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齿轮的精度对变速器齿轮副啸叫噪声有重要影响,提高齿轮精度是控制啸叫声的一个重要手段。以452AMT变速器主减齿轮为研究对象,把其传统的剃齿工艺更改为热后磨齿工艺,使齿轮精度提高3个等级,齿轮微观参数的正态分布标准差σ提高1倍以上,且更符合设计要求。最后把两种状态下各5台变速器先后通过下线台架EOL振动和1台整车NVH客观测试的单因素和正交试验的对比分析,变速器壳体振动强度下降1/2左右,车内主减齿轮副啮合阶次啸叫声加速和滑行时分别降低3 dB(A)和6 dB(A)左右。研究揭示齿轮精度对齿轮啸叫影响的机理,对变速器NVH的理论与应用具有一定的学术和工程意义。 相似文献
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《噪声与振动控制》2018,(6)
相对于传统内燃机汽车,电动汽车的动力总成的声音显著不同。传统汽车的低频发火阶次、机械及燃烧噪声,现在变为由电磁力和齿轮啮合而导致的更高频的啸叫声,这些高频噪声在主观感受上是令人烦恼的。以某电动车电驱动总成啸叫声为研究对象,首先测试引擎舱电驱动总成附近6个麦克风到车内驾驶员耳旁的空气声传递函数,然后将传递函数的倒数与加速工况下引擎舱内测得的6个麦克风平均声压级相乘,得到理论上的驾驶舱空气传播噪声。最后将理论计算结果和测试结果进行对比,结果表明低阶(8.58阶)的减速器噪声由空气传播声和结构传播声共同贡献,高阶(22阶和48阶)的减速器和电机噪声完全由空气传播声贡献。 相似文献
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针对某重型商用车在中低挡加速工况下驾驶室内出现的啸叫噪声问题。首先,对包括发动机、变速箱和中后驱动桥在内的动力传动系统进行了研究,重点分析了变速箱在问题挡位工作时的动力传递路线,明确了问题挡位下参与动力传递的啮合齿轮副。其次,设计整车道路加载试验,在发动机飞轮、驾驶室内、变速箱近场及壳体、中后驱动桥壳体及车架位置布置相应的转速、噪声及振动加速度传感器。对发动机转速进行追踪,采集7挡加速工况下各测点的噪声和振动信号。对试验数据进行处理分析,结果表明,除发动机激励外,驾驶室啸叫噪声主要由28阶和42阶激励引起且后者的影响更为显著。对变速箱主箱和副箱以及中后驱动桥位置的齿轮副进行阶次计算,结果表明,副箱行星齿轮机构中单个行星轮与外齿圈的啮合阶次为14.02阶,其2次和3次谐阶次与驾驶室内的啸叫噪声阶次相对应,定位出了问题出现的根源。最后,针对问题齿轮副,提出了相应的改进措施。 相似文献
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提出了一种基于转速信号自适应分段的多阶FRFT滤波方法,并应用于提取瞬变工况下变速器齿轮微弱故障特征。首先,根据设定的振动信号频率曲线曲率阈值将目标档位啮合频率时频曲线自适应分为若干段,使得每段内的信号频率近似线性变化;然后,在各分段内进行最小二乘拟合确定相应的FRFT最佳阶次,并在各段信号的最佳分数阶域进行滤波,实现基于转速自适应分段的多阶FRFT滤波。采用该方法分析实测变速器瞬变工况振动信号。结果表明,基于转速信号自适应分段确定多阶FRFT的最佳阶次,准确、快速、自适应性好;多阶FRFT滤波能够有效分离出瞬变工况下的啮合频率分量,隔离其他干扰;对分离出的啮合频率分量进行阶次包络解调分析,能有效提取出齿轮微弱故障特征。 相似文献
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《振动与冲击》2016,(11)
对于变速器齿轮早期微弱故障特征难以提取的问题,提出了一种基于曲线特征进行分段的多阶分数阶傅里叶变换(Fractional Fourier Transform,FRFT)滤波方法。首先,依据振动信号频率曲线的特征将目标档位的啮合频率曲线分成若干频率近似线性变化的信号段,然后通过计算确定相应信号段的分数阶傅里叶变换的滤波最佳阶次,再逐段进行滤波,从而分离出包含故障特征信息的目标阶比分量,进而进行故障特征提取。通过采用该方法分析变速器变加速工况振动信号,结果表明,基于曲线特征进行分段的多阶FRFT滤波能够有效分离出啮合频率分量,对分离出的分量进行阶次包络解调分析,能准确提取出齿轮微弱故障特征。 相似文献
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《振动与冲击》2021,(15)
纯电动汽车两挡机械式自动变速器(automated mechanical transmission, AMT)中,斜齿轮传动系统的非线性振动会引起变速器的振动和噪声。为研究两挡AMT斜齿轮系统的非线性振动特性,结合实际变速器结构,考虑齿轮系统的时变啮合刚度、齿侧间隙、静态传递误差以及轴承支撑刚度等因素,建立两挡AMT斜齿轮系统"弯-扭-轴"耦合动力学模型,分析了耦合振动特性的分岔图及其相图特性。结果表明:变速器工作在一挡时,随着转速增加,啮合频率不断增大,系统出现周期运动和混沌等现象;当承载齿轮副为单倍周期运动时,空载齿轮副扭转振动剧烈程度随着转速升高而增大;适当增大齿轮啮合阻尼比和啮合刚度,有利于减小承载齿轮最大扭振点的振幅。研究结果对纯电动汽车两挡AMT结构设计、动力学分析和换挡应用提供了技术支撑。 相似文献
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传动系统对整车振动和噪声有着重要的影响。作为一个复杂的多自由系统,包括齿轮啮合刚度的非线性和传动轴、半轴等柔性体。首先根据齿轮啮合传动的动力学模型,基于Hertz碰撞理论建立了变速器5档传动齿轮的啮合刚度分析模型;然后建立了车辆传动系统的多体动力学模型,包括变速器齿轮、传动轴、差速器、半轴和轮胎结构,分析得到系统固有特性;融合基于Hertz碰撞理论的变速器传动模型和基于多体动力学的刚柔动力学模型,对加速工况的强迫扭转振动进行了仿真与分析,对比了含非线性齿轮传动的刚体模型及刚柔结合模型的分析结果,最后通过实车进行了验证。 相似文献
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A method is proposed for estimating the parameters of a mixture of exponential and Weibull distributions for which the accuracy of preliminary estimates obtained by graphical analysis is refined in accordance with the criterion of maximum likelihood. The efficiency of the proposed method is supported by the results of statistical modeling. 相似文献
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Liebert A Wabnitz H Grosenick D Möller M Macdonald R Rinneberg H 《Applied optics》2003,42(28):5785-5792
A novel method for the determination of the optical properties of tissue from time-domain measurements is presented. The data analysis is based on the evaluation of the first moment and the second centralized moment, i.e., the mean time of flight and the variance of the measured distribution of times of flight (DTOF) of photons injected by short (picosecond) laser pulses. Analytical expressions are derived for calculation of absorption and of reduced scattering coefficients from these moments by application of diffusion theory for infinite and semi-infinite homogeneous media. The proposed method was tested on experimental data obtained with phantoms, and results for absorption and reduced scattering coefficients obtained by the proposed method are compared with those obtained by fitting of the same data with analytical solutions of the diffusion equation. Furthermore, the accuracy of the moment analysis was investigated for a range of integration limits of the DTOF. The moment analysis may serve as a comparatively fast method for evaluating optical properties with sufficient accuracy and can be used, e.g., for on-line monitoring of optical properties of biological tissue. 相似文献
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Conventional methods for summation of direct measurement errors are considered. Conditions under which these methods provide consistent results are stated. It is proposed to utilize for characteristic of the total error, its interval estimator or the half-sum of the value obtained by adding up its arithmetic and geometric random errors.Translated from Izmeritel'naya Tekhnika, No. 4, pp. 10–12, April, 1995. 相似文献
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An approximate analytical expression is derived for the velocity of the front of the wave of change of boiling modes on a
rod and on a plate. The impact of the Thomson effect and of the heater orientation in the gravity field is included. Adequate
agreement is demonstrated between the derived relations and experimental data. 相似文献
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由于空压机进气侧轴承箱蜗壳温度探头密封效果不好,使空压机及其后续管道受到油污染。后将温度探头的O形圈密封改为骨架油封,杜绝了轴承箱漏油问题。文章简介空压机的结构和技术参数,详细介绍了骨架油封的制作和优点。 相似文献
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M. M. Gadenin 《Inorganic Materials》2013,49(15):1352-1356
It is shown that conditions of attainment of marginal states in the material of structural components are formulated on the basis of analysis of force and deformation criteria of formation and development of destruction. The parameters of these criteria are data on types of structural materials, standard and special characteristics of their mechanical properties, structural forms of considered elements of the equipment, and their operating stress loading. In this case, the construction of a system of state equations for describing interrelation of current damage, external actions, and responses to them is based on the concept of calculating variations in properties of materials at all stages of the design life cycle. 相似文献
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V. T. Kornienko 《Strength of Materials》1991,23(7):760-765
The article suggests a method of evaluating the microstructural inhomogeneity of deformation of metals by modeling. The method includes the measurement of deformations of metal according to meshes of a dividing grid with small base and the calculation of the distribution parameters of microdeformations in model representation. It is shown that the modeling method makes it possible objectively to evaluate the microinhomogeneity of deformation of metals independently of the chosen mesh size of the dividing grid. New structural characteristics are introduced: the base and wave of variation expressing the degree of crumbling or amalgamation of metal grains by inhomogeneity of deformation.Translated from Problemy Prochnosti, No. 7, pp. 40–44, July, 1991. 相似文献
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水三相点是开尔文热力学温度的唯一基准点,也是ITS-90国际温标重要的定义固定点。因此,水三相点不确定度分析对整个温标的建立、温度量值传递起着至关重要的作用。近3年来,中国计量科学研究院研制出一系列高质量的水三相点容器,加强了水三相点的研究,为不确定度的分析提供了更为可靠的实验依据。同时,不确定度的分析也是客观评价新研制容器性能的一个重要指标。因此,根据实验结果对新研制容器所复现的水三相点进行了不确定度评定。评定结果表明,其扩展不确定度为0.16mK(k=2.69,P=0.99)。 相似文献