is performed only when the value is larger than the predetermined threshold value, the life of the battery serving as the power supply can be significantly extended. Further, when abnormal data is detected when the vehicle is stopped, the abnormal data is transmitted to the receiver, so that it is possible to warn of a change in the tire state when the vehicle is stopped prior to the start of driving.

In the present invention, the receiver is configured to operate with the auxiliary power supply even when the ignition switch is off, so that the receiver always updates the latest data to the memory and simultaneously turns on the ignition switch. Preferably, the data in the memory is displayed on a display device. In this way, the receiver is always activated, and the data display is linked to the ignition switch to notify the change in the tire state during stopping before starting operation without issuing a useless warning in an unmanned vehicle. be able to.

A switch for detecting the running state of the vehicle may be a centrifugal switch or a vibration switch. In particular, a vibration switch is preferable for detecting the running state of a vehicle because of its high sensitivity.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The configuration of the present invention will be described below in detail with reference to the accompanying drawings.

FIG. 1 illustrates a tire condition monitoring device according to an embodiment of the present invention. In the figure, a tire condition monitoring device includes a sensor 1 for measuring a physical quantity in a tire.
A transmitter 2 for transmitting data from the sensor 1, a control circuit 3 for controlling the operation of the sensor 1 and the transmitter 2,
A sensor module including a power supply 4 for supplying power to the control circuit 3 and a switch 5 for detecting a running state of a vehicle is mounted on wheels, and a receiver 6 for receiving data transmitted from the transmitter 2. Is mounted on the vehicle side.

As the sensor 1, a pressure sensor for measuring the air pressure in the tire, a temperature sensor for measuring the temperature in the tire, or the like can be used. Further, the pressure sensor and the temperature sensor may be used in combination, and the data of the pressure sensor may be temperature-compensated using the data of the temperature sensor in order to eliminate the influence of the pressure change due to the temperature.

The transmitter 2 is adapted to transmit data in radio frequency (RF) signals. The antenna of this transmitter 2 is connected to the wheel of the wheel on which the sensor module is mounted.

The control circuit 3 includes a theoretical operation circuit (ALU) 31 for instructing the driving of the sensor 1 and the transmitter 2, and a random access memory (RA) for temporarily storing data of the sensor 1.
M) 32, a read-only memory (EEPROM) 33 for setting comparison data, a stopping timer 34 for setting an operating interval during stopping, and a running timer for setting an operating interval during running. 35
And anti-collision timer 3 for preventing transmission signal collision
6 and a power supply controller 37 for distributing the power supplied from the power supply 4.

As the power source 4, a primary battery or a secondary battery can be used. Further, as the switch 5, a centrifugal switch that operates by detecting a centrifugal force or a vibration switch that operates by detecting a vibration by a vibrator can be used.

The receiver 6 is operated by the auxiliary power supply even when the ignition switch is off, and is configured to always update the latest data to the memory. In addition, the receiver 6 is set so that the data in the memory is supplied to a display device installed on a control panel or the like of the driver's seat and the data is displayed at the same time when the ignition switch is turned on.

FIGS. 2 and 3 show the control operations of the tire condition monitoring device at the time of stopping and running, respectively. In the stopped state, the control shown in FIG. 2 is performed.
That is, when the initial processing is performed, the interrupt disable flag is turned on, and the latest data R0 at that time is replaced with the previous data R1. After that, data is collected by the sensor 1 and the obtained data RS is replaced with the latest data R
Set to 0. This data R0 is compared with a data lower limit value RL set in the memory 33, and when the data R0 is smaller, data transmission is performed from the transmitter 2.

When the data R0 is larger than the data lower limit RL, a difference between the data R0 and the data R1 is obtained, and this difference is set as a data change value RC. When the data change value RC is larger than 0, the interrupt disable flag is turned off. When the data change value RC is smaller than 0, an absolute value is obtained, and this is set as a data change value RB. Then, the threshold value RD set in the memory 33 is compared with the data change value RB. When the threshold value RD is larger, the interrupt disable flag is turned off. When the data change value RB is larger than the threshold value RD, the transmitter 2
To send data. When the interruption prohibition flag is turned off, the stop timer 34 is turned on, and when the stop timer 34 expires, the interruption prohibition flag is turned on again.

On the other hand, in the running state, the control shown in FIG. 3 is performed. That is, when the switch 5 detects the running state and turns on, the interrupt condition is satisfied, and the process shifts to an interrupt process. In the interruption process, the collision prevention timer 36 is turned on. When the collision prevention timer 36 expires, the latest data R0 at that time is replaced with the previous data R1.
Then, the data RS obtained by the sensor 1 is set as the latest data R0, and data is transmitted from the transmitter 2. After the data transmission, if the switch 5 is still on, the running timer 35 is turned on, and if the running timer 35 expires,
The above data transmission is repeated. After the data transmission, if the switch 5 is turned off, the interrupt processing ends.

In the above-described tire condition monitoring device,
Since two systems of timers are used for controlling the operation of the sensor 1 and the stopped timer 34 is set longer than the running timer 36, a short interval (for example, 1 to 10) is set during running.
), The physical quantities (air pressure, temperature) in the tire can be monitored at long intervals (for example, 1 to 2 hours) while the vehicle is stopped. Therefore, consumption of the battery serving as the power supply 4 can be suppressed.

Moreover, although the obtained data is sequentially transmitted during traveling, the data is transmitted from the transmitter 2 only when the amount of change of the data is larger than a predetermined threshold during stoppage.
The power saving effect can be further enhanced. For example, the current consumed by the timer during the interval is several μA, the driving of the sensor is about 1 mA for about 0.5 seconds, and the current consumed by the transmitter is about 30 mA for about 0.5 seconds. Therefore, by reducing the number of transmissions, it is possible to greatly reduce battery consumption.

On the other hand, the display module including the receiver 6 maintains the data standby state by the auxiliary power supply even when the ignition switch is off, so that the data transmitted while the vehicle is stopped is stored in the memory. However,
When the ignition switch is off, it is assumed that there is no driver in the vehicle, so that the transmission data is not displayed and is merely stored in the memory. And
As soon as the ignition switch is turned on, the data in the memory is displayed on a predetermined display device. Therefore, when an abnormality occurs in the tires while the vehicle is stopped, the driver can know the abnormality data prior to the start of driving.

[0023]

As described above, according to the present invention, the control circuit switches the operation interval of the sensor based on the traveling state of the vehicle, and sets the operation interval at the time of stopping to be longer than the operation interval at the time of traveling. When the vehicle is stopped, the data is transmitted from the transmitter only when the data change amount is larger than a predetermined threshold value, so that the life of the battery serving as a power source can be greatly extended, and the tire condition at the time of the stop is reduced. Changes can be alerted prior to operation.

In particular, the receiver is configured to operate on the auxiliary power supply even when the ignition switch is off, so that the receiver always updates the latest data to the memory,
By setting the data in the memory to be displayed on the display device at the same time as the ignition switch is turned on, it is possible to notify the tire abnormality that occurred during the stop ahead of driving without issuing a useless warning in an unmanned vehicle be able to.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing a tire condition monitoring device according to an embodiment of the present invention.

FIG. 2 is a flowchart illustrating a control operation of the tire condition monitoring device according to the embodiment of the present invention when the vehicle is stopped.

FIG. 3 is a flowchart showing a control operation during running of the tire condition monitoring device according to the embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Sensor 2 Transmitter 3 Control circuit 4 Power supply 5 Switch 6 Receiver 34 Stop timer 35 Running timer

Claims (3)

[Claims] 1. A sensor for measuring a physical quantity in a tire,
A transmitter for transmitting data from the sensor, a control circuit for controlling the operation of the sensor and the transmitter, a power supply for supplying power to the control circuit, a switch for detecting a running state of the vehicle, and the transmitter And a receiver for receiving data transmitted from the control circuit, the control circuit switches the operation interval of the sensor based on the traveling state of the vehicle, and sets the operation interval when stopping to be longer than the operation interval when traveling. A tire condition monitoring device configured to transmit data from the transmitter only when the amount of change in the data is greater than a predetermined threshold when the vehicle is stopped. 2. The receiver is configured to operate with an auxiliary power supply even when an ignition switch is off, and the receiver always updates the latest data to a memory,
The tire condition monitoring device according to claim 1, wherein the data in the memory is displayed on a display device at the same time when an ignition switch is turned on. 3. The tire condition monitoring device according to claim 1, wherein the switch is a vibration switch.