A pressure controller and communication method of a proportional valve for vehicles based on CAN bus

Abstract

The invention discloses a CAN bus-based vehicle proportional valve pressure controller and a communication method. The vehicle proportional valve pressure controller is provided with a CAN module. The CAN module is connected to the CAN bus and can be connected to the vehicle through the CAN bus. ECU; thus by defining the CAN bus message protocol of the proportional valve controller, and based on the message protocol, communicate with the vehicle ECU through the CAN bus. This program is aimed at the communication technology between the vehicle proportional valve pressure controller and the vehicle ECU, and uses the CAN bus to replace the PWM interface, which effectively overcomes the existing problems of the existing vehicle proportional valve pressure controller based on PWM communication. problem, and at the same time, it can release the precious PWM resources of the automotive ECU.

Description

technical field [0001] The invention relates to the vehicle control technology, in particular to the communication technology of the vehicle proportional valve pressure controller. Background technique [0002] In order to reduce NOx emissions from diesel engines, exhaust gas recirculation technology is commonly used in passenger cars and trucks. Its basic principle is to introduce part of the burned exhaust gas from the exhaust pipe into the intake pipe through the air valve, mix with fresh air and enter the combustion chamber. Participate in combustion again, but the excessive exhaust gas recirculation rate will also have a greater impact on the ignition of the mixture and the performance of the engine, especially when the engine is idling, low speed, and light load, so it is necessary to issue control commands to the engine through the ECU. The gas valve controller controls the switch of the gas valve and the gas output pressure according to different working conditions t...

AI Technical Summary

Problems solved by technology

[0006] 1. The ECU on the car needs to communicate with many devices. Its IO resources are very precious, and the PWM resources are even more scarce. In many cases, due to the lack of PWM resources, in order to integrate the valve controller, it is necessary to reset the PWM resources. deployment, or even give up the acquisition of diagnostic information, the ECU cannot obtain the working status of the proportional valve, which will affect the reliable operation of the exhaust gas recirculation system

[0007] 2. Since the PWM duty cycle is used to represent the gas pressure of the proportional valve, its control accuracy depends on the accuracy of the PWM duty cycle, and the accuracy of the PWM duty cycle is related to the clock stability of the PWM generator and the PWM period used. Moreover, the PWM signal is susceptible to external interference, and it cannot achieve high control accuracy in actual use. At the same time, the fluctuation of the PWM duty cycle will also affect the stability of the final output air pressure of the proportional valve.

The PWM duty cycle accuracy of some car manufacturers' ECU can only reach 1%

[0008] 3. Due to the limited precision of the PWM output, an additional mapping table is required to set the corresponding relationship between the PWM duty cycle and the gas pressure to improve the pressure control accuracy, but this also reduces the controllable range of the pressure

[0009] 4. Use the PWM duty cycle to output diagnostic information. Since it cannot carry complex data protocols, the information that can be output is very limited. It can only transmit error codes and cannot output more internal states of proportional valves.

[0010] 5. The function of the pin is solidified, and it is impossible to expand the function in the later stage, such as program upgrade, debugging, etc., and the later maintenance cost is high

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