Wheel speed sensing signal processing circuit and automobile ABS (Anti-lock Braking System)

Abstract

The invention discloses a wheel speed sensing signal processing circuit and an automobile ABS (Anti-lock Braking System). The circuit comprises a resistor, a low pass filter, an amplitude limiting unit, a differential amplifier and a hysteresis shaping unit. One end of the resistor is connected with wheel speed sensing signals, and the other end of the resistor is grounded; the low pass filter receives the wheel speed sensing signals, filters out high frequency interference signals, and outputs first voltage signals; the amplitude limiting unit automatically adjusts the conduction slope according to the wheel speed sensing signals, so that high level signals of the wheel speed sensing signals are clamped on the preset direct current high level and low level signals of the wheel speed sensing signals are clamped on the preset direct current low level; the differential amplifier receives the wheel speed sensing signals and the first voltage signals passing the resistor, removes same-frequency interference signals and outputs second voltage signals; the hysteresis shaping unit receives the second voltage signals, performs hysteresis comparison with reference levels and outputs square wave signals. The circuit is novel in structure design, the anti-interference ability of the system can be effectively improved, and the wheel speed sensing signals can be processed more accurately.

Description

technical field [0001] The invention relates to the technical field of automotive electronic control integrated circuits, in particular to a wheel speed sensing signal processing circuit and an automotive ABS system. Background technique [0002] Automotive ABS system (Anti-lock Braking System, anti-lock braking system) is one of the indispensable safety systems of modern cars. The principle is that the electronic control unit processes, processes and judges the wheel speed information obtained by the wheel speed sensor to form instructions, so that the wheels can obtain the best braking efficiency, and at the same time, the wheels can be prevented from being locked and skidded. Make the car maintain good driving stability and directional maneuverability during the entire braking process. The wheel speed signal comes from the wheel speed sensor installed on the wheel, which is a sine wave that changes with the speed of the vehicle. At high speed, the output signal voltage a...

AI Technical Summary

Problems solved by technology

[0004] 1: The signal is input from a single end. When the ABS system is working, it is easily interfered by external signals, resulting in misjudgment of signal processing and poor system reliability;

[0005] 2: The limiting circuit will increase the production of EMI (Electromagnetic Interference, electromagnetic interference) when the Zener diode is turned on quickly, causing electromagnetic interference and reducing system reliability;

[0006] 3: The filter uses an RC first-order low-pass filter, which cannot well suppress interference signals outside the frequency range;

[0007] 4: Due to the harsh working environment of the automotive ABS system, when the maximum power supply and input voltage operating range are not met, the reference level of the comparator will drift with voltage and temperature, resulting in instability

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