Ultrasonic sensor

Abstract

The invention discloses an ultrasonic sensor. The ultrasonic sensor comprises a conductive shell, a piezoelectric ceramic piece, a positive electrode signal line, a negative electrode signal line and a PCB. The piezoelectric ceramic piece is fixed into the conductive shell, the PCB is sealed in the conductive shell through pouring sealant in a pouring mode, one end of the positive electrode signal line is electrically connected with the piezoelectric ceramic piece, the other end of the positive electrode signal line is electrically connected with the PCB, one end of the negative electrode signal line is electrically connected with the PCB, the conductive shell is provided with an installation hole, the other end of the negative electrode signal line is fixedly connected with a metal connecting piece, and at least one part of the metal connecting piece is fastened with the conductive shell after entering the installation hole. The ultrasonic sensor has the advantage of being high in reliability.

Description

technical field [0001] The invention relates to an ultrasonic sensor. Background technique [0002] With the development of the automotive industry, automotive electronics has evolved from simple human control to integrated, technological, and intelligent development. Among them, the reversing radar auxiliary system performs particularly well, judging the distance of obstacles when reversing the car, the initial human listens to whether the beeping of the buzzer is urgent, the distance display, the combination of the distance display and the simulated image, and the combination of the distance display and the real scene , Developed to the present intelligent system that automatically judges to find an empty parking space and automatically parks. Nowadays, we have entered the era of intelligent automatic parking, and the core of automatic parking is the sensor that perceives the distance. The reliability of the sensor is an important parameter of the entire system, and it is...

AI Technical Summary

Problems solved by technology

However, due to the small size of the sensor, and the core components are packaged in the aluminum shell 1 through the potting glue 4, it is not only difficult to find the fault by observation, but also the sensor will be damaged after disassembly, and it is even more difficult to find the fault. Therefore, It is objectively very difficult to find the cause of the fault

[0004] Through a lot of research and analysis, the applicant finally found the problem: the grounding negative signal line 6 is filled in the grounding hole 8 through the silver paste 9, and is in contact with the aluminum shell 1. The characteristic of the silver paste is that it needs to be baked at 150 degrees. Baking and curing, due to the high viscosity, the entire curing process cannot be vacuumed, and the internal air cannot be removed, resulting in air bubbles inside the silver paste after curing, resulting in large contact resistance, making the impedance between the ground negative signal line 6 and the aluminum shell 1 large, and affecting the signal. causing attenuation

And in the process of long-term use, or in the reliability test of high temperature and low temperature harsh environment, the shrinkage rate of silver paste is far from the shrinkage rate of aluminum material, which leads to the gradual increase of the impedance of the silver paste and the side wall of the ground hole, and the increase of internal friction. The energy is consumed, the performance of the sensor decreases, and the reliability decreases. In the harsh environment of high and low temperature for a long time, the impedance is infinitely driven close to infinity, so that the ground negative signal line 6 and the aluminum shell are in an open state.

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