Vehicle speed sensor used for automobile collision-preventing systems

Abstract

The invention discloses a vehicle speed sensor used for automobile collision-preventing systems. The vehicle speed sensor comprises an outer shell, a sensing head, two printed circuit boards (PCB) and a plurality of connecting leads and indicator lights, wherein the sensing head, the two PCBs and the indicator lights are connected by the connecting leads; the outer shell comprises a body, a tailstock and a head cover; the outer shell is made of a material the high temperature resistance of which is above 150 DEG C; a sensor module circuit is arranged at one PCB and a routing circuit is arranged at the other PCB; the sensing head, the PCB, the connecting leads and the indicator lights are arranged at the corresponding positions at the outer shell and encapsulated and solidified at one time by a plastic material. The vehicle speed sensor used for automobile collision-preventing systems provided by the invention is improved in the aspects of materials and process based on the existing proximity sensors and satisfies the performance requirement for vehicle speed sensors. In addition, the cost of the vehicle speed sensor is less than half of the cost of imported products and the production cycle is less than 1 / 3 of the imported products.

Description

technical field [0001] The invention relates to a sensor, in particular to a vehicle speed sensor for an automobile anti-collision system. Background technique [0002] With the development of economy and technology, highway traffic congestion and traffic accidents have become a serious problem worldwide. In order to ensure smooth transportation and traffic safety, and reduce the occurrence of accidents, in recent years, some developed countries have vigorously researched the "Intelligent Highway System (ITS Program)", in which millimeter-wave radar is used for vehicle distance measurement, The research and application of collision early warning has been widely valued by many countries. [0003] In the intelligent highway system, the sensor used to detect the speed of the vehicle is the vehicle speed sensor. like figure 1 As shown, the electrical part of the vehicle speed sensor is mainly composed of three parts: oscillator, switch circuit and amplifier output circuit. Th...

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Problems solved by technology

[0006] (1) The shell includes three parts: the main body, the tailstock and the top cover. Generally, the main body is made of nickel-plated copper. There is no problem with high temperature resistance, but the tailstock and the top cover are made of plastic and can only work below 110°C. Severely deformed, unable to realize its function; while the vehicle speed sensor is installed near the exhaust pipe of the car, the temperature is relatively high, and the actual measured temperature of the vehicle speed sensor is as high as 120°C;

[0007] (2) The silicone material used for potting will expand and deform at high temperature, causing the tailstock and top cover to fall off;

[0008] (3) Ordinary solder materials used for circuit connection will become soft when the temperature is above 150°C, which will lead to false soldering of the soldered part, causing the product to fail or intermittently fail;

[0009] (4) Since silica gel is used for multiple potting, and the molecular particles of silica gel are relatively large, the overall waterproof and shockproof effect of the product is poor;

[0010] (5) In the induction module, the magnetic tank and coil components are very sensitive to temperature, and it is difficult to meet the temperature requirements of the vehicle speed sensor by directly using the existing magnetic tank and coil components

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