JPH07198520A - Device for detecting abnormality of internal pressure in tire - Google Patents

Abstract

PURPOSE:To provide a detector for abnormality of internal pressure in a tire in order to detect the pressure reduction of the tire attached to an axle by detecting an increase in axle torque. CONSTITUTION:The detecting device is provided with a storage device l to store the range of reference axle torque in which the relation-ship between vehicle velocity and allowable range of torque that is applied to an axle 8 of respective tire 7 at a normal internal pressure is specified by kinds and states of road surface and by driven wheels or non-driven wheels, a change-over device to indicate the kinds and states of road surface, a vehicle velocity measuring device 3, and an axle torque measuring mechanism 4 that is mounted to the respective axle 8 to measure its torque for the respective axles 8. Furthermore, it is provided with a calculation device 5 that is electrically connected with the device 1, change-over device 3 and mechanism 4 and judges whether or not the axle torque at the measured velocity is within a range of reference axle torque, and an alarm device 6 to issue an alarm when the device 5 judges that it is not.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tire internal pressure abnormality detecting device. More specifically, in view of the fact that the axle torque increases due to a decrease in tire internal pressure, an alarm is issued when the axle torque exceeds a preset reference range, and the reference range indicates the type of road surface. The present invention relates to a tire internal pressure abnormality detection device defined for each state and for each driving wheel and non-driving wheel.

[0002]

2. Description of the Related Art Tires mounted on an automobile maintain a specified air pressure for each vehicle, thereby enabling safe and comfortable running. However, the tire air pressure may decrease due to external damage or poor management, and this may seriously affect not only the comfort of running but also the safety. In addition, the decrease in air pressure may increase unknowingly or may occur suddenly while driving. Therefore, it is necessary to warn the driver who is driving that the pressure reduction of the tire has reached a dangerous state, instead of fitting the dial gauge while the vehicle is stopped and performing measurement as in the past. Various methods for detecting a decrease in the air pressure of each tire have been proposed. That is, since the outer diameter of the tire becomes smaller as the air pressure decreases, a method of detecting by comparing the angular velocity with the vehicle speed, or a method of providing a sensor for detecting a change in the inner pressure in the tire is used.

However, the method of detecting by comparing the angular velocity with the vehicle velocity is 140 k as permitted in Germany.
When traveling at a high speed exceeding m / h (particularly 200 km / h or more), there is a problem that the difference in angular velocity between the normal inner pressure wheel and the pressure reducing wheel decreases, and the detection sensitivity decreases.

Further, the method of providing a sensor for detecting a change in internal pressure in the tire not only requires a constituent device to be mounted on the vehicle body side, but also makes the tire wheel special.
In the tire repair market, there is a problem that general users are limited in the degree of freedom to replace tires and wheels to compatible sizes, and the spread is hindered.

In view of the above circumstances, the present invention is that the axle torque is increased as the tire air pressure is reduced, and the difference between the axle torque at the time of normal internal pressure and the axle torque at the time of reduced pressure increases as the vehicle speed increases. Focusing attention, the necessary detection sensitivity can be secured even in the high-speed range over 140 km / h, and the tire internal pressure abnormality detection device is provided so that the system configuration device is only on the vehicle body side and does not require special devices for tires and wheels. The purpose is to do.

[0006]

SUMMARY OF THE INVENTION A tire internal pressure abnormality detecting device according to the present invention comprises: (a) a relationship between a vehicle speed and an allowable range of torque applied to an axle of each tire at a normal internal pressure, classified by road surface type and state; A storage device that stores a reference axle torque range defined for each of driving wheels and non-driving wheels, (b) a switch that can indicate the type and state of the road surface, (c) a vehicle speed measuring device, and (d) each An axle torque measuring mechanism that is mounted on an axle and measures torque for each axle; and (e) an axle at a measured speed that is electrically connected to the storage device, the switching device, the vehicle speed measuring device, and the axle torque measuring mechanism. It is provided with an arithmetic unit for comparing whether or not the torque is within the reference axle torque range, and (f) an alarm unit for issuing an alarm when the arithmetic unit judges that it is not.

[0007]

In the tire internal pressure abnormality detecting device of the present invention, the torque of each axle is calculated in real time based on the information from the axle torque measuring mechanism attached to each axle, and the axle torque at that time is also taken into consideration. When the vehicle exceeds the reference axle torque range, it judges that the tires mounted on the axle are decompressed and issues an alarm. The reference axle torque range is defined for each drive wheel and each non-drive wheel, and is compared and determined for each axle by the arithmetic unit. The reference axle torque range is defined for each type and condition of the road surface, and the data is selected by the switch.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A tire internal pressure abnormality detecting device of the present invention will be described below with reference to the accompanying drawings. The present invention is intended to read the change in the internal pressure of the tire mounted on the axle from the change in the axle torque, and considers the effect of the change in axle torque due to the change in the road surface condition. Therefore, the axle torque is measured in advance when the tire air pressure is normal under various road surface conditions, and when it exceeds the axle torque, it is determined that the air pressure has decreased. Such an allowable range of axle torque is referred to as a reference axle torque range (hereinafter, simply referred to as a reference range).

It is preferable that the reference range is defined for each type of road surface (asphalt, concrete, stone pavement, etc.) and condition (dry, wet, etc.) in all situations. In this embodiment, six types and conditions of road surfaces, which are particularly frequently used, asphalt (dry), asphalt (wet), concrete (dry), concrete (wet),
It is specified by actually measuring on stone pavement (dry) and stone pavement (wet). However, of course, it is possible to prescribe states other than these.

Further, since the value of the axle torque may be greatly different between the driving wheels and the non-driving wheels due to the distribution relationship between the driving role and the steering role, the reference range for each of the driving wheels and the non-driving wheels is different. Shall be specified by actual measurement. Therefore,
In this embodiment, a total of 12 reference range tables are created. Further, since the axle torque may vary greatly depending on the speed such as on a wet road surface, the reference range is created in relation to the speed.

Specifically, the allowable range of tire pressure reduction is 0 to 0.
30% (0-0.6kg at regular air pressure of 2kg / cm ²
/ Decompression up to / cm ² ) and changing the speed on the above-mentioned six road surfaces to conduct a running test to determine. Then, a curve as shown in FIG. 3 is obtained. If the curve is exceeded, it is determined that the air pressure is abnormal. The torque index is
It shows a relative torque value when the axle torque at a vehicle speed of 50 km / h is 100.

FIG. 1 is a system explanatory view showing an embodiment of a tire internal pressure abnormality detecting device of the present invention, which is equipped with a storage device 1 for storing the above-mentioned reference range, and detects a pressure reduction of a running tire. A switching device, 3 is a vehicle speed measuring device, 4 is an axle torque measuring mechanism, 5 is a computing device, and 6 is an alarm device. The vehicle speed measuring device 3 and the axle torque measuring mechanism 4 are provided on each tire 7. This is to detect an abnormality in the internal pressure of each tire 7. The reason why the vehicle speed measuring device 3 is provided for each tire 7 is that the speed of the tire 7 is different between left and right and front and back due to a circumferential difference when turning left or right. is there.

As shown in FIG. 1, the switching device 2 includes asphalt (dry), asphalt (wet), concrete (dry), concrete (wet), stone pavement (dry), stone pavement (wet) and off (OFF). It has 7 contact points and can be specified by the driver by turning the knob. If the vehicle is not classified into 6 types, such as running on sandy land, it cannot be detected and is turned off.

As the vehicle speed measuring device 3, any method or method such as a method using a rotation sensor and a tire circumference at a normal internal pressure, a method for directly measuring a running speed by measuring an air flow, or a reflection laser method can be used. Any thing can be used. Then, the computing device 5 preferably computes the speed for each tire 7 and compares it with the reference range. However, the average value of the speed calculated for each tire 7 may be compared with the reference range. When using the average value, it is preferable to set an allowable error so as to absorb an error from the true value and add this to the reference range.

As shown in FIG. 2, the axle torque measuring mechanism 4 is preferably configured to calculate the torque value from the twist of the axle 8 connected to the tire 7. That is, the torque T applied to the axle 8 is the diameter D of the axle 8,
Assuming that the twist angle per unit length is ψ, T = G × ψ × Ip ····, where Ip = π / 32 × D ⁴ (solid axis) G: Shear elastic coefficient Ip: Second polar moment of area Is expressed as

The above-mentioned twist angle ψ can be measured by using various optical and magnetic means. One example thereof will be described based on FIG. FIG. 2 shows a reflector 11 and a photoelectric switch 1.
This is a measuring method using Nos. 2 and 13. Photoelectric switch 12, 1
The reflection plate 11 that reflects the light emitted from the projector 3 of
It is attached to the side surface of the axle 8 in a slender shape in the axial direction. The photoelectric switches 12 and 13 are attached to the non-rotating portion of the vehicle body at positions where light can be projected and received by the reflection plate 11. If the axle 8 rotates with no load and there is no twist, the photoelectric switch 1
2 and 13 simultaneously receive the reflected light (see FIG. 2A). If twisting occurs, a difference occurs in the time of receiving the reflected light, and the twisting angle θ can be calculated from the relationship with the angular velocity (see FIG. 2B). That is, the photoelectric switch 1
The distance between 2 and 13 is Lcm, the photoelectric switch 12,
Assuming that the difference between the times when 13 receives the reflected light is t seconds and the number of rotations of the tire obtained from the vehicle speed measuring device is N rpm,
The twist angle θ is θ = 2πN / 60 × t Therefore, the twist angle ψ per unit length is expressed as ψ = θ / L .... The axle torque is obtained by substituting the equation into the equation to obtain the torque T.

In addition, a magnetic sensor using a magnetic material, a proximity switch, or the like can be used instead of the above-mentioned reflector. It is also possible to attach a strain gauge to the axle and measure the twist directly. Of these means,
It is preferable to use a photoelectric switch because it is less susceptible to the electrical and magnetic influences of the surroundings and ensures accurate measurement.

The arithmetic unit 5 receives the signal from the axle torque measuring mechanism 4 in real time during traveling and calculates the torque value of each axle 8. Also, the speed of each axle 8 is calculated from the signal from the vehicle speed measuring device 3. Then, out of the reference range stored in the storage device 1, the reference range for the type and state of the road surface designated by the switch 2 is read out and compared for each drive wheel and non-drive wheel. If it exceeds the reference range, it is judged to be abnormal and the alarm device 6 is activated.

It is preferable that the above-mentioned abnormality determination be logically devised by a statistical method in order to eliminate the influence of temporary irregularities on the road surface. For example, it is determined that the abnormality is detected by detecting the abnormality 8 times out of 10, or the abnormality is determined when the abnormal state is continuously detected for a certain time or more. Further, in order to eliminate the influence of a slope or the like, it is preferable to take measures such as not determining that the four wheels are abnormal when the torque changes in the same direction (for example, decreasing or expanding at the same ratio). Further, the lateral acceleration may be detected in order to eliminate the influence of the axle torque in the cornering, and when the lateral acceleration of a certain value or more is detected, the data may be excluded as invalid.

The alarm device 6 includes a lamp, a buzzer, a light,
It is possible to output an alarm by sound or a combination thereof. Further, since it can be detected for each tire, it is preferable to provide a warning light indicating the position of the tire on the warning display plate so that the abnormal wheel can be identified at a glance. The driver can detect an abnormality in the tire pressure from this alarm, stop the vehicle immediately, inspect the tire, and adjust the tire pressure with a portable air cylinder, a compressor, or the like as necessary. Alternatively, it is possible to go to the nearest gas station and replace tires while safe by low-speed safe driving.

[0021]

As described above, according to the tire pressure abnormality detecting device of the present invention, the axle torque under running is measured in advance by the axle torque measuring mechanism attached to the axle of each tire. It is constantly compared with the torque, and if the axle torque exceeds the reference range, it is determined that the air pressure of the tire mounted on the axle is abnormal.
Then, the axle torque is measured by a sensor such as a photoelectric switch provided on the axle. Therefore, the air pressure sensor can be easily attached to the conventional vehicle by a simple additional operation such as attaching a photoelectric switch to the axle without attaching the air pressure sensor inside the tire or changing the specifications of the conventional device. Further, since the tire internal pressure abnormality detection device of the present invention is mounted only on the vehicle body side and does not require a special device for the tire or the wheel, the user can limit the types of tires that can be replaced at the time of tire replacement to a narrow range. It is easy to spread and is not used.

[Brief description of drawings]

FIG. 1 is a system explanatory view of a tire pressure drop warning device of the present invention.

FIG. 2 is an explanatory diagram of a tire resistance detection mechanism of the present invention.

FIG. 3 is a diagram showing a relationship between torque and speed on a dry road surface.

[Explanation of symbols]

 1 Storage Device 2 Switching Device 3 Vehicle Speed Measuring Device 4 Torque Measuring Mechanism 5 Computing Device 6 Alarm Device 7 Tire 8 Axle

Claims (1)

[Claims] 1. A reference axle torque range which defines the relationship between (a) vehicle speed and the allowable range of torque applied to the axle of each tire at normal internal pressure by road surface type and state, and by driving wheels and non-driving wheels. A storage device for storing, (b) a switching device capable of instructing the type and state of the road surface, (c) a vehicle speed measuring device, and (d) an axle torque which is attached to each axle and measures torque for each axle. A measuring mechanism, and (e) the storage device,
An arithmetic unit electrically connected to the switching unit, the vehicle speed measuring unit, and the axle torque measuring mechanism for comparing whether or not the axle torque at the measured speed is within a reference axle torque range; and (f) the arithmetic unit. A tire internal pressure abnormality detection device, comprising an alarm device for issuing an alarm when it is determined to be no.