Measurement and analysis of angular velocity variations of twelve-cylinder diesel engine crankshaft

This paper presents the procedures for measuring and analyzing the angular velocity variation of twelve-cylinder diesel engine crankshaft on its free end and on the power-output end. In addition, the paper deals with important aspects of the measurement of crankshaft torsional oscillations. The method is based on digital encoders placed at two distances, and one of them is a sensor not inserted directly on the shaft, i.e. a non-contact method with a toothed disc is used. The principle based on toothed disc is also used to measure the actual camshaft angular velocity of in-line compact high-pressure pump the engine is equipped with, and this paper aims to demonstrate the possibility of measuring the actual angular velocity of any rotating shaft in the engine, on which it is physically possible to mount a toothed disc. The method was created completely independently during long-range development and research tests of V46 family engines. This method is specific for its particular adaptability for use on larger engines with extensive vibrations and torsional oscillations. The main purpose of this paper is a practical contribution to all the more interesting research of the use of engine crankshaft angular velocity as a diagnostic tool for identifying the engine irregular running.     

Dynamic damping of oscillations of the transmission output shaft of a car with an internal combustion engine

For the transmission gear box containing the mechanisms with immovable wheel axes and a planetary differential, the problem of synthesis of dynamic parameters of the model of the transmission output shaft providing dynamic damping of oscillations is solved. The problem is solved for the two highest stages of the transmission box on the fixed engine revolutions at two frequencies with the maximum amplitudes found during decomposition of the perturbing action of the engine into Fourier series. The method developed permits solving the problem of dynamic damping of oscillations for the transmission boxes with two-shaft composition. The unengaged gear wheels are used as the dynamic damper of oscillations transmitted from the engine crankshaft to the transmission. It permits reducing the wear of gear transmissions, decreasing the noise and vibration of transmission.     

Model-based diagnosis of large diesel engines based on angular speed variations of the crankshaft

This work aims at monitoring large diesel engines by analyzing the crankshaft angular speed variations. It focuses on a powerful 20-cylinder diesel engine with crankshaft natural frequencies within the operating speed range. First, the angular speed variations are modeled at the crankshaft free end. This includes modeling both the crankshaft dynamical behavior and the excitation torques. As the engine is very large, the first crankshaft torsional modes are in the low frequency range. A model with the assumption of a flexible crankshaft is required. The excitation torques depend on the in-cylinder pressure curve. The latter is modeled with a phenomenological model. Mechanical and combustion parameters of the model are optimized with the help of actual data. Then, an automated diagnosis based on an artificially intelligent system is proposed. Neural networks are used for pattern recognition of the angular speed waveforms in normal and faulty conditions. Reference patterns required in the training phase are computed with the model, calibrated using a small number of actual measurements. Promising results are obtained. An experimental fuel leakage fault is successfully diagnosed, including detection and localization of the faulty cylinder, as well as the approximation of the fault severity.     

跑马圈地钢曲轴上演“三国演义”

如果把发动机比喻为汽车“心脏”的话,曲轴则是汽车“心脏中的心脏”。作为发动机中承受冲击载荷、传递动力的重要零件,曲轴在工作中要承受交变载荷所引起的弯曲和剪切应力,对疲劳、耐磨和强度等性能指标都有非常高的要求,所以,在曲轴生产上,对材质以及毛坯加工技术、精度、表面粗糙度、     

A data processing method for determining instantaneous angular speed and acceleration of crankshaft in an aircraft engine–propeller system using a magnetic encoder

This paper presents a method for determining the instantaneous angular speed and instantaneous angular acceleration of the crankshaft in a reciprocating engine and propeller dynamical system from electrical pulse signals generated by a magnetic encoder. The method is based on accurate determination of the measured global mean angular speed and precise values of times when leading edges of individual magnetic teeth pass through the magnetic sensor. Under a steady-state operating condition, a discrete deviation time vs. shaft rotational angle series of uniform interval is obtained and used for accurate determination of the crankshaft speed and acceleration. The proposed method for identifying sub- and super-harmonic oscillations in the instantaneous angular speeds and accelerations is new and efficient. Experiments were carried out on a three-cylinder four-stroke Saito 450R model aircraft engine and a Solo propeller in connection with a 64-teeth Admotec KL2202 magnetic encoder and an HS-4 data acquisition system. Comparisons with an independent data processing scheme indicate that the proposed method yields noise-free instantaneous angular speeds and is superior to the finite difference based methods commonly used in the literature.     

内燃机曲轴-轴承系统曲轴变形引起的轴承润滑状态变化对曲轴强度的影响

在计及曲轴变形的轴承润滑分析的基础上,应用得到的轴承油膜压力分布作为载荷边界条件计算曲轴应力和强度,以分析目前曲轴强度计算中作用在轴颈上的载荷普遍采用假设的轴承油膜压力分布形式对结果精度的影响。计算中采用整体曲轴梁单元法计算曲轴变形和轴承负荷,采用动力学法进行曲轴轴承的润滑分析,应用有限元法计算曲轴应力。结果表明,计及曲轴受载变形的影响时,轴承油膜压力产生偏布且最大油膜压力明显增加,导致曲轴轴颈过渡圆角表面局部区域的应力数值明显增大,曲轴安全系数减小。因此为使曲轴设计更加合理、更接近实际,曲轴强度计算时应取曲轴—轴承系统为研究对象,根据轴承润滑分析实际计算结果,确定作用在曲轴轴颈上的载荷分布。     

柴油机曲轴柔性多体动力学仿真研究

基于柔性多体系统动力学分析曲轴缸体系统运动,同时准确计算出曲轴与缸体间的作用力。轴系系统模型包括曲轴、缸体以及飞轮,所有部件均做柔性化处理,求出柴油机在不同工况下载荷的变化情况。研究结果表明,柔性多体系统动力学可以较好反应轴系系统动力学运动过程。     

Fatigue features study on the crankshaft material of 42CrMo steel using acoustic emission

Crankshaft is regarded as an important component of engines, and it is an important application of remanufacturing because of its high added value. However, the fatigue failure research of remanufactured crankshaft is still in its primary stage. Thus, monitoring and investigating the fatigue failure of the remanufacturing crankshaft is crucial. In this paper, acoustic emission (AE) technology and machine vision are used to monitor the four-point bending fatigue of 42CrMo, which is the material of crankshaft. The specimens are divided into two categories, namely, pre-existing crack and non-preexisting crack, which simulate the crankshaft and crankshaft blank, respectively. The analysis methods of parameter-based AE techniques, wavelet transform (WT) and SEM analysis are combined to identify the stage of fatigue failure. The stage of fatigue failure is the basis of using AE technology in the field of remanufacturing crankshafts. The experiment results show that the fatigue crack propagation style is a transgranular fracture and the fracture is a brittle fracture. The difference mainly depends on the form of crack initiation. Various AE signals are detected by parameter analysis method. Wavelet threshold denoising and WT are combined to extract the spectral features of AE signals at different fatigue failure stages.     

棒材倍尺飞剪曲柄轴的有限元分析

建立了马钢VMC40N棒材倍尺飞剪曲柄轴的三维模型，对忽略惯性力和剪切机构自重的简化模型，应用Pro／Engineer软件进行了曲柄轴应力、变形和疲劳寿命的计算，并根据计算结果进行了分析和改进设计。用Pro／E软件解决复杂曲轴的设计校核问题方便高效。     

Non-linear torsional vibration characteristics of an internal combustion engine crankshaft assembly

Crankshaft assembly failure is one of the main factors that affects the reliability and service life of engines.The linear lumped mass method,which has been universally applied to the dynamic modeling of engine crankshaft assembly,reveals obvious simulation errors.The nonlinear dynamic characteristics of a crankshaft assembly are instructionally significant to the improvement of modeling correctness.In this paper,a general expression for the non-constant inertia of a crankshaft assembly is derived based on the instantaneous kinetic energy equivalence method.The nonlinear dynamic equations of a multi-cylinder crankshaft assembly are established using the Lagrange rule considering nonlinear factors such as the non-constant inertia of reciprocating components and the structural damping of shaft segments.The natural frequency and mode shapes of a crankshaft assembly are investigated employing the eigenvector method.The forced vibration response of a diesel engine crankshaft assembly taking into account the non-constant inertia is studied using the numerical integral method.The simulation results are compared with a lumped mass model and a detailed model using the system matrix method.Results of non-linear torsional vibration analysis indicate that the additional excitation torque created by non-constant inertia activates the 2nd order rolling vibration,and the additional damping torque resulting from the non-constant inertia is the main nonlinear factor.The increased torsional angular displacement evoked by the high order excitation torque relates to the non-constant inertia.This research project is aimed at improving nonlinear dynamics theory,and the confirmed nonlinear parameters can be used for the structure design of a crankshaft assembly.     

单缸曲轴连杆颈R边磨不出的原因

以Ｓ１９５曲轴的加工为例,从曲轴的加工特点、工艺、定位方法等方面进行分析,阐述了产生这一缺陷的原因并提出解决措施。     

汽车发动机曲轴加工工艺研究

目前,传统材料以及汽车发动机制造技术和现阶段的汽车行业市场发展趋势和要求之间还存在一定差异,汽车发动机机械加工技术也存在一些难以攻克的技术难点.在汽车生产制造中,对发动机曲轴机械生产的标准也越来越高.曲轴机械加工环境相对比较恶劣,很容易对曲轴机械加工质量产生不利的影响,所以,需要严格控制曲轴材料材质,保证曲轴加工工艺的...     

异型配重铁曲轴连杆颈车削夹具的设计与应用

S-217曲轴连杆颈车床是车削曲轴连杆颈主要设备之一.对称型配重铁曲轴连杆颈的加工,其圆周方向的定位一般是铣削末端配重铁边缘形成一平面加以定位.对于非对称型配重铁曲轴连杆颈的加工,则无法采用这种方法.文章采取了一种全新的、完全脱离依赖末端配重铁办法,首先在末端弧顶处铣一平面加以定位加工曲轴第1、6连杆颈(6拐曲轴),然后再以第6连杆颈外圆定位加工第2、5和3、4连杆颈.经生产实践证明,该方法定位精度高,加工过程稳定,具有很好的应用推广前景.     

发动机曲轴再制造工艺研究

阐述了采用磨削加工和镀铬修复相结合的方式对曲轴轴颈及后端凸缘进行再制造的工艺过程,分析了轴颈及后端凸缘发生腐蚀的原因,并分析了镀铬修复后曲轴的性能以及磨削加工减薄连杆颈后再加厚轴瓦的再制造方法,得出结论为对曲轴后端凸缘进行电镀铬修复时,材料性能提高,曲轴能够恢复其机械性能,曲轴疲劳极限弯矩符合发动机使用要求。     

发动机曲轴系统扭转振动计算方法及优化控制

以某一发动机曲轴系统为研究对象,建立了曲轴系统扭转振动的集总参数模型,并利用集总参数模型计算了曲轴前端在气缸压力作用下的扭转角位移;分析了减振器惯性质量绕曲轴中心线的转动惯量和扭转刚度对曲轴系统扭转振动的影响;最后,对扭转减振器进行了参数优化设计,并给出了优化结果.     

Reliability prediction of the fatigue life of a crankshaft

Crankshaft, the core element of the engine of a vehicle, transforms the translational motion generated by combustion to rotational motion. Its failure will cause serious damage to the engine so its reliability verification must be performed. In this study, the S-N data of the bending fatigue limit of a crankshaft are derived. To evaluate the reliability of the crankshaft, reliability verification and analysis are performed. For the purpose of further evaluation, the bending test of the original crankshaft is carried out, and failure mode analysis is made. The appropriate number of samples, the applied load, and the test time are computed. On the basis of the test results, Weibull analysis for the shape and scale parameters of the crankshaft is estimated. Likewise, the B10 life under 50% of the confidence level and the MTTF are exactly calculated, and the groundwork for improving the reliability of the crankshaft is laid. This paper was presented at the 4th Asian Conference on Multibody Dynamics(ACMD2008), Jeju, Korea, August 20–23, 2008. Do-Hyun Jung received his B.S. and M.S. degrees in Mechanical Engineering from Ajou University in 1988 and 1990, respectively. He then obtained his Ph.D. degree from Changwon National University in 2006. Dr. Jung is currently an Adjunct Professor at the School of Mechanical Engineering of Sunmoon University, Korea. He also manages the Reliability Application Research Center of the Reliability Division of KATECH. Dr. Jung’s fields of study include fatigue, reliability, and remanufacturing issues.     

基于刚柔耦合多体系统的发动机曲轴疲劳分析

在LMS(Leuven Measurement&System)中建立某型V8发动机曲轴系统的多体动力学模型,通过刚柔耦合动力学计算,得到部件的模态参与因子,将模态参与因子与模态进行线性叠加,得到部件的载荷历程,并将其作为疲劳分析的输入数据;利用LMS.Virtual.Lab的Durability模块对曲轴进行有限元疲劳分析,获得精确的曲轴疲劳寿命值和损伤分布.结论是:通过系统多柔体动力学仿真可以得到各阶模态参与因子的时间历程曲线和部件的载荷历程,同时保证了模态参与因子与有限元模型匹配;曲轴集中应力最大且寿命最短处为轴颈与曲柄的过渡圆角处.     

基于ANSYS和ADAMS的发动机曲轴动力学仿真

结合虚拟样机技术和有限元分析技术,使用Pro/ENGNEER和ADAMS建立发动机曲轴连杆机构的虚拟样机后,对曲轴连杆机构进行了多体动力学仿真,得到发动机曲轴承受的动态载荷,从曲轴所受载荷中找出最大值,然后使用ADAMS与ANSYS的接口,将载荷施加在曲轴的有限元模型上,最后使用ANSYS计算了曲轴的最大应力和应变,找出了曲轴受力的危险部位,为曲轴的优化设计提供参考.     

计入轴瓦变形的曲轴动应力和疲劳强度计算

采用动力学仿真软件ADAMS和有限元分析软件ANSYS,辅以手工编程相结合的方法,研究计入轴瓦变形时某四缸柴油机曲轴动应力分析和疲劳强度计算问题。解决计入轴瓦变形的曲轴—轴承系统动力学和摩擦学分析问题,得到动态油膜压力;采用ANSYS中的参数化编程语言APDL编写程序实现动态施加力边界条件,计算曲轴动应力;采用损伤积累理论计算曲轴疲劳强度。研究表明：计入轴瓦变形,主轴承最小油膜厚度大幅度下降,最大油膜压力大幅度上升,曲轴动力学响应和危险点的动应力也发生变化,曲轴疲劳寿命下降了15.6%。     

曲轴圆角强化技术及应用

结合曲轴圆角强化技术的实际应用及对目前国内外常用曲轴圆角局部强化技术的理解,介绍和分析了滚压、淬火、氮化、喷丸、激光冲击强化等曲轴强化技术的应用及强化机理,对提高曲轴的性能和疲劳寿命,具有一定的参考价值。