硫对离心铸造汽缸套切削性能的影响

一般来说，硫是有害元素。但对于灰铸铁来讲，含有少量的硫对于石墨的生核和切削性能都有非常重要的影响。在铸造生产过程中通过加入一定量的硫，提高铁液的含硫量，从而使铸件获得更好的切削性能。     

The polytropic volume method to detect engine events based on the measured cylinder pressure

Internal combustion engines deliver work using an intermittent thermodynamic process. For control and diagnosis purposes, it is useful to detect key events relative to the crank angle position. A new method to detect the intake valve closing (IVC), start of combustion (SOC), end of combustion (EOC) or exhaust valve opening (EVO), using the measured cylinder pressure as input, is described. The method is based on the observation that the compression and expansion processes are of polytropic nature. It is shown that the events can be detected by detecting the points where the real and the polytropic volume diverge.     

Analysis of the musculoskeletal system of the hand and forearm during a cylinder grasping task

Musculoskeletal disorders of the hand are mostly due to repeated or awkward manual tasks in the work environment and are considered a public health issue. To prevent their development, it is necessary to understand and investigate the biomechanical behavior of the musculoskeletal system during the movement. In this study a biomechanical analysis of the upper extremity during a cylinder grasping task is conducted by using a parameterized musculoskeletal model of the hand and forearm. The proposed model is composed of 21 segments, 28 musculotendon units, and 20 joints providing 24 degrees of freedom. Boundary conditions of the model are defined by the three-dimensional coordinates of 43 external markers fixed to bony landmarks of the hand and forearm and tracked with an optoelectronic motion capture system. External marker positions from five healthy participants were used to test the model. A task consisting of closing and opening fingers around a cylinder 25 mm in diameter was investigated. Based on experimental kinematic data, an inverse dynamics process was performed to calculate output data of the model (joint angles, musculotendon unit shortening and lengthening patterns). Finally, based on an optimization procedure, joint loads and musculotendon forces were computed in a forward dynamics simulation. Results of this study assessed reproducibility and consistency of the biomechanical behavior of the musculoskeletal hand system.     

Estimation of optimum number of cycles for combustion analysis using measured in-cylinder pressure signal in conventional CI engine

Analysis of measured in-cylinder pressure data provides various parameters that characterize engine combustion process. Advanced engine control technologies use cylinder pressure based combustion parameters for closed loop control. Four step signal processing (i) absolute pressure correction, (ii) crank angle position referencing, (iii) cycle averaging and (iv) filtering is typically applied to get sufficiently accurate cylinder pressure data for an engine cycle. This paper focuses on cycle averaging and filtering of in-cylinder pressure signal from a conventional compression ignition (CI) engine. Experiments are conducted at different engine load and compression ratios at 1500 rpm. The in-cylinder pressure trace of 2500 consecutive engine cycles is recorded and analyzed. Effect of in-cylinder pressure signal noise and cyclic variation on combustion analysis is investigated. A method based on standard deviation of pressure and pressure rise rate is used to find sufficient minimum number of engine cycles to be recorded for averaging to get reasonably accurate pressure data independent of cyclic variability.     

基于HyperWorks的柴油机缸盖的模态分析

缸盖是发动机的重要部件,其性能的好坏直接影响发动机的整体性能,利用HyperWorks软件对某款柴油机缸盖进行了有限元建模和模态分析,得到了缸盖在约束模态下的前六阶振型和固有频率,为发动机减振和降噪提供了理论依据.     

气瓶及安全附件检测技术研究

本文介绍了气瓶及安全附件的检验检测现状,对检验检测中的项目及方法进行了探讨,对检测设备的研制开发及应用进行了研究。     

发动机缸盖加工关键工艺研究

汽车机缸盖是发动机上的关键部件之一,其加工精度的好坏将直接影响发动机的整体性能.提高气门座圈和导管孔的加工精度不但能延长发动机的使用寿命,而且能够降低发动机的油耗.针对发动机缸盖上关键特征气门座圈和导管孔的加工,对发动机缸盖气门座圈和导管孔加工工艺的发展、加工过程中常用的加工刀具、加工过程中常用的冷却方式、切削参数的选择和主轴的刚性对特征加工精度影响这五个主要因素进行了研究和分析,并给出了提高气门座圈和导管孔的加工精度的建议.     

WP7缸盖内腔铸造缺陷的控制

针对我公司新开发的WP7缸盖铸件内腔出现的烧结、脉纹、残留砂等问题,从制芯覆膜砂材料、涂料等入手进行试验分析:最后确定采用高温低膨胀的覆膜砂和3861涂料有效解决了WP7缸盖内腔烧结和脉纹缺陷;并从制芯覆膜砂常温抗拉强度、溃散性及清理工艺方面进行分析试验,确定了适当的覆膜砂常温抗拉强度和铸件清理工艺方案,有效地解决残留砂的问题.     

缸盖渗漏缺陷的主要类型与成因分析

由于影响缸盖渗漏缺陷的因素众多,仅仅依靠几个铸件判定缺陷的类型非常困难.本文通过对23个缺陷缸盖的解剖,确定了缺陷的主要类型,采用扫描电镜等手段分析了缺陷形成原因,提出了工艺改进措施.     

消除离心铸造船用柴油机缸套白斑云斑缺陷的对策

分析离心铸造某型船用柴油机缸套白斑云斑缺陷的形成机理后认为:白斑是由浇注过程中浇注槽底聚集的铁豆掉入型腔对周围铁液激冷析出奥氏体枝晶以及铁液过冷所析出的粗大奥氏体偏聚形成的;云斑是由析出石墨偏聚及不均匀分布导致出现异常组织而形成.采取降低易偏析的Mn、P、S等元素、提高Cu、Ni等无限固溶元素,并改底漏式离心浇注为侧浇式,以及浇注时加入0.2%75FeSi等措施,可明显减少白斑云斑的出现,同时缸套本体抗拉强度提高约20～30MPa,金相组织中粗大石墨和粗大磷共晶明显减少.