JPH0346324Y2 - - Google Patents

Description

[Detailed description of the invention] (Field of industrial application) This invention measures the depth of the tread groove formed in the tread of an automobile tire, and determines whether the measured tread groove depth is appropriate. This invention relates to a tire tread groove measuring device for display.

(Prior art) As the tread of the tire wears out over time,
If the depth of the tread groove becomes small (shallow), for example, the braking force coefficient becomes small, making it dangerous for the vehicle to run.

Therefore, replacing the tires before the amount of wear on the treads becomes excessively dangerous is a factor in ensuring safe driving of the vehicle.

However, conventionally, the amount of wear on the tread, or the depth of the tread groove, has been measured visually by the driver or the mechanic at the repair shop, which makes it inaccurate to judge whether the tread is suitable or not, resulting in an extremely dangerous situation. This often leads to accidents.

On the other hand, a gauge is known that is inserted into a tread groove to measure the depth of the tread groove and numerically detect the depth.

(Problems that the invention aims to solve) However, this type of conventional measuring tool is complicated to operate, and there are many variations in measurement values, making it virtually impossible to perform proper measurements. .

On the other hand, there are requests for a system to be established at gas stations, automobile repair shops, etc. to periodically measure the depth of tread grooves and immediately replace unsuitable tires. This has not been realized because there is no equipment that can do it.

This invention was made to solve the above-mentioned conventional problems, and by simply passing a car through a predetermined measurement position, the depth of the tread groove can be measured instantly and accurately, and the measurement result can be used to determine whether the vehicle is suitable or not. An object of the present invention is to provide a tire tread groove measuring device that performs display.

(Means for Solving the Problems) In order to achieve the above object, this invention is installed at a predetermined position below a light-transmitting cover plate on which an automobile tire rides, and is designed to prevent light reflected from the tread and the bottom of the tread groove. A non-contact optical displacement meter that optically detects the depth of the tread groove based on the deviation, a comparison circuit that compares the output of this optical displacement meter with a reference value, and an output of the comparison circuit and the output of the optical displacement meter. The gist of the present invention is to have a configuration including a display device for displaying suitability.

With the above configuration, the distance from the optical displacement meter to the tread is detected as a reference amount, and the distance from the optical displacement meter to the bottom of the tread groove is also detected, and the above reference amount is subtracted from this value. The depth of the tread groove is detected optically without contact. This optically read tread groove depth signal is photoelectrically converted and output as an electrical signal from the displacement meter, and compared with a reference value corresponding to a preset appropriate tread groove depth in a comparison circuit. The measured depth of the tread groove, that is, the suitability of the amount of tread wear is displayed on the display.

An embodiment of this invention will be described below with reference to the drawings.

FIG. 1 is a partial cross-sectional view of the overall configuration of the measuring device according to this invention. It is composed of a light source L made of a diode, a light emitting system lens E, a light receiving system lens R, and a displacement detector D. Then, there are measurement lenses MR with a predetermined angle range on both sides of the standoff distance SO as shown by the solid line arrow, and this standoff distance
The distance to the measurement point displaced from the SO is taken out as the deviation l of the bright spot of the reflected laser beam on the displacement detector D, as shown by the dashed-dotted arrow, and the distance to the measurement point is the principle of triangulation. It is measured by This optical displacement meter 1 is housed in a measurement box 3 with a boss 2 fixed to the lower part. This measurement box 3 is buried in the measurement location by positioning a light-transmitting cover plate 4 made of aluminum mat that covers the upper opening so that it is flush with the ground surface, and a screw rod 5 is installed inside the box 3 so as to be rotatable. The female threaded portion of the boss 2 is screwed onto the threaded rod 5, and the rotation of the threaded rod 5 causes the optical displacement meter 1 to move horizontally from side to side along the guide rod 6. Note that the optical displacement meter 1 is positioned so that the aforementioned standoff distance SO coincides with the upper surface of the light-transmitting cover plate 4. 7 is a stepping motor for moving the optical displacement meter 1, and a reducer 8
Rotation is transmitted to the screw rod 5 via. The step of this motor 7 is the tread groove 10 of the tire 9.
Optical displacement meter 1 with steps sufficiently smaller than the width of
is set to articulate, and even if the automobile tire 9 is placed on an arbitrary location, the laser beam from the optical displacement meter 1 will be moved from right to left or from left to right. The tread groove 10 is always irradiated.

As shown in FIG. 2, the moving direction of the optical displacement meter 1, that is, the axis C ₁ of the screw rod 5 is inclined at a relatively large angle θ ₁ in the same projection plane with respect to the axis C ₂ of the tire 9. are communicating.

As a result, the axis C ₂ of the tire 9 at the time of measurement is changed to the normal axis C ₂ as shown by the dashed line C ₃ , for example.
Even if the axis C 2 intersects obliquely at a small angle θ ₂ with respect to the axis C ₂ , this axis C ₂ does not coincide with the axis C 1 of the screw rod 5 , which is the moving direction of the optical displacement meter 1 .

Therefore, a safety line (not shown) formed on the tread parallel to the axis _C2 of the tire 9 does not coincide with the axis _C1 of the threaded rod 5.

Therefore, the inconvenience of measuring the safety line can be avoided.

(Operation) Next, the operation will be explained. When the automobile tire 9 is placed on the light-transmitting cover plate 4 shown in FIG. 1, the power switch 11 shown in FIG. supplied to the circuit 14;
The motor 7 is rotated to move the optical displacement meter 1, and the synchronization circuit 12 causes the optical displacement meter 1 to emit a laser beam in synchronization with the movement step of the optical displacement meter 1. It goes without saying that a rectifier or the like may be inserted and connected as necessary.

The measured value is photoelectrically converted and output as an electrical signal from the optical displacement meter 1. After this measurement signal is amplified by a preamplifier 15, it is sent to a sample hold circuit 18 via a bandpass filter 16 and a waveform shaping circuit 17. The measured values are sampled and held until the optical displacement meter 1 finishes moving within the measurement box 3.

By the way, from the optical displacement meter 1, the tread groove 10
In addition to the measured value of the distance to the bottom of the groove, for example, if the tread groove 10 is clogged with mud or stones, or if the tire 9
Measurement signals for locations other than the ground plane are also output.
Therefore, the discrimination circuit 19 has a built-in limiter circuit, and is set in advance to exclude distances other than the distance corresponding to the deepest tread groove 10 of each type of tire 9. In other words, only the distance to the bottom of the tread groove is output, and this signal is sent to the comparator circuit 20.
It is compared with a preset reference value 21 corresponding to a proper tread groove bottom, and a comparison signal is inputted to a suitability indicator 22, where if it is proper, it is displayed in blue, and if it is improper, it is displayed in red. In addition, if it is inappropriate, the buzzer 23 will sound. Note that the measurement value is digitally displayed on the measurement value display 24 based on the measurement signal from the discrimination circuit 19. These components are controlled by a computer. Further, this control section can be grounded at a predetermined management location in addition to the location near the measurement box 3.

(Effect of the invention) As explained above, according to the tire tread groove measuring device of this invention, the depth of the tire tread groove can be automatically and Measurements can be taken quickly and very accurate measurements can be obtained.

[Brief explanation of the drawing]

Fig. 1 is an overall schematic configuration diagram showing a partial cross section of the measuring device according to this invention, Fig. 2 is an explanatory plan view showing the moving direction of the optical displacement meter with respect to the tire, and Fig. 3 is the electrical block configuration. It is a diagram. DESCRIPTION OF SYMBOLS 1... Non-contact optical displacement meter, 4... Light-transmitting cover plate, 9... Tire, 10... Tread groove, 20...
... Comparison circuit, 22, 24 ... Display device.

Claims (1)

[Scope of utility model registration request] A non-contact optical displacement meter is installed below a light-transmitting cover plate on which an automobile tire rides, and optically detects the depth of a tread groove based on the deviation of reflected light from the tread and the bottom of the tread groove. 1. A tire tread groove measuring device comprising: a comparison circuit for comparing the output of the meter with a reference value; and a display device for displaying suitability based on the output of the comparison circuit and the output of the optical displacement meter.