Automobile idle adjuster is mainly used to make the idle speed of engine be constant and reduce oil cost when automobile is in idle moving, which can increase idle speed and prevent engine from stopping. Automobile idle adjuster controls idle speed by controlling the mode of throttle valve channel. It also can increase idle speed automatically when the engine load is bigger. This can be happen when the air-conditioning unit, power steering or torque converter is introduced. In this paper, we mainly studied the effect, structure, working principle about step motor mode fro automobile idle adjuster. We also introduced the improvement about traditional automobile idle adjuster.

Digital simulation design is one of the mechanical product modern design methods. We have introduced the concept and meaning of digital mockup technology in mechanical design and its architecture, design cycle, which are concerned multi-domain UML, multi-body dynamics and multidisciplinary design. We also have analyzed the automobile digital simulation design method and digital mockup technology.

In this paper, we have studied the traditional Positive Crankcase Ventilation (PCV) valve equipment. Then we have improved the system by adding ventilation equipment. We have applied this kind of connection equipment on gas engine which has no PCV. This can determine the engine fuel-air ratio and make the engine get the best power performance, economical efficiency and emission behavior. Because emission amount is based on input air amount, so how to control the input air amount is the basis of the whole system. On the basis of traditional inlet manifold MVEM, we have considered the affection of PCV system, and we have simulated the actual input air process by getting improved module’s input air amount and inlet manifold pressure parameters. So the fuel-air ratio precision can be increased greatly. We also have prompted some improving directions about traditional inlet manifold. So we can ensure that engine can get a compact structure and good response on the all operation states.