Research On Exhaust Smoke Test Method And Control Technology Of In-use Diesel Engineering Machinery

With the increase of emission limits for non-road mobile machinery in my country,the monitoring of emissions from non-road diesel mobile machinery in use is becoming increasingly strict.In the possession of diesel engineering machinery,the national phase III accounted for about 85%of the total ownership.If these low-emission construction machinery with large residual value are directly scrapped,it will bring economic construction and social stability.Big negative impact.Therefore,it is necessary to study the emission upgrading technology of the diesel engineering machinery in use in order to make full use of its residual value,taking into account the common development of economic construction and environmental protection.Based on the in-use diesel engineering machinery hydraulic excavator,the vehicle-mounted emission characteristics and test methods were studied.The research results show that the overflow loading method can be used as an alternative method to carry out exhaust smoke measurement when the hydraulic excavator does not have free loading environmental conditions.The effective detection and accurate evaluation of exhaust smoke of diesel engineering machinery in use is the basis of its supervision and governance.The thesis develops an on-vehicle emission test system,selects hydraulic excavator as the object,and conducts research on exhaust smoke test method.It is believed that the peak value of exhaust smoke occurs during the sudden increase in engine load,the maximum smoke value occurs during the excavator's free loading process,the excavator with automatic idle speed function cannot use the free acceleration method for smoke measurement,In the free loading method,the exhaust loading method can be used to measure the exhaust smoke.Taking the hydraulic excavator as the object,the compressed air is used to supplement the air intake system of the diesel engine under the condition of overflow loading.According to the change of diesel engine smoke emission and oxygen concentration in the exhaust gas before and after the air supplement,the sudden load increase is proved.The increase in exhaust smoke is caused by the turbocharger's slow response and the excessive air coefficient in the cylinder.The use of air supplement technology can effectively reduce the smoke emission of the excavator under load surge conditions,and the nitrogen in the exhaust Oxide emissions have little effectThe loading test of the particulate matter post-processing system on the hydraulic excavator and loader showed that:the metal filter has low cost,low resistance,and good filtering performance,which can effectively reduce the exhaust smoke,but it is easy to block,ultrasonic,compressed air,heating and combustion can be used measures such as restoring its performance.The passive regenerative particulate trap has a good effect on diesel engine exhaust smoke control.The carrier material uses cordierite honeycomb ceramics,which has a large heat capacity and a small fluctuation in bed temperature under transient conditions,but it is low during continuous operation under load conditions,the carrier temperature is lower than the regeneration equilibrium point temperature,and the air intake throttle technology can be used to increase the exhaust temperature to meet the passive regeneration carrier bed temperature requirements.