柴油机高压共轨系统环形缝隙流动的粘温特性

Viscosity-temperature at the annular flow in pressurized common rails of a diesel engine

高压共轨系统中喷油器液压挺柱偶件、针阀偶件和高压泵柱塞偶件存在环形缝隙.而燃油的粘度特性会影响喷油器的回油量和高压泵的泄露油量.通过喷油器回油量试验总结了温度对高压共轨喷油器环形缝隙流动的燃油粘度特性的影响,用环形缝隙流动的燃油粘度特性解释了高压油泵控制占空比的温度特性,即回油体积流量随着轨压和脉宽的增加而线性增大;轨压越高,回油体积流量越大,温度造成的回油量差别越明显;各种工作轨压下的相对动力粘度随温度增加而下降;温度增加时,高压泵控制占空比增加,以补偿高压泵和喷油器的环形缝隙泄露油量.

In the pressurized common rails,the annular flow forms in hydraulic tappet couple,needle valve couple of injector and plunger couple of pressurized pump.The viscosity of fuel will affect the return oil of injector and leakage of the pressurized pump.Meanwhile,the duty cycle of the temperature of pressurized pump is explained by the fuel viscosity at annular flow.That is,the volume flow of return oil increases with the increase of rail pressure and pulse width.The relative dynamic viscosity of varied pressures decreases with the increase of temperature,while the duty cycle of pressurized pump increases as a compensation.