共查询到20条相似文献,搜索用时 31 毫秒
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T. Ramachandran K. P. Padmanaban 《The International Journal of Advanced Manufacturing Technology》2013,67(1-4):887-898
Though many computationally expensive internal combustion engine vibration models are available, simple and computationally efficient tools are required for preliminary design work. The unbalanced forces of rotating and reciprocating parts are the primary sources for the engine vibrations which in turn reduce the durability and reliability of consumer and commercial automotives. So, a significant vibration isolation is needed for both engine and interface between the engine mounts, and it could be obtained with the help of rotating balancing disks attached at both ends of the crank shaft. The masses of the balancing disks and their lead angles influence the effectiveness of vibration isolation that can be measured by the engine mount displacement caused due to engine vibrations. The optimized masses of balancing disks and their lead angles minimize the engine mount displacements that ensure the effective vibration isolation. In this paper, the genetic algorithm is employed to optimize the masses of the balancing disks and their lead angles with an objective of minimizing the engine mount displacements. 相似文献
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This paper presents vibration and noise control of flexible structures using squeeze mode electro-rheological mounts. After
verifying that the damping force of the ER mount can be controlled by the intensity of the electric fild, two different types
of ER squeeze mounts have been devised. Firstly, a small size ER mount to support 3 kg is manufactured and applied to the
frame structure to control the vibration. An optimal controller which consists of the velocity and the transmitted force feedback
signals is designed and implemented to attenuate both the vibration and the transmitted forces. Secondly, a large size of
ER mount to support 200 kg is devised and applied to the shell structure to reduce the radiated noise. Dynamic modeling and
controller design are undertaken in order to evaluate noise control performance as well as isolation performance of the transmitted
force. The radiated noise from the cylindrical shell is calculated by SYSNOISE using forces which are transmitted to the cylindrical
shell through two-stage mounting system. 相似文献
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In this study, a numerical analysis for the piston secondary dynamics of small refrigeration reciprocating compressors is performed. In general, the length of cylinder in this class of compressors is shortened to diminish the frictional losses of the piston-cylinder system. So, the contacting length between piston and cylinder wall is in variable with the rotating crank angle around the BDC of the reciprocating piston. In the problem formulation of the piston dynamics, the variation in bearing length of the piston and all corresponding forces and moments are considered in order to determine the piston trajectory, velocity and acceleration at each step. A Newton-Raphson procedure was employed in solving the secondary dynamic equations of the piston. The developed computer program can be used to calculate the entire piston trajectory and the lubrication characteristics as functions of crank angle under compressor running conditions. The results explored the effects of some design parameters and operating conditions on the stability of the piston, the oil leakage, and friction losses. 相似文献
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建立了直喷汽油机的三维数值模型和运动学模型,并进行了试验验证。模拟了直喷汽油机在直接起动过程中不同喷油策略和点火时刻下的燃烧特性、反转和正转过程的运动特性。结果表明:与单次喷油相比,采用两次喷油策略时,首个着火气缸内混合气燃烧后的最大气缸压力较大,而且其大小受到点火时刻的影响;首个着火气缸内混合气燃烧后的最大气缸压力较大,则直喷汽油机反转过程中转过的最大角度较大;在各种喷油条件下,第2个着火气缸在反转到其最大转角前2°左右点火,正转过程转速较高,有利于直喷汽油机的直接起动。 相似文献
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Multiobjective optimization for force and moment balance of a four-bar linkage using evolutionary algorithms 总被引:1,自引:0,他引:1
Mohammad Reza Farmani Abdolrahman Jaamialahmadi Meisam Babaie 《Journal of Mechanical Science and Technology》2011,25(12):2971-2977
In this study, force and moment balance of a planar four-bar linkage is implemented using evolutionary algorithms. In the
current problem, the concepts of inertia counterweights and physical pendulum are utilized to complete balance of all mass
effects, independent of input angular velocity. A proposed multiobjective particle swarm optimization, and non-dominated sorting
genetic algorithm II are applied to minimize two objective functions subject to some design constraints. The applied algorithms
produced a set of feasible solutions called pareto optimal solutions for the design problem. Finally, a fuzzy decision maker
is utilized to select the best solution among the obtained pareto solutions. The results show that optimal solutions minimize
the weights of applied counterweights and eliminate both shaking forces and moments transmitted to the ground, simultaneously. 相似文献
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S. Venkatesh 《Wear》1974,27(1):83-89
The operational life and reliability of I.C. engines are limited to a certain extent by the break down of the engine components due to wear. It is advantageous to know the condition of an engine and its components without disassembling for detailed measurements. This paper describes the possibility of employing chemical analysis of the used crank case oil to predict the wear of engine components. It is concluded that the acidity and carbon contents of the crank case oil play a significant role in assessing the wear of copper-lead bearings used for the big end of the connecting rod. 相似文献
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A. K. Rai H. K. Trivedi R. S. Bhattacharya C. J. Klenke N. H. Forster 《Tribology Letters》2010,39(2):143-149
State-of-the-art bearing materials, such as Pyrowear 675(P675) have been developed to meet the requirements of the next generation
of gas turbine engines. P675 bearings have exhibited higher land wear compared to conventional M50 bearings under contaminated
test conditions. Surface modification techniques can be applied to enhance the wear resistance of bearing land surfaces. A
coating has been developed to minimize abrasive wear of land surfaces. A new procedure using a 40 mm bearing test rig has
been developed to effectively evaluate land wear under simulated contaminated condition. Test conditions including contamination
concentration, test duration, test temperature and lubricant flow rate were optimized to obtain measureable wear on the land
surfaces in a reasonable test time. Results obtained using M50 Nil, P675 and M50 bearings are presented to illustrate the
viability of the test procedure. 相似文献
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The paper considers a model of a crankshaft of a two-cylinder four-stroke engine with using torsional waves and taking into account their reflections. The considered model of the crankshaft consists of elastically deformable main journals and of rigid bodies. The moments of external forces and mass moments are approximated by piece-wisely constant functions. Damping of the considered system is described by an equivalent damping. The analytical solutions for the functions utilized for determining displacements at an arbitrary time instant, have been obtained in the form of recurrence formulae. The stability condition of the solutions is given, under which the displacements of the main journals are relatively small. The plots of displacements have been drawn for selected parameters of the crankshaft for the centrelines of crank pins which can be either coincident or shifted. 相似文献
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理想的发动机悬架系统应隔离发动机工作转速范围内由发动机干扰力所引起的发动机振动,并阻止由冲击而激起的发动机弹跳,这意味着发动机悬架的动态刚度和阻尼是与频率和振幅有关的,改善依赖于频率和振幅特性的动态刚度与阻尼是发动机悬架系统发展的关键所在。传统的弹性悬架不能满足所有的要求,它仅能在静偏转和隔振之间进行折衷,特别在低频域,被动的液压悬架能比弹性悬架提供更好的特性,通常半主动技术,由于其可调性而被用来进一步改善液压悬架的特性,为了隔振、低频时主动发动机悬架系统非常硬,而在高频域内被调整的非常软,主动的发动机悬架已被认为是发动机悬架的新一代,发动机悬架系统的优化是相当可取的,但发动机悬架的优化工作出现一些局限性,文中综述国内,外发动机悬架技术的现状与进展。 相似文献
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Sung-Ryong Hong Seung-Bok Choi Moon-Shik Han 《International Journal of Mechanical Sciences》2002,44(10):2027-2045
A squeeze-mode electro-rheological (ER) mount has been designed, manufactured, and applied to the vibration control of a frame structure subjected to external excitations. After verifying that the damping force of the ER mount can be controlled by controlling the applied voltage, a frame structure system supported by spring mounts and the proposed ER mounts has been assembled. The governing equation of the structural system is derived in the modal coordinate and is rewritten as a state-space control model. An optimal controller, which consists of the velocity feedback signal of the frame structure and the force feedback signal transmitted from the exciting point to the mount position, is formulated in order to attenuate the imposed excitations. The controller has been optimized experimentally and control responses such as the acceleration of the frame structure and the transmitted force at each mount position are presented in both time and frequency domains. 相似文献
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A. D. Nazarov 《Journal of Friction and Wear》2011,32(5):345-355
The work presents the theoretical principles of how to compensate the total mass of crank gear parts and to eliminate the
auxiliary free total unbalanced moment emerging when reconditioned or improved pistons, connecting rods, piston rings, and
conrod liners are installed in V-8 engines. It is achieved by increasing the mass of the counterweights and the distance between
the center of gravity and the axis of rotation, by altering the angles of their arrangement, the mass-geometrical parameters,
and the design of the sump plugs in the conrod necks, and by creating an engine-plane-directed imbalance correction. These
methods enable compensation of the total unbalanced mass in order to eliminate the above-mentioned moment; they make it possible
to balance the crankshaft, improve durability, and reduce the vibration and noise of the V-8 engine. 相似文献
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将底盘传动系纳入发动机动力系统,提出了混凝土泵车发动机万有特性模型的现场测试方法.该方法无须将发动机从底盘上拆除进行台架测试试验,利用混凝土泵车液压系统对发动机进行现场加载,通过对液压参数的测试获得发动机输出扭矩,避免了对发动机转矩的直接测试.运用曲面插值法实现了发动机万有特性曲线的绘制,并以此为依据对该型号混凝土泵车工况进行优化,获得4种工况下与液压系统最佳匹配的发动机转速.试验验证:利用曲面插值法建立的某型号混凝土泵车发动机万有特性模型最大相对误差不超过5%,建模方法简单、精度高,以该模型为依据优化后的发动机工况节油效果明显,最大节油率为16.67%. 相似文献
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以横置的动力总成悬置系统为研究对象,系统地阐述了悬置系统的布置设计思想,解释了悬置系统中主惯性轴、扭矩轴以及弹性轴的定义,并对目前横置动力总成悬置系统的主要布置形式进行了研究与分析。在怠速扭矩激励下,悬置的安装位置应满足系统的扭矩轴和弹性轴重合,从而获得良好的隔振性能。同时对悬置系统的解耦作了相关的说明。横置动力总成悬置系统的布置设计分析,为悬置系统前期开发中悬置的安装位置和刚度的选择提供了参考价值。 相似文献
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Friction model of a marine diesel engine piston assembly 总被引:2,自引:0,他引:2
In modern marine diesel engines, power output and in-cylinder firing pressures are constantly increasing, leading to higher friction in engine components and especially in the piston assembly. A good understanding of the friction contributions of the various engine components is needed, if mechanical efficiency is to be improved. A friction model for the engine piston assembly has been developed and is presented in this paper. The model, based on lubrication theory, considers the detailed engine geometry and the complete lubricant action, and thus can be applied to a wide range of engines. In detail, the analysis takes into account the friction components of compression rings, oil control rings, piston skirt and gudgeon pin of the engine piston assembly. The model was applied to a four-stroke (medium speed) marine diesel engine and the effect of engine speed and load on friction was examined and compared with results from other semi-empirical models. The engine friction was predicted at constant rotational speed (generator operation) and variable rotational speed (propulsion operation). 相似文献