WO2012028378A1 - Détermination d'un couple agissant sur un arbre de direction - Google Patents

Détermination d'un couple agissant sur un arbre de direction Download PDF

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Publication number
WO2012028378A1
WO2012028378A1 PCT/EP2011/062340 EP2011062340W WO2012028378A1 WO 2012028378 A1 WO2012028378 A1 WO 2012028378A1 EP 2011062340 W EP2011062340 W EP 2011062340W WO 2012028378 A1 WO2012028378 A1 WO 2012028378A1
Authority
WO
WIPO (PCT)
Prior art keywords
steering shaft
shaft section
steering
interferometer
arrangement according
Prior art date
Application number
PCT/EP2011/062340
Other languages
German (de)
English (en)
Inventor
Ronny Ludwig
Original Assignee
Robert Bosch Gmbh
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Robert Bosch Gmbh filed Critical Robert Bosch Gmbh
Publication of WO2012028378A1 publication Critical patent/WO2012028378A1/fr

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Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
    • G01L3/00—Measuring torque, work, mechanical power, or mechanical efficiency, in general
    • G01L3/02—Rotary-transmission dynamometers
    • G01L3/04—Rotary-transmission dynamometers wherein the torque-transmitting element comprises a torsionally-flexible shaft
    • G01L3/10—Rotary-transmission dynamometers wherein the torque-transmitting element comprises a torsionally-flexible shaft involving electric or magnetic means for indicating
    • G01L3/12—Rotary-transmission dynamometers wherein the torque-transmitting element comprises a torsionally-flexible shaft involving electric or magnetic means for indicating involving photoelectric means

Definitions

  • the present invention relates to an arrangement for determining a torque acting on a steering shaft, a corresponding steering shaft, a steering assist system and an associated method.
  • Steering support systems for motor vehicles are known.
  • the steering shaft is divided into two parts in such systems, wherein a steering wheel-side first steering shaft portion is connected to a steering-tide-side second steering shaft portion via a torsion bar.
  • the torsion bar twists due to the frictional resistance between the tire and the road surface.
  • the applied steering torque Based on the rotation of the steering shaft sections to each other can be determined at a known spring constant of the torsion bar, the applied steering torque.
  • a steering assist force provided by a servo device is metered by a controller.
  • the angular positions of both sections of the steering shaft can be measured.
  • the twist angle corresponds to the difference of the angular positions. This angle of twist is usually small, so that inaccurate in the angular determinations have great effects on the determination of torque.
  • the corresponding angles must therefore be recorded with the greatest possible accuracy (angular resolution).
  • Known sensor arrangements for detecting a rotation angle evaluate with at least one magnetic field-sensitive sensor element, the magnetic field information of a magnetic pole wheel, which is rotated due to a torque acting on the torsion bar relative to the sensor element.
  • ferromagnetic rings used having axially extending teeth with which the magnetic flux between the magnetic pole and the sensor element can be influenced.
  • the flux rings can have axially extending and non-intermeshing teeth, with which the magnetic flux between the Magnetpolradrad and the
  • Sensor element can be influenced.
  • phase signals are determined in such methods, for example by scanning a corresponding coded area, for example on a wave, wherein the light reflected by the structuring of the coded area contains a pattern which is projected onto an opto-ASIC, for example, and converted into an angle signal.
  • Another optical method for determining a twist angle involves axially scanning two perforated disks respectively attached to the steering shaft sections. Both steering shaft sections twist to each other, the holes in the discs slide radially relative to each other. The changing intensity of the radiation penetrating through the correspondingly reducing openings can be detected with a photodiode. The incident light is thus a measure of the torsion.
  • the present application proposes an arrangement for determining a torque acting on a steering shaft having a steering wheel-side first steering shaft section, a steering gear side second steering shaft section, and a torsion bar connecting the steering shaft sections based on torsional rotation of the first steering shaft section relative to the second Steering shaft portion, a corresponding steering shaft and a steering assist system and a corresponding method with the features of the independent claims before.
  • Advantageous embodiments are the subject of the dependent claims and the following description.
  • the present invention is based on the use of an alternative optical measuring principle with high angular resolution.
  • the phenomenon of interference is used for this purpose.
  • a variation of an optical path length measured by an interferometer as a function of a rotational angle using asymmetrically mounted elements hereinafter more generally referred to as "eccentric elements"
  • eccentric elements asymmetrically mounted elements
  • the eccentric elements have at least partially reflective surfaces.
  • the solution according to the invention can be realized, in particular, with a steering shaft in which two steering shaft sections are connected to one another by a torsion bar lying advantageously on the inside, which permits, for example, a rotation of both shafts of a maximum of ⁇ 3 °.
  • a torsion bar lying advantageously on the inside, which permits, for example, a rotation of both shafts of a maximum of ⁇ 3 °.
  • an eccentric element is fixed in each case against rotation, preferably terminally.
  • Eccentric elements of both steering shaft sections advantageously have the smallest possible distance from each other and can be connected, for example via a press fit with the respective waves.
  • Other mounting options are also conceivable.
  • an interferometer Due to the adjacent arrangement of the eccentric elements, advantageously an interferometer can be used which has a single light source, for example a laser diode. The light beam emitted by the light source is split into two separate beams by use of a suitable lens.
  • a corresponding interferometer can be provided in a particularly cost-effective and with higher accuracy.
  • a single light source offers certain advantages in this respect, it is also possible, for example for reasons of redundancy, advantageously to use two separate radiation sources.
  • an interferometer is particularly suitable for reliably measuring smallest changes in the respective path length difference between the beam bundles, the achievable resolution being of the order of half the wavelength of the beam used Lichts lies.
  • Each maximum or minimum corresponds to a path length change by one wavelength, ie a position change by half a wavelength.
  • the speed of the measurable change is limited by the achievable count rate of a detector used or the evaluation electronics associated therewith.
  • the signals detected here are pulses of a quasi-digital nature, powerful detection devices or counters available from the prior art can be used.
  • the electronic evaluation is also independent of the rotational speed within the scope of the maximum counting rate of corresponding optical detectors.
  • the counting of the interference maxima or minima is, as mentioned, in the context of the inventive solution in a special way for determining a torque acting on a steering shaft.
  • the aforementioned high resolution can be additionally increased by the use of asymmetrically mounted disks, as explained in more detail below.
  • a steering system of the type of interest here is in continuous motion, with variable rotational speeds occurring, so that a quasi-stationary state, as required for intensity-based interferometry, can generally not be achieved.
  • the invention proposes an interferometric measuring torque sensor, wherein a rotation causes a change in the optical path length of a measuring beam by a rotational angle-dependent distance of an eccentric element with at least partially reflecting surface to the beam splitter of an interferometer and evaluated.
  • the proposed measurement method is a contactless one
  • Figure 1 shows a schematic representation of an interferometer according to the prior art.
  • Figure 2 shows a schematic, partially perspective view of a steering shaft with an arrangement according to a particularly preferred embodiment of the invention.
  • FIG. 3 shows, in a schematic longitudinal section illustration, a steering shaft with an arrangement according to a particularly preferred embodiment of the invention.
  • FIGS 4A-4C show a schematic plan view of a steering shaft portion with an arrangement according to a particularly preferred embodiment of the invention in different Wnkel einen.
  • FIG. 5 shows a detailed view of an arrangement according to a particularly preferred embodiment of the invention with structured surfaces.
  • Michelson interferometer shown.
  • the general mode of operation of an interferometer is based on the fact that a (coherent) output light beam 411 is split into two partial beams 412, 413.
  • the two partial beams 412, 413 pass through distances of different lengths or media, in which the transit time of the partial beams 412, 413 is different, so that a phase shift of the two partial beams 412, 413 results. If the two partial beams are brought together again to form a total beam 414 after passing through the respective routes, interference occurs.
  • a Michelson interferometer uses a semitransparent mirror 421 for splitting the output light beam.
  • a light source 41 for example a laser diode
  • the optical path length of one of the two partial beams 412, 413 is changed, for example by the surface 43 'or a corresponding reflecting measurement object being displaced along a distance A or by the refractive index of the medium being changed in one of the two so-called interferometer arms, the phases of the two waves against each other.
  • a detection of the resulting wave in a detector 44 in particular by a count the intensity maxima and / or minima, so even the smallest changes in the path difference between the two waves can be measured.
  • the detector is expediently designed as a photodetector, which thus alternately detects minima and maxima of the interference image during a change in length.
  • the monochromatic light of a beam source 41 can also be divided via a lens 41 'and / or an aperture 45 such that two beam paths can be distributed over a sufficiently dimensioned beam splitter.
  • FIG. 2 shows a steering shaft 100 with a steering wheel-side first steering shaft section 1 and a steering shaft-side second steering shaft section 2.
  • a torsion bar 3 connecting the steering shaft sections 1, 2 is indicated schematically.
  • Both the steering wheel side steering shaft section 1 and the steering gear side steering shaft section 2 have eccentric elements 10, 20 in the form of revolution cylinders with lateral surfaces 1 1, 21. The eccentric elements are advantageously attached to each other at a small distance D.
  • eccentric elements in the form of revolution cylinders, it is to be understood that the eccentric elements can take other forms, as far as this is expedient for the realization of a measuring method according to the invention.
  • cylinder segments can also be used. At a distance to the lateral surfaces of the two
  • an interferometer 4 is arranged as explained above, which is shown schematically here.
  • the interferometer 4 forms, together with the eccentric elements 10, 20, an arrangement 200 for determining a torque according to a particularly preferred embodiment of the invention.
  • an interferometer 4 The basic construction of an interferometer 4 has been explained in connection with FIG. 1, so that only essential elements are described here again.
  • a coherent light source 41 is provided whose light is split into two output beams 411 via a lens 41 'and shutters (not shown). In the following, only one of these beams will be explained further, but the explanation applies equally to the other beam as well.
  • the output beam 411 passes through a beam splitter 42 with a semi-transmissive mirror 421.
  • a measuring beam 412 is generated which impinges on a circumferential surface 11 of the eccentric element 10.
  • the reference beam 413 is transmitted to and reflected by a reflecting reference surface 43, for example a mirror.
  • the total beam 414 which optionally contains interfering waves, strikes a detector 44, for example a photodiode, in particular an avalanche photodiode (APD).
  • APD avalanche photodiode
  • FIG. 3 shows a steering shaft 100 with an arrangement 200 according to a particularly preferred embodiment of the invention in a sectional view.
  • FIG. 3 essentially corresponds in its elements to FIG. 2, with identical elements not being explained again for the sake of clarity.
  • FIG. 3 shows how a steering-wheel-side steering shaft section 1 is connected to a steering-shaft-side steering shaft section 2 via an inner torsion bar 3.
  • a two-part sensor housing consisting of a disk housing 102 and an optical housing 47 is shown. A space within the optical housing 47 is delimited from a space within the disk housing by a translucent and dust-proof separation 48.
  • the disk housing 102 has sealing rings 101 for sealing and protecting the inner eccentric elements 10, 20.
  • the optical housing 47 also has evaluation electronics (not shown), by means of which an evaluation of the sensor signals can be carried out.
  • FIG. 3 also shows how a coherent light beam 41 1, which is widened by a lens 41 'and is emitted by a light source 41, is split into individual beams by a diaphragm 45 and a further diaphragm 46. Further details of the interferometer 4 are shown in FIGS. 1 and 2.
  • both eccentric elements 10, 20 have exactly the same position relative to one another.
  • the relative position of the two eccentric elements 10, 20 changes from one another at times, ie the distance of the lateral surfaces of the eccentric elements Center elements 10, 20 to the interferometer 4 varies depending on the torque.
  • runtime differences of the measuring beams 412 of the waves reflected by the lateral surfaces are effected, which, as explained above, leads to a passage through intensity maxima and intensity minima in the total beams 414.
  • These maxima and / or minima represent a measure of the change in the path length difference, which can be determined by counting.
  • Each maximum or minimum corresponds to a path length change by one wavelength, ie a change in position of the respective eccentric element 10, 20 by half a wavelength.
  • the absolute path lengths or their absolute difference can not be measured, nor the direction of the movement.
  • the speed of the measurable change is limited by the achievable count rate.
  • the time difference between the count rates of both detectors is decisive.
  • FIGS. 4A to 4C each show a steering shaft section 1, 2 with an eccentric element 10, 20 fastened thereto in different positions in plan view.
  • the figures relate to a steering wheel side steering shaft section 1 and the steering gear side steering shaft section 2 in an analogous manner.
  • the interferometer 4 is shown in simplified form; in particular, no lens 41 'is indicated in the illustration of FIGS. 4A to 4C. Likewise, only one beam path is shown in each case.
  • the interferometer 4 has been explained in detail above, in contrast to the representation of Figure 1, the interferometer has a first aperture 45 and a second aperture 46, the semi-transparent mirror 421 is shown schematically and arranged in a beam splitter element 42.
  • FIGS. 4A to 4C are to be understood as purely exemplary and in no way limit the scope of the present invention.
  • the dimensions are merely illustrative of the inventive principles.
  • the interferometer 4 is located at a fixed distance X from an axis A ', A "of the steering shaft section 1, 2.
  • An eccentric element in the form of a rotary cylinder, which is at least partially reflective on the lateral surfaces 11, 21. is formed, for example, has 30 mm in diameter.
  • the axis of the eccentric 10 ', 20' is, for example, by a distance E, for example, 2 mm, eccentrically offset on the steering shaft section 1, 2.
  • the axis 1 ', 2' of the steering shaft section 1, 2 and the axis 10 ', 20' of the eccentric 10, 20 are thus arranged in parallel at a distance of 2 mm.
  • the steering shaft section 1, 2 has in the example shown a diameter of 20 mm, the eccentric 10, 20 has a diameter of 30 mm. This results in a maximum distance of the axis T, 2 'of the steering shaft section 1, 2 to an outermost point of the eccentric element 10, 20 to 17 mm, a minimum distance corresponding to 13 mm. As can be seen directly from the figure, a half revolution (180 °) of the shaft of the steering shaft section 1, 2 results in a change of a distance of the lateral surface of the eccentric element 10, 20 to the interferometer of 4 mm. Wrd as a light source 41, a monochromatic laser light source, for.
  • a blue-violet laser diode made of InGaN is used (as known, for example, from blue-ray devices) at 24 nm wavelength
  • a path length difference of 4 mm results in about 9,524 maximum or minimum transitions (at the mentioned 180 ° rotation), which is 53 Transitions per degree of rotation or a Wnkelauf- solution of 0.019 ° corresponds.
  • FIG. 4 shows a possible surface structuring of an eccentric element 10, 20 or its lateral surface 11, 21 and a locally fixed reference surface 43 of an interferometer 4. Since the lateral surface 1 1, 21 of the eccentric 10, 20 also varies in angle to the interferometer 4 as a function of the angle of rotation, it may be advantageous to form the surfaces such that regardless of the tilt angle always the same intensity is fed back to radiation. This can be done by a nanostructuring of the surface.
  • this hemispherical (spherical) structures are used, which always reflect the same proportion of radiation regardless of tilting.
  • FIG. 5 shows a partial view 510 of a microstructured surface 431 of a stationary, reflective reference surface 43 of an interferometer 4. represents, on soft from a beam splitter 42, a partial beam 413 impinges.
  • View 501 shows a spherical structure 515, the irradiated partial beam 413 and the reflected components 413 '.
  • a surface 11 1 on the lateral surface 11 of an eccentric element 10 is shown in partial view 520, with a measuring beam 412 passing through an optional diaphragm 46 impinging.
  • a measuring beam 412 passing through an optional diaphragm 46 impinging.
  • a measuring beam 412 passing through an optional diaphragm 46 impinging.
  • a measuring beam 412 passing through an optional diaphragm 46 impinging.
  • the view 501 in the views 502 and 503
  • spherical elements with corresponding beams are shown.
  • the partial view 520 which illustrates a surface 11 1 on the lateral surface 11 of an eccentric element 10, relates in the same way to a surface 211 on the lateral surface 21 of an eccentric element 20.
  • the structures mentioned are to be made so small in comparison to the irradiated beam (in the form of a "nanostructure" in the submicron range) that always a sufficiently large amount of light is fed back into the interferometer 4.
  • the intensities of the interfering waves it is also advantageous to provide the locally fixed reflecting reference surface 43 with such a surface.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Length Measuring Devices By Optical Means (AREA)

Abstract

La présente invention concerne un arrangement pour déterminer un couple agissant sur un arbre de direction (100), lequel présente une première section d'arbre de direction (1) côté volant, une deuxième section d'arbre de direction (2) côté mécanisme de direction et une barre de torsion (3) qui relie les sections d'arbre de direction, en se basant sur une torsion provoquée par le couple de la première section d'arbre de direction (1) par rapport à la deuxième section d'arbre de direction (2), comprenant des moyens (200) pour déterminer la position angulaire de la première section d'arbre de direction (1) et/ou de la deuxième section d'arbre de direction (2). Selon l'invention, les moyens pour déterminer la position angulaire de la première section d'arbre de direction (1) et/ou de la deuxième section d'arbre de direction (2) présentent un arrangement de mesure par interférométrie (200).
PCT/EP2011/062340 2010-09-02 2011-07-19 Détermination d'un couple agissant sur un arbre de direction WO2012028378A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE201010040139 DE102010040139A1 (de) 2010-09-02 2010-09-02 Bestimmung eines auf eine Lenkwelle einwirkenden Drehmoments
DE102010040139.0 2010-09-02

Publications (1)

Publication Number Publication Date
WO2012028378A1 true WO2012028378A1 (fr) 2012-03-08

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Application Number Title Priority Date Filing Date
PCT/EP2011/062340 WO2012028378A1 (fr) 2010-09-02 2011-07-19 Détermination d'un couple agissant sur un arbre de direction

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WO (1) WO2012028378A1 (fr)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102013204924A1 (de) 2013-03-20 2014-09-25 Schaeffler Technologies Gmbh & Co. Kg Messung eines auf eine Lenkwelle einwirkenden Drehmoments

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2002018894A1 (fr) * 2000-08-31 2002-03-07 Robert Bosch Gmbh Procede pour determiner un angle de rotation et/ou une difference angulaire a partir de signaux de mise en phase
WO2002042713A2 (fr) * 2000-11-21 2002-05-30 Fast Technology Ag Mesure d'angle par transducteur magnetique
US6587211B1 (en) * 1999-07-28 2003-07-01 Creo Srl Interferometric torque and power sensor
DE102005011196A1 (de) 2005-03-09 2006-09-14 Robert Bosch Gmbh Sensoranordnung zur Erfassung eines Differenzwinkels
DE102005021300A1 (de) * 2005-05-09 2006-11-16 Vs Sensorik Gmbh Drehgeber

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6587211B1 (en) * 1999-07-28 2003-07-01 Creo Srl Interferometric torque and power sensor
WO2002018894A1 (fr) * 2000-08-31 2002-03-07 Robert Bosch Gmbh Procede pour determiner un angle de rotation et/ou une difference angulaire a partir de signaux de mise en phase
EP1315954B1 (fr) 2000-08-31 2009-01-07 Robert Bosch Gmbh Procede pour determiner une difference angulaire a partir de signaux de mise en phase
WO2002042713A2 (fr) * 2000-11-21 2002-05-30 Fast Technology Ag Mesure d'angle par transducteur magnetique
DE102005011196A1 (de) 2005-03-09 2006-09-14 Robert Bosch Gmbh Sensoranordnung zur Erfassung eines Differenzwinkels
DE102005021300A1 (de) * 2005-05-09 2006-11-16 Vs Sensorik Gmbh Drehgeber

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