Control system for the Stirling engine

A new control system is proposed for Stirling engines. The system is based on a sealed external system for hydrogen sorption and desorption, with a thermoelectric heating and cooling system. It is intended to improve the operational reliability and the safety of the maintenance crew; to reduce the operational noise level; and to reduce the size and mass of the motor and simplify its design.     

An approximate thermal analysis of Stirling engine regenerators

This paper approximates the transport phenomena in a Stirling engine regenerator to aid its practical design. The mass flow rates are simplified by a square-wave function and the pressure variations, by a saw-tooth function with a phase difference. Approximate analytical solutions obtained in this study agree well with the available numerical solutions. Using the approximate solutions of the transport phenomena the entropy generation rates in a regenerator are analytically formulated and calculated, which come from axial conduction loss, imperfect heat regeneration, and pressure drop due to fluid friction. The geometry of the minimum entropy generation rate can represent the optimal design parameters of the regenerator     

微型斯特林制冷机用线性压缩机研究

通过建立活塞运动方程、电机驱动方程,对线性压缩机的运行参数进行推导,进而结合实验数据对新研制的线性压缩机进行了动力学分析;实验给出了频率、充气压力等对制冷机运行特性的影响,得出影响压缩机性能的重要参数及其相互关系,从而为微型斯特林制冷机的优化设计提供了研究依据。     

面向再制造的小型内燃机连杆设计技术研究

运用面向再制造的产品设计基本概念，在对小型内燃机连杆进行正常失效分析的基础上，提出了对小型内燃机连杆进行面向再制造的设计时，应考虑的主要问题和基本的设计技术。     

面向再制造的小型内燃机曲轴设计技术研究

运用面向再制造的产品设计基本概念,在对小型内燃机曲轴进行正常失效分析的基础上,研究和提出了对小型内燃机曲轴进行面向再制造的设计时,应考虑的主要问题和基本的设计技术.提出了应权衡内燃机寿命长短对内燃机再制造价值的综合影响,使产品主要零部件在整个寿命周期内的价值最大化的观点.     

一种发动机油底壳加工工艺探讨

对发动机油底壳的加工工艺进行了详细的探讨,并详细阐述了试制和批量两种加工工艺的夹具设计方案与加工工艺的特点,对批量生产过程中遇到的热变形误差累计的技术难点,进行了深入的探讨,并给出了具体的解决方案。     

Experimental investigation on the influence of engine operating conditions on combustion and nanoparticle emission characteristics of a small DI diesel engine

The influence of variations in engine speed, injection pressure, injection timing, and multiple injection strategies on the combustion and nanoparticle characteristics of a small Direct injection (DI) diesel engine was experimentally investigated. To measure the size distribution and number concentration of particle emissions, a rotating disk thermo-diluter (dilution system), a Condensation particle counter (CPC), and a Scanning mobility particle sizer (SMPS) were used. The injection pressure was changed from 60 MPa to 120 MPa, at an engine speed of 1200 rpm. Injection timing was varied from Before top dead center (BTDC) 40˚ to Top dead center (TDC). To investigate the effect of multiple-injection strategies, the injection strategies consisted of two pulse signals with different dwell time. The experimental results show that the peak combustion pressure and Rate of heat release (ROHR) profile are increased and ignition delay is shortened with the increase of injection pressure from 60 MPa to 120 MPa. The concentration of soot emission for 120 MPa is lower than that of 60 MPa at advanced injection timing from TDC up to BTDC 25°. As the injection timing advances to over BTDC 30°, soot emissions rapidly increase and the high injection pressure case (120 MPa) creates more emissions than the 60 MPa case. The overall trends of total particle number are relatively increased with high injection pressure for single injection conditions. In the advanced injection timings of over BTDC 30°, the trend of total particle number is high for all injection pressures. For multiple injections, the peak combustion pressures and ROHR of multiple-injection strategies are slightly lower compared with those of single-combustion results. Comparing the multiple injection strategies, soot emission is reduced with the retard of second injection timing (-30°+5°). The overall trends of particle size and total number for the 7 mg+3 mg case revealed the lowest level compared with other cases, which is 50% lower than that for the 5 mg+5 mg case. When compared with single injection results, the total particle number and Dp of multiple injection cases were eventually lower.

     

An investigation on the fuel behavior for a PFI type motorcycle engine

Recently, the electrically controlled fuel injection type motorcycle has been emphasized in order to meet regulations for exhaust emissions. However, there are many difficulties in selecting the control parameters because the pulsation phenomenon occurs in the intake port due to the higher speed operating range and the smaller layout than for a passenger car. Therefore, we investigated the injector spray characteristics which are applied to a 4-valve motorcycle gasoline engine. The spray characteristics were visualized by using a CCD camera synchronized with the stroboscope at 6000 rpm. Furthermore, we compared the simulation results using the VECTIS code with experimental results. The results showed that the trajectory of the spray was directed towards the lower wall of the intake port when the fuel was injected at closed valve timing. On the other hand, when the fuel was injected at open valve timing, a large portion of the fuel was lifted towards the upper half of the port. In addition, open valve injection makes fuel evaporation time short; this resulted in better mixture formation than a closed valve injection. From this result, we found that injection timing has a great effect on the mixture formation within a motorcycle cylinder.     

某型发动机燃油流量调节规律研究

发动机良好的燃油流量调节规律是发动机稳定工作的保证,为了更好的改善某型发动机燃油调节规律,本研究通过对燃油流量通道的建立,并对燃油通道执行机构电磁活门和回油活门占空比的分析,来研究燃油流量的调节规律。通过研究得出,燃油系统回油活门输出的位移信号与回油活门占空比成线性的关系,此结论可作为进一步改善此型发动机燃油流量调节规律的研究基础。     

内翅式套管相变蓄热器蓄热特性的模拟研究

翅片的添加可以有效改善相变蓄热速率低的问题,研究翅片结构参数对蓄热器强化蓄热的影响具有重要意义.该文采用FLUENT软件对内翅式套管相变蓄热器蓄热特性进行模拟研究,考虑自然对流作用下,探讨了蓄热器内翅片个数,翅片高度,翅片厚度等因素对石蜡蓄热过程的影响.研究表明:自然对流在内翅式套管相变蓄热器蓄热过程中发挥重要作用;翅...     

Study on the performance of celdek packed counter flow liquid desiccant regenerator

Journal of Mechanical Science and Technology - Regenerator is major component of liquid desiccant regeneration system. The influence of operating parameters; air flow rate, solution flow rate and...     

自由活塞斯特林制冷机中静压气体轴承的探讨

现代长寿命特林制冷机几乎都采用间隙密封、直线电机驱动和柔性板弹簧支撑技术,特别是还采用静压气体轴承以弥补柔性板弹簧刚度不足的缺点,消除摩擦,提高其寿命。本文分析了长寿命自由活塞斯特林制冷机中静压气体轴承的结构和性能影响因素以及其对制冷机性能的影响,为以后的研究提供帮助。最后,提出了以后的研究方向和重点。     

Combustion characteristics of a swirl chamber type diesel engine

A numerical model that utilizes Computational Fluid Dynamics (CFD) techniques is simulated for the analysis of a swirl chamber type diesel engine. This research also reveals the effects of swirl chamber passage hole geometry on the combustion characteristics of a swirl chamber type diesel engine depending on the shape, angle, and area of the jet passage. Turbulence kinetic energy is generated by compound effects of the pressure, heat release, NOx concentrations, and soot concentrations. Results show that combustion characteristics are affected by the passage hole areas and the passage hole inclination angles.     

Lubricating oil influence on exhaust hydrocarbon emissions from a gasoline fueled engine

Engine exhaust hydrocarbon emissions have been investigated for different lubricating oils, using gasoline as fuel. Six samples of lubricants have been tested: synthetic SAE 5W30 and SAE 5W40, semi-synthetic SAE 15W40 and SAE 20W50, and mineral SAE 15W40 and SAE 20W50. Experiments were carried out in a production engine mounted on a bench test dynamometer, varying engine load and speed in the range from 1500 to 6000 rev/min. The results demonstrate the influence of lubricant viscosity and base oil on hydrocarbon emissions. The synthetic oils showed the lowest hydrocarbon emission levels, especially in the low engine speed range.     

The influence of engine oil on diesel exhaust emissions

Increasingly stringent emission legislation, together with the requirements for improved diesel engine performance, such as fuel economy, friction reduction, and extended drain intervals, have led to attention being focused on engine oil quality. The use of low‐friction engine oils can improve engine fuel efficiency and lead to a significant reduction of gaseous emissions. Therefore, engine oil is of importance when considering engine design parameters. This paper describes a study of the contribution of engine oil to diesel exhaust emissions. The investigations have shown that diesel engine particulate emissions as well as hydrocarbons and NO_X emissions depend on the lubricant oil properties, in particular on the sulphur content, volatility, and metal content.     

某型增压中冷柴油机能量流仿真研究

能量流分析方法能够体现发动机系统间能量传递和转换的分布特征,对评估不同工作条件下的发动机性能表现,以及发动机辅助系统优化和发动机效率提升有重要意义。采用GT-SUITE软件搭建了某型增压中冷柴油机的仿真模型,通过仿真模型计算了该型柴油机在全负荷不同转速下的性能特征和能量流特征,分析了该发动机性能参数和能量占比随转速变化的规律。     

浅谈影响发动机试验数据准确性的几种因素

发动机试验,是用科学的试验方法揭示发动机内部的变化规律,找出提高其动力性、经济性、可靠性等各种性能的途径.从准备阶段到试验,再到试验后的数据处理,都存在着影响发动机试验数据准确性的因素:发动机的技术状态、安装位置、机油的添加量等会影响发动机的性能;试验人员的技术水平,测试仪器、试验方法的选择等会影响测试结果;试验条件的控制,测试数据的处理方法等也会影响测试结果.通过对试验全过程的分析可知,影响数据准确性的因素主要可分为样品、检测人员、测试仪器、试验方法及数据处理,试验环境和设施条件等几个方面.     

Sliding mode control of a shear-mode type ER engine mount

This paper presents feedback control characteristics of a shear-mode type electro-rheological (ER) engine mount. The field-dependent yield stress of an arabic gum-based ER fluid is obtained using a couette type electroviscometer, and it is incorporated into the governing equation of motion of the ER engine mount, which is derived from a bond graph model. A sliding mode controller which directly represents the field-dependent damping force is formulated by taking into account the stiffness and damping properties of the systems as parameter uncertainties. The controller is then experimentally realized by imposing a semi-active actuating condition. The effectiveness of the proposed ER engine mount is demonstrated showing capabilities of isolating the vibrations due to sinusoidal and random excitations.     

轿车发动机曲轴材料及工艺的研究

曲轴是汽车发动机上关键零件之一,其性能的好坏直接影响汽车质量和寿命.曲轴在发动机中承担最大负荷和全部功率,承受着强大的方向不断变化的弯矩及扭矩,也经受着高速运转中长时间的磨损,因此,要求曲轴材质具有较高的刚性和疲劳强度以及良好的耐磨性能.     

爪极结构参数对汽车电机间隙的影响

爪极是汽车发电机转子的重要组成部分,其离心力变形是影响电极间隙的重要因素,通过建立爪极的三维有限元应力分析模型,探讨了爪极的不同结构参数对电机间隙的影响关系,可以实现爪极结构参数的优化设计,供汽车发电极设计参考。