EP0939884A1 - Element de detection - Google Patents

Element de detection

Info

Publication number
EP0939884A1
EP0939884A1 EP97912170A EP97912170A EP0939884A1 EP 0939884 A1 EP0939884 A1 EP 0939884A1 EP 97912170 A EP97912170 A EP 97912170A EP 97912170 A EP97912170 A EP 97912170A EP 0939884 A1 EP0939884 A1 EP 0939884A1
Authority
EP
European Patent Office
Prior art keywords
magnetic
sensor
component according
sensor component
casing
Prior art date
Legal status (The legal status 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 status listed.)
Withdrawn
Application number
EP97912170A
Other languages
German (de)
English (en)
Inventor
Volker Windte
Roland Fischer
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Mercedes Benz Group AG
Original Assignee
DaimlerChrysler AG
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
Priority claimed from DE19648335A external-priority patent/DE19648335C2/de
Priority claimed from DE1997126914 external-priority patent/DE19726914A1/de
Application filed by DaimlerChrysler AG filed Critical DaimlerChrysler AG
Publication of EP0939884A1 publication Critical patent/EP0939884A1/fr
Withdrawn legal-status Critical Current

Links

Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01D—MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR
    • G01D5/00—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable
    • G01D5/12—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means
    • G01D5/14—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means influencing the magnitude of a current or voltage

Definitions

  • the invention relates to a sensor component according to the preamble of the independent claims.
  • a known sensor component of this type (DE 38 44 578 C2) has two magnetic sensors which are axially coupled via a torsion shaft and which are equipped as circular rings with circumferential magnetic coding as a measure of the angle of rotation.
  • the torsion shaft is part of a steering gear for motor vehicles and rotatably mounted together with other gear and drive parts within a bearing housing.
  • the gear housing is provided with an opening through which a magnetic field-sensitive sensor of a sensor device flanged on the outside of the gear housing is brought close to the cylindrical lateral surfaces of the magnetic encoders.
  • the magnetic encoders are protected against external mechanical influences, but at least one opening to be provided at a predetermined point and a seal between the sensor device and the gear housing are required.
  • the object of the invention is to create a sensor component which enables a simplified construction in the area of the coupling path between the magnetic encoder and the sensor device.
  • the magnetic sensor is seated in an envelope which is at least closed with respect to the sensor device and which closely encloses the magnetic sensor in the adjustment direction and provides reliable protection against mechanical influences of the magnetic encoder are guaranteed.
  • the sheath is at least largely permeable to the magnetic field lines emanating from the magnetic encoder, ie di- or paramagnetic.
  • a nitrogen-alloy steel with a high nitrogen content and great hardness is preferably used for the coating.
  • the magnetic encoder can be made in the manner of a tube or rod from a permanent magnetic material and can be designed with a magnetic coding running in the longitudinal direction.
  • it can be arranged, for example, in a hollow piston rod of a hydraulic power steering actuator, in which the tubular piston rod, which is closed over its entire circumferential surface, is mounted in a longitudinally displaceable manner in an actuator housing with the magnetic transmitter arranged therein.
  • the sensor device can be fixed radially to the piston rod at the point of exit of the piston rod from the actuator housing or also on an adjacent stationary support. The sensor device then detects the information to be read from the coding of the magnetic encoder during the longitudinal displacement of the piston rod.
  • the magnetic transmitter is designed in the manner of a circular disk or a circular ring with magnetic coding running in the circumferential direction, then it can also be arranged within a hollow steering spindle, the sensor device being able to be fixed in place on a support which supports the steering spindle or on another adjacent support.
  • the steering spindle is preferably formed from a magnetically transparent material, particularly preferably from an austenitic steel of great hardness and with a high nitrogen content of more than 0.3 percent by weight of nitrogen.
  • the magnetic encoder can also be fixed concentrically on the outer surface of the steering spindle and protected with its own casing attached to the steering spindle.
  • the magnetic encoder fixed within the envelope is movably mounted together with the envelope or a component carrying the magnetic encoder and the envelope, and the sensor device, on the other hand, is stationary. It is shown that the radial distance between the magnetic encoder designed as a scale and the associated sensor device can vary within wide limits, which depend on the pole pitch, for example between 0 and 15 mm, without significantly weakening the signals occurring at the sensor device . It is thus an assembly of the sensor device with little Adjustment effort achieved and with a small additional volume a free integration into the mechanical component in question is possible.
  • the sensor device can have a plurality of magnetic field-sensitive individual sensors, each of which is assigned to a magnetic sensor. For safety reasons, several magnetic encoders can also be operated in parallel. In addition, it is expedient to form the individual magnetic encoder from a plurality of partial magnetic encoders arranged parallel to one another, each of which is assigned at least one individual sensor and which carry different magnetic codes, so that not only the relative one is read from the pulse signals read from the mechanical adjustment movement by each partial magnetic encoder , but also the absolute angle of rotation or longitudinal displacement can be derived. Otherwise, the sensor device can have magnetoresistive sensors, Hall sensors and inductive sensors for detecting the magnetic fields that change in the magnetic polarity via the adjustment path of the magnetic encoder.
  • an austenitic steel with high hardness which has a very high nitrogen content
  • the steel has no magnetic components even during mechanical processing and can therefore be processed, in particular deformed, ground and / or polished, without further after-treatment.
  • This is particularly advantageous in the case of highly stressed structural elements whose translational and angular movement is to be measured, in particular in the case of hydraulic actuators, dampers, tension or compression rods which are guided in bushings and various types of linear drives.
  • FIG. 1 shows a linear travel sensor component on a hydraulic actuator
  • FIG. 2 shows a rotation angle sensor component in association with a rotatable shaft
  • FIG. 3 shows the basic structure of a bridge circuit made of magnetoresistive sensors
  • FIG. 4 the position of the sensors relative to the magnetic field to be measured
  • FIG. 5 shows the signal voltage on a length sensor as a function of the measuring path
  • Figure 6 shows the principle of absolute length measurement with two periodic magnetic tracks of different phases.
  • a rectilinearly adjustable hydraulic actuator 1 such as is used for steering aids in motor vehicles, is equipped with a piston 2 which is mounted in an axially adjustable manner in a cylinder space 3 in a linearly adjustable manner.
  • the cylinder space 3 is axially closed at both ends and is provided with openings in the end walls 4, through which a piston rod 6, which is rigidly connected to the piston 2 and points in the direction of its adjustment, is passed with the interposition of a sliding seal 5.
  • control pressure lines 9 open into the cylinder chamber 3, via which the longitudinal adjustment of the piston 2 and thus the piston rod 6 is hydraulically controlled.
  • the piston rod 6 is hollow at least over part of the length and is equipped with a magnetic sensor 10 in an area that is at least outside an end wall 4 over the displacement path of the piston 2.
  • the magnetic encoder 10 is arranged protected within the piston rod 6 by its unbroken jacket.
  • Magnetic encoder 10 is magnetically encoded over its active length, i. H. a number of magnetically oppositely polarized magnetic zones are strung together.
  • a sensor device 11 is fixed on the adjacent end wall 4, which is magnetically coupled to the magnetic transmitter 10 and, when the piston rod is adjusted longitudinally, detects the magnetic pole changes occurring in its detection range according to number and / or phase and an evaluation unit sends a corresponding signal sequence.
  • the piston rod 6 consists of non-magnetic, austenitic steel, so that the magnetic coupling to the sensor device 11 is transmitted at least largely unaffected by this covering. An austenitic, highly embroidered steel is preferably used.
  • the highly embroidered steel is a nitrogen alloy steel with a nitrogen content of more than 0.2 percent by weight, preferably more than 0.4 percent by weight of nitrogen, particularly preferably the nitrogen content is between 0.4 to 1 percent by weight.
  • the stick- Alloy steel has a high yield strength of more than 900 MPa, in particular up to 2500 MPa.
  • the nitrogen-alloy steel preferably also has chromium and manganese. Particular advantages of the nitrogen-alloyed steel are that it is corrosion-resistant, hard and at the same time non-magnetic and can in particular be machined without forming magnetic martensite components, as is the case with conventional austenitic steels.
  • the high-embroidered steel described has a very high nitrogen content and is only available with a so-called. Electro slag pressure remelting process can be produced, which makes it possible to produce highly embroidered steel parts in larger dimensions, in particular in dimensions of a few meters in length and a few decimeters in diameter.
  • Examples of such highly embroidered steels are e.g. CrMnl818 with a nitrogen content of at least 0.4 weight percent, in particular between 0.4 and 1.4 weight percent, steel grade 1.3816 with 0.65 weight percent nitrogen and steel grade 1.4456 with 0.95 weight percent nitrogen. Since the steel has a magnetic permeability of ⁇ ⁇ 1.5, it can be considered to be magnetically transparent.
  • the steel has a high toughness and a large yield point and is corrosion-resistant.
  • Common austenitic steels are up to a nitrogen content of max. about 0.3 percent by weight can be represented.
  • Conventional austenitic steels are preferably only used to reinforce magnetic sensors, but cannot be used as a sheathing material around magnetic encoders because of the martensite components that form during processing and / or hardening. It is therefore particularly advantageous to use a highly embroidered austenitic steel with a nitrogen content of at least 0.4 percent by weight as the piston rod 6, since it is hard enough for this use, does not form any deformation martensite during processing, and accordingly does not have any thermal aftertreatment for converting the martensite into austenite is necessary.
  • the surface the piston rod is immediately grindable and polishable, so that chrome plating of the surface of the piston rod 6 is not necessary for tempering and hardening the surface.
  • the use of the highly embroidered, austenitic steel as a covering material, in particular for magnetic scales and / or as a protective cover for magnetic encoders, is particularly advantageous because of the advantageous processing properties and its hardness and corrosion resistance.
  • the design of shock absorbers, piston rods, hydraulic rods and similar highly stressed construction elements, especially in connection with magnetic scales for position determination, is particularly compact and insensitive to environmental conditions. Magnet encoders and actuators can be combined and thus enable a particularly space-saving arrangement of such construction elements.
  • the magnetic transmitter 10 can in this case consist of a rod or tube of zone-wise magnetizable material and can be fixed directly within the hollow piston rod 6.
  • the sensor element consisting of magnetic encoder 10 and sensor device 11 is thus integrated into the structure of the hydraulic actuator.
  • the magnetic sensor 10 can consist of several partial magnetic sensors running parallel to each other. At least one individual sensor is assigned to each partial magnetic encoder, so that a failure of a sensor can be determined for reasons of safety. A single magnetic sensor or a partial magnetic sensor can be assigned several individual sensors in order to further increase security. Corresponding sensor components can also be provided on both end faces 4 of the hydraulic actuator 1.
  • annular magnetic sensors 10 which are arranged concentrically on a rotatably mounted shaft, which is designed in particular as a steering spindle of a motor vehicle.
  • the magnetic encoders 10 each carry a magnetic coding running over their circumferential surface, which can be read out by means of sensor devices 11, which are arranged in a stationary manner and are located radially to the magnetic encoders 10.
  • the shaft 11 is not formed Magnetic steel or another suitable dia- or paramagnetic material, particularly preferably made of austenitic, highly embroidered steel, the magnetic transmitter 10 can be arranged protected in a correspondingly adapted cavity within the shaft 11.
  • an outer non-magnetic tube in particular a tube made of nitrogen-alloy steel with a nitrogen content of at least 0.4 percent by weight nitrogen and a yield strength of more than 900 MPa, concentrically stationary to arrange and fix the sensor device 11 directly thereon.
  • each magnetic sensor 10 from a plurality of partial magnetic sensors arranged parallel to one another and to assign at least one individual sensor to each partial magnetic sensor.
  • the magnetic encoder and the monitored component form a unit and the scales and dimensions cannot be visually and mechanically recognized.
  • magnetic markings have to be attached to the outside of the casing 12 or the piston rod 6, which impair the mechanical strength of the surface and, as a possible breaking point and / or corrosion point, impair the service life of the highly stressed structural element.
  • a favorable design of the magnetic encoder is to provide a ferromagnetic layer on the inside of the casing (6, 12), the thermal expansion of which does not differ from that of the casing (6, 12).
  • the ferromagnetic layer can be coded or structured accordingly and replaces the massive magnetic scale. This enables advantageous weight savings.
  • Another favorable design of the magnetic transmitter is to provide the magnetic areas of the magnetic transmitter (10) on a rod made of solid material or drilled through, which is firmly connected to the casing (6, 12) at least at one point and one of the expansion coefficient of the casing (6, 12) has adapted expansion coefficients. Especially with thermal loads and strong temperature fluctuations the measurement is then not influenced by different thermal expansions of the magnetic encoder and sensor arrangement.
  • Magnetoresistive sensor chips as known for example from DE 42 37 540 C2, have been developed in analogy to corresponding optical sensor chips.
  • Such a chip contains two complete Wheatstone bridges made of magnetoresistive sensor strips with a barber pole structure.
  • the arrangement of the sensor strips in relation to a magnetic encoder 10 is shown in FIG. 3.
  • the resistances of the bridge are arranged on the chip in such a way that all barber pole structures have the same direction and experience the same change in resistance in an external magnetic field. They therefore do not provide a signal when the bridge is in the zero state.
  • a control of the bridges is possible by means of a magnetically coded magnetic transmitter 10. Between the strips of the first bridge and the strips of the second bridge there is a shift by a quarter of the period length to the scale.
  • FIG. 4 The relative arrangement of the sensor element to the magnetic fields of scale 10 to be detected is shown in FIG. 4. It follows that the signals from the two bridges are 90 ° out of phase with one another, ie there are sine and cosine for evaluation and interpolation Signal available. A corresponding measurement result is shown in FIG. 5. It shows the measured sine and cosine output voltage (in 0.1 V steps), the measurement path s determined therefrom (in pole lengths) and the deviations ⁇ from the actual measurement path (in 0.1 pole lengths) at a sensor distance of 2 mm from the surface of the scale.
  • the magnetoresistive sensors are manufactured using the microstructure technology known from semiconductor technology. This guarantees the required exact relative position of the individual sensors on a chip.
  • the sensor chips and magnetic encoders are preferably dimensioned such that a signal amplitude that is independent of the distance is achieved over a wide distance range. This is possible, although the distance from the magnetic encoder results in a rapidly decreasing magnetic field strength. They can be used up to temperatures of 150 ° C.
  • the optimal distance between the sensor element and the magnetic encoder should be slightly smaller than the scale period of the magnetic encoder. This enables distances of up to 0.01 mm to be detected.
  • Magnetoresistive sensors have the following advantages. At high field strengths there is no significant dependence of the signal on the magnetic field strength. There is no signal offset due to a bridge circuit, and temperature effects are largely compensated for. Installation takes place with little adjustment effort, the sensors can be easily integrated into the mechanical components due to the small volume. They allow a sufficient measuring speed.
  • absolute path measurements can also be carried out.
  • a known absolute path measuring system is based on the evaluation of magnetic marks, which are attached to two scales as magnetic encoders, each with a different period length. It applies that both scales must have a number of periods differing by one for the same total length. The number of the current period can be determined from such a double scale.
  • Fig. 6 serves to explain the evaluation method.
  • the calculated path is a sawtooth-shaped curve.
  • the measurement error ⁇ is a maximum of only fractions of a percent.
  • the interpolation value for the phase of the last period of the track lying at the corresponding position is added in order to increase the accuracy.
  • Hall effect sensors are similarly well suited in terms of sensitivity to magnetoresistive sensors.
  • Hall sensors are advantageous because they are inexpensive using the microstructure technology known from semiconductor technology. Logic are producible, require a small additional volume, can be integrated into the mechanical components in question and allow a sufficient measuring speed.
  • the Hall sensor signal is, however, dependent on the field strength and thus strongly on the distance. This requires very small tolerances during assembly. Inductive sensors cannot be easily produced using the methods known from semiconductor technology, since their dimensions are relatively large.
  • the use of the highly embroidered austenitic steel is particularly advantageous since it is non-magnetic and does not interfere with the measurement.
  • a cladding tube has a typical wall thickness of 0.25 to 0.33 of the entire diameter due to the dependence of the area moment of inertia on the radius R with R 4 . This leads to a high weight of such an arrangement.
  • the wall thickness of a casing of a magnetic encoder can be reduced by about 5%, in particular 10%, without impairing the stability of the casing.
  • the signal strength increases disproportionately when the distance between the sensor and the magnetic encoder is smaller.
  • it is possible to optimize the distance is set when the scale period corresponds to the distance between the sensor and the magnetic encoder.
  • the minimum possible distance is the wall thickness of the casing.

Landscapes

  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Measurement Of Length, Angles, Or The Like Using Electric Or Magnetic Means (AREA)
  • Transmission And Conversion Of Sensor Element Output (AREA)

Abstract

L'invention concerne un élément de détection comportant un transmetteur magnétique (10) et un dispositif de détection (11) associé, montés de manière à se déplacer l'un par rapport à l'autre. Afin d'obtenir une protection fiable du transmetteur magnétique (10) à l'encontre d'influences mécaniques, avec une structure simple, le transmetteur magnétique (19) est disposé à l'intérieur d'une enveloppe (6) rigide diamagnétique ou paramagnétique, fermée par rapport au dispositif de détection (11).
EP97912170A 1996-11-22 1997-10-10 Element de detection Withdrawn EP0939884A1 (fr)

Applications Claiming Priority (5)

Application Number Priority Date Filing Date Title
DE19648335 1996-11-22
DE19648335A DE19648335C2 (de) 1996-11-22 1996-11-22 Anordnung zur Positionsmessung
DE19726914 1997-06-25
DE1997126914 DE19726914A1 (de) 1997-06-25 1997-06-25 Sensorbauelement
PCT/EP1997/005612 WO1998023922A1 (fr) 1996-11-22 1997-10-10 Element de detection

Publications (1)

Publication Number Publication Date
EP0939884A1 true EP0939884A1 (fr) 1999-09-08

Family

ID=26031522

Family Applications (1)

Application Number Title Priority Date Filing Date
EP97912170A Withdrawn EP0939884A1 (fr) 1996-11-22 1997-10-10 Element de detection

Country Status (3)

Country Link
EP (1) EP0939884A1 (fr)
JP (1) JP2000514192A (fr)
WO (1) WO1998023922A1 (fr)

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE10045874A1 (de) * 2000-09-14 2002-03-28 Continental Teves Ag & Co Ohg Kraftfahrzeugsensorvorrichtung
DE10392801D2 (de) * 2002-07-02 2005-07-07 Continental Teves Ag & Co Ohg Stossdämpfer und Anordnung zur Erfassung von Stossdämpferbewegungen
DE102005063565B3 (de) * 2004-07-14 2016-07-07 Tenneco Automotive Operating Company Inc. Verfahren zur Herstellung einer Kolbenstange, Stoßdämpfer und Verschiebungssensor

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR890000890A (ko) * 1987-06-22 1989-03-17 미타 가츠시게 토크검출장치
SE501291C2 (sv) * 1992-09-23 1995-01-09 Mecman Ab Rexroth Anordning för positionering av kolvcylinderaggregat

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO9823922A1 *

Also Published As

Publication number Publication date
JP2000514192A (ja) 2000-10-24
WO1998023922A1 (fr) 1998-06-04

Similar Documents

Publication Publication Date Title
DE19818799C2 (de) Verfahren und Vorrichtung zum Messen von Winkeln
DE60109715T2 (de) Apparat und Verfahren zur Drehmomentmessung
DE19648335C2 (de) Anordnung zur Positionsmessung
DE3882962T2 (de) Multidrehungs-Positionsgeber.
EP3563116B1 (fr) Capteur de distance
EP1357365B1 (fr) Détecteur de position
DE19608740C2 (de) Drehmomentsensor
EP1797399B1 (fr) Dispositif de mesure de la position absolue d'au moins deux corps deplaçables ou mobiles en rotation l'un par rapport a l'autre
DE4030229C2 (de) Berührungsloser Winkelgeber
DE69409807T2 (de) Magnetischer Detektor der Bewegung eines Gegenstands
EP1102971A1 (fr) Systeme detecteur permettant de detecter un angle de rotation et/ou un couple de rotation
DE102009047222A1 (de) Sensoranordnung zum Ermitteln eines Drehmoments und zur Indexerkennung
WO2001051893A1 (fr) Capteur de deplacement lineaire et utilisation en tant que dispositif d'actionnement de vehicules motorises
DE102008059775A1 (de) Absolut messende Lenkwinkelsensoranordnung
EP3037796A1 (fr) Corps de ressort pour un recepteur de force comme cellule de mesure de force de pression, de couple et/ou de force de traction
DE102008052416A1 (de) Vorrichtung umfassend ein Betätigungselement eines Zahnräderwechselgetriebes
DE202013004061U1 (de) Schaltelement eines Fahrzeuggangräderwechselgetriebes
EP0939884A1 (fr) Element de detection
DE102005055905A1 (de) Längenmessanordnung mit einem magnetischen Maßstab mit gegenläufiger Magnetisierung
WO2020211891A1 (fr) Actionneur manuel doté d'un système de capteurs pour la détection du couple
DE3940894C2 (fr)
DE102019124972A1 (de) Sensoranordnung zur Erfassung eines Lenkmomentes sowie einer absoluten Winkelposition und Sensorvorrichtung mit dieser Sensoranordnung
EP3998460B1 (fr) Dispositif détecteur et procédé de détermination d'une grandeur cinématique
DE19757116C2 (de) Anordnung mit magnetischem Maßstab
DE19854687A1 (de) Drehmoments- oder Kraftsensor für in Wälzlagern gelagerte Wellen

Legal Events

Date Code Title Description
PUAI Public reference made under article 153(3) epc to a published international application that has entered the european phase

Free format text: ORIGINAL CODE: 0009012

17P Request for examination filed

Effective date: 19990414

AK Designated contracting states

Kind code of ref document: A1

Designated state(s): DE FR GB IT SE

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: THE APPLICATION IS DEEMED TO BE WITHDRAWN

18D Application deemed to be withdrawn

Effective date: 20030818