Classifications

• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
  • G01L5/00—Apparatus for, or methods of, measuring force, work, mechanical power, or torque, specially adapted for specific purposes
  • G01L5/0009—Force sensors associated with a bearing
  • G01L5/0019—Force sensors associated with a bearing by using strain gages, piezoelectric, piezo-resistive or other ohmic-resistance based sensors
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
  • F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
  • F16C19/00—Bearings with rolling contact, for exclusively rotary movement
  • F16C19/52—Bearings with rolling contact, for exclusively rotary movement with devices affected by abnormal or undesired conditions
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
  • F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
  • F16C19/00—Bearings with rolling contact, for exclusively rotary movement
  • F16C19/52—Bearings with rolling contact, for exclusively rotary movement with devices affected by abnormal or undesired conditions
  • F16C19/522—Bearings with rolling contact, for exclusively rotary movement with devices affected by abnormal or undesired conditions related to load on the bearing, e.g. bearings with load sensors or means to protect the bearing against overload
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
  • F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
  • F16C19/00—Bearings with rolling contact, for exclusively rotary movement
  • F16C19/02—Bearings with rolling contact, for exclusively rotary movement with bearing balls essentially of the same size in one or more circular rows
  • F16C19/14—Bearings with rolling contact, for exclusively rotary movement with bearing balls essentially of the same size in one or more circular rows for both radial and axial load
  • F16C19/18—Bearings with rolling contact, for exclusively rotary movement with bearing balls essentially of the same size in one or more circular rows for both radial and axial load with two or more rows of balls
  • F16C19/181—Bearings with rolling contact, for exclusively rotary movement with bearing balls essentially of the same size in one or more circular rows for both radial and axial load with two or more rows of balls with angular contact
  • F16C19/183—Bearings with rolling contact, for exclusively rotary movement with bearing balls essentially of the same size in one or more circular rows for both radial and axial load with two or more rows of balls with angular contact with two rows at opposite angles
  • F16C19/184—Bearings with rolling contact, for exclusively rotary movement with bearing balls essentially of the same size in one or more circular rows for both radial and axial load with two or more rows of balls with angular contact with two rows at opposite angles in O-arrangement

Definitions

• Strain sensor bearing comprising two strain gauges
• the invention relates to a bearing comprising a fixed ring, a rotating ring and at least one row of rolling bodies arranged in a raceway which is formed between said rings so as to allow their relative rotation.
• the fixed ring being integral with the chassis of said vehicle and the wheel being associated with the rotating ring.
• the fixed ring which is the first connecting member between the wheel and the chassis, is in particular used as a support for determining the forces which are exerted at the interface between the wheel and the roadway when the vehicle is moving.
• the forces can be determined by measuring the deformations of the fixed ring which are induced by the passage of the rolling bodies.
• the amplitude of these deformations is representative of the forces to be determined.
• the deformation signal depends on the speed of rotation. In particular, the quality of the measurement at low speed is insufficient and the determination is only available after measurement of the deformations induced by the passage of at least two successive rolling bodies.
• the invention aims in particular to remedy this problem by proposing a bearing comprising a system for determining the amplitude of the deformations of the fixed ring, said system being arranged to carry out a spatial interpolation of the deformation signal so as to have, at all instant and independently of the speed of rotation, a measurement of the deformations and therefore allow the determination of the forces.
• the invention provides a bearing comprising a fixed ring, a rotating ring and at least one row of rolling bodies arranged in a raceway which is formed between said rings so as to allow their relative rotation, said rolling bodies being equally distributed in the raceway with an angular difference ⁇ , said bearing comprising at least one system for determining the amplitude A of pseudo-sinusoidal deformations of an area of the fixed ring which are induced during rotation, the system for determining including:
• FIG. 1 is a perspective view of a bearing showing the gauges of four systems for determining the amplitude of pseudo sinusoidal deformations, said gauges being respectively arranged on a zone of the fixed ring;
• FIG. 2 is a functional representation of a first embodiment of a determination system according to the invention.
• FIG. 3 is a functional representation of a second embodiment of a determination system according to the invention.
• FIG. 4 is a schematic representation, on the fixed ring of the bearing of Figure 1, the positioning of the gauges relative to the angular distance between the rolling bodies.
• the invention relates to a bearing comprising a fixed ring 1, a rotating ring and at least one row of rolling bodies 2 arranged in a raceway 3 which is formed between said rings so as to allow the relative rotation of said rings.
• the fixed ring 1 is intended to be associated with a fixed structure and the rotating ring is intended to be associated with a rotating member.
• the bearing is a wheel bearing for a motor vehicle, the fixed structure being the chassis of said vehicle and the rotating member being the wheel.
• a wheel bearing is described comprising two rows of balls 2 which are arranged coaxially in a raceway 3 respectively provided between the fixed outer ring 1 and the rotating inner ring.
• the fixed ring 1 is provided with means for fixing to the chassis which are formed by a flange 4 comprising four radial projections 5 in which an axial hole 6 is made to allow fixing by screwing.
• the balls 2 are equally distributed in the raceway 3 with an angular difference ⁇ which is also called the spatial period.
• the distance between the balls 2 is maintained by placing them in a cage.
• the invention aims to allow the determination of the amplitude of the deformations of at least one zone 7 of the fixed ring 1, so as to be able to deduce therefrom the forces which apply to the interface between the wheel and the road on which said wheel turns.
• the passage of the balls 2 in the raceway 3 induces compression and relaxation of the fixed ring 1.
• the fixed ring 1 is subjected to periodic deformation which can be approximated by a sinusoid .
• pseudo sinusoidal deformations we will speak of pseudo sinusoidal deformations to designate the deformations of the fixed ring 1 during rotation.
• the pseudo sinusoidal deformation is characterized by an amplitude which depends on the loads undergone by the bearing and therefore on the forces which apply to the interface, and a frequency which is proportional to the speed of rotation of the rotating ring as well as to the number balls 2.
• the bearing comprises at least one system for determining the amplitude A of the pseudo-sinusoidal deformations of a zone 7 of the fixed ring 1 which are induced during rotation, said system comprising two strain gauges 8.
• the gauges 8 are each capable of delivering a signal which is a function of the deformation which it undergoes. As shown in Figures 1 and 4, the gauges 8 are distributed over the area 7 along a line which extends in the general direction of rotation. In particular, the gauges 8 which are arranged on a zone 7 of substantially flat deformation and centered on said zone so as to be spaced from the raceway by an equal distance.
• the determination system further comprises a device 9 for measuring two signals Vj which are respectively a function of the temporal variations of the signal emitted by each gauge 8 during rotation, said device being able to form, by combination of the signals Vj, two signals respectively SIN and COS of the same angle and the same amplitude, said amplitude being a function of A.
• the gauges 8 are based on resistive elements, in particular piezoresistive or magnetostrictive, so as to each have an electrical resistance Ri which varies as a function of the deformations undergone by said gauge 8.
• the gauges 8 may comprise either a block of several resistors which are combined to obtain an average resistance value which is representative of the resistance value at the position of the block, ie a single resistance.
• the measuring device 9 comprises a current loop mounting between the two gauges 8 and a reference resistor R re f whose value is fixed as a function of the deformations undergone by the area 7.
• the circuit further comprises a stage of differential amplifiers 11 which are arranged so as to obtain signals Vj.
• ⁇ Rj can be obtained in the case where the gauges 8 are equidistant from the raceway.
• at least one differential amplifier 11 has an adjustable gain so as to equalize the two amplitudes mentioned above.
• a measuring device 9 which makes it possible to obtain SIN and COS signals whatever the value of the spatial phase shift ⁇ between the gauges 8.
• the measuring device comprises two stages of differential amplifiers 11, the first stage being analogous to that of the first embodiment of FIG. 2, and the second stage comprises two differential amplifiers 11 so as to deliver the signals ⁇ - V 2 and Vi + V 2 .
• Vi + V 2 [2GAR cos ( ⁇ ) x sin ( ⁇ t + /.
• the amplitude of the signals (V ⁇ - V 2 ) and (V ⁇ + V 2 ) is different.
• at least one differential amplifier of the second stage has an adjustable gain.
• - V 2 ) can be adjusted to cos (-) / sin (-). ..
• the arrangement of the bearing shown in which the gauges 8 are arranged on a substrate 12 which is fixed to the deformation zone 7 of the fixed ring 1 is described.
• the substrate 12 is rigidly fixed to the ring fixed 1, for example by gluing or welding, so that it also has the function of transmitting the deformations between the fixed ring 1 and the gauges 8.
• gauges 8 described above are based on resistive elements
• other gauges 8 for example sensors chosen from surface acoustic wave sensors and magnetic field sensors, can be used in the context of the invention provided that they deliver a signal depending on a deformation.
• the magnetic field sensors can be based on sensitive elements of the magnetoresistance, giant magnetoresistance, Hall effect, magnetoresistance with tunnel effect, magnetostrictive layers.
• the gauges 8 are screen printed in a thick layer on the substrate 12, for example ceramic.
• a hybrid circuit type technology makes it possible to integrate the measuring device 9 and the calculating device 10 on the substrate 12.
• the screen printing allows a good adjustment of the value of the resistances as well as a good sensitivity to deformations, while ensuring precise positioning of the resistors on the substrate 12.
• the reference resistance R re f can be screen printed on an unsolicited area of the substrate 12 or be insensitive to stress, for example formed of a discrete component, so as to present a fixed value as a function deformations undergone by the zone 7 while exhibiting the same temperature drift as the resistors Rj.
• the deformation zone 7 is machined so as to be substantially flat and to extend above the two rows of balls 2.
• the gauges 8 are not equidistant from the raceway 3, so that the amplitude of the deformation measured is a function of the gauge 8 considered.
• the gains of the differential amplifiers 11 can be adjusted to equalize the amplitude of the output signals.
• the gauges 8 of two determination systems are integrated on the same substrate 12 so, in the vicinity of each raceway 3, that at least one determination system is provided for determining the amplitude of the deformations of zone 7.
• the gauges 8 are arranged on the outer periphery of the fixed ring 1, substantially facing each of the raceways 3 so as to increase the intensity of the signals to be measured.
• the substrate 12 carrying the gauges 8 makes it possible to determine the amplitude of the deformations induced respectively by essentially a row of balls 2, and this in the same axial plane.
• the positioning of the gauges 8 is not critical according to the invention, which makes it possible to greatly simplify the step of fixing the determination system on the fixed ring 1.
• the bearing can comprise at least three (eight in the embodiment shown in FIG. 1: four visible and four arranged symmetrically at the rear of the bearing) systems for determining the amplitude of the deformations of a zone 7 of the ring respectively fixed 1, said systems being connected or intended to be connected to a computer capable of calculating, as a function of the determined amplitudes, the forces applied during rotation on the fixed ring 1 and / or on an element integral with the rotating ring.
• a computer is described in document FR-2 839 553 from the applicant.

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• Engineering & Computer Science (AREA)
• General Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Chemical & Material Sciences (AREA)
• Analytical Chemistry (AREA)
• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Rolling Contact Bearings (AREA)

Priority Applications (1)

Applications Claiming Priority (2)

Publications (1)

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Family Applications (1)

Country Status (3)

Cited By (5)

Families Citing this family (2)

Citations (6)

• 2004
  • 2004-05-04 FR FR0404769A patent/FR2869982B1/fr not_active Expired - Fee Related
• 2005
  • 2005-05-03 WO PCT/FR2005/001106 patent/WO2005121731A1/fr not_active Application Discontinuation
  • 2005-05-03 EP EP05769762A patent/EP1743152A1/de not_active Withdrawn

Patent Citations (6)

Non-Patent Citations (1)

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