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中英文对照资料外文翻译文献
附录Ⅰ：Magnetoelastic Torque Sensor Utilizing a Thermal Sprayed Sen-Element for Automotive Transmission Applicationsinformation
ABSTRACT
emulateA Magnetoelastic bad Non-Contacting, Non-Compliant Torque Sensor is being developed by Siemens VDO for automotive transmission applications. Such a nsor would benefit the automotive industry by providing the feedback needed for preci 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.
除此之外Siemens VDO has prototyped transmission torque nsors operating on the principle of Inver- magnetostriction, also referred to as the Inver-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 caud 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.
Inver-magnetostriction, converly, defines changes in a material’s magnetic properties in respon to applied mechanical forces. Material that is highly magnetostrictive and elastic in nature is referred to as being magnetoelastic. The premi of the Siemens VDO torque nsor design is that a magnetoelastic material can be bonded to a cylindrical shaft and magnetized in its mechanical quiescent state to create a n- 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 n-element giving ri to a measurable magnetic field change. The magnetic field deviation that aris from the magnetoelastic n-element is directly proportional to the magnitude of the impod torque. In effect, the magnetic field is modulated by torque. A nsitive 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 nsor design is an intimate attachment of the n- element to the torque-bearing member. Inconsistencies in the boundary between the n-element and the torque-bearing member will result in aberrant coupling of stress into the n-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 itlf or may subquently be caud by systemically rendered malformations.
Thermal spray, the process where metal particles are deposited onto a substrate to form a coating, was ud to address the issue of curely affixing magnetic material to a torque-bearing member. In addition to achieving the prerequisite of an intimate and cure bond, the thermal spray process can be regulated such that the deposited magnetic material is pre-loaded with the internal stress needed to invoke the inver- magnetostriction effect.
Summarizing, the passive nature of the magnetic n- element provides an intrinsically simple kernel for the Siemens VDO torque nsor 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 nsing technique. When coupled with a magnetometer that is grounded in well- established fluxgate technol
ogy, the resultant nsor is inherently dependable and can potentially establish a new standard for torque measuring nsors.
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 lect the gear ratio bad generally on the throttle position, engine vacuum and the output shaft governor valve state. With the advent of electronic nsors and computerized engine controllers, transmission shift functions have been migrating towards clod-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 expod to temperature extremes -45 to +160 o C.
routersari是什么意思
One method for measuring torque is to examine the physical stress that develop in a shaft when it is subjected to an end-to-end twisting force. The principle stress 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)
sing along 童声版
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 mate
rial, thus, a lower G value would manifest in a shaft with a higher degree of twist for any given applied torque.
Torque induced stress that occur in the shaft material are transferred into an affixed magnetic coating and give ri 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 esnce, this is the premi of torque nsing by means of inver magnetostriction.ons是什么
TORQUE SENSOR EMBODIMENT
To effectively invoke the inver-magnetostriction effect, the magnetic material must be correctly pre-loaded with stress anisotropy in its quiescent state. In the ca 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 nsor is to accurately interpret torque regardless of its rotational position within a stationary magnetometer.
POSITIVE MAGNETOELASTIC DEVICES
emEarlier efforts to create such a torque nsing element relied on a n 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 ba 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 biad, 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 ca, 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 n element is “deposited” onto the ba 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 n element material is endowed with compressive stress by means of preci 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 nsor “presd-on ring” concept to one bad on a magnetoelastic material with a negative saturation magnetostriction constant, l s , the design is advanced in veral 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.中俄翻译
An important conquence of using the thermal spray technology is the intimate bond provided between the deposited magnetoelastic element and the ba shaft. By using a thermal spray process, the boundary whereby torque induced stress are transferred is free of such imperfections as voids, galled or furrowed material and localized stress gradients that are all characteristically associated with the presd-on ring technique. The 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 presd-on ring during extreme torque exposures. Any movement at this interface will manifest as a biasing of material stress 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 nsors wit
hout ancillary torque limiting protection devices.
