JPS6216697Y2 - - Google Patents

Description

[Detailed description of the invention] This invention detects magnetic changes caused by the vibration of a permanent magnet used in a vehicle detector, especially a vibration detection vibrator, and detects magnetic changes caused by the vehicle along with magnetic changes in the vehicle. The present invention relates to a vehicle detector that can detect vibrations caused by vibrations to ensure vehicle detection.

Conventional vehicle detection methods include those that use magnetism, those that use aerial sound, those that use underground sound, those that use light, and those that use radar.
There are various methods such as those using loop coils. Each of these has its own unique drawbacks.
In other words, those that use magnetism cannot be detected unless they are made of magnetic material such as iron, those that use aerial sound are susceptible to temperature changes, weather such as snow, and those that use underground sound Other sounds such as construction noises may be detected; those that use light tend to collect dirt and dust on the detector and become undetectable; those that use radar are too expensive; and those that use a loop coil The method used has drawbacks such as the need to excavate a wide area of the road, and vehicles cannot be reliably detected using each method alone.

This invention takes into consideration the individual shortcomings of each detection method and uses a combined detection method that detects two types of magnetic changes in the vehicle and vibrations caused by the vehicle, i.e., underground sound vibrations, thereby ensuring reliable vehicle detection. The aim is to solve the above drawbacks. This will be explained below with reference to the drawings.

Figure 1 shows an example of the configuration of a vehicle detector according to the present invention, in which 1 is a fluxgate type magnetic detector, 2
3 is a core, 3 is a coil, 4 is a permanent magnet, 5 and 6 are springs, 7 is a box, and 8 is a core support.

The fluxgate type magnetic detector 1 has a coil 3 wound around the outer circumference of a core 2 made of a high magnetic permeability material such as permalloy. is detecting the magnetic field of A permanent magnet 4 of the vibrator is suspended from a box body 7 via springs 5 and 6, and the permanent magnet 4 swings freely in response to vibrations. The permanent magnet 4 is disposed near the fluxgate type magnetic detector 1. For example, in a stationary state with no vibration, the fluxgate type magnetic detector is mounted on the core support 8 so that the axis of the core 2 coincides with the extension of the line connecting the S and N poles of the permanent magnet 4 of the vibrator. 1 is installed, and the distance between the permanent magnet 4 and the core 2 is maintained at such a distance that the permanent magnet 4 does not collide with the core 2 due to the swinging movement of the permanent magnet 4.

When the vibrations now travel underground and reach the box body 7, the permanent magnet 4 of the vibrator suspended by the springs 5 and 6 swings up and down, for example. Due to this swinging motion, the relative distance between the permanent magnet 4 and the center of the coil 3 of the fluxgate type magnetic detector 1, that is, from the core 2, changes. Therefore, the fluxgate type magnetic detector 1 can detect changes in the magnetic field caused by the swinging of the permanent magnet 4 and detect vibrations. At this time, changes in the magnetic field, for example, when a vehicle approaches and passes the fluxgate type magnetic detector 1, the fluxgate type magnetic detector 1 also detects changes in the magnetic field caused by the vehicle. The fluxgate type magnetic detector 1 detects a magnetic change in which the magnetic change of the permanent magnet 4 and the magnetic change of the permanent magnet 4 oscillated by the vibration are superimposed.

Figure 2 is a diagram showing various signals generated when a vehicle approaches or passes. A in the figure shows a magnetic signal indicating changes in the magnetic field in response to a vehicle approaching or passing, and B in the figure shows a magnetic signal generated underground as a vehicle approaches or passes. The transmitted vibration signals, and C in the same figure, respectively show the detection voltages detected by the flux gate type magnetic detector in response to the approach/passing of a vehicle.

As can be seen from FIG. 2, the maximum points of the magnetic signal and the vibration signal almost coincide, and when the vehicle approaches the fluxgate type magnetic detector 1, the oscillating motion of the permanent magnet 4, which is the vibrator, also occurs. It is understood that the detection voltage detected by the fluxgate type magnetic detector 1 also becomes the maximum.

FIG. 3 shows an example of the configuration of a magnetic signal/vibration signal discrimination circuit used in the vehicle detector of the present invention.
In the figure, reference numeral 9 denotes an input signal terminal, into which a superimposed detection voltage of the magnetic signal and vibration signal detected by the flux gate type magnetic detector 1 is input. 10 is an integrator, 12 is a level comparator, 13 is an AND circuit, 14 is a capacitor, 15
17 represents an AC amplifier, 17 represents a level comparator, and 18 represents an output terminal.

The detected voltage from the flux gate magnetic detector 1, in which the magnetic signal input to the input signal terminal 9 and the vibration signal are superimposed, is converted into a magnetic signal from which the voltage of the vibration signal component is removed by the integrator 10, that is, as shown in FIG. A magnetic signal voltage similar to A is obtained. The magnetic signal voltage is input to a level comparator 12. The level comparator 12 compares the voltage with a constant voltage, and when it exceeds the magnetic signal voltage corresponding to the vehicle, generates an output and inputs it to the AND circuit 13 at the next stage. When the magnetic signal voltage input to the level comparator 12 is lower than the constant voltage, for example, when the flux gate type magnetic detector 1 detects a magnetic signal or noise other than a vehicle, the level comparator 12 generates an output. There is nothing to do, and no signal is sent to the AND circuit 13 at the next stage.

On the other hand, the detection voltage from the flux gate type magnetic detector 1 input to the input signal terminal 9 is blocked by the capacitor 14 from the voltage of the magnetic signal component having an extremely low frequency, and only the voltage of the vibration signal component is sent to the AC amplifier 15. A vibration signal, that is, a vibration signal voltage similar to that shown in FIG. 2B is obtained. The vibration signal voltage is input to the level comparator 17. The level comparator 17 compares the voltage with a constant voltage, and when the voltage exceeds the vibration signal voltage corresponding to the vehicle, generates an output and inputs it to the AND circuit 13 at the next stage. When the vibration signal voltage input to the level comparator 17 is smaller than the above-mentioned constant voltage, for example, when the flux gate type magnetic detector 1 detects a vibration signal or noise other than the vehicle, the level comparator 17 generates an output. No signal is sent to the AND circuit 13 at the next stage.

When the outputs from the level comparators 12 and 17 are both generated and input to the AND circuit 13, the AND circuit 13 generates the output at the output terminal 18. When one or both of the level comparators 12 and 17 does not generate an output, the AND circuit 13 does not generate the output at the output terminal 18.

A fluxgate type magnetic detector that has a permanent magnet vibrator placed near the magnetic detector that detects magnetic changes in the vehicle in this way, and simultaneously detects magnetic signals and vibration signals caused by the vehicle. The vehicle can be reliably detected by the detection voltage from 1.

As explained above, according to the present invention, the simple structure of arranging a permanent magnet vibrator near the magnetic detector enables reliable combined detection, and compared to single detection, errors due to noise can be achieved. Detection becomes extremely low. Furthermore, since the vehicle detector of the present invention can be made small and lightweight, it has the advantage of being able to be installed on the shoulders of expressways and behind bridges of elevated roads. The vehicle detector of the present invention exhibits sufficient detection ability for vehicles that cause large vibrations, especially special vehicles that have track pillars.

[Brief explanation of the drawing]

FIG. 1 shows an example of the configuration of a vehicle detector according to the present invention.
FIG. 2 is a diagram showing various signals generated when a vehicle approaches or passes by, and FIG. 3 shows an example of the configuration of a magnetic signal and vibration signal discrimination circuit used in the vehicle detector of the present invention. 1...Fluxgate type magnetic detector, 4...
permanent magnet.

Claims (1)

[Scope of utility model registration request] A magnetic vehicle detector that detects the presence of a vehicle by detecting magnetic changes includes a magnetic detector that detects magnetic changes in the vehicle and a permanent magnet vibrator for detecting vibrations caused by the vehicle. By arranging a permanent magnet as a vibrator near the magnetic detector so as to simultaneously detect the magnetic change caused by the vibration of the vehicle and the magnetic change of the vehicle,
A vehicle detector characterized in that it detects magnetic signals and vibration signals simultaneously.