EP1964248A1 - Method for detecting a malfunction in an electromagnetic retarder - Google Patents

Method for detecting a malfunction in an electromagnetic retarder

Info

Publication number
EP1964248A1
EP1964248A1 EP06841953A EP06841953A EP1964248A1 EP 1964248 A1 EP1964248 A1 EP 1964248A1 EP 06841953 A EP06841953 A EP 06841953A EP 06841953 A EP06841953 A EP 06841953A EP 1964248 A1 EP1964248 A1 EP 1964248A1
Authority
EP
European Patent Office
Prior art keywords
intensity
current
primary coils
coils
retarder
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Withdrawn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
EP06841953A
Other languages
German (de)
French (fr)
Inventor
Bruno Dessirier
Jean-Claude Matt
Serge Newiadomy
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.)
Telma SA
Original Assignee
Telma SA
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 Telma SA filed Critical Telma SA
Publication of EP1964248A1 publication Critical patent/EP1964248A1/en
Withdrawn legal-status Critical Current

Links

Classifications

    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
    • H02H7/00—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions
    • H02H7/08—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for dynamo-electric motors
    • H02H7/085—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for dynamo-electric motors against excessive load
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60L—PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES; SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL; MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES
    • B60L7/00—Electrodynamic brake systems for vehicles in general
    • B60L7/28—Eddy-current braking
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02K—DYNAMO-ELECTRIC MACHINES
    • H02K11/00—Structural association of dynamo-electric machines with electric components or with devices for shielding, monitoring or protection
    • H02K11/04—Structural association of dynamo-electric machines with electric components or with devices for shielding, monitoring or protection for rectification
    • H02K11/042—Rectifiers associated with rotating parts, e.g. rotor cores or rotary shafts
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02K—DYNAMO-ELECTRIC MACHINES
    • H02K49/00—Dynamo-electric clutches; Dynamo-electric brakes
    • H02K49/02—Dynamo-electric clutches; Dynamo-electric brakes of the asynchronous induction type
    • H02K49/04—Dynamo-electric clutches; Dynamo-electric brakes of the asynchronous induction type of the eddy-current hysteresis type
    • H02K49/043—Dynamo-electric clutches; Dynamo-electric brakes of the asynchronous induction type of the eddy-current hysteresis type with a radial airgap
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
    • H02P9/00—Arrangements for controlling electric generators for the purpose of obtaining a desired output
    • H02P9/006—Means for protecting the generator by using control
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T10/00—Road transport of goods or passengers
    • Y02T10/60—Other road transportation technologies with climate change mitigation effect
    • Y02T10/64—Electric machine technologies in electromobility

Definitions

  • the invention relates to a fault detection method of an electric member carried by a rotary shaft of an electromagnetic retarder.
  • the invention also relates to such an electromagnetic retarder.
  • the invention applies to a retarder capable of generating a deceleration resistant torque on a main or secondary transmission shaft of a vehicle that it equips, when this retarder is actuated.
  • Such an electromagnetic retarder comprises a rotary shaft which is coupled to the main or secondary drive shaft of the vehicle to exert on it the retarding resisting torque to assist in particular the braking of the vehicle.
  • the deceleration is generated with inductor coils fed with direct current to produce a magnetic field in a metal part made of ferromagnetic material, in order to reveal eddy currents in this metal part.
  • the inductor coils may be fixed to cooperate with at least one metal part of movable ferromagnetic material having a general appearance of disk rigidly secured to the rotary shaft.
  • these inductive coils are generally oriented parallel to the axis of rotation and arranged around this axis, vis-à-vis the disc, being secured to a fixed flange. Two successive inductive coils are electrically powered to generate magnetic fields of opposite directions.
  • the inductor coils are electrically powered by a current from the electrical network of the vehicle, that is to say for example from a battery of the vehicle. But to increase the performance of the retarder, we use a design in which a current generator is integrated in the retarder.
  • the electrical supply of the inductor coils is provided by a current generator comprising primary stator coils supplied by the vehicle network, and rotor secondary coils integral with the rotating shaft, and defining three electrical phases.
  • the inductor coils are integral with the rotating shaft being radially protruding, to generate a magnetic field in a fixed cylindrical jacket which surrounds them.
  • a rectifier such as a diode bridge rectifier is interposed between the rotor secondary windings and the inductor coils, also being carried by the rotary shaft.
  • This rectifier converts the three-phase alternating current delivered by the secondary windings of the generator into DC power supply of the inductor coils.
  • Two inductive coils with radial action, consecutive around the axis of rotation generate magnetic fields of opposite directions, one generating a field oriented centrifugally, the other a centripetally oriented field.
  • the power supply of the primary coils allows the generator to produce the supply current of the inductor coils, which gives rise to eddy currents in the fixed cylindrical jacket, to generate a resistive torque on the rotating shaft, which slows down the vehicle.
  • Such a malfunction of the rectifier may be partial, that is to say only concern one of the electrical phases of the current delivered by the secondary windings, which is then not converted by the rectifier.
  • the available deceleration torque decreases by about one third of its nominal value, so that the driver of the vehicle does not necessarily realize this decrease, especially more than such a retarder is usually used in addition to a traditional braking system, which makes the gap even less noticeable.
  • Such a retarder can also be controlled via a central processing unit which distributes, from the braking commands exerted by the driver, the power required by the brakes traditional, and that demanded of the retarder. In this case, the driver can not see directly a decrease in the deceleration torque provided by the retarder.
  • the detection of a malfunction of the rectifier bridge or of another electrical member carried by the rotary shaft by means of electrical or other sensors mounted on the rotary shaft requires the transmission of data from the rotary shaft. to fixed parts of the retarder, which leads to complex solutions.
  • the object of the invention is to provide a low cost detection solution for a malfunction of an electrical member carried by the rotary shaft.
  • the subject of the invention is a method for detecting a fault of an electric member carried by a rotary shaft of an electromagnetic retarder, this retarder comprising stator primary coils, a control box for injecting into these primary coils. a current having an intensity corresponding to a theoretical intensity depending on an intensity reference, a sensor delivering a signal representative of an effective intensity value of the current flowing in these primary coils, a rotary shaft carrying secondary coils defining several phase and inductor coils and a current rectifier interposed between the secondary windings and the inductor coils, this method of comparing, in the control box, the theoretical intensity and the effective intensity to identify a defect in case of the difference between the theoretical intensity and the effective intensity greater than a value threshold.
  • the invention thus makes it possible to identify the presence of an electrical problem at the level of an electrical member carried by the rotary shaft simply by analyzing the electrical behavior of primary coils when excited. It is thus not necessary to provide a data transmission device between the rotary shaft and a fixed portion of the retarder, which makes it possible to implement a fault detector having a very simple design.
  • the invention also relates to a method as defined above, consisting in determining a difference between the theoretical intensity and a minimum or maximum value taken by the effective intensity of the current actually passing through the primary coils during a predetermined time interval.
  • the invention also relates to a method as defined above, in which the theoretical intensity is determined in the control box from the intensity setpoint and data representative of a transfer function of the retarder.
  • the invention also relates to a method as defined above, consisting in taking into account the intensity setpoint as a value representative of the theoretical intensity.
  • the invention also relates to a method as defined above, consisting in slaving, from the control box, the current injected into the primary coils on the signal delivered by the current sensor, and providing primary coils having a constant of time three times greater than the time constant of the secondary windings.
  • the invention also relates to a method as defined above, consisting of slaving, from the control box, the current injected into the primary coils on the signal delivered by the sensor, with a servocontrol having a sufficiently long reaction time for be insensitive to a fault of an electrical member carried by the rotary shaft.
  • the invention also relates to a method as defined above, consisting in providing a servocontrol having a cut-off frequency Fc satisfying the relation Fc ⁇ 1 / 3.2.pi. T2 in which Fc is expressed in Hertz and in which T2 is the time constant of the secondary windings expressed in seconds.
  • the invention also relates to a method as defined above, consisting in implementing inductive measurement turns as an actual current sensor.
  • the invention also relates to an electromagnetic retarder comprising stator primary coils, a control box for injecting into these primary coils a current having an intensity corresponding to a theoretical intensity depending on an intensity reference, a sensor delivering a signal representative of an effective current value of the current flowing in these primary coils, a rotating shaft carrying secondary windings defining a plurality of phases and inductive coils and a current rectifier interposed between the secondary windings and the inductor coils, and means for comparing the theoretical intensity with the effective intensity to identify a malfunction of an electric member carried by the rotary shaft in the event of a difference between the theoretical intensity and the effective intensity greater than a threshold value.
  • the invention also relates to an electromagnetic retarder as defined above, comprising means for controlling the current injected into the primary coils on the signal delivered by the sensor, and primary coils having a time constant greater than three times the time constant of the secondary windings.
  • the invention also relates to an electromagnetic retarder as defined above, comprising means for controlling the current injected into the primary coils on the signal delivered by the sensor, and in which this servocontrol has a cut-off frequency Fc satisfying the relation Fc ⁇ 1 / 3.2.pi. T2 in , which Fc is expressed in Hertz and in which T2 is the time constant of the secondary windings expressed in seconds.
  • the invention also relates to an electromagnetic retarder as defined above, wherein the sensor comprises one or more measuring inductive turns coiled with the primary coils.
  • FIG. 1 is an overall broken away view of an electromagnetic retarder to which the invention applies;
  • FIG. 2 is a schematic representation of the electrical components of the retarder according to the invention
  • FIG. 3 is a plot as a function of time of the actual current flowing in the primary coils of a retarder having a malfunction of its rectifier
  • FIG. 4 is a schematic representation of a servocontrol of the current of an electromagnetic retarder.
  • the electromagnetic retarder 1 comprises a main casing 2 of generally cylindrical shape having a first end closed by a cover 3, and a second end closed by a coupling piece 4 by which retarder 1 is attached to a gearbox case either directly or indirectly, here via a speed multiplier indicated by 6.
  • This casing 2 which is fixed, contains a rotary shaft 7 which is coupled to a transmission shaft not visible in the figure, such as a main shaft for transmitting to the wheels of the vehicle, or secondary such as a secondary output shaft. of gearbox via 6.
  • a current generator here of the three-phase type, which comprises fixed or statoric primary coils 8 surrounding rotor secondary coils, integral with the shaft. rotating 7.
  • These secondary windings are represented symbolically in FIG. 2, being identified by the reference 5.
  • These secondary windings 5 here comprise three distinct windings defining three corresponding phases 5A, 5B and 5C for delivering a three-phase alternating current having a frequency conditioned by the speed of rotation. rotating shaft 7.
  • An inner liner 9 of generally cylindrical shape is mounted in the main casing 2 while being slightly spaced radially from the outer wall of this main casing 2 to define a substantially cylindrical intermediate space 10 in which a cooling liquid of this liner 9 circulates.
  • This main casing which also has a generally cylindrical shape, is provided with a coolant intake duct 11 in the space 10 and a delivery duct 12 of the coolant out of this space 10.
  • This jacket 9 surrounds several induction coils 13 which are carried by a rotor 14 rigidly secured to the rotary shaft 7. Each induction coil 13 is oriented to generate a radial magnetic field, while having a generally oblong shape extending parallel to the 7.
  • the different inductor coils 13 are interconnected to each other so as to form a dipole.
  • the liner 9 and the body of the rotor 14 are made of ferromagnetic material.
  • the casing is a moldable aluminum-based part and seals intervene between the casing and the liner 9, the lid 3 and the part 4 are perforated.
  • the inductor coils 13 are electrically powered by the rotor secondary coils 5 of the generator via a rectifier bridge carried by the rotary shaft 7.
  • This rectifier bridge may be that which is indicated by 15 in FIG. 2, and which comprises six 15A diodes. -15F, for rectifying the three-phase alternating current from the secondary windings 5A-5C in direct current.
  • This bridge rectifier can also be of another type, for example being formed from MOSFET type transistors.
  • the rectifier bridge 15 is a three-branch circuit each carrying two diodes in series, each phase of the secondary windings is connected to a corresponding branch between the two diodes.
  • Each branch has an end connected to a first terminal of the load, which constitute the inductor coils 13, and a second end connected to a second terminal of this load 13.
  • the first phase 5A is connected to the two diodes 15A and 15D which are respectively connected to the first and the second terminals of the load 13.
  • the second phase 5B is connected to the diodes 15B and 15E which are themselves respectively connected to the first and second terminals of the load 13.
  • the third phase is connected to the diodes 15C and 15F which are themselves respectively connected to the first and second terminals of the load 13.
  • each branch of the rectifier delivers in the load 13 a current having the shape of the positive sinusoidal parts of the voltage signal of the phase corresponding to this branch, this current being zero when the voltage in question is negative.
  • the rotor 14 carrying the induction coils 13 has a general shape of a hollow cylinder connected to the rotary shaft 7 by radial arms 16.
  • This rotor 14 thus defines an annular internal space situated around the shaft 7, this internal space being ventilated by an axial fan 17 located substantially in line with the junction of the cover 3 with the casing 2.
  • a radial fan 18 is located at the opposite end of the casing 2 to evacuate the air introduced by the fan. axial 17.
  • the putting into service of the retarder consists in injecting into the primary coils 8 an excitation current coming from the electrical network of the vehicle and in particular from the battery, so that the current generator delivers an induced current on its secondary coils 5. This current supplies then the inductor coils 13 to produce a resisting torque slowing down of the vehicle.
  • the excitation current is injected into the primary coils 8 by means of a control box 19, shown in FIG. 2, which is interposed between a power supply source of the vehicle, and the primary coils 8.
  • the control box 19 and the primary coils 8 are connected in series between a mass M of the vehicle and a battery supply Batt of the vehicle battery.
  • a diode D is mounted across the primary coils 5 so as to prevent the flow of a reverse current in the primary coils.
  • This control unit 19 comprises an input capable of receiving a control signal representative of a level of retarding torque requested from the retarder.
  • This input can be connected to a lever or other that is operated directly by a driver of the vehicle.
  • This lever can be mobile gradually between two extreme positions, namely a maximum position corresponding to a maximum load torque request, and a minimum position in which the retarder is not requested.
  • the retarder is controlled by the housing 19 to exert on 1 rotating shaft 7 a resistive torque proportional to the position of the lever, relative to the maximum available deceleration torque.
  • the input of the control box 19 receives a control signal which corresponds to a value between zero and one hundred percent.
  • This input can also be connected to a brake control unit which autonomously determines a control signal of the retarder.
  • This brake control unit is then connected to one or more braking actuators available to the vehicle.
  • the driver does not act directly on the retarder, but it is the brake control unit that controls, from different parameters, the retarder and traditional brakes of the vehicle.
  • the control box 19, visible in FIG. 4, is an electronic box comprising, for example, an ASIC-type logic circuit operating at 5V, and / or a power control circuit capable of handling currents of high intensity.
  • This housing thus comprises an electronic or PU power module.
  • the control unit 19 determines a current setpoint Ci of excitation current to be injected into the primary coils 8, and it applies, via its module PU, to the primary coils 8 a voltage U to inject a current corresponding to this setpoint intensity Ci.
  • the current injected into the primary coils 8 has a theoretical intensity It which increases until reaching the set value Ci.
  • the value of the theoretical current It is determined in the control box from a transfer function Ft which depends in particular on the inductance and the electrical resistance of the primary coils 8 to be representative of the electrical behavior of the primary coils in transient state.
  • the retarder 1 also comprises a sensor 21 which measures the intensity Ie of the current effectively flowing in the primary coils 8 and which delivers a signal representative of this intensity.
  • This sensor 21 is connected to the control unit 19 which is programmed to compare the effective intensity Ie measured by the sensor 21 with the theoretical current It.
  • a difference between the theoretical current It and the effective current Ie greater than a predetermined value is indicative of a malfunction of an electric member of the rectifier 15, such as in particular the destruction of a diode.
  • the mutual currents resulting from this defective diode disturb the current flowing through the primary coils.
  • the current Ie effectively flowing in the primary coils 8 has a sinusoidal shape of high amplitude. This sinusoid has a frequency which is related to the speed of the rotary shaft 7.
  • the effective current curve Ie is substantially merged with the theoretical current curve It.
  • the detection from the control unit 19 of a difference between the effective current Ie and the theoretical current It greater than a predetermined value makes it possible to detect a fault of the rectifier 15 which is mounted on the rotary shaft 7. This detection is made without contact, that is to say without having to transmit data from sensors mounted on the rotary shaft 7 to a fixed portion of the retarder.
  • the predetermined value of deviation is advantageously twenty percent of the value of the theoretical current It because, as can be seen in FIG. 3, the amplitude of the mutual currents is relatively high, which facilitates their detection.
  • This predetermined value can also be a fixed value.
  • the intensity Ie comes from a current sensor which is connected in series with the primary coils 8.
  • this current sensor may also be in the form of one or more measuring inductive turns.
  • the voltage appearing at the terminals of these measuring inductive turns has the same speed as the current flowing in these inductive turns.
  • the effective intensity Ie may consist in determining the maximum or minimum value taken by the effective intensity Ie for a predetermined duration corresponding to several rotation periods of the shaft 7, and comparing this maximum or this minimum with the setpoint value. This .
  • the current It which is injected into the primary coils 8 is slaved on the sensor 21, so as to best correspond to the value of the intensity setpoint Ci, this slaving being implemented at the level of the control box 19.
  • the control unit comprises, in the aforementioned manner, a power electronics PU which is controlled by a corrector CR for injecting the excitation current Ii into the primary coils 8, which gives rise to the current induced in the secondary windings 5.
  • the intensity effective Ie is subtracted at 50 at the intensity setpoint Ci to constitute an input signal of the corrector CR which drives the power electronics PU.
  • the corrector When the corrector receives a negative signal input, it drives the power electronics PU to reduce the injected current, and when it receives a positive signal input it drives the power electronics to increase the injected current.
  • the effective current Ie flowing in the primary coils 8 corresponds to the current Ii injected by the control box 19 from which the mutual current Im resulting from a malfunction of the rectifier 15 is subtracted.
  • the theoretical current It is determined in the control box 15 from the set value Ci, on the basis of the transfer function Ft which is in particular representative of the intensity response of the primary coils 8 to the application of a U voltage. ⁇
  • the control of the injected current does not compensate for disturbances due to mutual currents in the event of a faulty diode.
  • This can be achieved by sizing the primary coils such that they have a time constant T1 greater than N times the time constant T2 of the secondary coils 5, where N designates a natural integer.
  • N is chosen to be greater than or equal to 3 so that this time constant T1 is greater than three times the time constant T2 in order to ensure optimum independence of the detection.
  • the servocontrol of the injected current is chosen to have a cut-off frequency Fc satisfying the relation Fc ⁇ l / (2.N.pi.T2), in which Fc is expressed in Hertz, and T2 in seconds, pi representing the number having a value close to 3.14.
  • Fc is expressed in Hertz
  • T2 in seconds
  • pi representing the number having a value close to 3.14.
  • N is a natural number which is advantageously chosen as three.
  • this component may be a diode or a transistor of the rectifier 15, but this component may also be a secondary winding 15A, 15B or 15C.
  • the example described above relates to a retarder in which the generator comprises three-phase secondary windings, but the invention also applies to a retarder comprising secondary windings having a different number of phases, equal to at least two.

Abstract

The invention relates to a method for detecting a malfunction in an electromagnetic retarder. More specifically, the invention relates to a retarder comprising: stator primary coils (8); a control unit (19) for injecting a current into the primary coils (8), said current having an intensity corresponding to an intensity set value (Ci); a sensor (21) which delivers a signal that is representative of an effective intensity value (Ie) of the current passing through the primary coils (8); and a shaft (7) bearing secondary windings (5) defining several phases and field coils (13), as well as a current rectifier (5) which is disposed between the secondary windings (5A, 5B, 5C) and the field coils (13). The inventive method consists in comparing the intensity set value (Ci) and the effective intensity (Ie) in the control unit (19) in order to identify a fault in the event that the intensity set value (Ci) and the effective intensity (Ie) differ by an amount greater than a threshold value. The invention is suitable for electric retarders (1) which are intended for heavy vehicles, such as trucks or other vehicles.

Description

Procédé de détection de défaut de fonctionnement d'un ralentisseur électromagnétique. Method for detecting malfunction of an electromagnetic retarder
DOMAINE DE L'INVENTION L'invention concerne un procédé de détection de défaut d'un organe électrique porté par un arbre rotatif d'un ralentisseur électromagnétique. L'invention concerne également un tel ralentisseur électromagnétique.FIELD OF THE INVENTION The invention relates to a fault detection method of an electric member carried by a rotary shaft of an electromagnetic retarder. The invention also relates to such an electromagnetic retarder.
L'invention s'applique à un ralentisseur capable de générer un couple résistant de ralentissement sur un arbre de transmission principal ou secondaire d'un véhicule qu'il équipe, lorsque ce ralentisseur est actionné.The invention applies to a retarder capable of generating a deceleration resistant torque on a main or secondary transmission shaft of a vehicle that it equips, when this retarder is actuated.
ETAT DE LA TECHNIQUE Un tel ralentisseur électromagnétique comprend un arbre rotatif qui est accouplé à l'arbre de transmission principal ou secondaire du véhicule pour exercer sur celui-ci le couple résistant de ralentissement pour notamment assister le freinage du véhicule. Le ralentissement est généré avec des bobines inductrices alimentées en courant continu pour produire un champ magnétique dans une pièce métallique en matériau ferromagnétique, afin de faire apparaître des courants de Foucault dans cette pièce métallique. Les bobines inductrices peuvent être fixes pour coopérer avec au moins une pièce métallique en matériau ferromagnétique mobile ayant une allure générale de disque rigidement solidaire de l'arbre rotatif.STATE OF THE ART Such an electromagnetic retarder comprises a rotary shaft which is coupled to the main or secondary drive shaft of the vehicle to exert on it the retarding resisting torque to assist in particular the braking of the vehicle. The deceleration is generated with inductor coils fed with direct current to produce a magnetic field in a metal part made of ferromagnetic material, in order to reveal eddy currents in this metal part. The inductor coils may be fixed to cooperate with at least one metal part of movable ferromagnetic material having a general appearance of disk rigidly secured to the rotary shaft.
Dans ce cas, ces bobines inductrices sont généralement orientées parallèlement à l'axe de rotation et disposées autour de cet axe, en vis-à-vis du disque, en étant solidarisées à un flasque fixe. Deux bobines inductrices successives sont alimentées électriquement pour générer des champs magnétiques de directions opposées .In this case, these inductive coils are generally oriented parallel to the axis of rotation and arranged around this axis, vis-à-vis the disc, being secured to a fixed flange. Two successive inductive coils are electrically powered to generate magnetic fields of opposite directions.
Lorsque ces bobines inductrices sont alimentées électriquement, les courants de Foucault qu'elles gênèrent dans le disque s ' opposent par leurs effets à la cause qui leur a donné naissance, ce qui produit un couple résistant sur le disque et donc sur 1 ' arbre rotatif, pour ralentir le véhicule. Dans ce mode de réalisation, les bobines inductrices sont alimentées électriquement par un courant provenant du réseau électrique du véhicule, c'est-à-dire par exemple à partir d'une batterie du véhicule. Mais pour augmenter les performances du ralentisseur, on recourt à une conception dans laquelle une génératrice de courant est intégrée au ralentisseur.When these inductive coils are electrically powered, the eddy currents they The annoying effects of the discs in the discomfort of the discomfort are caused by their effects on the cause which gave rise to them, which produces a resistant torque on the disc and thus on the rotating shaft, in order to slow down the vehicle. In this embodiment, the inductor coils are electrically powered by a current from the electrical network of the vehicle, that is to say for example from a battery of the vehicle. But to increase the performance of the retarder, we use a design in which a current generator is integrated in the retarder.
Ainsi, selon une autre conception connue des documents de brevet EP0331559 et FR1467310, 1 ' alimentation électrique des bobines inductrices est assurée par une génératrice de courant comprenant des bobines primaires statoriques alimentées par le réseau du véhicule, et des bobinages secondaires rotoriques solidaires de l'arbre rotatif, et définissant trois phases électriques. Les bobines inductrices sont solidaires de l'arbre rotatif en étant radialement saillantes, pour générer un champ magnétique dans une chemise cylindrique fixe qui les entoure .Thus, according to another known design of patent documents EP0331559 and FR1467310, the electrical supply of the inductor coils is provided by a current generator comprising primary stator coils supplied by the vehicle network, and rotor secondary coils integral with the rotating shaft, and defining three electrical phases. The inductor coils are integral with the rotating shaft being radially protruding, to generate a magnetic field in a fixed cylindrical jacket which surrounds them.
Un redresseur tel qu'un redresseur à pont de diodes est interposé entre les bobinages secondaires rotoriques et les bobines inductrices, en étant également porté par l'arbre rotatif. Ce redresseur convertit le courant alternatif triphasé délivré par les bobinages secondaires de la génératrice en courant continu d'alimentation des bobines inductrices . Deux bobines inductrices à action radiale, consécutives autour de l'axe de rotation génèrent des champs magnétiques de directions opposées, l'une générant un champ orienté de façon centrifuge, l'autre un champ orienté de façon centripète. En fonctionnement, l'alimentation électrique des bobines primaires permet à la génératrice de produire le courant d'alimentation des bobines inductrices, ce qui donne naissance à des courants de Foucault dans la chemise cylindrique fixe, pour générer un couple résistant sur l'arbre rotatif, qui ralentit le véhicule.A rectifier such as a diode bridge rectifier is interposed between the rotor secondary windings and the inductor coils, also being carried by the rotary shaft. This rectifier converts the three-phase alternating current delivered by the secondary windings of the generator into DC power supply of the inductor coils. Two inductive coils with radial action, consecutive around the axis of rotation generate magnetic fields of opposite directions, one generating a field oriented centrifugally, the other a centripetally oriented field. In operation, the power supply of the primary coils allows the generator to produce the supply current of the inductor coils, which gives rise to eddy currents in the fixed cylindrical jacket, to generate a resistive torque on the rotating shaft, which slows down the vehicle.
Afin de réduire le poids et d'augmenter encore les performances d'un tel ralentisseur, il est avantageux de l'accoupler à l'arbre de transmission du véhicule par l'intermédiaire d'un multiplicateur de vitesse, conformément a la solution adoptée dans le document de brevet EP1527509. La vitesse de rotation de l'arbre du ralentisseur est alors surmultipliée par rapport à la vitesse de rotation de l'arbre de transmission auquel il est accouplé. Cet agencement permet d'augmenter significativement la puissance électrique délivrée par la génératrice, et donc la puissance du ralentisseur.In order to reduce the weight and further increase the performance of such a retarder, it is advantageous to couple it to the drive shaft of the vehicle via a speed multiplier, in accordance with the solution adopted in EP1527509. The speed of rotation of the retarder shaft is then overdrive relative to the rotational speed of the transmission shaft to which it is coupled. This arrangement makes it possible to significantly increase the electric power delivered by the generator, and therefore the power of the retarder.
En cas de dysfonctionnement du redresseur de courant, la puissance électrique transmise aux bobines inductrice diminue, ce qui se traduit par une réduction du couple de ralentissement pouvant être exercé par le ralentisseur.In the event of malfunction of the current rectifier, the electrical power transmitted to the induction coils decreases, which results in a reduction in the deceleration torque that can be exerted by the retarder.
Un tel dysfonctionnement du redresseur peut être partiel, c'est-à-dire ne concerner que l'une des phases électriques du courant délivré par les bobinages secondaires, qui n'est alors pas convertie par le redresseur.Such a malfunction of the rectifier may be partial, that is to say only concern one of the electrical phases of the current delivered by the secondary windings, which is then not converted by the rectifier.
La génératrice étant par exemple du type triphasé, dans ce cas, le couple de ralentissement disponible baisse d'environ un tiers de sa valeur nominale, de telle sorte que le conducteur du véhicule ne se rend pas nécessairement compte de cette baisse, d'autant plus qu'un tel ralentisseur est généralement utilisé en appoint d'un système de freinage traditionnel, ce qui rend l ' écart encore moins perceptible .The generator being for example of the three-phase type, in this case, the available deceleration torque decreases by about one third of its nominal value, so that the driver of the vehicle does not necessarily realize this decrease, especially more than such a retarder is usually used in addition to a traditional braking system, which makes the gap even less noticeable.
Un tel ralentisseur peut de plus être piloté par l'intermédiaire d'une unité centrale de traitement qui répartit, à partir des commandes de freinage exercées par le conducteur, la puissance demandée aux freins traditionnels, et celle demandée au ralentisseur . Dans ce cas, le conducteur ne peut pas constater de façon directe une baisse du couple de ralentissement fourni par le ralentisseur . D'autre part, la détection d'un dysfonctionnement du pont redresseur ou d'un autre organe électrique porté par l'arbre rotatif au moyen de capteurs électriques ou autres montés sur l'arbre rotatif nécessite de transmettre des données depuis l'arbre rotatif vers des parties fixes du ralentisseur, ce qui conduit à des solutions complexes .Such a retarder can also be controlled via a central processing unit which distributes, from the braking commands exerted by the driver, the power required by the brakes traditional, and that demanded of the retarder. In this case, the driver can not see directly a decrease in the deceleration torque provided by the retarder. On the other hand, the detection of a malfunction of the rectifier bridge or of another electrical member carried by the rotary shaft by means of electrical or other sensors mounted on the rotary shaft requires the transmission of data from the rotary shaft. to fixed parts of the retarder, which leads to complex solutions.
OBJET DE L'INVENTIONOBJECT OF THE INVENTION
Le but de l ' invention est de proposer une solution de détection à moindre coût d'un dysfonctionnement d'un organe électrique porté par l'arbre rotatif.The object of the invention is to provide a low cost detection solution for a malfunction of an electrical member carried by the rotary shaft.
A cet effet, l'invention a pour objet un procédé de détection de défaut d'un organe électrique porté par un arbre rotatif d'un ralentisseur électromagnétique, ce ralentisseur comprenant des bobines primaires statoriques, un boîtier de commande pour injecter dans ces bobines primaires un courant ayant une intensité correspondant à une intensité théorique dépendant d'une consigne d'intensité, un capteur délivrant un signal représentatif d'une valeur d'intensité effective du courant circulant dans ces bobines primaires, un arbre rotatif portant des bobinages secondaires définissant plusieurs phases et des bobines inductrices ainsi qu'un redresseur de courant interposé entre les bobinages secondaires et les bobines inductrices, ce procédé consistant à comparer, dans le boîtier de commande, 1 ' intensité théorique et 1 ' intensité effective pour identifier un défaut en cas d'écart entre l'intensité théorique et 1 ' intensité effective supérieur à une valeur seuil . L'invention permet ainsi d'identifier la présence d'un problème électrique au niveau d'un organe électrique porté par 1 ' arbre rotatif simplement par analyse du comportement électrique des bobines primaires lorsqu'elles sont excitées. Il n'est ainsi pas nécessaire de prévoir de dispositif de transmission de données entre l'arbre rotatif et une partie fixe du ralentisseur, ce qui permet de mettre en œuvre un détecteur de défaut ayant une conception très simple.For this purpose, the subject of the invention is a method for detecting a fault of an electric member carried by a rotary shaft of an electromagnetic retarder, this retarder comprising stator primary coils, a control box for injecting into these primary coils. a current having an intensity corresponding to a theoretical intensity depending on an intensity reference, a sensor delivering a signal representative of an effective intensity value of the current flowing in these primary coils, a rotary shaft carrying secondary coils defining several phase and inductor coils and a current rectifier interposed between the secondary windings and the inductor coils, this method of comparing, in the control box, the theoretical intensity and the effective intensity to identify a defect in case of the difference between the theoretical intensity and the effective intensity greater than a value threshold. The invention thus makes it possible to identify the presence of an electrical problem at the level of an electrical member carried by the rotary shaft simply by analyzing the electrical behavior of primary coils when excited. It is thus not necessary to provide a data transmission device between the rotary shaft and a fixed portion of the retarder, which makes it possible to implement a fault detector having a very simple design.
L ' invention concerne également un procédé tel que défini ci-dessus, consistant à déterminer un écart entre 1 ' intensité théorique et une valeur minimale ou maximale prise par l'intensité effective du courant traversant effectivement les bobines primaires pendant un intervalle de temps prédéterminé.The invention also relates to a method as defined above, consisting in determining a difference between the theoretical intensity and a minimum or maximum value taken by the effective intensity of the current actually passing through the primary coils during a predetermined time interval.
L'invention concerne également un procédé tel que défini ci-dessus, dans lequel l'intensité théorique est déterminée dans le boîtier de commande à partir de la consigne d'intensité et de données représentatives d'une fonction de transfert du ralentisseur.The invention also relates to a method as defined above, in which the theoretical intensity is determined in the control box from the intensity setpoint and data representative of a transfer function of the retarder.
L'invention concerne également un procédé tel que défini ci-dessus, consistant à prendre en compte la consigne d'intensité comme valeur représentative de 1 ' intensité théorique . L'invention concerne également un procédé tel que défini ci-dessus, consistant à asservir, depuis le boîtier de commande, le courant injecté dans les bobines primaires sur le signal délivré par le capteur de courant, et à prévoir des bobines primaires ayant une constante de temps trois fois supérieure à la constante de temps des bobinages secondaires .The invention also relates to a method as defined above, consisting in taking into account the intensity setpoint as a value representative of the theoretical intensity. The invention also relates to a method as defined above, consisting in slaving, from the control box, the current injected into the primary coils on the signal delivered by the current sensor, and providing primary coils having a constant of time three times greater than the time constant of the secondary windings.
L ' invention concerne également un procédé tel que défini ci-dessus, consistant a asservir, depuis le boîtier de commande, le courant injecté dans les bobines primaires sur le signal délivré par le capteur, avec un asservissement ayant un temps de réaction suffisamment long pour être insensible à un défaut d'un organe électrique porté par l'arbre rotatif.The invention also relates to a method as defined above, consisting of slaving, from the control box, the current injected into the primary coils on the signal delivered by the sensor, with a servocontrol having a sufficiently long reaction time for be insensitive to a fault of an electrical member carried by the rotary shaft.
L'invention concerne également un procédé tel que défini ci-dessus, consistant à prévoir un asservissement ayant une fréquence de coupure Fc vérifiant la relation Fc < 1/3.2.pi. T2 dans laquelle Fc est exprimée en Hertz et dans laquelle T2 est la constante de temps des bobinages secondaires exprimée en secondes. L'invention concerne également un procédé tel que défini ci-dessus, consistant à mettre en œuvre des spires inductives de mesure comme capteur du courant effectif.,The invention also relates to a method as defined above, consisting in providing a servocontrol having a cut-off frequency Fc satisfying the relation Fc <1 / 3.2.pi. T2 in which Fc is expressed in Hertz and in which T2 is the time constant of the secondary windings expressed in seconds. The invention also relates to a method as defined above, consisting in implementing inductive measurement turns as an actual current sensor.
L'invention concerne également un ralentisseur électromagnétique comprenant des bobines primaires statoriques, un boîtier de commande pour injecter dans ces bobines primaires un courant ayant une intensité correspondant à une intensité théorique dépendant d'une consigne d'intensité, un capteur délivrant un signal représentatif d'une valeur d'intensité effective du courant circulant dans ces bobines primaires, un arbre rotatif portant des bobinages secondaires définissant plusieurs phases et des bobines inductrices ainsi qu'un redresseur de courant interposé entre les bobinages secondaires et les bobines inductrices, et des moyens de comparaison de 1 ' intensité théorique avec l ' intensité effective pour identifier un défaut de fonctionnement d'un organe électrique porté par l'arbre rotatif en cas d'écart entre l'intensité théorique et l'intensité effective supérieur à une valeur seuil . L'invention concerne également un ralentisseur électromagnétique tel que défini ci-dessus, comprenant des moyens d'asservissement du courant injecté dans les bobines primaires sur le signal délivré par le capteur, et des bobines primaires ayant une constante de temps supérieure à trois fois la constante de temps des bobinages secondaire .The invention also relates to an electromagnetic retarder comprising stator primary coils, a control box for injecting into these primary coils a current having an intensity corresponding to a theoretical intensity depending on an intensity reference, a sensor delivering a signal representative of an effective current value of the current flowing in these primary coils, a rotating shaft carrying secondary windings defining a plurality of phases and inductive coils and a current rectifier interposed between the secondary windings and the inductor coils, and means for comparing the theoretical intensity with the effective intensity to identify a malfunction of an electric member carried by the rotary shaft in the event of a difference between the theoretical intensity and the effective intensity greater than a threshold value. The invention also relates to an electromagnetic retarder as defined above, comprising means for controlling the current injected into the primary coils on the signal delivered by the sensor, and primary coils having a time constant greater than three times the time constant of the secondary windings.
L'invention concerne également un ralentisseur électromagnétique tel que défini ci-dessus, comprenant des moyens d'asservissement du courant injecté dans les bobines primaires sur le signal délivré par le capteur, et dans lequel cet asservissement a une fréquence de coupure Fc vérifiant la relation Fc < 1/3.2.pi. T2 dans , laquelle Fc est exprimée en Hertz et dans laquelle T2 est la constante de temps des bobinages secondaires exprimée en secondes .The invention also relates to an electromagnetic retarder as defined above, comprising means for controlling the current injected into the primary coils on the signal delivered by the sensor, and in which this servocontrol has a cut-off frequency Fc satisfying the relation Fc <1 / 3.2.pi. T2 in , which Fc is expressed in Hertz and in which T2 is the time constant of the secondary windings expressed in seconds.
L'invention concerne également un ralentisseur électromagnétique tel que défini ci-dessus, dans lequel le capteur comprend une ou plusieurs spires inductrices de mesure bobinée avec les bobines primaires .The invention also relates to an electromagnetic retarder as defined above, wherein the sensor comprises one or more measuring inductive turns coiled with the primary coils.
BREVE DESCRIPTION DES DESSINSBRIEF DESCRIPTION OF THE DRAWINGS
L'invention sera maintenant décrite plus en détail, et en référence aux dessins annexés qui en illustrent une forme de réalisation à titre d'exemple non limitatif.The invention will now be described in more detail and with reference to the accompanying drawings which illustrate an embodiment thereof by way of non-limiting example.
La figure 1 est une vue d'ensemble avec arrachement local d'un ralentisseur électromagnétique auquel s ' applique l ' invention ; La figure 2 est une représentation schématique des composants électriques du ralentisseur selon l'inventionFigure 1 is an overall broken away view of an electromagnetic retarder to which the invention applies; FIG. 2 is a schematic representation of the electrical components of the retarder according to the invention
La figure 3 est un graphe en fonction du temps du courant effectif circulant dans les bobines primaires d'un ralentisseur ayant un défaut de fonctionnement de son redresseur ; ,FIG. 3 is a plot as a function of time of the actual current flowing in the primary coils of a retarder having a malfunction of its rectifier; ,
La figure 4 est une représentation schématique d'un asservissement du courant d'un ralentisseur électromagnétique .FIG. 4 is a schematic representation of a servocontrol of the current of an electromagnetic retarder.
DESCRIPTION DE MODES DE REALISATION DE L'INVENTION Dans la figure 1, le ralentisseur électromagnétique 1 comprend un carter principal 2 de forme généralement cylindrique ayant une première extrémité fermée par un couvercle 3, et une seconde extrémité fermée par une pièce d'accouplement 4 par laquelle ce ralentisseur 1 est fixé à un carter de boîte de vitesses soit directement soit indirectement, ici via un multiplicateur de vitesse repéré par 6.DESCRIPTION OF EMBODIMENTS OF THE INVENTION In FIG. 1, the electromagnetic retarder 1 comprises a main casing 2 of generally cylindrical shape having a first end closed by a cover 3, and a second end closed by a coupling piece 4 by which retarder 1 is attached to a gearbox case either directly or indirectly, here via a speed multiplier indicated by 6.
Ce carter 2, qui est fixe, renferme un arbre rotatif 7 qui est accouplé à un arbre de transmission non visible sur la figure, tel qu'un arbre principal de transmission aux roues du véhicule, ou secondaire tel qu'un arbre secondaire de sortie de boîte de vitesses via le multiplicateur de vitesse 6. Dans une région correspondant à l ' intérieur du couvercle 3 est située une génératrice de courant, ici du type triphasé, qui comprend des bobines primaires 8 fixes ou statoriques qui entourent des bobinages secondaires rotoriques, solidaires de l'arbre rotatif 7.This casing 2, which is fixed, contains a rotary shaft 7 which is coupled to a transmission shaft not visible in the figure, such as a main shaft for transmitting to the wheels of the vehicle, or secondary such as a secondary output shaft. of gearbox via 6. In a region corresponding to the interior of the cover 3 is located a current generator, here of the three-phase type, which comprises fixed or statoric primary coils 8 surrounding rotor secondary coils, integral with the shaft. rotating 7.
Ces bobinages secondaires sont représentés symboliquement en figure 2 en étant repérés par la référence 5. Ces bobinages secondaires 5 comprennent ici trois bobinages distincts définissant trois phases correspondantes 5A, 5B et 5C pour délivrer un courant alternatif triphasé ayant une fréquence conditionnée par la vitesse de rotation de l ' arbre rotatif 7.These secondary windings are represented symbolically in FIG. 2, being identified by the reference 5. These secondary windings 5 here comprise three distinct windings defining three corresponding phases 5A, 5B and 5C for delivering a three-phase alternating current having a frequency conditioned by the speed of rotation. rotating shaft 7.
Une chemise interne 9 de forme générale cylindrique est montée dans le carter principal 2 en étant légèrement espacée radialement de la paroi externe de ce carter principal 2 pour définir un espace intermédiaire 10, sensiblement cylindrique, dans lequel circule un liquide de refroidissement de cette chemise 9. Ce carter principal, qui a également une forme générale cylindrique, est pourvu d'une canalisation d'admission 11 de liquide de refroidissement dans l'espace 10 et d'une canalisation de refoulement 12 du liquide de refroidissement hors de cet espace 10. Cette chemise 9 entoure plusieurs bobines inductrices 13 qui sont portées par un rotor 14 rigidement solidaire de l'arbre rotatif 7. Chaque bobine inductrice 13 est orientée pour générer un champ magnétique radial, tout en ayant une forme générale oblongue s ' étendant parallèlement à l ' arbre 7. Les différentes bobines inductrices 13 sont interconnectées les unes aux autres de façon à former un dipôle.An inner liner 9 of generally cylindrical shape is mounted in the main casing 2 while being slightly spaced radially from the outer wall of this main casing 2 to define a substantially cylindrical intermediate space 10 in which a cooling liquid of this liner 9 circulates. This main casing, which also has a generally cylindrical shape, is provided with a coolant intake duct 11 in the space 10 and a delivery duct 12 of the coolant out of this space 10. This jacket 9 surrounds several induction coils 13 which are carried by a rotor 14 rigidly secured to the rotary shaft 7. Each induction coil 13 is oriented to generate a radial magnetic field, while having a generally oblong shape extending parallel to the 7. The different inductor coils 13 are interconnected to each other so as to form a dipole.
De manière connue, la chemise 9 et le corps du rotor 14 sont en matériau ferromagnétique. Ici le carter est une pièce moulable à base d'aluminium et des joints d'étanchéité interviennent entre le carter et la chemise 9, le couvercle 3 et la pièce 4 sont ajourés. Les bobines inductrices 13 sont alimentées électriquement par les bobinages secondaires rotoriques 5 de la génératrice via un pont redresseur porté par l'arbre rotatif 7. Ce pont redresseur peut être celui qui est repéré par 15 sur la figure 2, et qui comprend six diodes 15A-15F, pour redresser le courant alternatif triphasé issu des bobinages secondaires 5A-5C en courant continu. Ce pont redresseur peut aussi être d'un autre type, en étant par exemple formé à partir de transistors de type MOSFET.In known manner, the liner 9 and the body of the rotor 14 are made of ferromagnetic material. Here the casing is a moldable aluminum-based part and seals intervene between the casing and the liner 9, the lid 3 and the part 4 are perforated. The inductor coils 13 are electrically powered by the rotor secondary coils 5 of the generator via a rectifier bridge carried by the rotary shaft 7. This rectifier bridge may be that which is indicated by 15 in FIG. 2, and which comprises six 15A diodes. -15F, for rectifying the three-phase alternating current from the secondary windings 5A-5C in direct current. This bridge rectifier can also be of another type, for example being formed from MOSFET type transistors.
Dans l'exemple de la figure 2, le pont redresseur 15 est un circuit à trois branches portant chacune deux diodes en série, chaque phase des bobinages secondaires est connectée à une branche correspondante, entre les deux diodes. Chaque branche a une extrémité connectée à une première borne de la charge, que constituent les bobines inductrices 13, et une seconde extrémité connectée à une seconde borne de cette charge 13.In the example of Figure 2, the rectifier bridge 15 is a three-branch circuit each carrying two diodes in series, each phase of the secondary windings is connected to a corresponding branch between the two diodes. Each branch has an end connected to a first terminal of the load, which constitute the inductor coils 13, and a second end connected to a second terminal of this load 13.
Ainsi, la première phase 5A est connectée aux deux diodes 15A et 15D qui sont connectées respectivement à la première et à la seconde borne de la charge 13. La seconde phase 5B est connectée aux diodes 15B et 15E qui sont elles-mêmes connectées respectivement à la première et à la seconde borne de la charge 13. La troisième phase est connectée aux diodes 15C et 15F qui sont elles-mêmes connectées respectivement à la première et à la seconde borne de la charge 13.Thus, the first phase 5A is connected to the two diodes 15A and 15D which are respectively connected to the first and the second terminals of the load 13. The second phase 5B is connected to the diodes 15B and 15E which are themselves respectively connected to the first and second terminals of the load 13. The third phase is connected to the diodes 15C and 15F which are themselves respectively connected to the first and second terminals of the load 13.
En fonctionnement, chaque branche du redresseur délivre dans la charge 13 un courant ayant l'allure des parties positives sinusoïdales du signal de tension de la phase correspondant à cette branche, ce courant étant nul lorsque la tension en question est négative.In operation, each branch of the rectifier delivers in the load 13 a current having the shape of the positive sinusoidal parts of the voltage signal of the phase corresponding to this branch, this current being zero when the voltage in question is negative.
Les trois phases étant décalées les unes par rapport aux autres d'un tiers de période, elles délivrent dans la charge un courant sensiblement constant, ayant une allure correspondant à la somme des parties positives des sinusoïdes des trois phases . Comme visible dans la figure 1, le rotor 14 portant les bobines inductrices 13 a une forme générale de cylindre creux relié à l'arbre rotatif 7 par des bras radiaux 16. Ce rotor 14 définit ainsi un espace interne annulaire situé autour de l'arbre 7, cet espace interne étant ventilé par un ventilateur axial 17 situé sensiblement au droit de la jonction du couvercle 3 avec le carter 2. Un ventilateur radial 18 est situé à l ' extrémité opposée du carter 2 pour évacuer l ' air introduit par le ventilateur axial 17.The three phases being shifted relative to each other by a third period, they deliver in the load a substantially constant current, having a shape corresponding to the sum of the positive portions of the sinusoids of the three phases. As can be seen in FIG. 1, the rotor 14 carrying the induction coils 13 has a general shape of a hollow cylinder connected to the rotary shaft 7 by radial arms 16. This rotor 14 thus defines an annular internal space situated around the shaft 7, this internal space being ventilated by an axial fan 17 located substantially in line with the junction of the cover 3 with the casing 2. A radial fan 18 is located at the opposite end of the casing 2 to evacuate the air introduced by the fan. axial 17.
La mise en service du ralentisseur consiste à injecter dans les bobines primaires 8 un courant d'excitation provenant du réseau électrique du véhicule et notamment de la batterie, pour que la génératrice de courant délivre un courant induit sur ses bobinages secondaires 5. Ce courant alimente alors les bobines inductrices 13 pour produire un couple résistant de ralentissement du véhicule.The putting into service of the retarder consists in injecting into the primary coils 8 an excitation current coming from the electrical network of the vehicle and in particular from the battery, so that the current generator delivers an induced current on its secondary coils 5. This current supplies then the inductor coils 13 to produce a resisting torque slowing down of the vehicle.
Le courant d'excitation est injecté dans les bobines primaires 8 au moyen d'un boîtier de commande 19, représenté en figure 2 , qui est interposé entre une source d'alimentation électrique du véhicule, et les bobines primaires 8. Dans l'exemple de la figure 2, le boîtier de commande 19 et les bobines primaires 8 sont montées en série entre une masse M du véhicule et une alimentation Batt de la batterie du véhicule. Comme visible dans cette figure, une diode D est montée aux bornes des bobines primaires 5 de façon à éviter la circulation d'un courant inverse dans les bobines primaires .The excitation current is injected into the primary coils 8 by means of a control box 19, shown in FIG. 2, which is interposed between a power supply source of the vehicle, and the primary coils 8. In the example of FIG. 2, the control box 19 and the primary coils 8 are connected in series between a mass M of the vehicle and a battery supply Batt of the vehicle battery. As shown in this figure, a diode D is mounted across the primary coils 5 so as to prevent the flow of a reverse current in the primary coils.
Ce boîtier de commande 19 comprend une entrée apte à recevoir un signal de pilotage représentatif d'un niveau de couple de ralentissement demandé au ralentisseur. Cette entrée peut être reliée à un levier ou autre qui est actionné directement par un conducteur du véhicule. Ce levier peut être mobile graduellement entre deux positions extrêmes, à savoir une position maximale correspondant à une demande de couple résistant maximal, et une position minimale dans laquelle le ralentisseur n'est pas sollicité. Lorsque le conducteur place ce levier dans une position intermédiaire, le ralentisseur est commandé par le boîtier 19 pour exercer sur 1 ' arbre rotatif 7 un couple résistant proportionnel à la position du levier, par rapport au couple maximal de ralentissement disponible. En d'autres termes, l'entrée du boîtier de commande 19 reçoit un signal de pilotage qui correspond à une valeur comprise entre zéro et cent pourcent .This control unit 19 comprises an input capable of receiving a control signal representative of a level of retarding torque requested from the retarder. This input can be connected to a lever or other that is operated directly by a driver of the vehicle. This lever can be mobile gradually between two extreme positions, namely a maximum position corresponding to a maximum load torque request, and a minimum position in which the retarder is not requested. When the driver places this lever in an intermediate position, the retarder is controlled by the housing 19 to exert on 1 rotating shaft 7 a resistive torque proportional to the position of the lever, relative to the maximum available deceleration torque. In other words, the input of the control box 19 receives a control signal which corresponds to a value between zero and one hundred percent.
Cette entrée peut aussi être reliée à un boîtier de commande de freinage qui détermine de façon autonome un signal de pilotage du ralentisseur. Ce boîtier de commande de freinage est alors relié à un ou plusieurs actionneurs de freinage dont dispose le véhicule. Dans ce cas, le conducteur n'agit pas directement sur le ralentisseur, mais c'est le boîtier de commande de freinage qui pilote, à partir de différents paramètres, le ralentisseur et les freins traditionnels du véhicule.This input can also be connected to a brake control unit which autonomously determines a control signal of the retarder. This brake control unit is then connected to one or more braking actuators available to the vehicle. In this case, the driver does not act directly on the retarder, but it is the brake control unit that controls, from different parameters, the retarder and traditional brakes of the vehicle.
Le boîtier de commande 19, visible figure 4, est un boîtier électronique comprenant par exemple un circuit logique de type ASIC fonctionnant sous 5V, et/ou un circuit de commande de puissance capable de gérer des courants d'intensité élevée. Ce boîtier comprend donc une électronique ou module de puissance PU.The control box 19, visible in FIG. 4, is an electronic box comprising, for example, an ASIC-type logic circuit operating at 5V, and / or a power control circuit capable of handling currents of high intensity. This housing thus comprises an electronic or PU power module.
Sur réception d'un signal de pilotage correspondant à une valeur non nulle, le boîtier de commande 19 détermine une consigne d'intensité Ci de courant d'excitation à injecter dans les bobines primaires 8, et il applique, via son module PU, aux bobines primaires 8 une tension U pour injecter un courant correspondant à cette intensité de consigne Ci . Le courant injecté dans les bobines primaires 8 a une intensité théorique It qui augmente jusqu'à atteindre la valeur de consigne Ci . La valeur du courant théorique It est déterminée dans le boîtier de commande à partir d'une fonction de transfert Ft qui dépend notamment de l'inductance et de la résistance électrique des bobines primaires 8 pour être représentative du comportement électrique des bobines primaires en régime transitoire.On receipt of a control signal corresponding to a non-zero value, the control unit 19 determines a current setpoint Ci of excitation current to be injected into the primary coils 8, and it applies, via its module PU, to the primary coils 8 a voltage U to inject a current corresponding to this setpoint intensity Ci. The current injected into the primary coils 8 has a theoretical intensity It which increases until reaching the set value Ci. The value of the theoretical current It is determined in the control box from a transfer function Ft which depends in particular on the inductance and the electrical resistance of the primary coils 8 to be representative of the electrical behavior of the primary coils in transient state.
Comme visible dans la figure 2, le ralentisseur 1 comprend également un capteur 21 qui mesure l'intensité Ie du courant circulant effectivement dans les bobines primaires 8 et qui délivre un signal représentatif de cette intensité. Ce capteur 21 est relié au boîtier de commande 19 qui est programmé pour comparer l'intensité effective Ie mesurée par le capteur 21 avec le courant théorique It .As can be seen in FIG. 2, the retarder 1 also comprises a sensor 21 which measures the intensity Ie of the current effectively flowing in the primary coils 8 and which delivers a signal representative of this intensity. This sensor 21 is connected to the control unit 19 which is programmed to compare the effective intensity Ie measured by the sensor 21 with the theoretical current It.
Un écart entre le courant théorique It et l'intensité effective Ie supérieur à une valeur prédéterminée est significatif d'un dysfonctionnement d'un organe électrique du redresseur 15, comme en particulier la destruction d'une diode.A difference between the theoretical current It and the effective current Ie greater than a predetermined value is indicative of a malfunction of an electric member of the rectifier 15, such as in particular the destruction of a diode.
En effet, lorsqu'une diode est défectueuse, celle- ci devient en permanence soit électriquement passante, soit non passante. Ceci provoque un déséquilibre électrique des trois phases 5A, 5B et 5C des bobinages secondaires 5, qui génère un courant dit mutuel dans les bobines primaires 8. Ce phénomène est visible dans le graphe de la figure 3 , dans lequel on a représenté le courant théorique It et l ' intensité effective Ie dans le cas où l'une des diodes du redresseur 15 est défectueuse.Indeed, when a diode is defective, it becomes permanently either electrically conductive or non-conducting. This causes an electrical imbalance of the three phases 5A, 5B and 5C of the secondary windings 5, which generates a so-called mutual current in the primary coils 8. This phenomenon is visible in the graph of FIG. 3, in which the theoretical current is represented. It and the effective current Ie in the case where one of the diodes of the rectifier 15 is defective.
Comme visible dans cette figure, les courants mutuels résultant de cette diode défectueuse perturbent le courant traversant les bobines primaires. Ainsi, au lieu d'avoir une allure sensiblement constante, le courant Ie circulant effectivement dans les bobines primaires 8 a une allure de sinusoïde de forte amplitude. Cette sinusoïde a une fréquence qui est liée au régime de l'arbre rotatif 7. En fonctionnement normal du ralentisseur, la courbe de courant effectif Ie est sensiblement confondue avec la courbe de courant théorique It.As shown in this figure, the mutual currents resulting from this defective diode disturb the current flowing through the primary coils. Thus, instead of having a substantially constant pace, the current Ie effectively flowing in the primary coils 8 has a sinusoidal shape of high amplitude. This sinusoid has a frequency which is related to the speed of the rotary shaft 7. In normal operation of the retarder, the effective current curve Ie is substantially merged with the theoretical current curve It.
Ainsi, la détection depuis le boîtier de commande 19 d'un écart entre le courant effectif Ie et le courant théorique It supérieur à une valeur prédéterminée permet de détecter un défaut du redresseur 15 qui est monté sur l'arbre rotatif 7. Cette détection est faite sans contact, c'est-à-dire sans avoir à transmettre des données issues de capteurs montés sur l'arbre rotatif 7 vers une partie fixe du ralentisseur.Thus, the detection from the control unit 19 of a difference between the effective current Ie and the theoretical current It greater than a predetermined value makes it possible to detect a fault of the rectifier 15 which is mounted on the rotary shaft 7. This detection is made without contact, that is to say without having to transmit data from sensors mounted on the rotary shaft 7 to a fixed portion of the retarder.
La valeur prédéterminée d ' écart est avantageusement de vingt pourcent de la valeur du courant théorique It car, comme visible dans la figure 3, l'amplitude des courants mutuels est relativement importante, ce qui facilite leur détection. Cette valeur prédéterminée peut également être une valeur fixe.The predetermined value of deviation is advantageously twenty percent of the value of the theoretical current It because, as can be seen in FIG. 3, the amplitude of the mutual currents is relatively high, which facilitates their detection. This predetermined value can also be a fixed value.
Le fait de baser la détection de défaut sur une comparaison du courant effectif Ie avec le courant théorique It permet en particulier d'effectuer une détection pertinente y compris lorsque le ralentisseur est en régime transitoire.Basing the fault detection on a comparison of the effective current Ie with the theoretical current It makes it possible in particular to perform a relevant detection even when the retarder is in a transient state.
Il est aussi possible de prévoir une détection basée sur une comparaison du courant effectif Ie avec la consigne de courant, dès lors que le ralentisseur est en régime permanent .It is also possible to provide detection based on a comparison of the effective current Ie with the current setpoint, as long as the retarder is in steady state.
Dans le cas de la figure 3, l'intensité Ie provient d'un capteur de courant qui est monté en série avec les bobines primaires 8. Mais ce capteur de courant peut aussi se présenter sous forme d'une ou plusieurs spires inductrices de mesure bobinées avec les bobines primaires 8. Dans ce cas, la tension apparaissant aux bornes de ces spires inductrices de mesure a la même allure que le courant circulant dans ces spires inductrices . Compte tenu des oscillations sinusoïdales provoquées par les courants mutuels résultant d'une diode défectueuse, la comparaison du courant théorique It avec 1 ' intensité effective Ie peut consister à déterminer la valeur maximale ou minimale prise par l ' intensité effective Ie pendant une durée prédéterminée correspondant à plusieurs périodes de rotation de l ' arbre 7, et à comparer ce maximum ou ce minimum avec la valeur de consigne Ci .In the case of FIG. 3, the intensity Ie comes from a current sensor which is connected in series with the primary coils 8. However, this current sensor may also be in the form of one or more measuring inductive turns. In this case, the voltage appearing at the terminals of these measuring inductive turns has the same speed as the current flowing in these inductive turns. Given the sinusoidal oscillations caused by the mutual currents resulting from a defective diode, the comparison of the theoretical current It with The effective intensity Ie may consist in determining the maximum or minimum value taken by the effective intensity Ie for a predetermined duration corresponding to several rotation periods of the shaft 7, and comparing this maximum or this minimum with the setpoint value. This .
Comme représenté schématiquement dans la figure 4 , le courant It qui est injecté dans les bobines primaires 8 est asservi sur le capteur 21, de manière à correspondre au mieux à la valeur de la consigne d'intensité Ci, cet asservissement étant mis en œuvre au niveau du boîtier de commande 19.As shown diagrammatically in FIG. 4, the current It which is injected into the primary coils 8 is slaved on the sensor 21, so as to best correspond to the value of the intensity setpoint Ci, this slaving being implemented at the level of the control box 19.
Le boîtier de commande comprend de manière précitée une électronique de puissance PU qui est pilotée par un correcteur CR pour injecter le courant d'excitation Ii dans les bobines primaires 8, ce qui donne lieu au courant induit dans les bobinages secondaires 5. L'intensité effective Ie est soustraite en 50 à la consigne d'intensité Ci pour constituer un signal d'entrée du correcteur CR qui pilote l'électronique de puissance PU.The control unit comprises, in the aforementioned manner, a power electronics PU which is controlled by a corrector CR for injecting the excitation current Ii into the primary coils 8, which gives rise to the current induced in the secondary windings 5. The intensity effective Ie is subtracted at 50 at the intensity setpoint Ci to constitute an input signal of the corrector CR which drives the power electronics PU.
Lorsque le correcteur reçoit en entrée un signal négatif, il pilote l'électronique de puissance PU pour diminuer le courant injecté, et lorsqu'il reçoit en entrée un signal positif il pilote l'électronique de puissance pour augmenter le courant injecté.When the corrector receives a negative signal input, it drives the power electronics PU to reduce the injected current, and when it receives a positive signal input it drives the power electronics to increase the injected current.
Comme représenté schêmatiquement en figure 4, le courant effectif Ie circulant dans les bobines primaires 8 correspond au courant Ii injecté par le boîtier de commande 19 auquel est soustrait en 40 le courant mutuel Im résultant d'un dysfonctionnement du redresseur 15.As shown schematically in FIG. 4, the effective current Ie flowing in the primary coils 8 corresponds to the current Ii injected by the control box 19 from which the mutual current Im resulting from a malfunction of the rectifier 15 is subtracted.
Le courant théorique It est déterminé dans le boîtier de commande 15 à partir de la valeur de consigne Ci, sur la base de la fonction de transfert Ft qui est notamment représentative de la réponse en intensité des bobines primaires 8 à l'application d'une tension U. Λ The theoretical current It is determined in the control box 15 from the set value Ci, on the basis of the transfer function Ft which is in particular representative of the intensity response of the primary coils 8 to the application of a U voltage. Λ
1515
Pour assurer une détection fiable de défaut d'une diode, l'asservissement du courant injecté ne compense pas les perturbations dues aux courants mutuels en cas de diode défectueuse. Ceci peut être obtenu en dimensionnant les bobines primaires de telle façon qu'elles aient une constante de temps Tl supérieure à N fois la constante de temps T2 des bobinages secondaires 5, N désignant un entier naturel. Avantageusement on choisit N supérieur ou égal à 3 pour que cette constante de temps Tl soit supérieure à trois fois la constante de temps T2 afin d'assurer une indépendance optimale de la détection.To ensure reliable fault detection of a diode, the control of the injected current does not compensate for disturbances due to mutual currents in the event of a faulty diode. This can be achieved by sizing the primary coils such that they have a time constant T1 greater than N times the time constant T2 of the secondary coils 5, where N designates a natural integer. Advantageously, N is chosen to be greater than or equal to 3 so that this time constant T1 is greater than three times the time constant T2 in order to ensure optimum independence of the detection.
Ceci peut également être obtenu par le choix d'un asservissement suffisamment lent vis-à-vis de la fréquence des oscillations dues aux courants mutuels. Un tel asservissement est ainsi insensible aux perturbations introduites par un dysfonctionnement d'un composant électrique porté par l'arbre rotatif. Dans ce cas, l'asservissement du courant injecté est choisi pour avoir une fréquence de coupure Fc vérifiant la relation Fc < l/ (2.N.pi .T2) , dans laquelle Fc est exprimée en Hertz, et T2 en secondes, pi représentant le nombre ayant une valeur proche de 3,14. De manière analogue, N est un entier naturel que l'on choisit avantageusement comme valant trois .This can also be achieved by choosing a servo slow enough vis-à-vis the frequency of oscillations due to mutual currents. Such a control is thus insensitive to the disturbances introduced by a malfunction of an electrical component carried by the rotary shaft. In this case, the servocontrol of the injected current is chosen to have a cut-off frequency Fc satisfying the relation Fc <l / (2.N.pi.T2), in which Fc is expressed in Hertz, and T2 in seconds, pi representing the number having a value close to 3.14. Similarly, N is a natural number which is advantageously chosen as three.
L'invention permet ainsi de détecter, sans contact; un défaut d'un composant électrique du rotor, ce composant pouvant être une diode ou un transistor du redresseur 15, mais ce composant pouvant également être un bobinage secondaire 15A, 15B ou 15C.The invention thus makes it possible to detect, without contact; a defect of an electrical component of the rotor, this component may be a diode or a transistor of the rectifier 15, but this component may also be a secondary winding 15A, 15B or 15C.
L'exemple décrit ci-dessus concerne un ralentisseur dans lequel la génératrice comprend des bobinages secondaires triphasés, mais l'invention s'applique également à un ralentisseur comprenant des bobinages secondaires ayant un nombre différent de phases, valant au minimum deux. The example described above relates to a retarder in which the generator comprises three-phase secondary windings, but the invention also applies to a retarder comprising secondary windings having a different number of phases, equal to at least two.

Claims

R E V E N D I C A T I O N S
1. Procédé de détection de défaut d'un organe électrique porté par un arbre rotatif (7) d'un raientisseur électromagnétique (1) , ce raientisseur comprenant des bobines primaires (8) statoriques, un boîtier de commande (19) pour injecter dans ces bobines primaires (8) un courant ayant une intensité correspondant à une intensité théorique (It) dépendant d'une consigne d'intensité (Ci), un capteur (21) délivrant un signal représentatif d'une valeur d'intensité effective (Ie) du courant circulant dans ces bobines primaires (8) , un arbre rotatif (7) portant des bobinages secondaires (5) définissant plusieurs phases et des bobines inductrices (13) ainsi qu'un redresseur de courant interposé entre les bobinages secondaires (5) et les bobines inductrices (13) , ce procédé consistant à comparer, dans le boîtier de commande, l'intensité théorique (It) et l'intensité effective (Ie) pour identifier un défaut en cas d'écart entre l'intensité théorique (It) et l'intensité effective (Ie) supérieur à une valeur seuil .1. A method for detecting a fault of an electrical member carried by a rotary shaft (7) of an electromagnetic driver (1), said greaser comprising statoric primary coils (8), a control box (19) for injecting into these primary coils (8) a current having an intensity corresponding to a theoretical intensity (It) dependent on an intensity reference (Ci), a sensor (21) delivering a signal representative of an effective intensity value (Ie ) of the current flowing in these primary coils (8), a rotary shaft (7) carrying secondary windings (5) defining a plurality of phases and inductor coils (13) and a current rectifier interposed between the secondary windings (5) and the inductive coils (13), which method consists of comparing, in the control box, the theoretical intensity (It) and the effective intensity (Ie) to identify a defect in the event of a difference between the theoretical intensity ( It) and the inte effective nsity (Ie) greater than a threshold value.
2. Procédé selon la revendication 1, consistant à déterminer un écart entre l'intensité théorique (It) et une valeur minimale ou maximale prise par 1 ' intensité effective (Ie) du courant traversant effectivement les bobines primaires (8) pendant un intervalle de temps prédéterminé .2. A method according to claim 1, comprising determining a difference between the theoretical intensity (It) and a minimum or maximum value taken by the effective intensity (Ie) of the current actually flowing through the primary coils (8) during a period of time. predetermined time.
3. Procédé selon la revendication 1 ou 2, dans lequel l'intensité théorique (It) est déterminée dans le boîtier de commande (19) à partir de la consigne d'intensité (Ci) et de données représentatives d'une fonction de transfert (Ft) du ralentisseur .3. Method according to claim 1 or 2, wherein the theoretical intensity (It) is determined in the control box (19) from the intensity reference (Ci) and data representative of a transfer function. (Ft) of the retarder.
4. Procédé selon la revendication 3, consistant à prendre en compte la consigne d'intensité Ci comme valeur représentative de l'intensité théorique It.4. Method according to claim 3, comprising taking into account the intensity setpoint Ci as a value representative of the theoretical intensity It.
5. Procédé selon l'une des revendications 1 à 4, consistant à asservir, depuis le boîtier de commande (19) , le courant injecté dans les bobines primaires (8) sur le signal délivré par le capteur de courant (21) , et à prévoir des bobines primaires (8) ayant une constante de temps (Tl) trois fois supérieure à la constante de5. Method according to one of claims 1 to 4, consisting of enslaving, from the control box (19), the current injected into the primary coils (8) on the signal delivered by the current sensor (21), and to provide primary coils (8) having a time constant (T1) three times greater than the constant of
5 temps (T2) des bobinages secondaires (5) .5 times (T2) of the secondary windings (5).
6. Procédé selon l'une des revendications 1 à 4, consistant à asservir, depuis le boîtier de commande (19) , le courant injecté dans les bobines primaires (8) sur le signal délivré par le capteur (21) , avec un6. Method according to one of claims 1 to 4, of servo, from the control box (19), the current injected into the primary coils (8) on the signal delivered by the sensor (21), with a
10 asservissement ayant un temps de réaction suffisamment long pour être insensible à un défaut d'un organe électrique porté par l'arbre rotatif (7).10 servo having a reaction time long enough to be insensitive to a fault of an electrical member carried by the rotary shaft (7).
7. Procédé selon la revendication 6, consistant à prévoir un asservissement ayant une fréquence de coupure7. The method of claim 6, comprising providing a servocontrol having a cutoff frequency
15 Fc vérifiant la relation Fc < l/ (3.2.pi.T2) dans laquelle Fc est exprimée en Hertz et dans laquelle T2 est la constante de temps des bobinages secondaires exprimée en secondes .Fc satisfying the relation Fc <l / (3.2.pi.T2) in which Fc is expressed in Hertz and in which T2 is the time constant of the secondary windings expressed in seconds.
8. Procédé selon l'une des revendications 20 précédentes consistant à mettre en œuvre des spires inductives de mesure comme capteur du courant effectif (Ie) .8. Method according to one of the preceding claims 20 to implement inductive measuring turns as effective current sensor (Ie).
9. Ralentisseur électromagnétique comprenant des bobines primaires (8) statoriques, un boîtier de commande9. Electromagnetic retarder comprising stator primary coils (8), a control box
25. (19) pour injecter dans ces bobines primaires (8) un courant ayant une intensité correspondant à une intensité théorique (It) dépendant d'une consigne d'intensité (Ci), un capteur (21) délivrant un signal représentatif d'une valeur d'intensité effective du courant circulant dans25. (19) for injecting into these primary coils (8) a current having an intensity corresponding to a theoretical intensity (It) dependent on an intensity reference (Ci), a sensor (21) delivering a signal representative of an effective intensity value of the current flowing in
30 ces bobines primaires (8) , un arbre rotatif (7) portant des bobinages secondaires (5) définissant plusieurs phases et, des bobines inductrices (13) ainsi qu'un redresseur de courant interposé entre les bobinages secondaires (5) et les bobines inductrices (13) , et desThese primary coils (8), a rotary shaft (7) carrying secondary coils (5) defining a plurality of phases and inductor coils (13) and a current rectifier interposed between the secondary coils (5) and the coils inductors (13), and
35 moyens de comparaison de l'intensité théorique (It) avec l'intensité effective (Ie) pour identifier un défaut de fonctionnement d'un organe électrique porté par l'arbre rotatif (7) en cas d'écart entre l'intensité théorique (It) et l'intensité effective (Ie) supérieur à une valeur seuil .35 means for comparing the theoretical intensity (It) with the effective intensity (Ie) to identify a malfunction of an electrical member carried by the shaft rotary (7) in the event of a difference between the theoretical intensity (It) and the effective intensity (Ie) greater than a threshold value.
10. Ralentisseur électromagnétique selon la revendication 9, comprenant des moyens d'asservissement du courant injecté dans les bobines primaires (8) sur le signal délivré par le capteur (21), et des bobines primaires (8) ayant une constante de temps (Tl) supérieure à trois fois la constante de temps (T2) des bobinages secondaire.10. An electromagnetic retarder according to claim 9, comprising means for controlling the current injected into the primary coils (8) on the signal delivered by the sensor (21), and primary coils (8) having a time constant (T1). ) greater than three times the time constant (T2) of the secondary windings.
11. Ralentisseur électromagnétique selon la revendication 10, comprenant des moyens d'asservissement du courant injecté dans les bobines primaires (8) sur le signal délivré par le capteur (21) , et dans lequel cet asservissement a une fréquence de coupure Fc vérifiant la relation Fc < l/ (3.2.pi.T2) dans laquelle Fc est exprimée en Hertz et dans laquelle T2 est la constante de temps des bobinages secondaires exprimée en secondes.11. An electromagnetic retarder according to claim 10, comprising means for controlling the current injected into the primary coils (8) on the signal delivered by the sensor (21), and wherein this servocontrol has a cut-off frequency Fc satisfying the relationship. Fc <l / (3.2.pi.T2) in which Fc is expressed in Hertz and in which T2 is the time constant of the secondary windings expressed in seconds.
12. Ralentisseur selon l'une des revendications 9 à 11, dans lequel le capteur (21) comprend une ou plusieurs spires inductrices de mesure bobinée avec les bobines primaires . 12. Retarder according to one of claims 9 to 11, wherein the sensor (21) comprises one or more measuring inductive turns coiled with the primary coils.
EP06841953A 2005-12-19 2006-12-15 Method for detecting a malfunction in an electromagnetic retarder Withdrawn EP1964248A1 (en)

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FR0553939A FR2895166B1 (en) 2005-12-19 2005-12-19 METHOD OF DETECTING FAULT OF FURNITURE OF ELECTROMAGNETIC RETARDER
PCT/FR2006/002750 WO2007080279A1 (en) 2005-12-19 2006-12-15 Method for detecting a malfunction in an electromagnetic retarder

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