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
  • G01L5/22—Apparatus for, or methods of, measuring force, work, mechanical power, or torque, specially adapted for specific purposes for measuring the force applied to control members, e.g. control members of vehicles, triggers
  • G01L5/221—Apparatus for, or methods of, measuring force, work, mechanical power, or torque, specially adapted for specific purposes for measuring the force applied to control members, e.g. control members of vehicles, triggers to steering wheels, e.g. for power assisted steering
• • 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
  • G01L3/101—Rotary-transmission dynamometers wherein the torque-transmitting element comprises a torsionally-flexible shaft involving electric or magnetic means for indicating involving magnetic or electromagnetic means
  • G01L3/105—Rotary-transmission dynamometers wherein the torque-transmitting element comprises a torsionally-flexible shaft involving electric or magnetic means for indicating involving magnetic or electromagnetic means involving inductive means

Definitions

• the present invention relates to an inductive torque sensor comprising at least one exciter coil, at least one oscillator circuit coupled to the exciter coil and coupled during operation a periodic AC signal into the exciter coil, a stator PCB having a first receiver means and a second receiver means, each a plurality of periodically repeating receiver structures, at least two rotors rotatable relative to each other and relative to the stator circuit board and affecting the amount of inductive coupling between the exciter coil and the receiver means, and evaluation means adapted to evaluate the signals induced in the receiver means.
• the previously used hydraulic power steering systems are successively replaced by electrically driven power steering systems.
• suitable torque sensors are necessary, which can detect the steering torque.
• the steering torque is usually determined by the rotation (torsion) of a certain portion of the steering column, in which a torsion element is arranged.
• the torsion of two steering column sections is measured relative to each other, without the absolute angular position of the steering column relative to the vehicle must be determined.
• inductive torque sensors which are suitable for determining the steering torque, measure the rotation within the steering column in general by means of sensor means, which are designed in two parts. Both parts rotate under the influence of a torsional moment relative to each other and rotate in total during the steering movement.
• a movable contacting is required, which comprises a so-called clock spring.
• clock spring For design reasons, it is desirable to be able to dispense with such a clock spring.
• a torque sensor of the type mentioned is known for example from German Patent Application DE 199 41 464 A1.
• two receiver coil sets with different angular periodicities which are in a non-integer relationship to one another, are arranged approximately in one plane.
• a first rotor of the inductive torque sensor is disposed at one end of a torsion element and a second rotor is disposed at the opposite end of the torsion element.
• the torque can be determined by subtracting the measured angles.
• the application of the differential angle method in the sensor arrangement described in the above-mentioned document may be prone to error and thus adversely affect the measurement result, since the (approximately) arranged in a plane receiver means influence each other. The measurement results are therefore often associated with a large measurement error.
• the present invention has for its object to provide an inductive torque sensor of the type mentioned, in which the achievable measurement accuracy can be increased in the subtraction of the measured angular sizes and the cost of determining the torque can be reduced.
• the subclaims relate to advantageous developments of the invention.
• An inventive inductive torque sensor is characterized according to claim 1 in that the number N of the receiver structures of the first receiver means and the number M of the receiver structures of the second receiver means are in an integer ratio to each other.
• the receiver structures of the first and / or the second receiver means are formed as receiver coils, each comprising a periodically repeating loop structure.
• the number N of the receiver structures of the first receiver means to the number M of the receiver structures of the second receiver means is in a ratio of 2: 1. It has surprisingly been found that with such a ratio, the achievable measurement accuracy is particularly high and the measurement errors are correspondingly small.
• the first rotor has a number N 'of rotor segments.
• the number N 'of the rotor segments of the first rotor corresponds to the number N of the receiver structures of the first receiver means.
• the second rotor has a number M 'of rotor segments.
• the number M 'of the rotor segments of the second rotor corresponds to the number M of the receiver structures of the second receiver means.
• the receiver structures of the first receiver means may, for example, have an angular periodicity of 15 ° or 20 °.
• the receiver structures of the second receiver means may have an angular periodicity of 30 ° or 40 °.
• the rotor segments of the first rotor have an angular periodicity of 15 ° or 20 °.
• the rotor segments of the second rotor have an angular periodicity of 30 ° or 40 °.
• Fig. 1 is a schematic representation of an inductive torque sensor according to a preferred embodiment of the present invention.
• An inductive torque sensor 1 which is constructed in accordance with a preferred embodiment of the present invention, comprises a stator circuit board 2 and a first rotor 3 and a second rotor 4, wherein the stator circuit board 2 between the two rotors 3, 4 is arranged.
• the two rotors 3, 4 are rotatable relative to one another and relative to the stator circuit board 2.
• the inductive torque sensor 1 has an exciter coil, not explicitly shown here, as well as an oscillator circuit likewise not explicitly shown, which generates a periodic alternating voltage signal during operation of the inductive torque sensor 1 and couples it into the exciter coil.
• the inductive torque sensor 1 is provided for determining the steering torque of a steering column 5 of a motor vehicle.
• the steering column 5 has a first steering column section 50 and a second steering column section 51, between which a torsion element 6 (torsion spring element) extends.
• the steering torque is determined by the rotation (torsion) of the region of the steering column 5 in which the torsion element 6 is arranged. there the torsion of the two steering column sections 50, 51 is measured relative to each other, without the absolute angular position of the steering column 5 relative to the vehicle must be determined.
• the first rotor 3 is disposed at a first end of the torsion element 6 and the second rotor 4 is disposed at a second end of the torsion element 6, which is opposite to the first end.
• the stator circuit board 2 has at its two rotors 3, 4 facing sides in each case a receiver means 20, 21.
• a first receiver means 20 associated with and facing the first rotor 3 has a number N of periodically repeating receiver structures.
• a second receiver means 21 associated with and facing the second rotor 4 has a number M of periodically repeating receiver structures, the ratio of the number of receiver structures N of the first receiver means 20 to the number M of receiver structures of the second receiver means 21 being integer.
• the number of receiver structures N of the first receiver means 20 may not be identical to the number M of receiver structures of the second receiver means 21.
• the ratio N: M 2: 1.
• the receiver structure of the first receiver means 20 has an angular periodicity of 15 °.
• the receiver structure of the second receiver means 20 has an angular periodicity of 30 °.
• the receiver structure of the first receiver means 20 may for example also have an angular periodicity of 20 °.
• the two receiver means 20, 21 are preferably designed as receiver coils which each have a periodically repeating loop structure which forms the receiver structure of the respective receiver means 20, 21.
• the two rotors 3, 4 serve as rotatable inductive coupling elements which, when rotated, influence the strength of the inductive coupling between the exciter coil and the receiver structures of the receiver means 20, 21 assigned to them.
• the first rotor 3 has a number N 'of rotor segments with the same angular periodicity as its associated receiver structure of the first receiver means 20.
• the second rotor 4 also has a number M 'of rotor segments with the same angular periodicity as the receiver structure of the second receiver means 21 assigned to it.
• the rotor segments of the first rotor 3 have in this embodiment, an angular periodicity of 15 ° and the rotor segments of the second rotor 4 have an angular periodicity of 30 °.
• the rotor segments of the first rotor 3 may, for example, also have an angular periodicity of 20 °, and the rotor segments of the second rotor 4 may have an angular periodicity of 40 °.
• the torsion of the two steering column sections 50, 51 of the steering column 5 can be determined by a subtraction of the measured angles (differential angle method).
• the angular positions of the two steering column sections 50, 51 in front of and behind the torsion element 6 are determined independently of each other.
• the inductive torque sensor 1 has an evaluation circuit, likewise not explicitly shown here, for evaluating the signals induced in the receiver structures of the receiver means 20, 21 during the relative rotation of the two steering column sections 50, 51.
• the steering torque which acts on the steering column 5 of the motor vehicle, can be detected reliably and with low measurement errors.
• the steering torque can be converted by the arranged in the steering column 5 torsion bar 6 in differential angle. Due to the different rotation of the two rotors 3, 4 with corresponding steering movements, which are evaluated according to the differential angle method, it can be concluded that acting steering moments. Due to the integer ratio of the numbers N, M of the receiver structures of the two receiver means 20, 21 can be reduced in a particularly advantageous manner possible error influences not only when viewing the full circle (360 °), but even at much smaller angles of rotation.

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• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Electromagnetism (AREA)
• Power Steering Mechanism (AREA)
• Force Measurement Appropriate To Specific Purposes (AREA)

Applications Claiming Priority (2)

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• 2008
  • 2008-01-31 DE DE102008006865.9A patent/DE102008006865B4/de active Active
• 2009
  • 2009-01-29 US US12/865,515 patent/US8453518B2/en active Active
  • 2009-01-29 EP EP09704941A patent/EP2240751A1/de not_active Withdrawn
  • 2009-01-29 WO PCT/EP2009/051009 patent/WO2009095442A1/de not_active Ceased

Non-Patent Citations (1)

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