Device and method for measuring rotational speed of engine based on differential pressure signals of exhaust back pressure

Abstract

The invention discloses a device and a method for measuring rotational speed of an engine based on differential pressure signals of exhaust back pressure. The device provided by the invention comprises a DPF particle collector, exhaust back pressure difference transducers, a signal transmission cable and a controller, wherein the exhaust back pressure difference transducers are arranged at the front end and the rear end of the particle collector and connected with the controller through the signal transmission cable; and a signal conditioning unit, a signal processing unit, a signal analysis unit and a communication unit are sequentially connected and arranged in the controller. The method provided by the invention includes the steps that pressure difference signals are isolated, filtered and amplified through the signal conditioning unit in the controller; then signal voltage is adjusted to the input range allowable for digital processing, and the digital to analog conversion is performed for sample data; Fourier transform (FFT) is performed for the signals, subjected to conversion, through a digital processing unit, and the impulse frequency is converted into the rotational speed value of the engine taking the revolution/minute (RPM) as the unit through the arranged engine stroke and the amount of cylinders; and finally, the rotational speed is output and displayed through the communication unit in the manner of UART or CAN. The device provided by the invention is not directly contacted with the rotating shaft of the engine, has simple structural form and reasonable design, and is convenient to install and debug.

Description

technical field [0001] The invention relates to the technical field of motor vehicle engine detection, and more specifically relates to a device and method for measuring motor vehicle engine speed by using an exhaust back pressure differential sensor in a diesel particulate filter system. Background technique [0002] As motor vehicle emission regulations become increasingly stringent, particulate matter after-treatment technology has become an important way to control diesel vehicle emissions. One of the most effective measures in after-treatment technology is the use of diesel particulate filter (DPF). In the DPF system, the engine speed needs to be measured and recorded accurately. This is also an important content of automotive fault diagnosis research. [0003] The traditional engine speed measurement is to install a tachometer in contact with the engine shaft on the engine shaft, and read it from the engine electronic control unit (ECU) through CAN. This method requi...

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Problems solved by technology

This method requires an additional sensor, which not only affects the entire vehicle circuit but also in...

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