JPH07230587A - Alarm device for drop of tire air pressure - Google Patents

Abstract

PURPOSE:To provide an alarm device for drop of tire air pressure to notify a driver of a vehicle having the air-supplied tires at the right and left sides of an axle of a fact that the difference of air pressure is produced among these tires. CONSTITUTION:A CPU decides whether the differential pressure is produced based on the detection outputs of the differential pressure detectors 6a and 6b as long as the apparent speed or the apparent distance traveled is not included in a allowable range. If the differential pressure is confirmed, the LED of the corresponding tire is turned on. Then the integrated distance traveled or the integrated traveling time is updated if the number of pulses counted at the wheel side in a time interruption mode is more than the fixed value despite the normal differential pressure. Meanwhile a tire air pressure check request signal is outputted to display if the integrated distance traveled or the integrated traveling time is larger than the fixed value.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tire pressure drop warning device, and more particularly to a tire pressure drop warning device for informing a driver of a decrease in tire air pressure when air pressures of tires of a plurality of wheels are uniformly leaked for a long time. Tire pressure drop warning device.

[0002]

2. Description of the Related Art A decrease in tire air pressure or a flat tire has a great influence on vehicle performance, and it is dangerous for a driver to continue driving without noticing it. For this reason, a device that measures the tire air pressure and issues a warning when the air pressure falls below a predetermined level has been proposed, for example, in Japanese Utility Model Laid-Open No. 5-22244. However, this proposed method requires a complicated pressure sensing mechanism in the rotating part.

On the other hand, a wheel rotation sensor for detecting the rotation of the tire is provided, the rotation states of a plurality of wheels are compared with each other from the output of the rotation sensor, and the air pressure is relatively reduced due to the difference in the number of rotations. An air pressure drop warning device provided with an arithmetic unit for judging the wheel that has been used and warning means for giving a warning to the driver when a relative drop in air pressure is judged is disclosed in, for example, Japanese Patent Laid-Open No. 63-303011 and Japanese Patent Laid-Open No. Kaihei 5-1
It is proposed in Japanese Patent No. 16512. JP-A-63-30
The 3011 publication has an advantage that it can be realized at an extremely low cost, especially when combined with a system that already uses a wheel-side sensor such as an ABS (anti-lock braking system).

[0004]

However, the above-mentioned device has a problem that a warning cannot be issued when the air pressures of all the wheels uniformly decrease due to the minute leaks which are present on all the wheels evenly. There is. Further, many large trucks generally have an axle having a plurality of rims that are regulated to rotate at the same time and multiple wheels having wheels on the left and right sides of the axle, and in recent years, there is one axle for passenger cars. A dual wheel tire having independent air pressure on the rim is proposed in, for example, Japanese Patent Laid-Open No. 5-116511. In vehicles with multiple wheels, even if the tire pressure in one of the wheels decreases, the effective radius of rotation of the tire is not significantly affected, and even if the tire pressure decreases in one of the tires, detection is not possible. It is possible. As described above, this problem can be solved by directly measuring the air pressure of each tire, but there is a drawback in that a vehicle with multiple wheels having a large number of tires must use many complicated and expensive tire air pressure detection means.

Therefore, a main object of the present invention is to provide an air pressure drop warning device which can detect the air pressure drop in one of the multiple wheels with a relatively simple structure.

[0006]

The invention according to claim 1 is
In a vehicle equipped with a plurality of pneumatic tires on each of the left and right axles, the differential pressure of the air pressure between the plurality of tires mounted on at least one rim of each of the left and right tires is not less than a predetermined value. Differential pressure detection means for outputting a differential pressure signal in response to the detection, vehicle-side detection means mounted on the vehicle body side for detecting that the differential pressure detection means has output the differential pressure signal, And an informing means for informing the driver of the warning according to the detection output of the upper side detecting means.

According to the invention of claim 2, in addition to the invention of claim 1, a wheel rotation sensor for measuring the rotation of at least two or more independently rotating wheels and an output of the wheel rotation sensor. And a calculation means for comparing the rotation states of a plurality of wheels with each other to determine the wheel whose air pressure is relatively decreased from the difference in the number of rotations, and the notification means issues a warning according to the determination result of the calculation means. Notify me.

According to a third aspect of the present invention, in addition to the first or second aspect of the present invention, it further comprises a periodic inspection signal output means for outputting a signal urging periodic inspection of tire pressure.

In the invention according to claim 4, the periodic inspection signal output means according to claim 3 outputs a signal urging periodical inspection when the accumulated traveling distance or accumulated traveling time reaches a predetermined value. To do.

[0010]

The tire pressure drop warning device according to the present invention comprises:
If the differential pressure of the air pressure between at least one of the left and right tires is equal to or greater than a predetermined value, a differential pressure signal is output, the differential pressure signal is detected on the vehicle upper side, and a warning is issued to the driver. To do.

[0011]

1 is a diagram showing the arrangement of wheels, a wheel rotation sensor, and a differential pressure detector of a vehicle to which the present invention is applied.

In FIG. 1, front wheel tires 2a and 2b are provided in front of a frame 1 of a vehicle body, and wheel speed sensors 3a and 3b for detecting respective rotation speeds.
Is provided. Behind the frame 1, rear tires 4
a, 5a, 4b and 5b are provided in a so-called compound wheel structure. A differential pressure detector 6a is provided to detect a difference in air pressure between the tires 4a and 5a (hereinafter referred to as differential pressure), and a differential pressure detector to detect a differential pressure between the tires 4b and 5b. 6b is provided. Furthermore, tire 5
In order to detect the rotational speeds of a and 5b, the wheel speed sensor 7
a and 7b are provided.

FIG. 2 is a diagram showing a specific structure of the rear wheel shown in FIG. In FIG. 2, tires 4a, 5a, 4
b and 5b are rims 13a, 14a, 13b and 1 respectively.
4b, each bearing by an axle 8. The differential pressure detector 6a includes a differential pressure detector 9a for detecting the differential pressure between the tires 4a and 5a, a transmitting antenna 10a for transmitting the detected output, a receiving antenna 11a for receiving the transmitted detected output, and a receiving antenna. 11a is connected to the receiver 12a. Similarly, the differential pressure detector 6b
Includes a differential pressure detector 9b, a transmitting antenna 10b, a receiving antenna 11b, and a receiver 12b. Transmitting antenna 10
a and 10b are provided concentrically with the axle 8, rotate with the tires 5a and 5b, and receive antennas 11a and 11b.
b is provided concentrically with the axle 8 and the transmitting antenna 10
Each of a and 10b is electromagnetically coupled and fixed to the frame 1. The wheel speed sensors 7a and 7b are also fixed to the frame 1 and detect the rotation of the tires 5a and 5b.

FIG. 3 is a longitudinal sectional view showing an example of the differential pressure detecting section shown in FIG. In FIG. 3, the differential pressure detector 9a includes a piston 902 that is movable left and right in the cavity 901,
The piston 902 is pressed from the left and right inside the cavity 901 by spring springs 903 and 904. Cavity 9
An inlet hole 905 for introducing the air pressure of the tire 4a shown in FIG. 2 is formed on the left side of 01, and an inlet hole 906 for introducing the air pressure of the tire 5a is formed on the right side.

A waist 90 is formed in the center of the piston 902.
7 is formed and there is a contact 90 made of a conductive material.
The tip on one side of 8 is in contact. The contactor 908 is pressed upward by a spring spring 910. A protrusion 909 is formed below the contactor 908.
An insulating case 911 is provided below the contactor 908. The contacts 912 and 913 are provided inside the insulating case 911.
Are arranged to face each other.

The air pressure of the tires 4a and 5a is controlled by the introduction hole 90.
If the pressure difference between the two is equal, the piston 902 is located in the center of the cavity 901. Therefore, the tip of the contactor 908 is pressed upward by the coil spring 910, and the piston 90
It is in contact with the second constricted portion 907. Then, for example, when the air pressure of the tire 4a becomes lower than the air pressure of the tire 5a, the piston 902 moves to the left. Piston 90
The second constricted portion 907 pushes down the tip of the contact 908.
Therefore, the protruding portion 909 of the contactor 908 contacts the contact points 912 and 913, and the differential pressure detection signal is output. On the contrary, when the air pressure of the tire 5a becomes lower than the air pressure of the tire 4a, the protruding portion 909 of the contactor 908 similarly causes the contact point 91 to move.
2 and 913 are contacted and a differential pressure detection signal is output.

FIG. 4 is a sectional view showing another example of the differential pressure detector. The differential pressure detector 90a shown in FIG. 4 is the tire 4a.
The contact points 912 and 913 are short-circuited by the contactor 914 when the pressure difference between the contact points 912 and 513 is equal, and the contact between the contact points 912 and 913 is disconnected when the pressure difference occurs. Therefore, the contact 91 is provided on the upper part of the insulating case 911.
2 and 913 are arranged so as to face each other, and the contactor 914 is pressed upward by a spring spring 910 provided under the contactor 912 so that the contact points 912 and 913 always contact each other.

When a differential pressure is generated between the tires 4a and 5a, the piston 902 moves leftward or rightward and pushes the contactor 914 downward, so that the contactor 914 separates from the contact points 912 and 913 and the differential pressure detection signal is output. Is output as.

In the differential pressure detecting portion 9a shown in FIG. 3 described above, since the above-mentioned protruding portion 909 is separated from the contact points 912 and 913, when the cable connected to the contact points 912 and 913 is broken, it is abnormal. Although it is not possible to inform the driver that there is such a difference, in the differential pressure detection unit 90a shown in FIG. 4, since the contactor 914 is constantly in contact with the contacts 912 and 913, a differential pressure is generated when the cable is disconnected. Since it will be the same state as when it was, the driver injects air into the tire 4a or 5a and displays that the differential pressure is generated even after the differential pressure becomes equal, so it is judged that the device is abnormal. There is an advantage that you can.

FIG. 5 is a diagram for explaining the operation of transmitting the detection result of the differential pressure detecting section to the receiver shown in FIG. 2 by the electromagnetic coupling loop.

The contact 912 of the differential pressure detector 9a shown in FIG.
And 913 are shown by a contact S, and a capacitor C1 is provided at the contact S.
Are connected in series, to which the capacitor C2 and the coil L1 are connected in parallel. The coil L1 is an inductance component of the transmitting antenna 10a. Transmitting antenna 10
The receiving antenna 11a is electromagnetically coupled to the antenna a, and the receiving antenna 11a includes a coil L2 having an inductance component.

Further, as shown in FIG. 5A, when a pulse signal is supplied to the receiving antenna 11a when the contact S is opened, the receiving antenna 11a transmits the transmitting antenna 1
The pulse signal is transmitted to 0a. Since the contact S is opened in the transmitting antenna 10a, the parallel resonant circuit of the coil L1 and the capacitor C2 resonates, and the resonance signal is transmitted from the transmitting antenna 10a to the receiving antenna 11a.

Next, as shown in FIG. 5 (b), when the differential pressure is detected and the contact S is closed, the coil L1 and the capacitors C1 and C2 resonate in parallel on the transmitting side. The frequency becomes higher. This resonance signal is transmitted to the receiving antenna 11a, and by detecting the period difference T on the receiving side, it is possible to detect whether or not a differential pressure is generated. That is, in the differential pressure detection unit shown in FIG. 3, the period difference T when the differential pressure is generated becomes small, and in the example shown in FIG. 4, the period difference T becomes large.

FIG. 6 is a schematic block diagram of an embodiment of the present invention. In FIG. 6, the receiver 12a shown in FIG.
12b and the wheel speed sensors 3a, 3b, 7a, 7b are connected to the control unit 20, and further to the control unit 20, a low air pressure warning display device 30 and a regular inspection request signal display device 40 are connected.

FIG. 7 is a concrete block diagram of the control unit shown in FIG. The outputs of the receivers 12a, 12b and the wheel speed sensors 3a, 3b, 7a, 7b shown in FIG. 6 are given to the CPU 102 via the input interface 101. The CPU 102 has an EEPROM 103 and a ROM
104 and the RAM 105 are connected. EEPRO
M103 stores an integrated value of the traveling distance and the traveling time. R
The OM 104 stores a program based on the flow charts shown in FIGS.
5 stores various data. Further, the CPU 102 is connected to the low air pressure warning display device 30 and the regular inspection request signal display device 40 via the output interface 106. The low air pressure alarm display device 30 informs the driver that the air pressure has decreased, and the regular inspection request signal display device 40 informs the driver that the air pressure should be regularly inspected. The regular inspection request signal display device 40 includes a reset switch 122, which will be described later with reference to FIG.
A reset signal from the reset switch 122 is given to the CPU 102 via the input interface 107.

Further, the DC voltage + B from the battery is supplied to the constant voltage circuit 10 via the switch 112 and the fuse 113.
Given to 8. The constant voltage circuit 108 sets the DC power supply + B to a constant voltage and supplies it to the CPU 102. Further, the DC power supply + B is made to have a constant voltage by the constant voltage circuit 109 via the fuse 114, and is given to the uninterruptible clock circuit 111. The uninterruptible clock circuit 111 is for counting the integrated value of the traveling time, and the power is always supplied even when the key of the vehicle is turned off, and the power is supplied even when the battery is completely discharged. So that the backup battery 110 is provided.

FIG. 8 is an external view of the low air pressure alarm display device 30 and the regular inspection request signal display device 40 shown in FIG. In FIG. 8, the low air pressure warning display device 30 includes
Light emitting diodes (LED) 111 to 116 for indicating a decrease in air pressure are provided corresponding to each of the tires 2a, 2b, 4a, 4b, 5a, 5b, and an alarm buzzer 117 is further provided at the center. It is provided. The periodic inspection request signal display device 40 includes a display 121 and a reset switch 122 for displaying that periodic inspection is required.
And are provided.

9 to 11 are flow charts for explaining the operation of the embodiment of the present invention.

Next, the operation of the embodiment of the present invention will be described with reference to FIGS. First, the CPU 10
Reference numeral 2 calculates the product of the rotational speeds of the wheel speed sensors 3a, 3b, 7a, 7b input via the input interface 101 and a constant depending on the corresponding tire diameter, that is, the apparent speed. Instead of the apparent speed, the product of the number of revolutions of each tire per unit time and a constant depending on the tire diameter, that is, the apparent travel distance may be obtained. The constant that depends on the tire diameter is R
It is stored in the OM 104. The CPU 102 determines whether the maximum value and the minimum value of the apparent speed or the apparent travel distance are within the allowable range. If these values are within the allowable range, the CPU 102 determines that the input interface 10
Based on the outputs of the differential pressure receivers 12a and 12b given via 1, it is determined whether or not a differential pressure above a predetermined level is detected. If the differential pressure is more than a predetermined value, L of the corresponding compound wheel part
Turn on the ED. That is, if the pressure difference between the tires 4a and 5a is not less than a predetermined value, the LEDs 113 and 1 shown in FIG.
Make 14 blink. At the same time, the CPU 102 issues an alarm with the alarm buzzer 117.

If the differential pressure is within a predetermined value, it is determined to be normal, and it is determined whether periodical inspection is necessary.
Then, the routine proceeds to the routine inspection required determination time interruption routine shown in FIG. 11, and it is determined whether or not the number of wheel-side pulses during the time interruption is less than n. If the number of pulses on the wheel side is larger than n, the cumulative traveling distance or cumulative traveling time stored in the RAM 105 is updated. Here, the total traveling distance is obtained by the following equation.

Total traveling distance = previous value + 2πr pulse number /
The number of pulses per one rotation of the tire and the cumulative running time can be calculated by the following formula.

Integrated running time = previous value + time interruption interval In the above-mentioned determination step, if it is determined that the number of wheel-side pulses is smaller than n, the data stored in the EEPROM 103 is updated to the latest data. Then, it is determined whether or not the total traveling distance or the traveling time is larger than the set value, and if it is larger, the tire air pressure inspection request signal is output. The CPU 102 lights the indicator 121 of the regular inspection request signal display device 30 shown in FIG. 8 in response to the tire pressure inspection request signal.

If the apparent traveling distance or the apparent traveling speed of each tire is not within the allowable range, it is determined that the relative air pressure is abnormal. Then, the LED corresponding to the maximum tire having the apparent speed or the maximum tire having the apparent mileage is turned on. That is, the tire having the maximum apparent speed or mileage is determined to have a reduced air pressure, the corresponding LED of the LEDs 111 to 116 is turned on, and the alarm is issued by the alarm buzzer 117.

When the reset switch 122 of the periodic inspection request signal display device 40 is operated, the input interface 10
An interrupt signal is given to the CPU 102 via 7,
102 performs the process shown in FIG. That is, CP
U102 stops the alarm of buzzer 117 and performs reset processing.

As described above, according to this embodiment, the wheel side needs to generate a signal only when a differential pressure is generated. Therefore, unlike the pressure measuring system that needs to be constantly monitored, the wheel side is different from this embodiment. Without using the electromagnetically coupled transmitting means listed in, even if a battery is mounted and normal radio wave transmitting means is adopted, power is not consumed if the air pressure difference is normal, so it is not limited to lithium batteries, for example. However, there is an advantage that the battery life can be secured.

[0036]

As described above, according to the first aspect of the invention, the difference in air pressure between at least one of the left and right tires is detected and a differential pressure signal is output. Since a signal is detected on the vehicle body side to issue an alarm, even if there is a difference in air pressure between the tires of the multiple wheels with a relatively simple structure, the driver can be immediately notified and an accident can be prevented. be able to.

According to the second aspect of the present invention, it is impossible to give a warning due to the differential pressure to the wheels of the axle on which the plurality of pneumatic tires are not mounted on the left and right sides, but the wheel rotation is measured. By applying the conventional method of comparison by combining with the invention of claim 1, an inexpensive pneumatic alarm system can be obtained. Furthermore, by applying the conventional method of measuring and comparing wheel rotations even for axles equipped with multiple pneumatic tires on each of the left and right sides, multiple pneumatic tires cause a decrease in air pressure, If an abnormality cannot be detected depending on the pressure, a warning can be issued from the comparison result of the wheel rotations, and the reliability is improved.

According to the third aspect of the present invention, it is impossible to warn by comparing the wheel rotations or by detecting the pressure difference between a plurality of wheels to determine a decrease in air pressure. It is possible to prevent the decrease in air pressure due to minute air leakage that occurs to be left unattended.

[Brief description of drawings]

FIG. 1 is a diagram showing an arrangement of wheels, a wheel-side sensor, and a differential pressure detector of a vehicle to which the present invention is applied.

FIG. 2 is a diagram showing a specific configuration of a rear wheel shown in FIG.

FIG. 3 is a vertical cross-sectional view showing an example of the differential pressure detection unit shown in FIG.

FIG. 4 is a cross-sectional view showing another example of the differential pressure detector.

FIG. 5 is a diagram for explaining an operation of transmitting a detection result of a differential pressure detection unit to a receiver by an electromagnetic coupling loop.

FIG. 6 is a schematic block diagram of an embodiment of the present invention.

7 is a specific block diagram of the control unit shown in FIG.

8 is an external view of the low air pressure alarm display device and the regular inspection request signal display device shown in FIG.

FIG. 9 is a flowchart for explaining the operation of the embodiment of the present invention.

FIG. 10 is a flowchart showing an interrupt process when a reset switch is operated.

FIG. 11 is a flow chart showing a routine for routinely checking required determination time interruption.

[Explanation of symbols]

 2a, 2b, 4a, 4b, 5a, 5b Tires 3a, 3b, 7a, 7b Wheel-side sensor 6a, 6b Differential pressure detector 9a, 9b Differential pressure detector 10a, 10b Transmit antenna 11a, 11b Receive antenna 12a, 12b Receive Machine 20 Control unit 30 Low air pressure alarm display device 40 Regular inspection request signal display device 101 Input interface 102 CPU 103 EEPROM 104 ROM 105 RAM RAM 106 Output interface 107 Input interface 108, 109 Constant voltage circuit 110 Backup battery 111 Uninterruptible clock circuit

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[Procedure amendment]

[Submission date] March 16, 1995

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] 0027

[Correction method] Change

[Correction content]

FIG. 8 is an external view of the low air pressure alarm display device 30 and the regular inspection request signal display device 40 shown in FIG. In FIG. 8, the low air pressure warning display device 30 includes
Light emitting diodes (LED) 131 to 136 for indicating a decrease in air pressure are provided corresponding to each of the tires 2a, 2b, 4a, 4b, 5a, 5b, and an alarm buzzer 117 is further provided at the center. It is provided. The periodic inspection request signal display device 40 includes a display 121 and a reset switch 122 for displaying that periodic inspection is required.
And are provided.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Name of item to be corrected] 0029

[Correction method] Change

[Correction content]

Next, the operation of the embodiment of the present invention will be described with reference to FIGS. First, the CPU 10
Reference numeral 2 calculates the product of the rotational speeds of the wheel speed sensors 3a, 3b, 7a, 7b input via the input interface 101 and a constant depending on the corresponding tire diameter, that is, the apparent speed. Instead of the apparent speed, the product of the number of revolutions of each tire per unit time and a constant depending on the tire diameter, that is, the apparent travel distance may be obtained. The constant that depends on the tire diameter is R
It is stored in the OM 104. The CPU 102 determines whether the maximum value and the minimum value of the apparent speed or the apparent travel distance are within the allowable range. If these values are within the allowable range, the CPU 102 determines that the input interface 10
Based on the outputs of the differential pressure receivers 12a and 12b given via 1, it is determined whether or not a differential pressure above a predetermined level is detected. If the differential pressure is more than a predetermined value, L of the corresponding compound wheel part
Turn on the ED. That is, if the pressure difference between the tires 4a and 5a is equal to or higher than a predetermined value, the LEDs 133 and 1 shown in FIG.
Blink 34. At the same time, the CPU 102 issues an alarm with the alarm buzzer 117.

[Procedure 3]

[Document name to be amended] Statement

[Correction target item name] 0033

[Correction method] Change

[Correction content]

If the apparent traveling distance or the apparent traveling speed of each tire is not within the allowable range, it is determined that the relative air pressure is abnormal. Then, the LED corresponding to the maximum tire having the apparent speed or the maximum tire having the apparent mileage is turned on. That is, it is determined that the tire having the maximum apparent speed or mileage has a reduced air pressure, the corresponding LED of the LEDs 131 to 136 is turned on, and the alarm buzzer 117 issues an alarm.

[Procedure amendment 4]

[Document name to be corrected] Drawing

[Correction target item name] Figure 8

[Correction method] Change

[Correction content]

[Figure 8]

Claims (4)

[Claims] 1. A vehicle in which a plurality of pneumatic tires are mounted on each of the left and right axles, and a pneumatic pressure difference between the plurality of tires is mounted on at least one rim of each of the plurality of left and right tires. Differential pressure detecting means for outputting a differential pressure signal in response to detecting that the differential pressure signal is greater than or equal to a predetermined value, mounted on the vehicle body side, for detecting that the differential pressure detecting means outputs the differential pressure signal Of the vehicle upper side detecting means, and an informing means for informing the driver of a warning according to the detection output of the vehicle upper side detecting means. 2. A wheel rotation sensor that measures the rotation of at least two or more independently rotating wheels, and the rotation states of the plurality of wheels are compared with each other according to the output of the wheel rotation sensor. A calculation means for determining a wheel in which the air pressure is relatively reduced from the difference in the number of revolutions, and the notification means notifies a warning according to the determination result of the calculation means. The tire pressure drop warning device according to claim 1. 3. The tire pressure drop warning device according to claim 1, further comprising a periodic inspection signal output means for outputting a signal for prompting periodical inspection of the tire air pressure. 4. The periodic inspection signal output means outputs a signal urging periodical inspection when the accumulated traveling distance or accumulated traveling time reaches a predetermined value. 3 Tire pressure drop warning device.