JPS6145600Y2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to an improvement of a loop coil sheet for a sensor used to determine the type of vehicle passing on the road.

Conventionally, sensors used to measure the amount of traffic such as vehicles have been used to measure the number of passing vehicles by converting the tire pressure generated when vehicles pass into air pressure via rubber hoses installed on the road, and to measure the number of passing vehicles. There is a method of measuring the number of vehicles passing by by installing them on the ground and using the changes in inductance that occur when vehicles pass. In the above-mentioned rubber hose type, both ends of the hose that cross the road surface are fixed, but they are easily damaged and have problems in terms of durability. Furthermore, in order to prevent a decrease in sensitivity for detecting air pressure, the diameter of the rubber hose must be increased, which poses a problem in that noise and vibrations caused by passing vehicles occur. The loop coil method is generally used by cutting a groove in the road surface and burying the loop coil in it, so it is necessary to block traffic for such construction, and installation work takes a long time. The impact on traffic was significant.

In order to solve these problems, it was devised to form the loop coil into a sheet, and as a result, the construction time required to install it on the road surface was significantly shortened.

However, with the vehicle detection method that uses a loop coil as a sensor, no particular problem occurs as long as the detection sensitivity is within a certain range, but the type of vehicle passing by is determined from changes in the amount of inductance that occur in the loop coil due to differences in vehicle structure. In the vehicle type discrimination method, it was necessary to adjust the sensitivity of the detection section, including the loop coil, to a predetermined value.

The first method used for this sensitivity adjustment was to bring a metal plate cut to a certain size close to the loop coil sheet at a certain distance. However, this method required a device to move the metal plate to a predetermined position, and it also took a long time to adjust the sensitivity, so it was not a very desirable method.

The next method used was to create a board made of insulating material with a small loop coil built into it, place this board on a loop coil sheet installed on the road, and short-circuit the small loop coil with a resistor with a predetermined resistance value. This method produced the same effect as the inductance change produced in a loop coil set on the road surface when the metal plate was moved.

However, even with this method, when adjusting the sensitivity, it is necessary to carry the small loop coil onto a loop coil sheet installed on the road surface, so the drawback remains that sensitivity cannot be adjusted at any time when there is heavy traffic. was.

The purpose of this invention is to solve the above problems, and to make it possible to adjust the sensitivity even in heavy traffic without having to carry the small loop coil onto a loop coil sheet installed on the road surface.

To explain this invention with reference to an embodiment shown in the attached drawings, a rectangular loop coil 1 formed by winding a cord 1a to form a flat cable is fixed to a flexible insulating plate 2, and the rectangular loop coil 1 is A small-sized sensitivity adjustment loop coil 3 is embedded in the flexible insulating plate 2 or fixed by other means, and a resistor 4 and a switch 5 are connected externally in series to the sensitivity adjustment loop coil 3 for vehicle type identification. 6 is a switch box, 7 is a cord for connecting the loop coil 3 for sensitivity adjustment and the resistor 4 in the switch box 6 and the switch 5, 8 is the loop coil 1, This is a code for connecting a detection circuit that is not installed.

The sensitivity adjustment of this invention is done by the sensitivity adjustment loop coil 3.
This is done by closing a switch 5 in a switch box 6 which is externally connected via a cord 7, thereby adjusting the amount of change in inductance occurring in the first loop coil 1 to a predetermined value.

Therefore, according to the present invention, the problems of the conventional method can be solved, and there is no need to carry calibration equipment onto the loop coil sheet 1 installed on the road surface, so safety during measurement is improved. Furthermore, since sensitivity adjustment can be performed at any time, measurement accuracy can also be improved.

[Brief explanation of the drawing]

The accompanying drawings show an embodiment of the present invention, and FIG. 1 is a plan view of a portion thereof, FIG. 2 is a plan view of other portions, and FIG. 3 is an enlarged sectional view of the portion taken along the line - in FIG. 1. 1... Loop coil, 1a... Cord, 2...
Flexible insulating plate, 3...Loop coil for sensitivity adjustment,
4...Resistance, 5...Switch.

Claims (1)

[Scope of utility model registration request] A rectangular loop coil 1 formed by winding a cord 1a into a flat cable shape is attached to a flexible insulating plate 2.
A loop coil 3 for adjusting sensitivity is fixed to the flexible insulating plate 2, and a resistor 4 and a switch 5 are connected in series to the loop coil 3 for external adjustment. coil sheet.