Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
  • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
  • F15B15/00—Fluid-actuated devices for displacing a member from one position to another; Gearing associated therewith
  • F15B15/20—Other details, e.g. assembly with regulating devices
  • F15B15/28—Means for indicating the position, e.g. end of stroke
  • F15B15/2815—Position sensing, i.e. means for continuous measurement of position, e.g. LVDT
  • F15B15/2861—Position sensing, i.e. means for continuous measurement of position, e.g. LVDT using magnetic means

Definitions

• Telescopic device with electromagnetic position detection is Telescopic device with electromagnetic position detection.
• the present invention relates to a telescopic device such as a damper usable for example in a motor vehicle suspension.
• a damper generally comprises a cylinder slidably receiving a rod.
• Shocks incorporating a device for detecting positions of the rod relative to the cylinder have been made for this purpose.
• dampers having a rod which is arranged to have a magnetic characteristic whose value varies along the rod. The detection device is fixed relative to the cylinder and measures the value of this characteristic. It is then possible to deduce the position of the rod from the measured value.
• An object of the invention is to provide a telescopic device with position detection which is simple and reliable.
• a telescopic device comprising a cylinder slidably receiving a rod, and a device for detecting a position of the rod relative to the cylinder, the rod comprising a succession of magnetic zones and non-magnetic forming magnetic singularities arranged along the rod in patterns of which at least one has a particular configuration to form a reference pattern and the detection device is fixed relative to the cylinder and comprises a set of at least two magnetic detectors which are associated with permanent magnets and which are arranged adjacently in an axial direction of the rod so that the detector assembly has a field covering an area of the rod having an axial dimension greater than an axial dimension of the reference pattern for measuring magnetic field modulations produced by these magnets during a displacement of the rod.
• FIG. 1 is a diagrammatic view in longitudinal section of a telescopic device according to a first embodiment
• FIG. 2 is a partial diagrammatic view in elevation and with cutaway of a rod of the telescopic device according to the first embodiment
• - Figure 3 is a view similar to that of Figure 2 of the rod of the telescopic device according to a first variant of the first embodiment
• - Figures 4 and 5 are partial schematic longitudinal sectional views of the rod of the telescopic device, according to a second and a third variant of the first embodiment.
• the invention is here described in application to a telescopic device forming a motor vehicle suspension damper.
• the damper generally designated 1
• the damper comprises in known manner a cylinder 2 slidably receiving a rod 3 shown schematically.
• the rod 3 comprises magnetic zones and non-magnetic zones forming magnetic singularities arranged along the rod in patterns of which at least one has a particular configuration to constitute a reference pattern.
• the magnetic zones are non-magnetized.
• the rod 3 thus comprises a core 4 of non-magnetic material which is externally provided with grooves 5, 6 delimiting between them flanges 7, 8.
• the grooves 5 have an identical width.
• the groove 6 has a width different from that of the grooves 5.
• the grooves 5, 6 respectively receive magnetic layers 9, 10 of corresponding width.
• the magnetic layers 9, 10 have an outer surface that is flush with the outer surface of the flanges 7, 8 such that the shaft 3 has a smooth outer surface. This ensures good contact of the outer surface with the not shown sealing elements which conventionally equip the cylinder 2.
• the flanges 7 have the same width.
• the flange 8 has a width different from that of the flanges 7.
• the magnetic layers 9, 10 and the flanges 7, 8 constitute magnetic singularities.
• the layer 10 and the flange 8 each form a single pattern, representative of a particular point on the axis of the rod 3. These patterns are referred to as reference patterns.
• the layers 9 and the flanges 7 form patterns that are described as relative because they can locate a point on the axis of the rod 3 starting from a reference pattern as will be explained later.
• the damper 1 also comprises a detection device for detecting a position of the rod 3 relative to the cylinder 2.
• the detection device comprises a bar 11 of magnetic detectors 12 adjacent.
• the detectors 12 are HALL effect detectors here and are associated with permanent magnets for detecting in a manner known per se a characteristic representative of a magnetic field produced by the magnets.
• the bar 11 is fixed on the cylinder 2 and extends parallel to the rod 3 facing the outer surface thereof. By this arrangement and the juxtaposition of the fields of the magnetic detectors 12 (also called field or sensitivity cones), the bar 11 has a global field covering an area of the outer surface of the rod 3 which has an axial dimension greater than an axial dimension reference motifs.
• the magnetic detectors 12 are connected to a processing unit 13 in which are memorized the positions of the reference patterns on the rod 3. The operation of the detection device will now be described.
• the magnetic flux produced by the magnets will undergo a variation depending on whether they are facing a flange or a groove. This variation will be detected by the associated detectors.
• the detectors 12 opposite a flange will emit a signal representative of the presence of the flange while the detectors 12 opposite a groove will emit a signal representative of the presence of the groove. If the flange in question is a collar 8 or the groove in question is a groove 6, the zone of the rod 3 opposite these detectors 12 is identified so that the processing unit 13 can deduce the position of the rod 3.
• the processing unit counts the relative patterns so that the processing unit can at any time determine the distance separating the zone of the rod 3 facing the magnetic detectors 12 and the identified reference pattern. From this information, the processing unit can determine the position of the rod 3 with respect to the cylinder 2.
• the displacement of the rod comprising the magnetic and non-magnetic zones in front of the stationary magnets produces a variation in the flux of these rods. which is detected by the associated detectors.
• the rod 3 comprises a core 14 of magnetic material which is provided externally with grooves 15, 16 delimiting between them flanges 17, 18.
• the grooves 15 have an identical width.
• the groove 16 has a width different from that of the grooves 15.
• the grooves 15, 16 respectively receive nonmagnetic layers 19, 20 of corresponding width.
• the magnetic layers 19, 20 have an outer surface that is flush with the outer surface of the flanges 17, 18 such that the shaft 3 has a smooth outer surface.
• the operation of the device according to this variant is identical to that previously described.
• the core 14 is covered with a filling layer 21 which is made of non-magnetic material.
• the filling layer fills the grooves 15, 16 and covers the flanges 17, 18 with a smooth outer surface 22.
• the filling layer 21 may for example be deposited by thermal spraying or electrolysis.
• the rod 3 comprises a core 24 of magnetic material which is externally provided with grooves 25, 26 delimiting between them flanges 27, 28.
• the grooves 25, 26 and the flanges 27, 28 have as before different widths to form reference patterns and relative patterns.
• the core 24 is received in a tube 29 of non-magnetic material having a smooth outer surface.
• the tube 29 can simply provide the rod 3 a smooth outer surface simplifying sealing with the cylinder 2 or also provide a role of mechanical reinforcement.
• the invention is not limited to the embodiment described and variants may be provided without departing from the scope of the invention as defined by the claims.
• the invention has been described in relation to a motor vehicle suspension damper, the invention is not limited to this invention. application and can be used also in any telescopic device such as cylinders, elastic coupling elements ...
• the detectors 12 may also be magnetoresistive detectors. Although the assembly formed by the detectors 12 has been described in the form of a bar, the detectors 12 may be independent of each other and for example simply aligned on a common direction.
• the rod 3 may also comprise alternatively a non-magnetic or magnetic core having an outer surface covered with magnetic and non-magnetic parts forming the patterns.
• the magnetic and amagnetic parts are, for example, rings of small thickness which have different widths to form reference patterns or relative patterns.
• the core may be received in a tube which provides a protection function of the magnetic singularities and / or a function of mechanical reinforcement of the rod, or which provides a smooth external surface to the rod.
• the reference patterns can be obtained by varying the width of the grooves and / or the spacing of the grooves.
• to obtain a smooth outer surface of the rod it is possible to cover the rod with a protective layer for example based on hard chrome.
• the magnetic singularities can be achieved by combining the embodiments described.

Landscapes

• Engineering & Computer Science (AREA)
• Physics & Mathematics (AREA)
• Fluid Mechanics (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Measurement Of Length, Angles, Or The Like Using Electric Or Magnetic Means (AREA)
• Vehicle Body Suspensions (AREA)
• Actuator (AREA)
• Geophysics And Detection Of Objects (AREA)
• Switches With Compound Operations (AREA)
• Switches That Are Operated By Magnetic Or Electric Fields (AREA)

Priority Applications (1)

Applications Claiming Priority (2)

Publications (2)

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Family Applications (1)

Country Status (7)

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Family Cites Families (5)

• 2004
  • 2004-03-03 FR FR0402175A patent/FR2867237B1/fr not_active Expired - Fee Related
• 2005
  • 2005-03-03 PL PL05732822T patent/PL1721087T3/pl unknown
  • 2005-03-03 EP EP05732822A patent/EP1721087B1/de not_active Expired - Lifetime
  • 2005-03-03 ES ES05732822T patent/ES2300008T3/es not_active Expired - Lifetime
  • 2005-03-03 AT AT05732822T patent/ATE384211T1/de not_active IP Right Cessation
  • 2005-03-03 WO PCT/FR2005/000500 patent/WO2005088154A1/fr not_active Ceased
  • 2005-03-03 DE DE602005004385T patent/DE602005004385T2/de not_active Expired - Lifetime

Non-Patent Citations (1)

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