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机械毕业设计钢筋切断机外文翻译

机械毕业设计钢筋切断机外文翻译
机械毕业设计钢筋切断机外文翻译

附录Ⅰ:Magnetoelastic Torque Sensor Utilizing a Thermal Sprayed Sense-Element for Automotive Transmission Applications

Brian D. Kilmartin

Siemens VDO Automotive Corporation ABSTRACT

A Magnetoelastic based Non-Contacting, Non-Compliant Torque Sensor is being developed by Siemens VDO for automotive transmission applications. Such a sensor would benefit the automotive industry by providing the feedback needed for precise computer control of transmission gear shifting under a wide range of road conditions and would also facilitate cross-platform usage of a common transmission unit.

Siemens VDO has prototyped transmission torque sensors operating on the principle of Inverse- magnetostriction, also referred to as the Inverse-Joule Effect and the Villari Effect. Magnetostriction, first documented in the mid 1800’s, is a structural property of matter that defines a material’s dimensional changes as a result of exposure to a magnetic field. Magnetostriction is caused when the atoms that constitute a material reorient in order to align their magnetic moments with an external magnetic field. This effect is quantified for a specific material by its saturation magnetostriction constant, which is a value that describes a material’s maximum change in length per unit length.

Inverse-magnetostriction, conversely, defines changes in a material’s magnetic properties in response to applied mechanical forces. Material that is highly magnetostrictive and elastic in nature is referred to as being magnetoelastic. The premise of the Siemens VDO torque sensor design is that a magnetoelastic material can be bonded to a cylindrical shaft and magnetized in its mechanical quiescent state to create a sense- element. While under torque, principle tensile and compressive stress vectors in the form of counter- spiraling, mutually orthogonal helices develop in the shaft and are conveyed to the magnetoelastic sense-element giving rise to a measurable magnetic field change. The magnetic field deviation that arises from the magnetoelastic sense-element is directly proportional to the magnitude of the imposed torque. In effect, the magnetic field is modulated by torque. A sensitive magnetometer then translates the field strength into an analog voltage signal, thereby completing the torque-to-voltage transducer function.

Critical to the success of the Siemens VDO torque sensor design is an intimate attachment of the sense- element to the torque-bearing member. Inconsistencies in the boundary between the sense-element and the torque-bearing member will result in aberrant coupling of stresses into the sense-element manifesting in performance degradation. Boundary inconsistencies can include such imperfections as voids, contaminates, lateral shearing, and localized zones

of stress pre-load. Such inhomogeneities may be inherent to an attachment method itself or may subsequently be caused by systemically rendered malformations.

Thermal spray, the process where metal particles are deposited onto a substrate to form a coating, was used to address the issue of securely affixing magnetic material to a torque-bearing member. In addition to achieving the prerequisite of an intimate and secure bond, the thermal spray process can be regulated such that the deposited magnetic material is pre-loaded with the internal stresses needed to invoke the inverse- magnetostriction effect.

Summarizing, the passive nature of the magnetic sense- element provides an intrinsically simple kernel for the Siemens VDO torque sensor that makes for a highly reliable and stable design. The thermal spray process adds robustness to the mechanical aspect by permitting torque excursions to an unprecedented ±2000% of full scale (per prototype validation testing of certain constructs) without the need for ancillary torque limiting protection devices. Furthermore, accuracy, repeatability, stability, low hysteresis, rotational position indifference, low cost and amenability to the high-volume manufacturing needs of the automotive marketplace are all attributes of this torque sensing technique. When coupled with a magnetometer that is grounded in well- established fluxgate technology, the resultant sensor is inherently dependable and can potentially establish a new standard for torque measuring sensors.

INTRODUCTION

As is well known, automotive transmissions are designed to alter the power transfer ratio between the engine and the drive wheels effectively optimizing engine loading. The engine thereby runs in a narrow and efficient operating band even though the vehicle travels over a wide range of speeds. For automatic transmissions, shift valves select the gear ratio based generally on the throttle position, engine vacuum and the output shaft governor valve state. With the advent of electronic sensors and computerized engine controllers, transmission shift functions have been migrating towards closed-loop operation under software processing control. Along with this progression came the realization that the transmission output torque would provide a valuable feedback parameter for shift and traction control algorithms. The measurement of output torque, however, proved elusive due to the extremely harsh operating conditions. One particular SUV application under consideration required 1% accuracy in measurements of roughly 2700 Nm with possible torque excursion of 4700 Nm; all while exposed to temperature extremes -45 to +160 o C.

One method for measuring torque is to examine the physical stresses that develop in a shaft when it is subjected to an end-to-end twisting force. The principle stresses are compressive and tensile in nature and develop along the two counter-spiraling, mutually orthogonal 45 o helices. They are defined by the equation :

t = Tr / J

Where T is the torque applied to the shaft, r is the shaft radius and J is the polar moment of inertia.

Setting p r4/ 2 = J for a solid cylindrical shaft and r = d/2 yields:

t = 16T / p d

Once again, T is the torque applied to the shaft and d is the shaft diameter.

Furthermore, the degree of twist experienced by the shaft for a given torque is given by2: q = 32(LT) / (p d4G)

Where L is the length of the shaft, T is the applied toque, d is the diameter of the shaft and G is the modulus of rigidity of the shaft. The modulus of rigidity defines the level of elasticity of the shaft material, thus, a lower G value would manifest in a shaft with a higher degree of twist for any given applied torque.

Torque induced stresses that occur in the shaft material are transferred into an affixed magnetic coating and give rise to measurable changes in its surrounding magnetic field that are directly proportional to the magnitude of the applied torque; with the polarity of the magnetic field, i.e., north or south, governed by the direction of the applied torque. In essence, this is the premise of torque sensing by means of inverse magnetostriction.

TORQUE SENSOR EMBODIMENT

To effectively invoke the inverse-magnetostriction effect, the magnetic material must be correctly pre-loaded with stress anisotropy in its quiescent state. In the case of a cylindrically shaped magnetic element, the anisotropic forces must be circumferential (i.e., tangential) in nature and can be either compressive or tensile –depending on the polarity or sign of the material’s saturation magnetostriction constant. Achieving a homogenous pre-load throughout the magnetic material is crucial if the sensor is to accurately interpret torque regardless of its rotational position within a stationary magnetometer.

POSITIVE MAGNETOELASTIC DEVICES

Earlier efforts to create such a torque sensing element relied on a sense element made of material with a positive saturation magnetostriction constant. This embodiment was realized with a ring-shaped magnetoelastic element made from 18% nickel-iron alloy that intrinsically requires tensile circumferential pre- loading 3 . Such a pre-load was achieved by pressing the ring onto a tapered area of the base shaft – effectively stretching it. The effect of tensile stress on the magnetic hysteresis behavior is shown in Figure 1 where the remnant inductance, B r , nearly triples. The “easy-axes” of the magnetic domains align circumferentially due to the anisotropy defined by the principal tensile stress vector. When magnetically biased, the system in effect operates as a circumferentially shorted magnet with B approaching B r and H approaching zero.

NEGATIVE MAGNETOELASTIC DEVICES

To advance the state of the art, Siemens VDO Automotive has opted for a magnetoelastic element witha negative saturation magnetostriction constant. In this case, the alloy is very high in nickel content exhibiting a saturation magnetostriction, l s , in the range of -3e-5 dl/l and requires the stress pre-load to be tangentially compressive in nature. To achieve this embodiment, the magnetoelastic material that constitutes the sense element is “deposited” onto the base shaft using a high- velocity-oxygen-fuel (HVOF) thermal spray process. The coating thickness is only 0.5mm with an axial length of 25mm. The sense element material is endowed with compressive stress by means of precise control of the thermal spray process parameters. This proprietary procedure transforms a deposition process that normally confers isotropic material properties into one that renders the requisite stress anisotropy.

Prototype Fabrication

Magnetoelastic Element

The specification for the shaft requires the measurement of torque levels of 2700 Nm with no deleterious effects following exposures of up to 4700 Nm. Operating temperature is -45 o C to 160 o C.

By converting from the earlier torque sensor “pressed-on ring” concept to one based on a magnetoelastic material with a negative saturation magnetostriction constant, l s , the design is advanced in several respects. Primarily, its resiliency against stress/corrosion cracking is enhanced by 1) the inherent insusceptibility of high nickel content alloys towards corrosives and 2) by the lower porosity of material in compression. This is in distinct contrast with the high iron content ring placed in tension which is vulnerable to fissuring, material creep and stress corrosion cracking which can, over time, relieve the necessary anisotropic forces causing performance

degradation.

An important consequence of using the thermal spray technology is the intimate bond provided between the deposited magnetoelastic element and the base shaft. By using a thermal spray process, the boundary whereby torque induced stresses are transferred is free of such imperfections as voids, galled or furrowed material and localized stress gradients that are all characteristically associated with the pressed-on ring technique. These imperfections can induce aberrations in the magnetic field shape thereby imparting torque measurement errors relative to the rotational position of the shaft with respect to a stationary magnetometer. Furthermore, the strong bond at the interface effectively eliminates the slippage commonly associated with the interference fit of a pressed-on ring during extreme torque exposures. Any movement at this interface will manifest as a biasing of material stresses causing a zero-shift measurement error. This is not a concern when the magnetoelastic element is deposited using an HVOF thermal spray gun. Torque excursions to an unprecedented ±2000% of full scale have been successfully applied directly to prototype sensors without ancillary torque limiting protection devices.

In addition, depositing the magnetoelastic element onto a rotating shaft provides an inherently mechanically balanced assembly that imposes no angular velocity (RPM) or angular acceleration limits on the system.

Other thermal spray technology attributes are its amenability to high volume manufacturing environments, the robustness of the process insuring consistent reproducibility, and an overall reduction in fabrication steps –such as the elimination of machining procedures to mass-produce rings, cutting operations for precisely matching tapers on the shaft and ring, and pressing operations to install rings onto shafts.

Magnetic Field Shaping

Contributions from the mechanical mounting tolerances of system components (e.g., bearings and bushings) can manifest as a misalignment between the centroid centerlines of the magnetometer and the magnetoelastic element. Once calibrated, any displacement in the positional relationship between these two components will alter the system’s transfer function, possibly causing the overall error to exceed specification. The sharply focused nature of the magnetic field radially emanating from the magnetoelastic element during the application of torque (see Figure 3) accentuates this effect. This error can be minimized by shaping the physical structure of the magnetoelastic element resulting in a contouring of the magnetic field to a more favorable shape. As shown in Figure 4, the magnetic field is made to be less pronounced with an hourglass shaped magneto elastic element and sensitivity to misalignment is, thus, reduced. In this example, the magneto elastic element is contoured such that the air gap between the magneto elastic element and the magnetometer is reduced when axial displacement between their centroid centerlines occurs. The expected reduction in magnetic signal strength caused by this displacement is thus compensated by the air gap reduction.

Shafts can be fabricated with a variety of contoured surface adaptations and the thermal sprayed magnetoelastic element’s shape will expect edly follow suit. As is evident, a pressed-on ring manifestation of the magnetoelastic element would be incompatible with this technique. Various contours are being considered for further reducing the sensitivity to misalignment and for improving other performance parameters such as magnetic field strength and hysteresis.

Cylindrical Shaft Shown with Superimposed Associated Magnetic Field (i.e., Radially Directed Flux Density)

Contoured Shaft (Hourglass Shape) Shown with Superimposed Associated Magnetic Field (i.e., Radially Directed Flux Density)

In Figures 3 and 4, the spatial image of the shaft is mapped using a laser displacement system and the superimposed magnetic field is mapped in 3-space with a hall cell.

Magnetometer

Rounding out the torque sensor hardware complement is a non-contacting magnetometer that translates the magnetic signal emitted by the shaft’s sense element into an electrical signal that can be read by system-level devices. Coupling the torque signal to some interim co nditioning electronics magnetically is an attractive option due to its “non-contacting” attribute. A signal transference scheme capable of spanning an air gap is advantageous since

it requires no slip rings, brushes or commutators that can be affected by wear, vibration, corrosion or contaminants.

The fundamental magnetometer embodiment, shown in Figure 5, is circular with the shaft passing through its center. The magnetometer encompasses the magnetoelastic element of the shaft and the shaft is allowed to freely rotate within the fixed magnetometer. Power and the output signal pass through the magnetometer’s wiring harness.

Transmission Torque Sensor Magnetometer

The magnetometer actually performs several functions beyond measuring a magnetic field’s strength. These functions include magnetic signal conditioning, electrical signal conditioning, implementation of self-diagnostics, and the attenuation of magnetic and electromagnetic noise sources.

The magnetic detection method chosen for the torque sensor is fluxgate magnetometry, also known as saturable-core magnetometry. This is a well-established technology that has been in use since the early 1900’s. Fluxgate magnetometers are capable of measuring small magnetic field of strengths down to about 10 -4 A/m (or 10 -6 Oe) with a high level of stability. This performance is roughly three orders of magnitude better than that achieved by Hall Effect devices. Although many fluxgate designs use separate drive and pickup coils, the torque sensor magnetometer was designed to use a single coil for both functions.

Magnetic signal conditioning is accomplished by use of flux guides integral to the magnetometer. These flux guides amplify the magnetic signal radiating from the shaft’s sense element prior to detection by the fluxgates thereby improving the signal-to-noise ratio. The flux guides provide additional signal conditioning by integrating inhomogeneities in the magnetic signal relative to the shaft rotational position that might otherwise be misinterpreted as torque variations. The flux guide configuration is shown in Figure 6 and a magnetic simulation of the resulting field concentration is shown in Figure 7.

Flux guides surrounding magnetoelastic element

Axial view of magnetic simulation with flux gu ide material’s relative DC permeability set to 50,000 (e.g., HyMu “80”)

To further improve the magnetometer’s immunity to stray signals present in the ambient, common-mode rejection schemes are employed in the design of both the electronic and magnetic circuits. For example, wherever possible, differential circuitry was used in the

electronic design in order to negate common-mode noise. This practice was carried over to the magnetic design through the use of symmetrically shaped flux guides and symmetrically placed fluxgates that cancel common- mode magnetic signals that originate outside the system.

Finally, to augment the electrical and magnetic common- mode rejection strategies, EMI and magnetic shielding practices were incorporated into the design to further improve the signal-to-noise ratio. Stray magnetic and electro-magnetic signals found in the ambient are prevented from reaching the fluxgates and the shaft’s magnetic torque-sensing element through the use of shielding material that encompasses these critical components.

The functional diagram of Figure 8 depicts the concept of the magnetometer by showing a simplified version of the circuitry with extraneous components removed for additional clarity. An application specific integrated circuit (ASIC) contains all the circuitry necessary to perform the indicated functions.

Magnetometer Functional Diagram

Summarizing, the multi-function, fluxgate based magnetometer design provides the optimal platform for detecting the modulated magnetic field that emanates from the shaft’s torque-sensing magnetic element. By coupling time-proven fluxgate technology with an innovative flux guide configuration and with sophisticated electronic circuitry, the resultant magnetometer is durable, accurate, and stable and comprehensively achieves the design goals dictated by the application.

CONCLUSION

The latest developments in the magnetoelastic torque sensor that are presented here advance the current state of the technology by addressing many obstacles that have delayed its

acceptance by the automotive industry. Thermal spray deposition of the magnetoelastic element has resolved problems that have plagued earlier versions of the magnetoelastic torque sensor’s active element. The lack of integrity of the shaft/magnetoelastic element interface, stress-corrosion cracking, long term stability, inhomogeneity of magnetic properties and manufacturing processes that run counter to high volume production, are no longer hindering the introduction of magnetoelastic torque sensors into the automotive marketplace. With design goals clearly defined and an aggressive development program invariably progressing, the prospect of an automotive, magnetoelastic based non-compliant torque sensor is now more readily attainable.

ACKNOWLEDGMENTS

I would like to acknowledge the efforts of Ivan Garshelis who pioneered this approach to torque sensing and who had the unwavering vision to recognize this technology’s potential; and Carl Gandarillas whose scientific and analytical investigative approach has explicated much of the mystery associated with thermal sprayed magnetics. I would also like to express my gratitude to the torque sensor development team at Siemens VDO Automotive for their dedication and the extra effort that they put forth; and to Siemens VDO Automotive management for having the courage to invest in a new technology and the patience to see it through.

REFERENCES

1. Raymond J. Roark and Warren C. Young, Formulas for Stress and Strain, 5 th Edition, McGraw-Hill; Chapter 9, Torsion

2. Stephen H.Crandall and Norman C. Dahl, An Introduction to the Mechanics of Solids, McGraw-Hill; Chapter 6, Torsion

3. Ivan J. Garshelis, Magnetoelastic Devices, Inc., IEEE Transaction On Magnetics ; 0018-9464/92 V ol. 28, No. 5 September 5, 1992

ADDITIONAL SOURCES

1. Richard L. Carlin, Magnetochemistry; Springer-Verlag

2. Rollin J. Parker, Advances In Permanent Magnetism; John Wiley & Sons

3. Etienne du Tremolet de Lachhesserie, Magnetostriction Theory and Applications of Magnetostriction; CRC Press

4. Richard M. Bozorth, Ferromagnetism; IEEE Press

附录Ⅱ:磁力矩传感器利用一个热喷涂感知元件在汽车变速器中的应用

转载自:2003年发动机电子控制

布赖恩D.基尔马丁

西门子威迪欧汽车电子公司

摘要

一个非接触式的,非兼容扭矩的传感器是由西门子VDO正在开发应用于汽车传动之中。这种传感器将有利于为道路条件下广泛手柄精确的计算机控制传输所需的反馈,并且汽车行业还将促进跨平台的通用传输单元的使用。

西门子VDO的原型传递扭矩传感器上的逆磁致伸缩原理也被称为逆焦耳效应。磁致伸缩,首先在19世纪中期的记载,是一种物质的结构属性,它定义为接触磁场而导致材料的尺寸变化。磁致伸缩是由于当原子构成的材料重新调整,使其与外部磁场的磁矩相配合。量化这种效应是通过其饱和磁致伸缩常数,这是一个用于描述长度单位长度材料的最大变化的具体材料。

逆磁致伸缩,相反,它定义为一个物质响应外加机械力的磁性能的变化。磁致伸缩材料是弹性,性质是被提到的磁弹性。西门子威迪欧扭矩传感器设计的前提是,磁材料可粘接圆柱形轴,并在其机械静止状态,创造一个感觉元素磁化。而根据扭矩原则和反螺旋原则,螺旋的形式相互正交发展轴压应力矢量,并转达了磁感元素引起了一个可衡量的磁场变化。磁场的偏差,从磁感元件产生所施加的扭矩大小成正比。实际上即场调制的扭矩。然后一个敏感的磁力转换成模拟电压信号场强,从而完成了扭矩至电压传感器的功能。

至关重要的是西门子威迪欧扭矩传感器设计的成功,是与检测元件的扭矩轴承成员密切相关。元素和扭矩受力构件之间的不一致,在某种意义上,将导致耦合进入意识中的元素体现异常及性能的压力下降。边界不一致可以包括不完善的空隙,污染,横向剪切和压力预装本地化区。这种不均匀性,可能是固有的附件方法本身也可能是随后被系统地呈现畸形引起的。

热喷涂,金属粒子的过程,其中有一个基板上,形成涂层沉积,是用来安全地解决张贴磁性材料导致轴承成员扭矩的问题。除了要实现的一个亲密和安全的债券的先决条件,热喷涂过程中可以调节,使预先的内应力需要调用的沉积的磁性物质逆磁致伸缩效应加载。

概括来说,对于西门子VDO提供的磁感元素的被动性的扭矩传感器,使得一个高度可靠和稳定的设计本质变得简单。热喷涂过程机械方面的鲁棒性,允许无需辅助力矩限制保护装置需要扭矩游览到一个前所未有的_2000满刻度(每原型验证测试的某些构造)。此外,准确性,重复性,稳定性,低滞后,旋转位置的不重视,成本低,顺从的大批量制造的汽车市场需求是该传感技术扭矩的所有属性。当与一个就是在成熟的磁通

门磁力耦合技术为基础,由此产生可能建立一个力矩测量传感器本身可靠并有的新标准。

简介

众所周知,汽车变速器旨在改变发动机和驱动车轮之间的负荷功率有效地优化发动机传输率。该发动机因此虽然在车辆运行在在一个狭窄的传播的速度,高效的工作频段。对于自动变速箱,转向齿轮一般根据节气门位置选择阀门,发动机真空度和输出轴调节阀的状态。随着电子传感器和计算机引擎控制器的问世,变速器换挡功能已迁移实现闭环操作下的软件处理的控制。随着这一进程来实现,该变速箱输出扭矩将提供一个转变和牵引力控制算法的有价值的反馈参数。输出扭矩的测量,然而,事实证明由于工作条件极其恶劣难以实现。一个特殊的越野车正在考虑测量应用程序接触到 -45 -+160的

极端的温度所需的漂移精度达1%约2700牛顿米与4700 Nm的扭矩可能所有时间。

一个用于测量扭矩的方法是检查实体强调在发展轴时,受到的终端到终端扭力。该原则强调的压缩和拉伸性质和发展沿着两条反急剧上升,相互垂直45度螺旋。他们定义的公式:

σ= Tr / J

其中T是适用于轴的扭矩,r为半径的轴和J是极惯性矩。

设定@R4 / 2= J为一个坚实的圆柱形转轴和r=的D /2产量:

σ = 16T /@d 3

再次,T是适用于轴的扭矩和D是轴的直径。

此外,扭曲的程度由轴经历了一个给定的转矩给定By2的:

σ = 32(LT) / (@ d4 G)

其中L是轴的长度,T是采用转矩,D是轴的直径和G是轴的抗弯刚度。刚性模量定义轴的材料,因此弹性水平,较低的G值会表现在具有较高的扭转力矩任何特定应用程度的轴。

扭矩诱导应力发生在材料为一贴磁性涂层的轴上,导致在其周围的磁场衡量的变化有直接正比于所施加的扭矩大小;与磁场,即极性,受所施加力矩的方向北或是南极,。从本质上讲,这是通过遥感手段逆磁致伸缩扭矩的前提。

力矩传感器的体现

为了有效地调用逆磁致伸缩效应,磁性材料必须预先正确在其各向异性静态应力上加载。在一个圆柱状磁性元件的情况下,力的性质必须是在圆周各向异性的(即切线),可以是压缩或拉伸- 根据极性或材料的饱和磁致伸缩常数符号而定。实现整个磁性材料同质预负荷是至关重要的,如果传感器准确地解释它的转动力矩的位置无论在一个固定的磁力仪。

正磁弹性器件

以前的努力创造这样一个扭矩传感元件靠作出了积极饱和磁致伸缩常量元素材料。这体现为实现了作出一个环形的磁18%的镍铁合金预拉环的元素的本质要求。这种预

负荷达到了按到一个基轴的圆锥面积环- 有效地把它拉开。拉应力的磁滞行为的影响见图1,其中的残余电感,溴,近三倍。“易轴“的磁畴对准圆周因为受主拉应力矢量

定义的各向异性。当磁偏置时,在系统运行的影响作为一个与B接近溴和H趋近于零圆周短路磁铁。

图1

对于一个“积极的”磁材料的BH曲线,提出前(A)和后(b)的拉伸应力的应用。

负磁弹性器件

为了推动国家的技术,西门子威迪欧汽车已选择了一个带有负磁饱和磁致伸缩常数元素。在这种情况下,在镍合金是完美体现了饱和磁致伸缩,_s含量高,在- 3E的5升/ L范围内,需要强调预装的性质将切压。为了达到这点要求,磁材料构成的意义元素是“沉积“的基础上使用高速氧燃料(超音速)轴的热喷涂工艺。该涂层厚度只有25mm的轴向长度为0.5毫米。检测元件的材料被赋予了压应力的热喷涂工艺参数的精确控制手段。这种专有的程序转换一个沉积的过程,通常授予为一体,令所需的应力各向异性各向同性材料特性。

原型制造

磁性元素

对于轴规范要求的水平与2700 Nm的扭矩高达4700以下Nm的风险没有有害影响的计量。操作温度为45℃至160oC。

图2

热喷涂的一个典型代表传动轴

从早期的扭矩转换传感器“压上环“的概念,在具有负饱和磁致伸缩常数,磁材料的基础之一,在几个方面是先进的设计。首先,其对应力弹性/腐蚀开裂是加强 1)高镍含量对合金的内在的腐蚀性和 2)由压缩材料较低的孔隙率。这是与高铁含量的张力环,放置易受裂隙,材料的蠕变和应力腐蚀开裂,可随着时间的推移,缓解必要的各向异性造成的性能下降的力量对比鲜明。

一种采用热喷涂技术的一个重要后果是亲密的债券之间的沉积磁元件和基轴提供。通过使用热喷涂工艺,即边界诱导应力场传递扭矩是为空洞,无擦伤等缺陷或皱纹和局部应力梯度材料都是典型的按下与上环的技术。这些缺陷可以诱发磁场畸变,从而形成传授扭矩测量误差相对于轴就转动一个固定的磁力计的位置。此外,在界面粘结力强有效地消除了通常与过盈配合相关工程延误一压上暴露在极端扭矩环。任何在此界面运动将作为材料偏压舱单强调造成零移测量误差。这不是一个问题时,磁元件存放使用超音速热喷涂枪。扭矩游览了前所未有的_2000满刻度%已成功地直接应用于传感器的原型没有配套限制保护装置的扭矩。

此外,存放到一个元素的磁旋转轴提供了一个内在的机械平衡的程序集,并没有规定角速度(转速)或系统上的角加速度限制。

其他的热喷涂技术主要是它可采到大批量制造环境中,对重复性过程的稳健性保险相一致,并在总体上减少制作步骤- 如加工程序,消除大规模生产环,切割锥度操作精确匹配对轴和环,并按操作安装到轴环。

磁场成型

从机械安装公差的系统组件(如轴承和轴套)的贡献可以作为磁之间的中心线和质心磁元件失调的体现。一旦校准,任何在这两个组件之间的位置关系的位移将改变系统的传递函数,并可能导致总体误差超过规定值。该磁场重点突出自然产生的放射状磁元件的扭矩在应用程序(参见图3)突出了这种效果。这个错误可以尽量减少塑造磁在磁

场到一个更有利的轮廓形状造成元件的物理结构。如图4所示,磁场是由较少受形磁元件和敏感性的错位,因此,减少沙漏明显。在这个例子中,磁元件,使得轮廓之间的磁元件和磁气隙减少时,中心线之间的质心轴向位移发生。在这个位移磁信号强度预期减少造成的赔偿因此减少了空气间隙。

轴可以根据一个轮廓表面的热喷涂适应和磁元件制造形状中的仿真元件。由于是显而易见的,按上环的磁元件的表现使得这种技术不兼容。各种轮廓正在考虑进一步削减和改善不对的敏感性,如磁场强度和滞后性等性能参数。

图3

圆柱轴显示(即径向导演磁通密度)与相关的磁场叠加

图4

轮廓轴(沙漏形状)与相关的磁场叠加(即径向导演磁通密度)所示

在图3和4轴的空间图像映射使用激光位移系统和磁场叠加在三维空间映射到一个大的单元。

磁力仪

扭矩传感器硬件配合出的舍入是一种非接触式磁强计的磁信号转换轴的检测元件发出的成电信号,可以通过系统级的设备来读取。扭矩信号耦合到一些临时调节电子磁

是一个具有吸引力的选择,由于其“非接触式”属性。一个信号转移方案跨越一个空隙,因为它有能力,无需滑环的刷子或可由磨损,震动,腐蚀或污染物的影响交换子。

磁强计的基本体现,如图5所示,是与通过它的中心轴传递的。磁力计包含了磁轴与轴元素允许范围内自由转动的固定磁强计。电源和输出信号经过磁强计的线束。

图5

传递扭矩传感器的磁强计

实际进行的磁场之外的实力多种功能磁强计测量。这些功能包括磁信号调节,电信号调节,自我诊断功能的实现,以及磁和电磁噪声源衰减。

磁性检测方法的选择是因磁通门传感器扭矩磁学的饱和核心磁强而闻名。这是一个成熟的技术,已使用了自1900年代初期。磁通门磁力仪是测量小的磁场强度下降约

10-4A条/米,高层次的稳定(或10-6Oe)的能力。这种性能大约三个数量级以上的霍尔效应装置来实现更好的订单。虽然在许多磁通门单独的驱动器和皮卡线圈设计中使用,磁强计扭矩传感器的设计使用两种功能的单线圈。

磁信号调节是通过使用不可或缺的磁力计引导的助焊剂。这些流量引导磁信号从轴的检测元件的流量放大辐射,从而改善闸前检测信号的信噪比。磁通引导提供整合的磁信号相对于轴转动的位置,否则额外的信号调理可能会被误解为扭矩变化不均匀。磁通引导配置如图6和由此产生的磁场模拟领域集中在图7所示。

图6 周围的磁元素通量指南

图7

磁性与磁轴位模拟指导材料的透气性相对直流设置为50,000(例如,HyMu“80“)

目前为了进一步提高磁强计偏离信号的环境的免疫力,共模抑制性能是受雇于电子和磁电路的设计。例如,会尽量,在微分电路中含电子设计以否定的共模噪声。这种做法是结转的磁设计,通过对称型助焊剂使用引导和对称放置磁信号的共模取消外部发起的系统。

最后,为了增加电和磁共模抑制策略,电磁干扰和电磁屏蔽的做法被纳入设计中,进一步提高了信号的信噪比。杂散磁场和电磁环境中无法发现信号到达通过屏蔽材料,包括这些关键组件使用轴的磁扭矩传感元件。

图8图描绘的磁强计的概念功能呈现在与其他删除多余的简化版本组件的清晰电路中。特定应用集成电路(ASIC)包含了所有必要的电路来执行指定的功能。

磁强计功能框图

总结的来说,多功,磁通门磁力仪的设计提供了调制磁场检测。耦合时间证明的一个创新通量指南配置和复杂的电子电路磁通门技术,由此产生的磁力是耐用,准确,稳定,全面达到设计由应用程序决定的目标。

结论

在新发展磁弹性扭矩传感器的提出提前解决这一拖延了汽车行业的许多障碍,它接受了目前的技术状态。元素的磁热喷涂沉积已经解决了困扰的磁弹性扭矩传感器的有源元件的早期版本中的问题。应力腐蚀开裂,长期稳定,磁性质和制造工艺违背大批量生产的不均匀性,不再是阻碍了磁弹性扭矩传感器的汽车引入市场缺乏对轴/磁元素界面。由于设计目标明确和大胆的发展计划都进展,一个汽车,不符合规定的磁的扭矩传感器的前景现在更容易实现。

致谢

我想表达Ivan Garshelis 努力开创扭矩传感这种方法他用坚定不移的眼光来认识这一技术的潜力和卡尔甘达里利亚斯其科学和分析调查方法有很多与热喷涂磁性关联的神秘阐述。我也想表达我的感激之情对于扭矩传感器在西门子威迪欧汽车发展的奉献精神和额外的努力,他们提出了团队和西门子威迪欧汽车管理勇于投资新技术和耐心看到它通过。

参考文献

1、雷蒙德j的罗克和华伦长杨,应力与应变,第5版,麦格劳希尔公式;第9章

2、斯蒂芬阁下克兰德尔和诺曼三达尔,就固体,麦格劳希尔力学导论;第6章

3、伊万j的Garshelis,磁器件公司,国立磁学;0018-9464/92卷。 28日,第5号1992年9月5日

其他资料来源

1、理查德L ·卡林,磁化学;斯普林格-出版社

2、罗林j的帕克,在永磁进展;约翰Wiley&Sons出版

3、艾蒂安杜Tremolet德Lachhesserie,磁致伸缩理论与应用; CRC出版

4、理查德M. Bozorth,铁磁性;清华大学出版社

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土木外文翻译--高温下钢筋混凝土中钢筋的性能

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机械类外文翻译

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外文文献原文: Friction , Lubrication of Bearing In many of the problem thus far , the student has been asked to disregard or neglect friction . Actually , friction is present to some degree whenever two parts are in contact and move on each other. The term friction refers to the resistance of two or more parts to movement. Friction is harmful or valuable depending upon where it occurs. friction is necessary for fastening devices such as screws and rivets which depend upon friction to hold the fastener and the parts together. Belt drivers, brakes, and tires are additional applications where friction is necessary. The friction of moving parts in a machine is harmful because it reduces the mechanical advantage of the device. The heat produced by friction is lost energy because no work takes place. Also , greater power is required to overcome the increased friction. Heat is destructive in that it causes expansion. Expansion may cause a bearing or sliding surface to fit tighter. If a great enough pressure builds up because made from low temperature materials may melt. There are three types of friction which must be overcome in moving parts: (1)starting, (2)sliding, and(3)rolling. Starting friction is the friction between two solids that tend to resist movement. When two parts are at a state of rest, the surface irregularities of both parts tend to interlock and form a wedging action. To produce motion in these parts, the wedge-shaped peaks and valleys of the stationary surfaces must be made to slide out and over each other. The rougher the two surfaces, the greater is starting friction resulting from their movement . Since there is usually no fixed pattern between the peaks and valleys of two mating parts, the irregularities do not interlock once the parts are in motion but slide over each other. The friction of the two surfaces is known as sliding friction. As shown in figure ,starting friction is always greater than sliding friction . Rolling friction occurs when roller devces are subjected to tremendous stress which cause the parts to change shape or deform. Under these conditions, the material in front of a roller tends to pile up and forces the object to roll slightly uphill. This changing of shape , known as deformation, causes a movement of molecules. As a result ,heat is produced from the added energy required to keep the parts turning and overcome friction. The friction caused by the wedging action of surface irregularities can be overcome

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