Variable nozzle turbocharging control method and system

Abstract

The invention provides a control method and a system for nozzle changeable turbocharger, which relates to an electric control system of a nozzle changeable turbocharger with an electrohydraulic servo ratio electromagnetic valve as an executor. The invention is characterized in that based on the acquired rotate speed of an engine and the acquired position signal of an accelerator pedal, a target boost pressure value and a target position driving signal value are worked out; and a control algorithm of the PWM signal value used to drive the electrohydraulic servo valve adopts an open loop feedforward control with the optimum position of the electromagnetic valve as the a control target, and a closed loop digital PI feedback control with a boost pressure in an air inlet pipe as a control target. In order to improve the control precision and the response speed of the control system, the control parameters of the closed loop PI control is obtained by checking up a two-dimensional MAP graph according to the rotate speed signal of the engine and the position signal of the accelerator pedal. Compared with the prior pneumatic control system, the electric control system has quick control response speed; and, compared with the control system in which a step motor is used as the executor, the executor of the invention has the advantages of big output torque and high precision.

Description

technical field [0001] The invention relates to an engine variable nozzle turbocharger system, in particular to a diesel engine variable nozzle turbocharger system using an electro-hydraulic servo proportional solenoid valve as an actuator. Background technique [0002] The turbocharger should adapt to the engine's wide speed range. The disadvantages of the fixed section turbocharger are: (1) When the engine is running at low speed, due to the little energy provided by the exhaust gas, the speed of the turbocharger is too low to provide suitable boost pressure and sufficient intake air volume , the engine cannot produce a large low-speed torque, which makes it difficult to significantly improve its low-speed performance. (2) When the engine is running at high speed, the supercharger may overspeed due to the high exhaust temperature and pressure. (3) There is only aerodynamic connection between the supercharger and the engine, and the response lag of the supercharger is obv...

AI Technical Summary

Problems solved by technology

The disadvantages of the fixed section turbocharger are: (1) When the engine is running at low speed, due to the little energy provided by the exhaust gas, the speed of the turbocharger is too low to provide suitable boost pressure and sufficient intake air volume , the engine cannot produce large low-speed torque, which makes it difficult to significantly improve its low-speed performance

(2) When the engine is running at high speed, the supercharger may overspeed due to the high exhaust temperature and pressure

(3) There is only aerodynamic connection between the supercharger and the engine, and the response lag of the supercharger is obvious during the acceleration process

The advantage of this mechanism is that the adjustment speed is fast, and the stepping motor can quickly move from the minimum position to the maximum position under the drive of the electric signal. The disadvantage is that the stepping motor advances in a single step and cannot continuously adjust the position of the nozzle section.

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