心静电磁

"Grounding in parking systeminduction coil"It's an oscillating circuit. It consists of a circular groove with a diameter of about 1m or a rectangular groove with an equivalent area on the ground, and then two to three turns of wire are embedded in the groove to form an induction coil buried in the ground. The coil is a part of the oscillation circuit, and the oscillation circuit and the capacitor constitute the oscillation circuit.

The principle is stable and reliable oscillation, oscillation signal by the transformation of the microcontroller into the composition of the frequency measurement circuit, by the microcontroller to measure the frequency of the oscillator. When a large metal object such as a car passes by, the change of the vibration frequency is caused by the change of the space medium (when there is a metal object, the vibration frequency increases). This change is used as a vehicle through the "groundinduction coil"The confirmation signal. At the same time, the time interval between the start and end of the signal can be used to measure the moving speed of the vehicle. This is a "ground induction coil". The key technology is that the designed oscillator is stable and reliable, and the frequency changes obviously when the vehicle passes.

1. Coil material

In the design process, usually only consider the groundinginduction coilThe circumference and number of turns, and the materials used are often ignored by designers. When the project enters the implementation stage, the mechanical strength of the wire and the high and low temperature anti-aging performance need to be considered, and the acid and alkali corrosion resistance needs to be considered in some harsh environments. However, in actual use, once the traditional wire is aged or the tensile strength is insufficient, the wire is damaged and the detector will not work normally. Therefore, it is recommended to use more than 1.0mm PTFE high temperature multi-stranded flexible wire.

2. Coil shape

(1) Rectangular device

In general, the detection coil should be rectangular. The two long sides are perpendicular to the moving direction of the metal object, and the recommended spacing is 1m. The length of the long side depends on the width of the road, and the two ends are usually 0.3m to 1m narrower than the road spacing.

(2) Inclined 45 ° installation

In some cases, when it is necessary to detect bicycles or motorcycles, the coil can be installed at an inclination of 45 ° to the driving direction.

(3) "8" shape installation

In some cases, when the road surface is wide (more than 6 meters) and the vehicle chassis is too high, this installation form can be used to disperse the detection points and improve sensitivity. This type of installation can also be used to detect sliding doors, but the coil needs to be close to the sliding door.

3. Number of coil turns

In order to make the detector work in good condition, the electric induction of the coil is kept between 100uh-300uh. When the coil inductance is constant, the number of turns of the coil has an important relationship with the circumference. The smaller the circumference, the more turns. Generally, refers:

Since various metal substances such as cable pipes, steel bars, and sewer covers may be buried under the road, they have a greater impact on the actual inductance value of the coil. The data in the above table is only for user reference. In the actual construction process, the user should use the inductance tester to actually test the inductance value of the grounding induction coil to determine the actual number of turns, as long as the final inductance value of the coil is within a reasonable working range (such as between 100uh-300uh).

4. Output lead

When the coil is wound, leave a sufficient length of wire to connect to the loop inductor and make sure that there is no joint in. After the coil cable is wound, the lead-out cable needs to be made into a tight twisted pair, and it is required to be wound at least 1 meter 20 times. Otherwise, the output lead without twisted pair will introduce dry closure, which will make the coil inductance unstable.