Engine speed characteristics


Character of engine revolving speed refers to the functional relationship between the engine crankshaft speed and the power, torque and unit fuel consumption of the engine. This functional relationship is expressed by a curve, which is called the engine speed characteristic curve or engine characteristic curve for short, and is usually obtained by test methods. Knowing the characteristic curve of the engine, the traction characteristics of the car can be obtained. The relationship between the traction force of the car and the driving speed of the car, the change of the traction force of different gears, the maximum driving speed of the car, the maximum gradeability and other traction performance of the car are all It can be analyzed with the help of the traction characteristics of the car.

The basic concept of engine characteristics

(1) Engine characteristics: refers to the relationship between engine performance indicators and engine adjustments and operating conditions.

(2) Engine performance indicators: mainly include power, torque, fuel consumption rate, effective thermal efficiency, exhaust temperature, exhaust smoke, etc., which vary with the adjustment and operation of the engine.

(3) Engine adjustment: mainly refers to the advance angle of diesel engine fuel supply, the advance angle of gasoline engine ignition, and the mixture concentration.

(4) Engine operation: mainly refers to engine speed and load.

(5) Engine characteristic curve: Refers to the engine characteristic expressed in the form of a curve.

Classification of engine characteristics

(1) Adjustment characteristics: refers to the relationship between engine performance indicators and engine adjustments.

(2) Performance characteristics: refers to the relationship between engine performance indicators and engine operating conditions.

Extraction of engine characteristics

Engine characteristics need to be carried out on a special test bench, such as on an engine dynamometer to simulate actual engine operating conditions and work at the required speed and load. Measure performance parameters such as power, fuel consumption, exhaust emissions, cylinder pressure, etc. under various working conditions.

The universal characteristics of the engine

The load characteristic can only analyze the change of the engine performance parameters with the load at a certain speed, while the speed characteristic can only be analyzed in a certain fuel adjustment mechanism. The performance parameters of the internal combustion engine under the position change with the speed.

In fact, the speed and load of the internal combustion engine change in a wide range. To analyze the performance of the engine under various working conditions, many graphics are needed, which are very inconvenient and unclear. The relationship between engine performance parameters, speed and load can be shown on a graph, which is called universal characteristic, also known as multi-parameter characteristic, and the corresponding curve is called universal characteristic curve.

Speed ​​control characteristics

The speed control characteristics refer to the diesel engine performance parameters (torque, power, speed, fuel consumption rate, etc.) with the load when the position of the speed control handle of the diesel injection pump is fixed. Changing relationship. The corresponding curve is called the speed control characteristic curve.

The speed control characteristic curve is used to evaluate the actual working performance index of the diesel engine with a governor, and it can also be used to evaluate the working performance of the governor.

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