Classifications

• • 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

Definitions

• the invention relates to a method for controlling an electromagnetic retarder comprising a current generator including primary coils in which an excitation current is injected.
• 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 slowdown is generated with inductor coils fed with direct current to produce
• I 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 eddy currents that they generate in the disc are opposed by their effects to the cause that gave rise to them, which produces a resistive torque on the disc and thus on the rotary shaft. , to slow down the vehicle.
• 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.
• a current generator is integrated in the retarder.
• the electrical supply of the inductor coils is provided by a generator comprising stator primary coils fed by the vehicle network, and rotor secondary coils integral with the rotary shaft. .
• the inductor coils are then integral with the rotary shaft by being radially projecting, so that they rotate with the rotary shaft 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 secondary rotor windings of the generator and the inductor coils, for converting the alternating current delivered by the secondary windings of the generator into DC power supply of the inductor coils.
• Two consecutive radial inductor coils around the axis of rotation generate magnetic fields of opposite directions, one generating a centrifugally oriented field, 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 rotary shaft. , which slows down the vehicle.
• 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.
• the object of the invention is a method of determining the maximum allowable current of the excitation current of the primary coils of an electromagnetic retarder to improve its performance and reliability.
• the subject of the invention is a method for determining, in a control box, a maximum allowable intensity (Imax) of an excitation current to be injected in stator primary coils of an electromagnetic retarder comprising a shaft.
• rotary device carrying secondary windings and induction coils fed electrically by these secondary windings, the primary coils and the secondary coils forming a generator, this retarder comprising a fixed cylindrical jacket surrounding the induction coils and in which the inductor coils generate eddy currents, and a fluid circulation cooling circuit of this jacket, this method of determining the maximum intensity in real time from measurements representative of the rotational speed (Na) of the rotary shaft, the power calorific that the cooling circuit is able to dissipate, and the flow rate of the coolant, these data from sensors connected to the control box.
• Na rotational speed
• the optimization in real time of the intensity of the excitation current which is injected into the primary coils according to the operating conditions of the retarder makes it possible to increase the braking torque. It makes it possible to integrate different distinct operating constraints in order to determine a maximum allowable current intensity which is optimal at each instant in view of the thermal operating conditions of the retarder.
• the invention also relates to a method as defined above, in which the measurements representative of the heating power that the cooling circuit is capable of dissipating comprise a difference value between the temperature of the cooling liquid at the inlet and at the outlet of the cooling circuit and a representative value of the coolant flow.
• the invention also relates to a method as defined above, of determining a first intensity from the rotational speed of the rotary shaft, a second intensity from the heat output that the cooling circuit is capable of dissipating. , and a third intensity from the coolant flow rate and assigning to the maximum allowable intensity the smallest value among the first, the second and the third intensity.
• the invention also relates to a method as defined above, in which the maximum intensity in the control box are determined from tables of digital values stored in this control box, these tables comprising values representative of the maximum permissible current for different operating conditions.
• the invention also relates to a method as defined above, in which the values are stored in the form of a crossed dynamic table.
• the invention also relates to a method as defined above, consisting in determining the representative value of the coolant flow rate from the engine speed of a vehicle engine and a characteristic abacus of a driven water pump. by this heat engine, this water pump causing the circulation of the coolant.
• the invention also relates to a method as defined above, in which the significant value of the engine speed is derived from data transmitted by a CAN bus.
• Figure 1 is an overall view with a local tear of an electromagnetic retarder to which the invention applies;
• Figure 2 is a schematic representation of the electrical components of the retarder to which the method according to the invention is applied;
• FIG. 3 is a curve representative of the admissible intensity as a function of the speed of rotation of the rotary shaft
• FIG. 4 is a representative curve of the critical jacket temperature as a function of the coolant flow rate.
• 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 part 4 by which the retarder 1 is fixed to a housing gearbox either directly or indirectly, here via a speed multiplier marked 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 a gearbox via the speed multiplier 6.
• a current generator which comprises fixed or statoric primary coils 8 which surround rotor secondary coils, integral with the rotary shaft 7.
• These secondary windings are symbolically represented in FIG. 2 and marked by reference numeral 5.
• These secondary windings 5 here comprise three separate windings 5A, 5B and 5C for delivering a three-phase alternating current having a frequency conditioned by the speed of rotation of the shaft. rotating 7.
• a fixed 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 coolant of this jacket 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 discharge duct 12 of the coolant out of this space 10.
• the cooling circuit of the retarder can be connected in series with the cooling circuit of the engine of the vehicle that the retarder team.
• the input 11 is connected to the output of the heat engine, the output 12 being connected to the input of a cooling radiator of this circuit.
• 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 tree 7.
• 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 secondary rotor windings 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 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 at the junction of the lid 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 17.
• the biasing of the retarder consists in supplying the primary coils 8 with an excitation current coming from the electrical network of the vehicle and in particular from the battery so that the generator delivers a current at its secondary coils 5.
• This current delivered by the generator then feeds the inductor coils 13 so as to generate eddy currents in the fixed cylindrical jacket 9 to produce a resistive torque ensuring the slowing down of the vehicle.
• the excitation current is injected into the primary coils 8 by means of a control box described hereinafter.
• the electric power delivered by the secondary windings 5 of the generator is greater than the electrical power supply of the primary coils 8, since it is the result of the magnetic field of the primary coils 8 and the work provided by the rotary shaft.
• the shaft 7 of the retarder is connected to the transmission shaft of the vehicle wheels via the multiplier 6 acting on a secondary shaft of the gearbox connected to the main shaft of the -this.
• This retarder comprises a control unit 19 represented in FIG. 2, which is interposed for example between a vehicle power supply source, and the primary coils 8.
• the control unit 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 8 so as to prevent the flow of a reverse current in the primary coils.
• the control unit 19 of the retarder is an electronic box comprising for example an ASIC type logic circuit operating at 5V, and / or a Power control circuit capable of handling high current currents.
• This control unit 19 comprises an input capable of receiving a control signal from the retarder, representative of a level of retarding torque requested from the retarder.
• the control unit 19 determines in real time a maximum intensity Imax admissible for the current to be injected in the primary coils 8. It then defines the value of the intensity Ie of the excitation current, starting from the maximum intensity Imax and of the value taken by the control signal.
• the maximum permissible intensity Imax of the excitation current Ie to be injected in the primary coils is determined in the control box 19 in real time on the basis of data and measurements representative of the rotational speed of the rotary shaft 7, the heat output that the cooling system is able to dissipate, and the flow rate of the coolant.
• the control box 19 first determines three intensities, denoted respectively II, 12 and 13, corresponding to three distinct criteria, and it assigns Imax the lowest of the three values II, 12 and 13.
• the first intensity, II is a threshold value of the excitation current Ie, beyond which the current If flowing in the inductor coils 13 is too high, and causes damage to the inductor coils 13 or the rectifier bridge 15, or secondary windings 5A-5C.
• This first intensity II depends mainly on the rotation speed Na of the rotary shaft 7, since for the same value of excitation current Ie injected into the primary coils, the intensity of the current If flowing in the inductor coils 13 increases with the rotation regime Na of the shaft 7.
• the intensity 12 is a threshold value beyond which the heating power generated by the eddy currents is greater than the heat output that the cooling circuit is capable of discharging. If the intensity of the excitation current Ie is greater than 12, the coolant boils.
• the intensity 13 is a threshold value beyond which the temperature of the cylindrical liner 9 is too high and also causes the boiling of the coolant, even if it is capable of evacuating the heating power generated. by the currents of Foucault.
• the intensity II is determined by reading in a data table stored in the control box 19, which comprises, for different values of the rotation speed Na, the admissible current for the excitation current Ie.
• This table corresponds to the graph of FIG. 3, representative of the current Ie admissible as a function of the regime Na, and which is a decreasing curve with a horizontal asymptote.
• the rotational speed Na of the rotary shaft 7 can come from a speed sensor rotational equipment of the retarder, or be deduced from data available on a CAN data bus of the vehicle to which the housing 19 is connected.
• the factor of the speed multiplier 6 is stored in the control box 19 to enable the determination of the speed Na from the data of the CAN bus.
• the second intensity 12 is determined from data and measurements representative of the heating power that the liquid cooling circuit is capable of dissipating, so as to generate eddy currents generating a corresponding heat output. to the heat output that the cooling system is able to dissipate.
• This heating capacity is conditioned mainly by a difference, denoted DT, between the temperature of the coolant inlet 11 of the cooler and the outlet 12 of the grinder, and by the flow rate, denoted D, of the coolant in the stirrer.
• the heating capacity that the cooling circuit can dissipate is even higher than the difference DT and the flow D are important.
• the temperature difference DT is determined from two thermal probes placed respectively at the inlet 11 and at the outlet 12 of the cooling circuit, these probes being connected to the control box 19.
• the flow rate D of the coolant corresponds to the rotational speed of a water pump driven by the engine of the vehicle, and which causes the circulation of the liquid in the cooling circuit.
• the flow rate D results from the rotational speed of the heat engine, denoted Nt, and an abacus representative of the characteristic of this pump.
• the control box 19 retrieves on the CAN bus the rotational speed Nt to determine the flow rate D from the pump chart stored in this control box 19.
• the heating power to be dissipated by the liquid cooling circuit corresponds mainly to the heating power resulting from the eddy currents flowing in the cylindrical jacket 9. This is directly related to the intensity of the current, denoted If, which flows in the coils. 13. This current If itself has an intensity depending on the rotational speed Na of the rotary shaft 7, and the intensity of the excitation current Ie.
• Determining the second intensity 12 consists in first identifying a threshold value of the current If flowing in the inductor coils beyond the heat output generated by the eddy currents would be greater than the heat output that the liquid cooling circuit is capable of dissipating.
• This threshold value of the intensity of the current If which therefore depends on the difference DT and the rate D, is for example read in a digital data table stored in the control box 19.
• the value of the second intensity 12 of the excitation current is read in another data table.
• This other data table indicates the value of Ie for different values of If and Na.
• the third intensity 13 corresponds to a condition to be met by the temperature of the jacket, which must remain below a critical temperature, noted Tc, not to cause the boiling liquid to cool.
• This critical temperature Tc depends mainly on the flow rate D of coolant, according to a law of evolution represented on the graph of FIG. 4: the higher the flow rate D, the higher the critical temperature Tc can be important.
• the temperature of the cylindrical jacket 9 depends mainly on the intensity If of the current flowing in the inductor coils 13.
• this third intensity 13 consists in first reading the critical temperature Tc admissible for the rate D considered in a data table stored in the control box 19, this data table corresponding to the graph of FIG. 4. The value of the current If flowing in the inductor coils 13 and corresponding to the critical temperature Tc is then read in another data table which gives, for different critical temperatures Tc, the corresponding value of If, for normal operating conditions, c that is, for a coolant temperature close to one hundred and five degrees.
• the value of 13 is then determined from the regime Na of the rotary shaft 7 and the current If determined above, by reading in another data table mapping Ie and If for different values of the control Na.
• the data is stored in the control box 19 as separate data tables, but. these data can be stored in the form of one or more crossed dynamic tables.
• the intensities 12 and 13 are determined by referring, intermediately, to threshold values of the current If flowing in the inductive coils 13, and by determining the intensity of the excitation current, 12 or 13 at the value of If desired, for the Na regime considered.
• the value of 12 can be directly read from a table giving values of 12 from different D-flow rate values and DT differences.
• the value of 13 can be determined by direct reading in a data table giving values of 13 corresponding to different values of the rate D.
• the invention also increases the reliability and longevity of the retarder by avoiding to operate in a range beyond its possibilities.

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• Engineering & Computer Science (AREA)
• Power Engineering (AREA)
• Transportation (AREA)
• Mechanical Engineering (AREA)
• Dynamo-Electric Clutches, Dynamo-Electric Brakes (AREA)
• Motor Or Generator Cooling System (AREA)

Applications Claiming Priority (2)

Publications (1)

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ID=37016187

Family Applications (1)

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Family Cites Families (12)

• 2005
  • 2005-12-22 FR FR0554045A patent/FR2895595B1/fr not_active Expired - Fee Related
• 2006
  • 2006-12-15 US US12/092,144 patent/US20080290727A1/en not_active Abandoned
  • 2006-12-15 CN CNA2006800487162A patent/CN101346876A/zh active Pending
  • 2006-12-15 WO PCT/FR2006/002749 patent/WO2007080278A2/fr not_active Ceased
  • 2006-12-15 MX MX2008008347A patent/MX2008008347A/es unknown
  • 2006-12-15 EP EP06841952A patent/EP1964254A2/de not_active Withdrawn
  • 2006-12-15 BR BRPI0618817-6A patent/BRPI0618817A2/pt not_active IP Right Cessation

Non-Patent Citations (1)

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