JP2002248913A - Trouble diagnosis apparatus for tire pneumatic pressure alarming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a trouble diagnosis apparatus for a tire air pressure diagnosis device that can securely set whether or not there is any trouble with a transmitter for a tire air pressure detector of which transmission frequency is valuable to a vehicle speed by setting a trouble diagnosis time based on vehicle information which is made by a receiver side that performs trouble diagnosis of the transmitter. SOLUTION: A transmitter 2 for a tire air pressure detection can change its transmission frequency into two stages with an opening and closing of a centrifugal switch 12 as a trigger; a long transmission distance if a vehicle speed including stop is in a low speed range while a short transmission distance if a vehicle speed is in a high speed range. In the meantime, by setting a trouble diagnosis time t in a higher vehicle speed set vehicle speed, when a vehicle speed V is in less than a set vehicle speed range including a vehicle speed when the vehicle speed V becomes a long transmission period, the diagnosis apparatus does not perform a trouble diagnosis but a vehicle is in a way of running in a range of more than set vehicle speed which becomes a short transmission frequency. In addition, when a trouble diagnosis time t which is set without receiving data from the transmitter 2 for the tire air pressure detection passes, the transmitter 2 for tire air pressure detection is made to be a means to diagnose troubled.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention belongs to the technical field of a failure diagnosis device for a tire pressure alarm device.

[0002]

2. Description of the Related Art Conventionally, as a tire pressure warning device,
For example, Japanese Patent No. 2639856 (Tokuhyohei 8-50)
No. 5939) is known.

[0003] According to this conventional publication, a transmitter for detecting tire pressure attached to each wheel modulates information such as a pressure value and a sensor value at a fixed cycle, transmits the information using electromagnetic waves, and installs the information in a vehicle cabin. In the device where the received receiver receives this, demodulates and judges the pressure value in the data and issues a tire pressure warning command when the pressure drops, the transmitter for tire pressure detection is installed in the transmitter to ensure battery life. A technique in which the opening and closing of the installed centrifugal switch is used as a trigger to change the transmission cycle in two stages, such as a long transmission interval in a low vehicle speed region including a stop, and a short transmission interval in a higher vehicle speed region. Is described.

[0004]

However, the conventional tire pressure warning device does not have a configuration for diagnosing that the tire pressure detecting transmitter is out of order. Is a failure, there is a problem that the tire pressure alarm device does not operate normally not only when the tire pressure drops but also when the tire is punctured.

[0005] Therefore, a fixed failure diagnosis time is set in advance, and when the set failure diagnosis time elapses without receiving data from the tire pressure detection transmitter, the tire pressure detection transmitter has failed. It is conceivable to install a transmitter failure diagnosis device for diagnosing the problem.

However, since the transmission cycle is changed in two stages such that the transmission interval is long in a low speed range and the transmission interval is short in a high speed range. If the receiver cannot confirm the data transmission from the transmitter even after the elapse of time, it is possible to distinguish whether it cannot be confirmed because the transmission cycle is long or the transmitter for tire pressure detection is out of order. Can not.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and an object of the present invention is to set a failure diagnosis time based on vehicle speed information on a receiver side for performing a failure diagnosis of a transmitter. It is another object of the present invention to provide a failure diagnosis device for a tire pressure alarm device capable of reliably diagnosing the presence or absence of a failure in a tire pressure detection transmitter whose transmission cycle is variable depending on vehicle speed.

[0008]

In order to achieve the above object, according to the first aspect of the present invention, a tire pressure detecting transmitter attached to each wheel transmits information such as a pressure value and a sensor value at a constant cycle. A device that modulates and transmits using an electromagnetic wave, and a receiver installed in the vehicle cabin receives and demodulates the signal to determine a pressure value in the data and issue a tire pressure warning command when the pressure is reduced. The pressure detection transmitter increases the transmission interval in a region where the vehicle speed is low including stop, and in a region where the vehicle speed is higher than that, in a tire pressure warning device that changes the transmission cycle such that the transmission interval is shortened. A vehicle speed detection means for detecting the vehicle speed, and a data transmission cycle of the tire pressure detection transmitter is predicted based on a vehicle speed detection value from the vehicle speed detection means. Based on the prediction, a diagnosis threshold value indicating that the transmitter is out of order is obtained. Because Failure diagnosis time setting means for setting a diagnosis time, and a transmitter for diagnosing a failure in the tire pressure detection transmitter when a set failure diagnosis time elapses without receiving data from the tire pressure detection transmitter. Failure diagnosis means.

According to a second aspect of the present invention, in the failure diagnosis device for a tire air pressure alarm device according to the first aspect, the tire pressure detecting transmitter is provided with a centrifugal force installed in the transmitter to ensure battery life. Triggered by the opening and closing of a force switch, the transmitter changes the transmission cycle in two stages, such as a long transmission interval in a low vehicle speed region including a stop, and a short transmission interval in a higher vehicle speed region. The failure diagnosis time setting means is a means for setting a failure diagnosis time in a region equal to or higher than a set vehicle speed at which a vehicle speed detection value is a short transmission cycle, and the transmitter failure diagnosis means is configured such that the vehicle speed detection value is less than a set vehicle speed. Area, do not perform transmitter failure diagnosis,
The tire pressure detection transmitter fails when the vehicle is running in the area above the set vehicle speed, which is a short transmission cycle, and when the set failure diagnosis time elapses without receiving data from the tire pressure detection transmitter. It is a means for diagnosing that.

According to a third aspect of the present invention, in the failure diagnosis device for a tire pressure warning device according to the second aspect, the failure diagnosis time setting means determines that the transmitter has failed in a region where the detected vehicle speed is equal to or higher than the set vehicle speed. The failure diagnosis time to diagnose that there is
It is a means for setting a long time as the vehicle speed increases.

According to a fourth aspect of the present invention, in the failure diagnosis device for a tire air pressure warning device according to the first to third aspects, the transmitter failure diagnosis means determines that the transmitter for tire pressure detection has a failure. It is a means for activating an alarm installed in the vehicle cabin when a diagnosis is made.

[0012]

According to the first aspect of the present invention, in the tire air pressure warning device, a tire pressure detecting transmitter attached to each wheel transmits information such as a pressure value and a sensor value at a constant cycle. The signal is modulated and transmitted using electromagnetic waves. A receiver installed in the vehicle compartment receives the signal, demodulates it, determines the pressure value in the data, and issues a tire pressure warning command when the pressure drops. Here, the tire pressure detecting transmitter changes the transmission cycle such that the transmission interval is lengthened in a region where the vehicle speed is low including stoppage, and the transmission interval is shortened in a region where the vehicle speed is higher than that.

The vehicle speed is detected by the vehicle speed detecting means, and the failure diagnosis time setting means predicts the data transmission cycle of the tire pressure detecting transmitter based on the detected vehicle speed from the vehicle speed detecting means, and transmits the data based on the prediction. When a failure diagnosis time, which is a diagnosis threshold value indicating that the machine is faulty, is set, and the transmitter failure diagnosis means passes the failure diagnosis time set without receiving data from the tire pressure detection transmitter, It is diagnosed that the tire pressure detecting transmitter is out of order.

In other words, when diagnosing a failure of the tire pressure detecting transmitter whose data transmission cycle can be changed according to the vehicle speed, if a fixed failure diagnosis time is set, the transmitter side transmits the signal even after the failure diagnosis time has elapsed. If you can't confirm the data transmission from, please check if the transmission cycle is too long to confirm.
It cannot be distinguished whether the tire pressure detecting transmitter cannot be confirmed because of a failure. On the other hand, by setting the failure diagnosis time using the vehicle speed detection value, the failure diagnosis time is set to an optimal value that can be distinguished as a failure based on the prediction of the data transmission cycle.

Therefore, by setting the failure diagnosis time based on the vehicle speed information on the receiver side that performs the failure diagnosis of the transmitter, it is possible to reliably determine whether or not the tire pressure detection transmitter whose transmission cycle is variable depending on the vehicle speed. Can be diagnosed.

According to the second aspect of the present invention, in the tire pressure detecting transmitter, the opening and closing of a centrifugal force switch installed in the transmitter as a trigger to secure the battery life triggers the vehicle speed including the stop. The transmission cycle can be changed in two stages, such as a long transmission interval in a low region and a short transmission interval in a region with a higher vehicle speed. On the other hand, the failure diagnosis time setting means sets a failure diagnosis time in a region equal to or higher than the set vehicle speed at which the vehicle speed detection value has a short transmission cycle, and the transmitter failure diagnosis means has a region in which the vehicle speed detection value is less than the set vehicle speed. When the transmitter failure diagnosis is not performed, the vehicle is traveling in an area at or above the set vehicle speed that is a short transmission cycle, and the failure diagnosis time set without receiving data from the tire pressure detection transmitter is When the elapsed time has elapsed, it is diagnosed that the tire pressure detecting transmitter is out of order.

That is, in the tire pressure detecting transmitter, a region where the vehicle speed including the stop is low (region where the centrifugal force switch is open).
In a long transmission interval (for example, one hour), and in a region where the vehicle speed is higher (a region where the centrifugal switch is closed), the transmission cycle is changed in two stages such as a short transmission interval (for example, one minute). In the case of a long transmission interval, if the data reception is missed once for some reason, the receiver sets the transmission interval to two.
Even after waiting twice as long (for example, two hours), no data is received, and if a longer failure diagnosis time is set, failure diagnosis cannot be performed as needed.

Therefore, by setting the failure diagnosis time only in the vehicle speed region with a short transmission interval, it is possible to surely diagnose whether or not there is a failure in the tire pressure detection transmitter whose transmission cycle can be changed in two stages depending on the vehicle speed. .

According to the third aspect of the present invention, in the failure diagnosis time setting means, the failure diagnosis time for diagnosing that the transmitter is faulty in a region where the detected vehicle speed is equal to or higher than the set vehicle speed becomes longer as the vehicle speed increases. Set to time.

That is, in the tire air pressure warning device of the radio wave transmission / reception type, there is a peculiar phenomenon that the reception probability decreases as the vehicle speed increases.

Therefore, by setting the failure diagnosis time to be longer as the vehicle speed increases, it is possible to prevent the reliability of the failure diagnosis from lowering due to a decrease in the reception probability due to the increase in the vehicle speed.

According to the fourth aspect of the present invention, when the transmitter failure diagnosing unit diagnoses that the transmitter for detecting tire pressure is out of order, a command to activate an alarm installed in the vehicle compartment is issued. It is.

Accordingly, the driver is informed by the alarm device that the tire pressure detecting transmitter is malfunctioning, and the transmitter is repaired or replaced with a new one, so that the tire pressure alarm device is immediately brought into a normal state. Can be returned to.

[0024]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment for realizing a failure diagnosis device for a tire pressure alarm device according to the present invention will be described below based on a first embodiment corresponding to claims 1 to 4.

(First Embodiment) First, the configuration will be described. FIG. 1 is an overall system showing a failure diagnosis device for a tire pressure alarm device according to a first embodiment, in which 1 is a tire pressure alarm controller, 2 is a transmitter for detecting tire pressure, and 3 is a vehicle speed sensor (vehicle speed detection means). 4 is a warning lamp (alarm), 5 is a 5V power supply circuit, 6 is a receiving circuit (receiver), 7
Is a vehicle speed input circuit, 8 is an EEPROM, 9 is a microcomputer, 10 is a warning lamp output circuit, 11 is a pressure sensor, 12 is a centrifugal switch, 13 is an ASIC,
4 is a transmitter, 15 is a transmitting antenna, and 16 is a receiving antenna.

The tire pressure alarm controller 1 comprises:
A 5V power supply circuit 5, a receiving circuit 6 for receiving transmission data from the tire pressure detecting transmitter 2, a vehicle speed input circuit 7 for inputting a vehicle speed signal from the vehicle speed sensor 3, and an E for performing ID registration and the like.
EPROM 8 (a read-only memory capable of electrically erasing stored information), a microcomputer 9 for inputting received data from the receiving circuit 6 and vehicle speed information from the vehicle speed input circuit 7, and receiving an alarm command from the microcomputer 9. A warning lamp output circuit 10.

The microcomputer 9 includes a tire pressure warning control unit for executing a tire pressure warning control process based on data received from the reception circuit 6, and a reception data from the reception circuit 6 and a signal from the vehicle speed input circuit 7. A transmitter failure diagnosis unit (transmitter failure diagnosis unit) that executes a transmitter failure diagnosis process based on the vehicle speed information has a control program.

The tire pressure warning control unit receives transmission data from the tire pressure detection transmitter 2 by the reception antenna 16 and the reception circuit 6 installed in the vehicle interior, and judges the pressure value in the reception data. When the pressure drops, a tire pressure warning command is issued to the warning lamp output circuit 10.

The transmitter failure diagnosing section determines whether or not transmission data has been received from the tire pressure detecting transmitter 2 during traveling at a set vehicle speed (for example, 40 km / h) or higher. When the failure diagnosis time t set based on the vehicle speed V from the vehicle speed input circuit 7 has elapsed without receiving the signal, the tire pressure detecting transmitter 2
Is diagnosed as a failure and the warning lamp output circuit 10
Issue a transmitter failure alarm command.

The tire pressure detecting transmitter 2 is attached to each wheel, and is open when the centrifugal force is small and closes when the centrifugal force is large. Centrifugal switch 12
A vehicle speed including a stop triggered by opening and closing of a centrifugal switch 12 provided for ensuring battery life, having an ASIC 13 which is an application-specific integrated circuit, a transmitter 14, and a transmitting antenna 15. The transmission cycle is changed in two stages, such as a long transmission interval (1 hour) in a region where the transmission speed is low, and a short transmission interval (1 minute) in a region where the vehicle speed is higher than that, and the pressure value information from the pressure sensor 11 is modulated. , Using an electromagnetic wave.

Next, the operation will be described.

[Transmitter Failure Diagnosis Processing] FIG. 2 is a flowchart showing the flow of the transmitter failure diagnosis processing executed by the transmitter failure diagnosis section of the microcomputer 9, and each step will be described below.

At step 20, it is determined whether or not the ignition switch is turned on. When the ignition switch is turned on, the transmitter failure diagnosis processing from step 21 is executed.

In step 21, it is determined whether or not the vehicle speed V from the vehicle speed input circuit 7 is a set vehicle speed (for example, 40 km / h or more). If NO, the process proceeds to step 22 and YES.
In the case of, the process proceeds to step 23.

In step 22, V <4 in step 21
When it is determined that the speed is 0 km / h, the data waiting timer T is deactivated, and the process returns to step 21 again.

In step 23, V ≧ 4 in step 21
When it is determined that the speed is 0 km / h, the data waiting timer T is activated, and the process proceeds to step S24.

In step 24, it is determined whether or not data has been received within one minute after the timer has been activated. If YES (data has been received), the process proceeds to step 25; if NO (data has not been received), Proceed to step 26.

In step 25, the transmitter 2 is determined to be normal because the data has been received in step 24, the data waiting timer T is cleared, and the process returns to step 21.

In step 26, since no data has been received in step 24, it is determined whether the data waiting timer T is less than the failure diagnosis time t. If YES, the process returns to step 23; After diagnosing a failure, the process proceeds to step 27. Here, the failure diagnosis time t is, as shown in FIG. 3, to compensate for a decrease in the reception probability due to an increase in the vehicle speed.
For a vehicle speed V of t = 0.05V + 2.5 (however, 40 km / h or more), it is set by a linear function rising to the right (failure diagnosis time setting means).

In step 27, T ≧ t in step 26
When it is determined that a failure has occurred, a transmitter failure alarm command is output to the warning lamp output circuit 10.

[Tire Air Pressure Alarm Control Action] The transmitter 2 for tire pressure detection modulates data including the pressure value from the pressure sensor 11 and transmits the modulated data using electromagnetic waves at a predetermined period described later. The transmitted data is received by the receiving antenna 16 and the receiving circuit 6 installed in the vehicle interior.

Then, the tire pressure warning control section of the microcomputer 9 reads the pressure value in the data received from the receiving circuit 6 and judges whether or not the pressure value is equal to or less than the set pressure threshold value. When the pressure drop is determined to be equal to or lower than the pressure threshold value, a tire pressure warning command is output to the warning lamp output circuit 10.

The warning lamp output circuit 10 outputs a signal to turn on the warning lamp 4 based on the warning command, and the driver can know the decrease in tire pressure by turning on the warning lamp 4.

Here, the data transmission cycle from the tire pressure detecting transmitter 2 is triggered by the opening and closing of a centrifugal force switch 12 installed in the transmitter 2 in order to secure the battery life, and includes the vehicle speed including the stop. Is longer (for example, 1 hour) in a region where the centrifugal force switch 12 is open, and a region where the vehicle speed is higher than that (a region where the centrifugal switch 12 is closed).
In this case, the transmission time can be changed in two steps such as a short transmission interval (for example, one minute).

[Transmitter Fault Diagnosis Operation] First, when the vehicle is stopped at a speed of less than 40 km / h or running at a low speed, step 20 → step 21 → step 22 in the flowchart of FIG.
The flow from step 21 to step 22 is repeated unless the vehicle speed V becomes 40 km / h or more.

That is, when the vehicle is traveling at a low speed of less than 40 km / h, the failure diagnosis of the tire pressure detecting transmitter 2 is not performed.

That is, in the tire pressure detecting transmitter 2,
In a region where the vehicle speed including the stop is low (for example, less than 40 km / h), the transmission period is a long transmission interval (for example, one hour),
If data reception is missed once for some reason, the receiver will not receive data even if it waits twice the transmission interval (for example, 2 hours). In addition, failure diagnosis cannot be performed according to necessity.

On the other hand, when the vehicle is traveling at a speed of 40 km / h or more and the transmitter 2 for transmitting tire pressure is transmitting data normally, step 20 in the flowchart of FIG.
The flow proceeds from step 21 to step 23 to step 24. In step 24, since data can be received every one minute which is the transmission cycle, the process proceeds to step 25, the data waiting timer T is cleared, and step 21 →
The flow of Step 23 → Step 24 → Step 25 is repeated.

That is, when traveling at a speed of 40 km / h or more, the failure diagnosis of the tire pressure detecting transmitter 2 is performed, but since the tire pressure detecting transmitter 2 normally transmits data,
When the data waiting timer T is cleared at the time when the data is received, it is assumed that step 24
Therefore, even if the data cannot be received within one minute and the process proceeds to step 26, it is determined that T <t, and the transmitter failure alarm is not issued.

On the other hand, when the vehicle is traveling at a speed of 40 km / h or more, and the tire pressure detecting transmitter 2 is not transmitting data due to a failure, in the flowchart of FIG. 2, step 20 → step 21 → step 23 → step In step 24, since data cannot be received, the process proceeds to step 26, and the flow proceeds to step 2.
In step 6, it is determined whether or not the data waiting timer T is less than the failure diagnosis time t. If YES, the process returns to step 23, the data waiting timer T is increased, the process proceeds from step 24 to step 26, and the data waiting is performed again in step 26. Step 2 is repeated until it is determined that the timer T is less than the failure diagnosis time t.
The flow of 3 → Step 24 → Step 26 is repeated.

Then, in step 26, when the determination is NO, that is, when the data waiting timer T becomes equal to or longer than the failure diagnosis time t, the tire pressure detecting transmitter 2 is diagnosed as having failed and the routine proceeds to step 27, where a warning lamp output circuit is provided. A transmitter failure alarm command is output to 10. That is, 40km
/ h or more, and when the tire pressure detecting transmitter 2 is not transmitting data due to a failure, the tire pressure detecting transmitter 2 is set when the data waiting timer T exceeds the failure diagnosis time t. Is diagnosed as a failure and a transmitter failure alarm is issued.

That is, in the tire pressure detecting transmitter 2,
For example, in a vehicle speed range of 40 km / h or more, the transmission cycle is a short transmission interval (for example, 1 minute). In this case, even if data reception is missed once for some reason, the receiver has a time twice as long as the transmission interval. (For example, 2 minutes), the next data can be received, and the failure diagnosis time t is, for example, 50 km / h.
Can be set to a short time such as 5 minutes in accordance with the transmission cycle, whereby the presence or absence of a failure of the tire pressure detection transmitter 2 whose transmission cycle can be changed in two stages depending on the vehicle speed is reliably diagnosed. be able to.

Further, the failure diagnosis time t is, for example, 50
By setting the time longer as the vehicle speed V increases, such as 5 minutes at km / h and 7.5 minutes at 100 km / h, the reliability of failure diagnosis decreases due to a decrease in reception probability due to the increase in vehicle speed. Can be prevented.

In addition, when it is diagnosed that the transmitter 2 for detecting tire pressure is faulty, the warning lamp 4 installed in the vehicle compartment is turned on. Can be notified to the driver by turning on the warning lamp 4.

Next, the effects will be described.

(1) Transmitter 2 for tire pressure detection based on vehicle speed V
Is set, and a failure diagnosis time t, which is a threshold value for diagnosis that the tire pressure detection transmitter 2 is faulty, is set based on the prediction, that is, the tire pressure detection transmitter 2
The failure diagnosis time t is set based on the vehicle speed information on the receiver side that performs the failure diagnosis of the tire pressure, so that the presence / absence of the failure of the tire pressure detection transmitter 2 whose transmission cycle is variable depending on the vehicle speed can be surely diagnosed. Can be.

That is, when diagnosing a failure of the tire pressure detecting transmitter 2 whose data transmission cycle can be changed according to the vehicle speed, if a fixed failure diagnosis time is set, the receiver side transmits even if the failure diagnosis time has elapsed. When the data transmission from the device 2 cannot be confirmed, it cannot be distinguished whether the data cannot be confirmed because the transmission cycle is long or the tire pressure detecting transmitter is out of order. On the other hand, by setting the failure diagnosis time t using the vehicle speed V, the failure diagnosis time t becomes
It is set to an optimal value that can be used to determine whether a failure has occurred based on the prediction of the data transmission cycle.

(2) The transmitter 2 for detecting tire pressure is triggered by opening / closing of a centrifugal force switch 12 installed in the transmitter 2 in order to secure battery life, and is long in an area where the vehicle speed is low including stop. In a region where the transmission interval is higher than the vehicle speed, the transmission cycle can be changed in two steps such as a short transmission interval, whereas in a region where the vehicle speed V is equal to or higher than a set vehicle speed (for example, 40 km / h) where the transmission period is short. When the vehicle speed V is less than the set vehicle speed, the transmitter failure diagnosis is not performed, the vehicle is traveling in the region where the vehicle speed is equal to or higher than the set vehicle speed, which is a short transmission cycle, and the tire pressure is Since the tire pressure detection transmitter 2 is diagnosed as having failed when the set failure diagnosis time t has elapsed without receiving data from the detection transmitter 2, the transmission cycle is changed in two stages depending on the vehicle speed. Tires The presence or absence of a failure of the detection transmitter 2 can be reliably diagnosed.

That is, in the transmitter 2 for detecting tire pressure,
A long transmission interval (for example, one hour) in a region where the vehicle speed including the stop is low (the region where the centrifugal force switch 12 is open), and a short transmission interval (in the region where the vehicle speed is higher (region where the centrifugal force switch 12 is closed)). For example, the transmission cycle is changed in two stages, such as 1 minute. In the case of a long transmission interval, if data is missed once for some reason, the receiver will not receive data even if it waits twice as long as the transmission interval (for example, 2 hours). If the failure diagnosis time is set, failure diagnosis cannot be performed as needed.

(3) The failure diagnosis time t for diagnosing that the tire pressure detecting transmitter 2 has failed in a region where the vehicle speed V is equal to or higher than the set vehicle speed is set to be longer as the vehicle speed V increases. It is possible to prevent the reliability of the failure diagnosis from lowering due to the lowering of the reception probability due to the rise.

(4) When it is diagnosed that the tire pressure detecting transmitter 2 is out of order, the warning lamp 4 installed in the vehicle cabin is turned on. The driver is notified by turning on the lamp 4.

As a result, by repairing the tire pressure detecting transmitter 2 or replacing the tire pressure detecting transmitter 2 with a new one, the tire pressure alarm device can be immediately returned to a normal state.

(Other Embodiments) The failure diagnosis device for a tire pressure alarm device according to the present invention has been described based on the first embodiment, but the specific configuration is not limited to these embodiments. Without departing from the spirit of the invention described in each claim of the claims, a change or addition of the design is allowed.

For example, in the first embodiment, the example of the tire pressure detecting transmitter 2 in which the transmission cycle can be changed in two steps according to the vehicle speed has been described. The present invention can also be applied to a tire pressure detection transmitter that can be changed. In this case, the failure diagnosis time t is set according to a plurality of steps or a stepless transmission cycle predicted based on the vehicle speed.

In the first embodiment, an example in which the failure diagnosis of the transmitter is not performed in a vehicle speed range of 40 km / h or less has been described. However, even in a low vehicle speed range, the transmission cycle from the tire pressure detection transmitter is on the order of minutes. If it is set to, the failure diagnosis of the transmitter may be performed even in the constant vehicle speed region including the stop.

In the first embodiment, a warning lamp is used as an example of a warning device. However, a warning buzzer for warning a failure by sound or a combination of a warning lamp and a warning buzzer can be used as a warning device.

[Brief description of the drawings]

FIG. 1 is an overall system diagram showing a failure diagnosis device for a tire pressure alarm device according to a first embodiment.

FIG. 2 is a flowchart illustrating a flow of a transmitter failure diagnosis process executed by a transmitter failure diagnosis unit of the microcomputer of the first embodiment.

FIG. 3 is a diagram illustrating a failure diagnosis time characteristic set by a transmitter failure diagnosis unit of the microcomputer of the first embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Tire pressure alarm controller 2 Tire pressure detection transmitter 3 Vehicle speed sensor (vehicle speed detection means) 4 Warning lamp (alarm) 5 5V power supply circuit 6 Receiver circuit (receiver) 7 Vehicle speed input circuit 8 EEPROM 9 Microcomputer 10 Warning lamp Output circuit 11 Pressure sensor 12 Centrifugal switch 13 ASIC 14 Transmitter 15 Transmitting antenna 16 Receiving antenna

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Yoshiki Anno 2nd Takaracho, Kanagawa-ku, Yokohama-shi, Kanagawa F-term in Nissan Motor Co., Ltd. (reference) 2F055 AA12 BB20 CC60 DD20 EE40 FF31 FF34 GG31 HH01

Claims (4)

[Claims] 1. A tire pressure detecting transmitter mounted on each wheel modulates information such as a pressure value and a sensor value at a constant cycle, transmits the modulated information by using electromagnetic waves, and a receiver installed in a vehicle cabin. In response to this, it is a device for demodulating and judging the pressure value in the data and issuing a tire pressure alarm command at the time of pressure decrease, wherein the transmitter for tire pressure detection has a longer transmission interval in a low vehicle speed region including stop. In a region where the vehicle speed is higher than that, in a tire pressure warning device that changes the transmission cycle to shorten the transmission interval, a vehicle speed detection unit that detects a vehicle speed, and a vehicle speed detection value from the vehicle speed detection unit. A failure diagnosis time setting means for predicting a data transmission cycle of the tire pressure detection transmitter and setting a failure diagnosis time which is a diagnosis threshold value that the transmitter has a failure based on the prediction; Transmitter failure diagnostic means for diagnosing that the tire pressure detecting transmitter has failed when a set failure diagnosis time has elapsed without receiving data from the tire pressure alarm. Device failure diagnosis device. 2. The failure diagnosis device for a tire pressure alarm device according to claim 1, wherein the transmitter for detecting tire pressure triggers opening / closing of a centrifugal force switch installed in the transmitter to secure battery life. In a low vehicle speed area including a stop, a long transmission interval,
In a region where the vehicle speed is higher than that, the transmitter changes the transmission cycle in two steps such as a short transmission interval, and the failure diagnosis time setting means is a region where the vehicle speed detection value is equal to or higher than the set vehicle speed in which the transmission period is short. In the transmitter failure diagnosis means, when the vehicle speed detection value is in a region less than the set vehicle speed, does not perform the transmitter failure diagnosis, more than the set vehicle speed to be a short transmission cycle Driving in the area of
A tire pressure warning device for diagnosing a failure in the tire pressure detection transmitter when a set failure diagnosis time elapses without receiving data from the tire pressure detection transmitter. Fault diagnosis device. 3. The failure diagnosis device for a tire pressure alarm device according to claim 2, wherein the failure diagnosis time setting means diagnoses that the transmitter has a failure in a region where the detected vehicle speed is equal to or higher than the set vehicle speed. A failure diagnosis device for a tire pressure alarm device, characterized in that the time is set to a long time as the vehicle speed increases. 4. The failure diagnosis device for a tire air pressure warning device according to claim 1, wherein the transmitter failure diagnosis means determines that the transmitter for tire pressure detection has failed. A failure diagnosis device for a tire pressure warning device, which is a means for operating an alarm device installed in the tire.