共查询到20条相似文献,搜索用时 125 毫秒
1.
2.
3.
4.
5.
6.
7.
8.
本文介绍了多楔带轮系的结构与特点,结合多楔带在汽车发动机前端附件传动系中的应用,对发动机多楔带轮系的布置原则和方法进行了探讨,提出了在设计过程中应该重点考虑的事项。 相似文献
9.
10.
11.
本文研究了一种汽车发动机可变定时配气机构。对其工作原理与设计思路进行了分析,着重探讨了其结构组成及运动原理,并绘制了传动和调节的机构运动简图和算出了机构的自由度。建立了参数化的三维模型,并用反转法绘制了摆动输出凸轮的轮廓曲线。研究表明,机构的关键技术是根据发动机的需要来确定最佳的杆长参数及理想的输出凸轮轮廓曲线。 相似文献
12.
13.
利用商用软件STAR—CD及ES—ICE对某D6114柴油机在的缸内燃烧过程进行了数值模拟计算,分析和比较了不同喷油提前角对缸内燃烧过程和燃烧室表面热流的影响。研究结果表明:喷油提前角提前,柴油机缸内的燃烧效果优于喷油提前角推迟,燃烧过程中缸内的压力和温度比推迟喷油提前角时要大,同时缸内的最高燃烧压力和最高温度也高;喷油提前角对缸盖和活塞顶壁面平均热流的影响与其对缸内平均温度的影响相似,对缸套壁面的影响是喷油提前角提前越早,传给缸套的热流越小。数值计算结果为高功率、高强化和低热损的柴油机设计提供理论依据。. 相似文献
14.
Duk-Sang Kim Young-Joon Park Seang-Wock Lee Yong-Seok Cho 《Journal of Mechanical Science and Technology》2008,22(1):141-147
Emission regulations for automobiles have become more stringent and the improvement of emission during cold start has been
a major key issue to meet these regulations. Among many kinds of factors that affect cold start operation, ignition timing
is crucial to improve emission characteristics due to the influence on exhaust gas temperature. Recent progress in variable
valve timing allows optimized valve event strategies under various ranges of engine operating conditions including cold start.
This study investigates effects of ignition and exhaust valve timing on exhaust gas temperature, combustion stability and
emission characteristics through cold start bench tests of an SI engine.
Experimental results show that exhaust valve timings and ignition timings significantly affect exhaust gas temperature and
stability of engine operation under cold start condition. Exhaust valve timing also affects CO and NOx emission due to changes in residual gas fraction of the combustion chamber. Ignition timing mainly affects exhaust gas temperature
and HC emission. A control strategy, advanced exhaust valve timing and retarded ignition, is plausible in order to achieve
reduction of exhaust emission while maintaining stability under cold start operation of SI engines. 相似文献
15.
16.
发动机采用可变气门正时技术可以提高进气克量,使充量系数增加,发动机的扭矩和功率可以得到进一步的提高.文章分析了本田VTEC发动机的可变气门正时技术.研制了一种组合式正时凸轮轴.可以灵活改变凸轮外轮廓(即凸轮曲线)的长度,改变气门的开起时间和气门处于最大开口的持续时间,可以改善发动机的配气效果. 相似文献
17.
18.
19.
A variable valve timing (VVT) can improve fuel efficiency, reduce CO2 emissions and increase torque output enabling optimization
of these outputs at different engine conditions. To achieve VVT in internal combustion engine, new devices such as mechanical,
hydraulic, motor-driven and electromagnetic actuators have been developed in past years to replace the conventional camshaft
valve train system used currently. Among these, the electromagnetic actuator using solenoids is the most advanced system to
provide the most flexibility to valve timing, but it has critical drawback of high power consumption. In this paper, a new
electromagnetic engine valve actuator that uses permanent magnets to latch the valve is introduced. 相似文献