An electronic proximity switch

Abstract

The invention discloses an electronic type proximity switch which comprises a switch base and a switch body.The switch body is partially located in the switch base, the part, located in the switch base, of the switch body comprises a PCB, a switch circuit is formed on the PCB, and the switch circuit is characterized by comprising an MR chip used for sensing external magnetic field variations.Due to the fact that the MR chip serves as a sensing element, the proximity switch has the advantages of being resistant to shock, resistant to temperature and high in sensitivity, the influence of general transportation vibration or artificial knocking vibration produced in the switch installation process on the internal circuit is reduced, the proximity switch is stable in performance, reliable and practical, and the proximity switch can keep normal operation even under the situation that the outdoor environment temperature is low.

Description

technical field [0001] The invention relates to a switch, in particular to an electronic proximity switch. Background technique [0002] At present, the existing elevator or elevator leveling proximity switch is a bistable switch of the reed switch category. The principle is that there are two spring pieces that can be closed and opened in the glass tube, and a small magnetic ring or magnetic piece is placed on the reed switch, and the external large magnet is used to drive the reed switch to close. After the large magnet leaves, the small magnetic ring on the reed switch It is magnetic, so that the reed in the reed switch remains closed. When the large magnet driven by the outside is reversed, because the magnetism is stronger than that of the small magnetic ring fixed on the reed switch, it can close the reed switch. The reed is opened to realize the function of magnetic retention. [0003] At present, the performance of this switch structure is unstable, the shock resis...

AI Technical Summary

Problems solved by technology

[0003] At present, the performance of this switch structure is unstable, the shock resistance is poor, and the failure rate is high in low-temperature environments. The distance between the reeds inside the reed tube changes and cannot work normally, which is due to poor shock resistance; 2. In a low temperature environment, the reeds inside the reed tube will change and cause abnormal switching

Especially in the northern region when the temperature is -20°C, the performance switch will always be closed, unable to work, and the elevator cannot work normally.

3. The existing switch has no LED indication function. Since the proximity switch is in a position with poor visibility and difficult to install, when the elevator lifting system fails, the working status of the proximity switch cannot be judged intuitively, and the switch needs to be disassembled for reuse. Auxiliary instrument judgment, which brings inconvenience to the subsequent after-sales maintenance of the elevator

[0004] In addition, the existing bistable switch, the external circuit is a 3-wire type, such as Figure 8-1 and Figure 8-2 As shown, since the main circuit of the switch itself is divided into two circuits, NPN and PNP, and the subsequent circuit connected to the switch is the inverter circuit: First, the conventional inverter has positive and negative power terminals and signal input terminals, and the inverter circuit It also has two circuits, NPN and PNP. When using a 3-wire switch, it must be connected to the switch corresponding to the NPN and PNP circuit, otherwise the switch will not work normally, which will lead to complicated wiring methods; second, the mainstream frequency conversion in the market There is only one signal input terminal and one common terminal, and the two are used for switch wiring, so the 3-wire switch cannot be connected normally, and the versatility is insufficient

In addition, half of the power consumption of the 3-wire switch is about 1mA. Excessive power consumption is not good for the load circuit of the inverter. If too many 3-wire switches are connected in parallel, it may even cause Inverter burnt out

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