JP2645938B2 - Tire pressure warning device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is used as a device for automatically detecting tire pressure while a vehicle is running and sending an alarm to a driver's seat when the detected tire pressure is abnormal. The present invention relates to a technology for accurately testing this tire pressure alarm device with a small number of man-hours at the time of product testing in a mass production process and at the time of repair of a service factory.

[0002]

2. Description of the Related Art A pressure switch for detecting tire pressure and an electromagnetic resonance circuit which is changed by the pressure switch are provided on the tire side, and the resonance state of the resonance circuit is wirelessly detected from a device provided on the vehicle body. A tire pressure detecting device is disclosed in Japanese Utility Model Laid-Open No. 61-81396, Japanese Utility Model Application Laid-Open No. 1-14.
No. 7,706, and Japanese Utility Model Laid-Open No. 2-116395.

[0003] These prior arts are all excellent ideas that can monitor the tire pressure during traveling by a radio signal, detect the decrease in tire pressure early, and send an alarm to the driver's seat.

[0004]

However, the technology using the above-mentioned principle has a considerably high reliability mounted on a normal automobile even though much research has been carried out. Because they cannot be offered at affordable prices, they are not actually installed in commercial vehicles. The main cause is that the transmitter including the sensor mounted on the tire and the electromagnetic resonance circuit is subjected to severe vibrations as the vehicle travels. Therefore, it is necessary to change the structure of the wheel and the like, so that it is no longer possible to use a wheel that is conventionally mass-produced. There are three tires and ten tires, and a reasonable control circuit for centrally controlling these tires cannot be obtained at a low cost so that it can be easily used in a practical vehicle.

[0005] Another problem is that automobiles are manufactured and tested consistently on a production line.
When a production vehicle is equipped with a tire pressure warning device, the test process for this is complicated. That is, if the tire pressure warning device performs a test as practical, it is necessary to release the air pressure of the already mounted tire and run it, which is pulled on the production line and progresses slowly This is not a good test for products. Even if the test is simulated by some means, the test process becomes considerably complicated. Moreover, the number of man-hours required increases the product price.

The present invention is an improvement of the present invention. When a tire pressure warning device is installed in a vehicle that is continuously mass-produced on a production line, its performance test can be performed in a short time, with a small number of work steps, and accurately. It is an object of the present invention to provide a device that can be implemented rationally.

[0007] The present invention also provides an apparatus for easily and accurately testing a tire pressure alarm device in a test performed as a maintenance and repair service after an automobile equipped with a tire pressure alarm device is sold to a customer. The purpose is to do.

[0008]

SUMMARY OF THE INVENTION The present invention comprises a pressure sensor,
A transmitter whose resonance frequency changes in accordance with the output of the pressure sensor is mounted on the tire side, an antenna facing the transmitter, a control circuit for transmitting and receiving signals to and from the antenna, and an alarm output of the control circuit are displayed. An indicator is mounted on the vehicle body side, the control circuit includes a transmission circuit that transmits a short pulse signal to the antenna, and a reception circuit that receives a resonance signal transmitted by the transmitter in response to the transmission of the pulse signal. A frequency discriminating circuit for discriminating the frequency of the resonance signal, and a program control circuit for sending the alarm output based on the output of the frequency discriminating circuit, wherein the program control circuit connects a test device. A diagnostic terminal and the program control when the test equipment is connected to the diagnostic terminal. Characterized by comprising a means for performing a while performing communication test program between the testing device by setting the circuit in the test mode.

Further, the program control circuit includes means for generating a plurality of failure codes for each cause when an abnormality is detected by the test program, and means for transmitting the failure codes to the test apparatus. Preferably, the test device includes a display device for displaying a test code transmitted from the program control circuit.

[0010]

In the apparatus of the present invention, software to be executed in the test mode is loaded in the program control circuit in advance. Further, a diagnostic terminal is provided in the program control circuit, and a configuration is adopted in which a test device can be connected to the diagnostic terminal by a connector.

When a test device is connected to the test terminal,
The program control circuit automatically detects this connection and switches its control mode to the test mode. In the test mode, the quality of each part is sequentially executed for each connected wheel according to a preset procedure, and when a failure is detected, a predetermined failure code is transmitted to the test apparatus, and the display panel of the test apparatus is transmitted. To display the details of the failure.

This series of test programs can be executed in a few seconds. If there is a failure, the part causing the failure can be rationally inspected according to the display of the test apparatus.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The basic structure of the apparatus according to the embodiment of the present invention and its operating principle will be described first. FIG. 1 is a block diagram of an apparatus according to an embodiment of the present invention. Each tire is provided with a pressure sensor 1 for detecting its air pressure. The pressure sensor 1 is a pressure switch that closes a contact when the tire air pressure is equal to or higher than a predetermined value and opens a contact when the tire air pressure is lower than the predetermined value. The transmitter 2 is electrically connected to the pressure switch. This transmitter 2 is a resonance circuit. The capacitance of the capacitor of the resonance circuit changes by the pressure switch of the pressure sensor 1, and the resonance frequency changes.

On the vehicle side, an antenna 3 is installed so as to face each transmitter 2. The antenna 3 is provided for each tire, and is connected to the control circuit 4 by electric wiring. The output of the control circuit 4 is connected to a display 5 provided in the driver's seat.

FIG. 2 is a diagram for explaining the principle of operation of this embodiment. The pressure sensor 1 is a pressure switch, and the contact 7 is closed when the tire air pressure is equal to or higher than a predetermined value, but opens when the tire air pressure falls below the predetermined value.
The transmitter 2 includes one coil L1 and capacitors C1 and C2 connected in parallel to the coil L1, of which the capacitor C1 is connected via the contact 7 of the pressure switch. . Therefore, when the tire pressure is sufficiently high, the two capacitors C1 and C2 are connected in parallel, but when the tire pressure decreases, the capacitor C1 is disconnected and the capacitor C2 is disconnected.
Only the coil L1 is connected.

As described above, the resonance frequency of the transmitter 2 changes according to the opening and closing of the contact 7. Incidentally, when the contact 7 is closed and the two capacitors are in parallel, the resonance frequency is about 87 KHz, and when the capacitor C1 is disconnected, the resonance frequency becomes about 140 KHz.

FIG. 3 is a block diagram of the control circuit 4. The antenna 3 is connected to the antenna terminal 10. A pulse having a short width is oscillated by the oscillator 11 (pulse width: several μS, repetition time: several tens μS in this embodiment), amplified by the transmission circuit 12, and transmitted from the antenna 3 as an electromagnetic wave. When this electromagnetic wave is sensed by the coil L1 of the transmitter 2, the resonance circuit including the coil and the capacitor is stimulated to sustain the damped oscillation at the resonance frequency. This resonance frequency is captured by the antenna 3 as an electromagnetic wave, and is input from the receiving circuit 13 to the frequency discriminating circuit 14. This operation is sequentially performed for each wheel under the control of the program control circuit 15, and if at least one of the tire pressure drops is detected, the display terminal 19 is displayed.
An alarm output is sent to the driver and the indicator 5 in the driver's seat is turned on.

Here, in the apparatus of the embodiment of the present invention, the program control circuit 15
4 and means for executing the test program while communicating with the test apparatus 8 by setting the program control circuit 15 to the test mode when the test apparatus 8 is connected to the diagnostic terminal 24. It is characterized by.

The program control circuit 15 includes means for generating a plurality of failure codes for each cause when an abnormality is detected by the test program, and means for transmitting the failure codes to the test apparatus 8. , The test device 8 includes a display device 9 for displaying the test code transmitted from the program control circuit 15.

Next, the operation when the test of the program control circuit 15 is performed using the test apparatus 8 (hereinafter referred to as a diagnostic monitor) will be described with reference to FIG. FIG.
9 is a flowchart for explaining a test procedure of the program control circuit 15 by a diagnostic monitor. Table 1 is a list of failure codes.

When the diagnostic monitor is connected and the starter switch is turned on, the program control circuit 15 reads the axle selection port and starts executing the test program corresponding to the vehicle type.

First, a check is started from the antenna 3 which can be tested without running. Next, the engine is started and run for about 30 m, and checks for all types of failure codes (see Table 1) are executed in the procedure shown in FIG. If the failure code is finally “1”, the system including the program control circuit 15 and all the pressure sensors 1 function normally, and the tire pressure is not low. If it is other than "1", it means that a failure of the failure code has occurred.

[0023]

[Table 1] Next, the configuration of the diagnostic monitor will be described with reference to FIGS. FIG. 5 is a diagram showing the configuration of the diagnostic monitor. FIG. 6 is a perspective view showing the appearance of the diagnostic monitor.

As shown in FIG. 5, the internal configuration of the diagnostic monitor is composed of a display LED lamp 50 and a buzzer 51. The buzzer 51 sounds while the LED lamp 50 is on. Also, as shown in FIG. 6, it is compact for convenient carrying. Note that the program control circuit 15 reads that the diagnostic monitor is connected due to a short circuit between the setting terminal 52 and the GND (ground terminal) 53.

FIG. 7 shows the output signal form of the fault code and the display means. This output signal is configured so that the worker can recognize it with a buzzer sound. FIG. 7 is a diagram showing an output signal form of a failure code.

As shown in FIG. 7, the failure code is a combination of long and short signals such as a Morse code, and can be displayed by the LED lamp 50 and the buzzer 51 of the diagnostic monitor. Note that “5” is represented by a repetition of a dot, which is not used for the purpose of avoiding erroneous recognition as “1” which is a repetition of a dot. For the same reason, “10” and “15” which are multiples of “5” are not used.

[0027]

According to the present invention, when a tire pressure warning device is installed in a vehicle which is continuously mass-produced on a production line, its performance test can be performed accurately and rationally in a short time with a small number of work steps. .

Further, according to the present invention, the tire pressure alarm device can be simply and accurately tested in a test performed as a maintenance and repair service after a vehicle equipped with the tire pressure alarm device is sold to a customer. The results of the test are output by easy-to-understand means such as blinking of an LED lamp and sounding of a buzzer.

[Brief description of the drawings]

FIG. 1 is a block diagram of an apparatus according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram of the operation principle of the device according to the embodiment of the present invention.

FIG. 3 is a configuration diagram of a control circuit of the device according to the embodiment of the present invention.

FIG. 4 is a flowchart showing the operation of the test apparatus (diag monitor) of the apparatus according to the embodiment of the present invention.

FIG. 5 is a diagram showing a configuration of a test apparatus (diag monitor) of the apparatus according to the embodiment of the present invention.

FIG. 6 is a perspective view of a test apparatus (diag monitor) of the apparatus according to the embodiment of the present invention.

FIG. 7 is an output signal form diagram for a test apparatus (diag monitor) of the apparatus according to the embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Pressure sensor 2 Transmitter 3 Antenna 4 Control circuit 5 Display 7 Contact 8 Test device 9 Display device 10 Antenna terminal 11 Oscillator 12 Transmission circuit 13 Receiving circuit 14 Frequency discrimination circuit 15 Program control circuit 16 Storage circuit 17, 18 I / O circuit 19 Display terminal 20 Bit terminal 21 Bit wire 22 Connector 23 Harness wire 24 Diag terminal 50 LED lamp 51 Buzzer 52 Setting terminal 53 GND

Claims (2)

(57) [Claims] 1. A pressure sensor, a transmitter whose resonance frequency changes according to the output of the pressure sensor is mounted on a tire side, an antenna facing the transmitter, a control circuit for transmitting and receiving signals to and from the antenna, An indicator for displaying an alarm output of the control circuit is attached to the vehicle body. The control circuit includes a transmission circuit that transmits a short pulse signal to the antenna, and the transmitter that transmits the pulse signal in response to the transmission of the pulse signal. A tire pressure alarm device comprising: a receiving circuit that receives a resonance signal to be transmitted; a frequency discrimination circuit that discriminates the frequency of the resonance signal; and a program control circuit that sends out the alarm output based on the output of the frequency discrimination circuit. The control circuit has a diagnostic terminal for connecting the test device, and the diagnostic device is connected to the diagnostic terminal. Means for setting the program control circuit to a test mode when the test is performed and executing a test program while communicating with the test apparatus. 2. The program control circuit includes: means for generating a plurality of failure codes for each cause when an abnormality is detected by the test program; and means for transmitting the failure codes to the test apparatus. The tire pressure warning device according to claim 1, wherein the test device includes a display device that displays a test code transmitted from the program control circuit.