【作者】 李淑静；

【导师】 闫兵；

【作者基本信息】 西南交通大学 ， 动力机械及工程， 2013， 硕士

【摘要】 内燃机振动控制是内燃机设计、应用中的热点问题。对内燃机进行动力学分析确定其激振力,是内燃机振动控制和隔振设计的基础和重要环节。目前,获得内燃机的激振力可以采用理论计算和实验识别两种方法。工程应用中内燃机的实际激振力往往和理论计算值具有一定偏差,因此用实验方法确定内燃机激振力更能符合实际情况,具有直接的工程应用价值。本课题围绕内燃机整机振动激振力的识别问题,结合国内首次采用的动力包双层隔振系统设计项目,主要进行了以下研究分析工作：(1)从理论上对动车的内燃机进行激励源分析,确定了该内燃机的主要激励源为3.0谐次倾倒力矩和6.0谐次倾倒力矩,其往复惯性力(矩)和旋转惯性力(矩)在理论上为零。(2)应用内燃机整机振动激振力识别的测振法原理,编写了激振力识别计算程序。(3)通过实测和查询文献资料,确定了各系统参数的可能波动范围。定量分析了系统参数(惯量参数、刚度、阻尼、质心位置)误差对内燃机整机振动激振力识别精度的影响。(4)最后进行了柴油发电机组的多工况、多测点的整机振动激振力识别实验,并对实验数据进行了时频域分析。在初步掌握了该柴油发电机组的整机振动特性后,进行了整机振动激振力的实验识别计算,探索了多工况、多测点情况下整机振动激振力识别计算方法,并进行了识别精度验证。(5)通过对该柴油发电机组的整机振动激振力实验识别技术的研究,提出如下指导意见和建议：如缺乏对柴油发电机组隔振系统振动特性的了解并且设备条件允许,可以进行大量测点的整机振动测试,然后运用本文提出的统计的直方图法进行激振力识别。如已掌握了柴油发电机组隔振系统的振动特性或者测点有限的情况下,可以用本文提出的布置原则,有选择地布置3-4个测点。另外,在测量过程中,为满足激振力识别的刚体假设条件,建议把内燃机安装在坚固的大质量台架上,测点也可选在大质量大刚度的台架上,即可减少因局部振动过大、结构共振等干扰造成的信号异常现象。综上所述,因测量误差、测点位置差异、机组结构的复杂性等因素的存在,不同的测点组合会得出不同的激振力识别结果。为了提高激振力识别精度,针对大量测点的整机振动激振力识别实验,本文提出的运用统计直方图法来识别计算往复式机械整机振动激振力的方法是一个大胆的创新,以后可将此方法进行推广,并在实践中得以不断完善。更多还原

【Abstract】 Control of vibration in internal combustion engine is a hot issue among internal combustion engine design and application. Dynamic analysis and vibration force verification on internal combustion engine both are key segments and bases for vibration control and vibration isolation design in internal combustion engine field. Though, two methods, theoretical computation and experimental strategy, for vibration source acquisition about internal combustion engine are applicable, deviations between them always emerges, however, experimental method is thought to be closer to practical situations and possess direct engineering application value.This subject aims at the recognition of exciting force from the body vibration of an internal combustion engine. With the domestic first use of dual-layer vibration isolation system, the main researches done are as the following:(1) The main vibration sources are verified through theoretical analyses to be3order and6order overturn torque. Reciprocating inertia force (torque) and rotational inertia force (torque) are zero theoretically.(2) A program for vibration force source recognition has been designed according to the theory for exciting force extraction from the body vibration of an internal combustion engine.(3) The deviation of each systematic parameter has been verified through measurements and references. The influence of systematic parameters’(inertia parameters, stiffness, damping, coordinates of center of mass) errors on the accuracy of recognition has been assessed.(4) At last, exciting forcesrecognizing test of has been done over multi-working conditions and multi-test points on a diesel gen set, and the data has been analysed on both time-domain and frequency-domain.Moreover, computations on the recognition of vibration forces from the body vibration test has been accomplished and the investigation of the computation method about vibration force source recognition over multi-working conditions and multi-test points has been investigated, in addition, the verification of the recognizing accuracy has been conducted.(5) Through this research on the experimental recognition technology of the exciting force extraction from the body vibration of an internal combustion engine, the following suggestions have been proposed:multiple test points are applicable in body vibration test given the lack of acknowledge about the vibration isolation system of the diesel gen set and sufficient equipment provision, and the statistical method proposed in this article can be adopted on vibration force recognition, otherwise, the principle of test points arrangement introduced by this article, i.e. arrange3-4points selectively. In addition, it is suggested that the internal combustion engine should be mounted on a solid test rig with huge mass to fulfill rigid body assumption as more as possible, also, test points are suggest to be mounted on the position with greater rigidity so as to avoid interferences such as local vibration and resonance which is responsible for abnormal signals.In conclusion, different combinations would yield different recognition outcomes owing to measurement error, coordinate errors of test points and the complicity of the gen set. To improve the accuracy of recognition when encountering massive test points condition, histogram statistical method has been introduced and this is an extraordinary innovation. The author believed that this method could be adopted and improved in the future practices.更多还原