Method and device for calculating fuel injection quantity of an engine

Abstract

The invention provides a calculation method and a calculation device for the fuel injection quantity of an engine. The method comprises the following steps of: calculating the currently required torque of the engine; and judging whether the currently required torque is lower than the minimum calibrated torque of a torque / fuel quantity conversion MAP or not or whether the currently required torque is higher than the maximum calibrated torque of the torque / fuel quantity conversion MAP or not, and if the currently required torque is lower than the minimum calibrated torque of the torque / fuel quantity conversion MAP or the currently required torque is higher than the maximum calibrated torque of the torque / fuel quantity conversion MAP, calculating a fuel injection quantity corresponding to the currently required torque according to a corresponding relationship between the required torque and the fuel injection quantities of two points in the torque / fuel quantity conversion MAP by utilizing a positive correlation linear algorithm. When the currently required torque of the engine is lower than the minimum calibrated torque, the fuel injection quantity calculated by the method is lower than a fuel injection quantity corresponding to the minimum calibrated torque; and when the currently required torque of the engine is higher than the maximum calibrated torque, the fuel injection quality calculated by the method is higher than a fuel injection quantity corresponding to the maximum calibrated torque. The calculated fuel injection quantity is more rational, so that the easily occurring problem of instable idling or stalling of the engine is reduced.

Description

technical field [0001] The invention relates to the field of mechanical control, in particular to a method and device for calculating the fuel injection quantity of an engine. Background technique [0002] The torque / fuel quantity conversion MAP diagram is a three-dimensional map in which the abscissa is the engine speed, the ordinate is the required torque, and the rotational speed and the required torque correspond to a specific fuel injection quantity. In National III and National IV electronically controlled engines, the fuel injection quantity is usually calibrated by calculating the corresponding fuel injection quantity based on the current engine speed and current demand torque, as well as the torque / fuel quantity conversion MAP. [0003] However, in the current prior art, when the current demand torque of the engine is less than the minimum calibration torque in the torque / fuel conversion MAP diagram, the fuel injection quantity corresponding to the minimum calibrati...

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Problems solved by technology

[0003] However, in the current prior art, when the current demand torque of the engine is less than the minimum calibration torque in the torque / fuel conversion MAP diagram, the fuel injection quantity corresponding to the minimum calibration torque in the torque / fuel conversion MAP diagram is injected. Oil, at this time due to excessive fuel injection, the engine idle speed is prone to instability; when the current demand torque of the engine is greater than the maximum calibrated torque in the torque / fuel conversion MAP diagram, convert the MAP diagram according to the torque / fuel conversion Inject fuel at the fuel injection volume corresponding to the maximum calibrated torque. At this time, because the fuel injection volume is too small, it is easy to cause the engine to stall.

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