WO1994028613A1 - Moteur cc a aimants permanents alimente par batterie - Google Patents

Moteur cc a aimants permanents alimente par batterie Download PDF

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Publication number
WO1994028613A1
WO1994028613A1 PCT/AU1994/000257 AU9400257W WO9428613A1 WO 1994028613 A1 WO1994028613 A1 WO 1994028613A1 AU 9400257 W AU9400257 W AU 9400257W WO 9428613 A1 WO9428613 A1 WO 9428613A1
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WO
WIPO (PCT)
Prior art keywords
motor
direct current
permanent magnet
armature
turns
Prior art date
Application number
PCT/AU1994/000257
Other languages
English (en)
Inventor
Colin Edward Cartwright
Original Assignee
Colin Edward Cartwright
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
Priority claimed from PCT/GB1993/002291 external-priority patent/WO1994011941A1/fr
Priority claimed from PCT/GB1993/002293 external-priority patent/WO1994011162A1/fr
Application filed by Colin Edward Cartwright filed Critical Colin Edward Cartwright
Priority to AU67178/94A priority Critical patent/AU6717894A/en
Publication of WO1994028613A1 publication Critical patent/WO1994028613A1/fr

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Classifications

    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02K—DYNAMO-ELECTRIC MACHINES
    • H02K23/00—DC commutator motors or generators having mechanical commutator; Universal AC/DC commutator motors
    • H02K23/26—DC commutator motors or generators having mechanical commutator; Universal AC/DC commutator motors characterised by the armature windings
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J7/00—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02K—DYNAMO-ELECTRIC MACHINES
    • H02K23/00—DC commutator motors or generators having mechanical commutator; Universal AC/DC commutator motors
    • H02K23/02—DC commutator motors or generators having mechanical commutator; Universal AC/DC commutator motors characterised by arrangement for exciting
    • H02K23/04—DC commutator motors or generators having mechanical commutator; Universal AC/DC commutator motors characterised by arrangement for exciting having permanent magnet excitation

Definitions

  • This invention relates to improvements to permanent magnet
  • Direct Current (D.C.) electric motors Such motors are generally used in battery powered hand-held tools such as screw drivers and drills and certain propulsion vehicles. These motors may have permanent magnets situated around the yolk of the motor (providing stationary magnetic field) and a split commutator which distributes electric power to electro-magnet armature pole-pieces. Such motors are known as permanent magnet direct current motors.
  • a further problem with battery driven permanent magnet motors is that they are designed such that the battery and motor are not ideally matched, therefore the performance of such tools can be improved by suitable matching.
  • an arrangement including: a permanent magnet direct current motor; and a battery means for providing electrical power to the permanent magnet direct current motor, wherein the resistance of the permanent magnet direct current motor is substantially greater than that of the internal resistance of the battery means.
  • an arrangement including: a permanent magnet direct current motor; and a battery means for providing electrical power to the permanent magnet direct current motor, wherein the resistance across the battery means is substantially greater than that of the internal resistance of the battery means.
  • an arrangement including: a permanent magnet direct current motor; and a battery means for providing electrical power to the permanent magnet direct current motor, the battery means having a low internal resistance whereby it is possible to damage the battery means by drawing excessive currents, wherein the arrangement is adapted such that the current drawn by the motor will not cause damage to occur to the battery means when the motor is in a stalled condition for a substantial period of time.
  • an arrangement including:
  • SUBSTITUTE SHEET (Rule 2o> a permanent magnet direct current motor; and a battery means for providing electrical power to the permanent magnet direct current motor, wherein the total circuit resistance of the battery means and permanent magnet direct current motor is such that the magnetic saturation of at least one armature pole-piece is saturated to a maximum imit when the permanent magnet direct current motor's output shaft is stalled.
  • the maximum limit is 25% of saturation.
  • an arrangement including: a permanent magnet direct current motor; a battery means for providing electrical power to the permanent magnet direct current motor; and, a current limiting means adapted to limit the current flowing from the battery to the armature of the permanent magnet direct current motor, wherein the current limiting means limits the current so that the magnetic saturation of at least one armature pole-piece is saturated to a maximum limit when the permanent magnet direct current motor's output shaft is stalled.
  • the maximum limit is 25% of saturation.
  • an arrangement including: a battery means having an output voltage of at least 5 volts; and a permanent magnet direct current motor adapted to be electrically connected to the battery means, the permanent magnet direct current motor having an efficiency of greater than 40% when the motor drives a variable load over at least 15% of the total output torque range at the output of the motor, wherein the efficiency is calculated by: where output power is the power at the output of the motor's shaft and input power is the input power to the motor.
  • an arrangement including: battery means having an output voltage of at least 5 volts; and permanent magnet direct current motor adapted to be electrically connected to the battery means, the permanent magnet direct current motor having an efficiency of greater than 50% when the motor drives a variable load over at least 15% of the total output torque range at the output of the motor, wherein the efficiency is calculated by: where output power is the power at the output of the motor's shaft and input power is the input power to the motor.
  • an arrangement including: a battery means having an output voltage of at least 5 volts; and a permanent magnet direct current motor adapted to be electrically connected to the battery means, the permanent magnet direct current motor having an efficiency of greater than 55% when the motor drives a variable load over at least 15% of the total output torque range at the output of the motor, wherein the efficiency is calculated by: where output power is the power at the output of the motor's shaft and input power is the input power to the motor.
  • an arrangement including: a battery means having an output voltage of at least 5 volts; and a permanent magnet direct current motor adapted to be electrically connected to the battery means, the permanent magnet direct current motor having an efficiency of greater than 60% when the motor drives a variable load over at least 15% of the total output torque range at the output of the motor, wherein the efficiency is calculated by: efficiency ⁇ ] output power / input power x 100 where output power is the power at the output of the motor's shaft and input power is the input power to the motor.
  • a battery means having an output voltage of at least 5 volts; and a permanent magnet direct current motor adapted to be electrically connected to the battery means, the permanent magnet direct current motor being wound such that each individual coil between two armature commutator segments has more than 30 turns.
  • the direct current permanent magnet motor is wound such that when it is connected to a 12 Volt battery means the motor's stall current does not exceed 4 amps.
  • the battery means comprises at least one Nickel Cadmium battery.
  • the battery means has an internal resistance of less than 250 milli Ohms per cell.
  • the arrangement is part of a portable power tools such as a drill or screwdriver.
  • a direct current permanent magnet motor having an efficiency of greater than 40% when the motor drives a variable load over at least 15% of the total output torque range at the output of the motor, wherein the efficiency is calculated by: e ffi ci en cy- Joutput power / input power x 100 where output power is the power at the output of the motor's shaft and input power is the input power to the motor.
  • each individual coil between two armature commutator segments has between 35 to 400 turns.
  • each individual coil between two armature commutator segments has between 50 to 400 turns. in another preferred form, and referring to any of the above alternative forms, each individual coil between two armature commutator segments has between 75 to 400 turns. In another preferred form, and referring to any of the above alternative forms, each individual coil between two armature commutator segments has between 100 to 400 turns.
  • each individual coil between two armature commutator segments has between 125 to 400 turns.
  • each individual coil between two armature commutator segments has between 35 to 375 turns. In another preferred form, and referring to any of the above alternative forms, each individual coil between two armature commutator segments has between 50 to 375 turns.
  • each individual coil between two armature commutator segments has between 75 to 375 turns.
  • each individual coil between two armature commutator segments has between 100 to 375 turns.
  • each individual coil between two armature commutator segments has between 125 to 375 turns.
  • each individual coil between two armature commutator segments has between 35 to 350 turns. In another preferred form, and referring to any of the above alternative forms, each individual coil between two armature commutator segments has between 50 to 350 turns.
  • each individual coil between two armature commutator segments has between 75 to 350 turns.
  • each individual coil between two armature commutator segments has between 100 to 350 turns.
  • each individual coil between two armature commutator segments has between 125 to 350 turns.
  • each individual coil between two armature commutator segments has between 35 to 325 turns. In another preferred form, and referring to any of the above alternative forms, each individual coil between two armature commutator segments has between 50 to 325 turns.
  • each individual coil between two armature commutator segments has between 75 to 325 turns.
  • each individual coil between two armature commutator segments has between 100 to 325 turns.
  • each individual coil between two armature commutator segments has between 125 to 325 turns.
  • each individual coil between two armature commutator segments has between 35 to 300 turns. In another preferred form, and referring to any of the above alternative forms, each individual coil between two armature commutator segments has between 50 to 300 turns.
  • each individual coil between two armature commutator segments has between 75 to 300 turns. In another preferred form, and referring to any of the above alternative forms, each individual coil between two armature commutator segments has between 100 to 300 turns.
  • each individual coil between two armature commutator segments has between 125 to 300 turns.
  • each individual coil between two armature commutator segments has between 35 to 275 turns. In another preferred form, and referring to any of the above alternative forms, each individual coil between two armature commutator segments has between 50 to 275 turns.
  • each individual coil between two armature commutator segments has between 75 to 275 turns.
  • each individual coil between two armature commutator segments has between 100 to 275 turns.
  • each individual coil between two armature commutator segments has between 125 to 275 turns.
  • each individual coil between two armature commutator segments has between 35 to 250 turns. In another preferred form, and referring to any of the above alternative forms, each individual coil between two armature commutator segments has between 50 to 250 turns.
  • each individual coil between two armature commutator segments has between 75 to 250 turns. In another preferred form, and referring to any of the above alternative forms, each individual coil between two armature commutator segments has between 100 to 250 turns.
  • each individual coil between two armature commutator segments has between 125 to 250 turns.
  • each individual coil between two armature commutator segments has between 35 to 225 turns. In another preferred form, and referring to any of the above alternative forms, each individual coil between two armature commutator segments has between 50 to 225 turns.
  • each individual coil between two armature commutator segments has between 75 to 225 turns.
  • each individual coil between two armature commutator segments has between 100 to 225 turns.
  • each individual coil between two armature commutator segments has between 125 to 225 turns.
  • each individual coil between two armature commutator segments has between 35 to 200 turns. In another preferred form, and referring to any of the above alternative forms, each individual coil between two armature commutator segments has between 50 to 200 turns.
  • each individual coil between two armature commutator segments has between 75 to 200 turns. In another preferred form, and referring to any of the above alternative forms, each individual coil between two armature commutator segments has between 100 to 200 turns.
  • each individual coil between two armature commutator segments has between 125 to 200 turns.
  • each individual coil between two armature commutator segments has between 35 to 175 turns. In another preferred form, and referring to any of the above alternative forms, each individual coil between two armature commutator segments has between 50 to 175 turns.
  • each individual coil between two armature commutator segments has between 75 to 175 turns.
  • each individual coil between two armature commutator segments has between 100 to 175 turns.
  • each individual coil between two armature commutator segments has between 125 to 175 turns.
  • the wire gauge of each individual coil is the thickest that can be wound upon the armature for the given number of turns.
  • an arrangement including: a permanent magnet direct current motor; a battery means for providing electrical power to the permanent magnet direct current motor; and, a current limiting means adapted to limit the current flowing from the battery to the armature of the permanent magnet direct current motor, wherein the current limiting means limits the current so that the magnetic saturation of at least one armature pole-piece is saturated to a maximum limit when the permanent magnet direct current motor's output shaft is stalled.
  • the maximum limit is 25%.
  • the diameter if the armature is less than 50mm.
  • the length of the armature is less than 35mm.
  • the wire gauge of each individual coil is less than 0.4mm.
  • capacitors are connected across each pole- piece winding. This offers the additional advantage of substantially reducing radio frequency interference. This is not achievable with motors currently used for example in commercially available power tools. With such tools the excessive currents required by the armature and physical size capacitor constraints do not readily allow for such capacitors to be connected across each pole winding.
  • the invention can be illustrated by reference to one form of electric motor namely a small direct current electric motor although the applicability of the discoveries may extend beyond this specific application.
  • the invention will be described with respect to small electric motors in which the armature has a plurality of poles established by reason of a laminated ferromagnetic core and insulated wire wound around, as a coil, each of the poles of the common core.
  • Each of the coils is connected electrically to appropriate segments of a commutator and there are brushes engaging the commutator to supply current to the respective coils as they rotate relative to a yoke.
  • the yoke is comprised of a permanent magnet or magnets with which the magnetic field created within each of the coils of the armature interact in a consecutive way.
  • This describes a conventional small permanent magnet direct current (D.C.) motor of a type of which millions exist.
  • D.C. permanent magnet direct current
  • Such motors are generally used in battery powered hand-held tools such as screw drivers and drills; or propulsion vehicles that are powered by Solar Cells, batteries or a combination of both.
  • These motors may have permanent magnets situated around the yoke of the motor (providing a stationary magnetic field) and a split commutator which distributes electric power to electro-magnet armature pole-pieces.
  • Such motors are known as permanent magnet direct current motors.
  • an electrical motor comprising two parts, these being adapted to be caused to have relatively reacting forces between the respective parts upon the supplying of electrical current into at least a first one of the parts to effect a magnetic field to react magnetically with the other of the parts, wherein the first one of the parts includes a plurality of coils of electrically conducting insulated wire around a former, and a second one of the parts has a magnetic field adapted to interact with a field from the coils, the number of turns of windings around the former for each of the coils on the first one of the parts being substantially greater than the number of turns that would conventionally exist hitherto in respect of motors which are otherwise the same.
  • the electrical motor is a direct current motor. In preference, the electrical motor is a permanent magnet motor.
  • an electric motor having a permanent magnetic field or fields and a plurality of coils wound upon a former or formers to provide an electromagnetic field for provide a relative mechanical movement between the permanent magnetic field and the electromagnetic field, wherein the coils for providing the electromagnetic field are wound such that when the motors rated voltage is applied thereto the electromagnetic field and its associated former are substantially magnetically saturated under stall conditions of the motor.
  • an electric motor having a permanent magnetic field or fields and a plurality of coils wound upon a former or formers to provide an electromagnetic field for effecting a relative mechanical movement between the permanent magnetic field and the electromagnetic field, wherein the coils for providing the electromagnetic field are wound such that when the motor's rated voltage is applied thereto the electromagnetic field and its associated former are within the non linear portion of their magnetization curve when the motor is under stall conditions such that the amount of flux density attributable to the non linear portion is at least 20% of the total flux density of the electromagnetic field and its associated former.
  • a direct current supply means electrically connected to an electric motor having a permanent magnetic field or fields and a plurality of coils wound upon a former or formers to provide an electromagnetic field for effecting a relative mechanical movement between the permanent magnetic field and the electromagnetic field, wherein the coils for providing the electromagnetic field are wound such that under stall conditions the current flowing from the direct current supply and into the coils is such that the amount of flux density attributable to the non linear portion of the coils' and core's magnetization curve is at least 20% of the total flux density of the coils and core.
  • an electric motor comprising a yoke and an armature, the armature being adapted to be supplied with direct electrical current through a commutator to each of a plurality of poles, the armature having a magnetically permeable core providing a former for each of the plurality of poles for the armature, there being a coil wound around the former in respect to each pole, the arrangement being characterised in that the number of turns in the windings of each coil for a respective pole, their location and other characteristics are such that there will be effected, at stall, a magnetic field which is substantially greater than required when supplied with a current supply at the motors rated voltage such that the magnetic field is in the non linear portion of the magnetization curve of the core acting as the former.
  • the motor is a direct current motor.
  • the coils and core are in the form of an armature.
  • the amount of flux density attributable to the non linear portion of the magnetization curve is at least 20% but no more than 25% of the total flux density of the coils and core.
  • the amount of flux density attributable to the non linear portion of the magnetization curve is at least 25% but no more than 30% of the total flux density of the coils and core.
  • the amount of flux density attributable to the non linear portion of the magnetization curve is at least 30% but no more than 35% of the total flux density of the coils and core. In preference, the amount of flux density attributable to the non linear portion of the magnetization curve is at least 35% but no more than 40% of the total flux density of the coils and core.
  • the amount of flux density attributable to the non linear portion of the magnetization curve is at least 40% but no more than 45% of the total flux density of the coils and core.
  • the amount of flux density attributable to the non linear portion of the magnetization curve is at least 45% but no more than 50% of the total flux density of the coils and core.
  • the amount of flux density attributable to the non linear portion of the magnetization curve is at least 50% but no more than 55% of the total flux density of the coils and core.
  • the amount of flux density attributable to the non linear portion of the magnetization curve is at least 55% but no more than 60% of the total flux density of the coils and core. In preference, the amount of flux density attributable to the non linear portion of the magnetization curve is at least 60% but no more than 65% of the total flux density of the coils and core. In preference, the amount of flux density attributable to the non linear portion of the magnetization curve is at least 70% but no more than 80% of the total flux density of the coils and core.
  • the amount of flux density attributable to the non linear portion of the magnetization curve is at least 80% but no more than 100% of the total flux density of the coils and core.
  • the amount of flux density attributable to the non linear portion of the magnetization curve is at least 90% but no more than 95% of the total flux density of the coils and core. In preference, the amount of flux density attributable to the non linear portion of the magnetization curve is at least 95% of the total flux density of the coils and core.
  • non linear portion of the magnetization curve is above the knee of the magnetization curve.
  • non linear portion of the magnetization curve is further characterised by:
  • the armature has a core comprised of a ferromagnetic material.
  • each coil is formed from wire having a gauge which offers substantial resistance to current flowing there through at the motors rated voltage.
  • each of the coils of the armature have a resistance such that the resistance across the brushes is no less than greater than 1.2 ohms.
  • the motor is connected to an electric power supply with a voltage which is the motors rated voltage.
  • an arrangement including: a permanent magnet direct current motor; and a direct current supply means for providing electrical power to the permanent magnet direct current motor, wherein the resistance of the motor is when connected across the direct current supply means is no less 20% of the internal resistance of the direct current supply means.
  • an arrangement including: a permanent magnet direct current motor; and a direct current supply means for providing electrical power to the permanent magnet direct current motor, the direct current supply means having a low internal resistance whereby it is possible to damage the direct current supply means by drawing excessive currents, wherein the arrangement is adapted such that the current drawn by the motor will not cause damage to occur to the direct current supply means when the motor is in a stalled condition for a substantial period of time.
  • an arrangement including: a permanent magnet direct current motor; and a direct current supply means for providing electrical power to the permanent magnet direct current motor, wherein the windings of the armature of the motor are such that under stall conditions the current flowing in the armature does not exceed the current rating of the battery.
  • an arrangement including: a permanent magnet direct current motor; and a direct current supply means for providing electrical power to the permanent magnet direct current motor, wherein the windings of the armature of the motor are such that under stall conditions the current flowing in the armature is between the range of 100% to 110% of the current rating of the battery.
  • an arrangement including: a permanent magnet direct current motor; and a direct current supply means for providing electrical power to the permanent magnet direct current motor, wherein the windings of the armature of the motor are such that under stall conditions the current flowing in the armature is between the range of 95% to 100% of the current rating of the battery.
  • an arrangement including: a permanent magnet direct current motor; and a direct current supply means for providing electrical power to the permanent magnet direct current motor, wherein the windings of the armature of the motor are such that under stall conditions the current flowing in the armature is between the range of 90% to 95% of the current rating of the battery.
  • an arrangement including: a permanent magnet direct current motor; and a direct current supply means for providing electrical power to the permanent magnet direct current motor, wherein the windings of the armature of the motor are such that under stall conditions the current flowing in the armature is between the range of 85% to 90% of the current rating of the battery.
  • an arrangement including: a permanent magnet direct current motor; and a direct current supply means for providing electrical power to the permanent magnet direct current motor, wherein the windings of the armature of the motor are such that under stall conditions the current flowing in the armature is between the range of 80% to 85% of the current rating of the battery.
  • an arrangement including: a permanent magnet direct current motor; and a direct current supply means for providing electrical power to the permanent magnet direct current motor, wherein the windings of the armature of the motor are such that under stall conditions the current flowing in the armature is between the range of 75% to 80% of the current rating of the battery.
  • an arrangement including: a permanent magnet direct current motor; and a direct current supply means for providing electrical power to the permanent magnet direct current motor, wherein the windings of the armature of the motor are such that under stall conditions the current flowing in the armature is between the range of 65% to 75% of the current rating of the battery.
  • a direct current supply means having an output voltage of at least 5 volts; and a permanent magnet direct current motor adapted to be electrically connected to the direct current supply means, the permanent magnet direct current motor being wound such that each individual coil between two armature commutator segments has more than 60 turns.
  • the direct current supply means is a battery.
  • the direct current supply means is a solar cell.
  • the battery comprises at least one Nickel Cadmium battery cell.
  • the battery has an internal resistance of less than 250 milli Ohms per cell.
  • the arrangement resides in a portable power tools such as a drill or screwdriver. In preference, the arrangement resides in a propulsion vehicle.
  • each individual coil between two armature commutator segments has between 75 to 200 turns.
  • each individual coil between two armature commutator segments has between 100 to 200 turns.
  • each individual coil between two armature commutator segments has between 125 to 200 turns. In another preferred form, and referring to any of the above forms, each individual coil between two armature commutator segments has between 75 to 175 turns.
  • each individual coil between two armature commutator segments has between 100 to 175 turns.
  • each individual coil between two armature commutator segments has between 125 to 175 turns.
  • each individual coil between two armature commutator segments has between 75 to 150 turns. In another preferred form, and referring to any of the above forms, each individual coil between two armature commutator segments has between 100 to 150 turns.
  • each individual coil between two armature commutator segments has between 105 to 150 turns.
  • each individual coil between two armature commutator segments has between 110 to 150 turns.
  • each individual coil between two armature commutator segments has between 115 to 150 turns.
  • each individual coil between two armature commutator segments has between 120 to 150 turns. In another preferred form, and referring to any of the above forms, each individual coil between two armature commutator segments has between 100 to 125 turns.
  • each individual coil between two armature commutator segments has between 100 to 120 turns. In another preferred form, and referring to any of the above forms, each individual coil between two armature commutator segments has between 105 to 120 turns.
  • each individual coil between two armature commutator segments has between 100 to 105 turns.
  • each individual coil between two armature commutator segments has between 105 to 115 turns. In another preferred form, and referring to any of the above forms, each individual coil between two armature commutator segments has between 110 to 115 turns.
  • the useful flux densisty of the yoke's magnetic field is approximately 900 Gauss (this may vary depending upon the type of permanent magnets used).
  • the current can be increased resulting in thicker windings or an increased voltage.
  • very high currents would be required (eg at least 30 to 40 Amps) which may destroy the armature's windings.
  • the number of turns of the coils can be increased and the cross-sectional area or gauge of wire used can be preferably decreased resulting in an increase in the resistance of the windings. This quite simply, at first sight, appears to be contrary to every known guiding principle in the design of these types of motors.
  • an electric motor having a permanent magnetic field or fields and a plurality of coils wound upon a former or formers to provide an electromagnetic field for provide a relative mechanical movement between the permanent magnetic field and the electromagnetic field, wherein the coils for providing the electromagnetic field are wound such that when the motors rated voltage is applied thereto the flux density of the electromagnetic field and its associated former are substantially identical to the flux density of the permanent magnetic field or fields when the motor is stalled.
  • a direct current supply means electrically connected to an electric motor having a permanent magnetic field or fields and a plurality of coils wound upon a former or formers to provide an electromagnetic field for effecting a relative mechanical movement between the permanent magnetic field and the electromagnetic field, wherein the coils for providing the electromagnetic field are wound such that the current flowing from the direct current supply and into the coils is such that the flux density of the electromagnetic field and its associated former have a similar value of flux density to that of the permanent magnetic field or fields when the motor is stalled.
  • an arrangement including: a permanent magnet direct current motor; and a direct current supply means for providing electrical power to the permanent magnet direct current motor, wherein the flux density of the armature has a similar value of flux density to that of the permanent magnetic field or fields when the motor stalled.
  • the coils and core are in the form of an armature.
  • the said flux density is the useful flux of the armature poles and permanent magnet.
  • similar value has the meaning no more than 20% difference.
  • similar value has the meaning no more than 2% difference. In preference, similar value has the meaning no more than 1% difference.
  • the armature has a core comprised of a ferromagnetic material.
  • each coil is formed from wire having a gauge which offers substantial resistance to current flowing therethrough at the motor's rated voltage.
  • each of the coils of the armature have a resistance such that the resistance across the brushes is no less than greater than 1.2 ohms.
  • the motor is connected to an electric power supply with a voltage which is the motor's rated voltage.
  • the direct current supply means is a battery.
  • the direct current supply means is a solar cell.
  • the battery comprises at least one Nickel Cadmium battery cell.
  • the arrangement resides in a portable power tools such as a drill or screwdriver.
  • the arrangement resides in a propulsion vehicle.
  • each individual coil between two armature commutator segments has between 75 to 200 turns.
  • each individual coil between two armature commutator segments has between 100 to 200 turns.
  • each individual coil between two armature commutator segments has between 125 to 200 turns. In another preferred form, and referring to any of the above forms, each individual coil between two armature commutator segments has between 75 to 175 turns.
  • each individual coil between two armature commutator segments has between 100 to 175 turns.
  • each individual coil between two armature commutator segments has between 125 to 175 turns. In another preferred form, and referring to any of the above forms, each individual coil between two armature commutator segments has between 75 to 150 turns.
  • each individual coil between two armature commutator segments has between 100 to 150 turns.
  • each individual coil between two armature commutator segments has between 105 to 150 turns.
  • each individual coil between two armature commutator segments has between 110 to 150 turns.
  • each individual coil between two armature commutator segments has between 115 to 150 turns. In another preferred form, and referring to any of the above forms, each individual coil between two armature commutator segments has between 120 to 150 turns.
  • each individual coil between two armature commutator segments has between 100 to 125 turns. In another preferred form, and referring to any of the above forms, each individual coil between two armature commutator segments has between 100 to 120 turns.
  • each individual coil between two armature commutator segments has between 105 to 120 turns.
  • each individual coil between two armature commutator segments has between 100 to 105 turns. In another preferred form, and referring to any of the above forms, each individual coil between two armature commutator segments has between 105 to 115 turns.
  • each individual coil between two armature commutator segments has between 110 to 115 turns.
  • This invention also relates to a portable multi purpose power tool powered by direct current power supply.
  • Direct current multi purpose power tools have been developed so that for example they can be used both as a drill or a screwdriver. Such tools have gearing to reduce the output speed from the direct current motor which is an integral part of the tool. The reason for the gearing is due to the design and type of motor which generally has an output shaft speed requiring speed reduction. Furthermore, such motors impose demands upon the direct current power supply (battery) and therefore the motor can rapidly drain the stored battery charge.
  • power tools are generally in the shape of a pistol. Hence, when working in tight corners or in confined spaces the pistol shape may not be suitable and therefore it may be impractical to use such power tools in these circumstances.
  • a portable power tool including: a first direct current storage means adapted to be electrically connected to a direct current motor by a switch means; and a circuit modification means adapted to allow a second direct current storage means to be inserted in series with the first direct current storage means.
  • the portable power tool has a means of changing the turning direction of the motor.
  • the second direct current storage means is contained within an attachment means adapted to engage the portable power tool.
  • the attachment means has an circuit modification means activator, wherein when the portable power tool is engaged by the attachment means the circuit modification means activator, in conjunction with the circuit modification means, inserts the second direct current storage means in series with the first direct current storage means.
  • the attachment means has a switch means adapted to electrically connect the first direct current storage means and second direct current storage means to the direct current motor.
  • an attachment means adapted to engage a power tool having a first direct current storage means, the attachment means having a second direct current storage means adapted to be inserted in series with the first direct current storage means.
  • the attachment means has a switch means adapted to provide a series connection of the first direct current storage means and second direct current storage means to a direct current electrical motor adapted to drive the power tool.
  • a portable power tool arrangement including: a power tool having a first direct current storage means adapted to be electrically connected to a direct current motor by a first switch means; a second direct current storage means contained within an attachment means, the attachment means engaging the power tool such that the second direct current storage means is inserted in series with the first direct current storage means, wherein the attachment means is adapted to disengage the power tool such that when disengaged the second direct current storage means is removed from being in series with the first direct current storage means.
  • the second direct current storage means is adapted to be removed from being in series with the first direct current storage means such that the first direct current storage means remains adapted to be electrically connected to the direct current motor by the switch means.
  • the portable power tool has a means of changing the turning direction of the motor.
  • the attachment means has a second switch means adapted to electrically connect the first direct current storage means and second direct current storage means to the direct current motor.
  • the attachment means has an interlock means adapted to activate the first switch means when the attachment means engages the power tool such that the second switch means provides the electrical connection between both the first direct current storage means and second direct current storage means and the direct current motor.
  • the motor is a permanent magnet direct current motor; and the first and second battery means for providing electrical power to the permanent magnet direct current motor have a low internal resistance whereby it is possible to damage either of the battery means by drawing excessive currents, wherein the arrangement is adapted such that the current drawn by the motor will not cause damage to occur to either of the battery means when the motor is in a stalled condition for a substantial period of time.
  • the direct current permanent magnet motor is wound such that when it is connected to a 12 Volt battery means the motors stall current does not exceed 4 amps.
  • the direct current permanent magnet motor has an efficiency of greater than 45% when the motor drives a variable load over at least 15% of the total output torque range at the output of the motor, wherein the efficiency is calculated by: efficiency - ⁇ output power / input power x 100 where output power is the power at the output of the motor's shaft and input power is the input power to the motor.
  • the direct current permanent magnet motor has an efficiency of greater than 50% when the motor drives a variable load over at least 15% of the total output torque range at the output of the motor, wherein the efficiency is calculated by: efficiency ⁇ ,] output power / input power x 100 where output power is the power at the output of the motor's shaft and input power is the input power to the motor.
  • each individual coil between two armature commutator segments has between 35 to 400 turns. In another preferred form, and referring to any of the above alternative forms, each individual coil between two armature commutator segments has between 50 to 400 turns.
  • each individual coil between two armature commutator segments has between 75 to 400 turns.
  • each individual coil between two armature commutator segments has between 100 to 400 turns. In another preferred form, and referring to any of the above alternative forms, each individual coil between two armature commutator segments has between 125 to 400 turns.
  • each individual coil between two armature commutator segments has between 35 to 375 turns.
  • each individual coil between two armature commutator segments has between 50 to 375 turns. In another preferred form, and referring to any of the above alternative forms, each individual coil between two armature commutator segments has between 75 to 375 turns.
  • each individual coil between two armature commutator segments has between 100 to 375 turns.
  • each individual coil between two armature commutator segments has between 125 to 375 turns.
  • each individual coil between two armature commutator segments has between 35 to 350 turns.
  • each individual coil between two armature commutator segments has between 50 to 350 turns. In another preferred form, and referring to any of the above alternative forms, each individual coil between two armature commutator segments has between 75 to 350 turns.
  • each individual coil between two armature commutator segments has between 100 to 350 turns.
  • each individual coil between two armature commutator segments has between 125 to 350 turns.
  • each individual coil between two armature commutator segments has between 35 to 325 turns.
  • each individual coil between two armature commutator segments has between 50 to 325 turns. In another preferred form, and referring to any of the above alternative forms, each individual coil between two armature commutator segments has between 75 to 325 turns.
  • each individual coil between two armature commutator segments has between 100 to 325 turns.
  • each individual coil between two armature commutator segments has between 125 to 325 turns.
  • each individual coil between two armature commutator segments has between 35 to 300 turns.
  • each individual coil between two armature commutator segments has between 50 to 300 turns. In another preferred form, and referring to any of the above alternative forms, each individual coil between two armature commutator segments has between 75 to 300 turns.
  • each individual coil between two armature commutator segments has between 100 to 300 turns.
  • each individual coil between two armature commutator segments has between 125 to 300 turns.
  • each individual coil between two armature commutator segments has between 35 to 275 turns.
  • each individual coil between two armature commutator segments has between 50 to 275 turns. In another preferred form, and referring to any of the above alternative forms, each individual coil between two armature commutator segments has between 75 to 275 turns.
  • each individual coil between two armature commutator segments has between 100 to 275 turns.
  • each individual coil between two armature commutator segments has between 125 to 275 turns.
  • each individual coil between two armature commutator segments has between 35 to 250 turns.
  • each individual coil between two armature commutator segments has between 50 to 250 turns. In another preferred form, and referring to any of the above alternative forms, each individual coil between two armature commutator segments has between 75 to 250 turns.
  • each individual coil between two armature commutator segments has between 100 to 250 turns. In another preferred form, and referring to any of the above alternative forms, each individual coil between two armature commutator segments has between 125 to 250 turns.
  • each individual coil between two armature commutator segments has between 35 to 225 turns.
  • each individual coil between two armature commutator segments has between 50 to 225 turns. In another preferred form, and referring to any of the above alternative forms, each individual coil between two armature commutator segments has between 75 to 225 turns.
  • each individual coil between two armature commutator segments has between 100 to 225 turns.
  • each individual coil between two armature commutator segments has between 125 to 225 turns.
  • each individual coil between two armature commutator segments has between 35 to 200 turns.
  • each individual coil between two armature commutator segments has between 50 to 200 turns. In another preferred form, and referring to any of the above alternative forms, each individual coil between two armature commutator segments has between 75 to 200 turns.
  • each individual coil between two armature commutator segments has between 100 to 200 turns. In another preferred form, and referring to any of the above alternative forms, each individual coil between two armature commutator segments has between 125 to 200 turns.
  • each individual coil between two armature commutator segments has between 35 to 175 turns.
  • each individual coil between two armature commutator segments has between 50 to 175 turns. In another preferred form, and referring to any of the above alternative forms, each individual coil between two armature commutator segments has between 75 to 175 turns.
  • each individual coil between two armature commutator segments has between 100 to 175 turns.
  • each individual coil between two armature commutator segments has between 125 to 175 turns.
  • the wire gauge of each individual coil is the thickest that can be wound upon the armature for the given number of turns.
  • the wire gauge of each individual coil is less than 0.4mm.
  • capacitors are connected across each pole- piece winding. This offers the additional advantage of susbtantially reducing radio frequency interference. This is not achievable with motors currently used for example in commercially available power tools. With such tools the excessive currents required by the armature and physical size capacitor constraints do not readily allow for such capacitors to be connected across each pole winding.
  • the armature is "excited” in conventional manner, prior to being inserted into the permanent magnetic field during assembly of the motor. Exciting of the armature is preferably achieved by mounting the armature in a test block and passing an electric current therethrough. This is found to reduce any tendency towards mismatching of the magnetic poles of the motor and avoids high eddy current formation during running of the motor.
  • Figures 1a to 1d illustrate a 3 pole-piece direct current permanent magnet motor
  • Figures 2a to 2d illustrate a 7 pole-piece direct current permanent magnet motor
  • Figure 3 (a,b,c,d) to Figure 17 (a,b,c,d) illustrate the characteristics discovered by increasing the number of windings of an armature
  • Figure 18 is a comparison of the number of turns per coil and the current required to provide a torque of 1 Newton metre;
  • Figure 19 illustrates a standard magnetization curve
  • Figure 20 illustrates the circuitry used to obtain the test results
  • Figure 21 illustrates what is meant by usefil flux
  • Figure 22 illustrates a portable power tool
  • Figure 23 illustrates an attachment to the power tool which provides additional voltage to the power tool;
  • Figure 24 illustrates the switch mechanism of the power tool
  • Figure 25 illustrates the electrical circuit of the power tool and the attachment means.
  • a direct current electric motor containing permanent magnets may also act as an electrical generator.
  • the generated electro-motive force (e.m.f.) is proportional to the rate of rotation of the armature. This is because the induced e.m.f. in an armature pole-piece is proportional to the rate of change of magnetic flux through the pole-piece, which in turn is proportional to the angular velocity of the pole- piece as it sweeps past the permanent magnet.
  • the armature rotates, the
  • SUBSTTTUTE SHEET (Rule 26) induced e.m.f. in each pole piece is intrinsically an A.C. signal containing sign reversals and maximum and minima voltages (the minima being zero volts).
  • the position of brushes in contact with the motor's armature, which are also electrically connected to external terminals, are arranged so that the induced e.m.f. at the terminals is always of the same electrical polar sense for a given armature rotation direction.
  • At least one of the pole pieces has a non-zero induced e.m.f. as the armature rotates.
  • the brushes are positioned to capture this non-zero e.m.f.
  • the r.p.m. of a free running motor is defined by the generated induced e.m.f. equalling the supplied e.m.f.
  • the r.p.m. is dependent upon the permanent magnet field, the geometry of the brushes, the armature and the supply e.m.f.
  • the free running r.p.m. is a little less than the theoretical value.
  • the rotational velocity of the ideal motor described above is independent of the electrical resistance of the pole piece windings, brushes and commutator.
  • the induced e.m.f. in the pole-pieces is approximately proportional to the number of windings on each pole-piece for a given motor and armature r.p.m.
  • the free running r.p.m. is approximately inversely proportional to the number of windings for a given supply voltage. That is the fewer the turns the greater the free running r.p.m.
  • the free running r.p.m. is proportional to the supply voltage.
  • M and r1 can be assumed constant, there is an optimum number of turns which is a function of the chosen mass of conductor and internal resistance of the supply plus commutator and brushes. Note that this is optimum is not a function of supply voltage. This maximizes the torque at heavy loads for given internal supply resistance and given brushes and commutator. In general this is approximately true of the efficiency as well at high loads, so long as no magnetic saturation occurs.
  • the current drain is approximately; 5 V(1-rpm/rpmfree)/R, and the power is approximately proportional to rpmV(1 -rpm/rpmfree)/R, where V is the supply voltage, rpm is the angular velocity and rpmfree is the free running angular velocity for supply voltage ⁇ o v.
  • V and R should be chosen to not allow too much saturation or too excessive heating to occur.
  • the more turns per pole-piece will improve the motor's efficiency. This is basically because the generated magnetic field is proportional to the number of turns for a given current. That is the more turns, the smaller the battery current drain required to produce a given torque. Also, the smaller this current, the smaller the power inefficiency losses from the internal resistance of the battery and resistive losses of the brushes, armature and conductors feeding the motor via the switch. However, there is a limit to the number of turns providing improved efficiencies. This related to the insulation of the wires in which the insulation affects the flux within the armature and therefore there is a range of turns which are suitable for a specific application.
  • the 0.28mm gauge motor at 125 turns per pole-piece illustrates that once the number of turns per-pole is determined then the thickest wire gauge that can be used improves the efficiency of the motor. Furthermore, motors having a small number of turns and thick windings are inefficient. (This inefficiency may, be due to magnetic saturation of the armatures poles or because the magnetic field within the armatures poles exceeds that of the flux provided by the permanent magnetic field or fields).
  • the above efficiency results were measured and calculated by coupling the shaft of a HC683G of 22 turns and 0.9mm gauge (adapted to be used as a generator) to the output shaft of the motor being tested. Thus by varying the current in the HC683G generator by means of a variable resistor across the generators output, and measuring its generated voltage across the variable resistor, the efficiency was calculated as follows:-
  • FIGs 1 a to 1d The physical dimensions of the HC683G are illustrated in FIGs 1 a to 1d, this motor as sold has 22 turns and 0.9mm gauge wire per pole-piece.
  • This motor again as sold has 22 turns and 0.9mm gauge wire per-pole-piece.
  • This motor as sold has 24 turns and 0.9mm gauge wire per-pole-piece.
  • the motor illustrated in FIGs 2a to 2d is a 7 pole-piece D.C. permanent magnet motor, this motor as sold has 9 turns and 0.9mm gauge per pole and each pole is wound around 3 pole pieces.
  • capacitors can be connected across each pole-piece winding (if required). This offers the additional advantage of substantially reducing radio frequency interference. This is not achievable with motors currently used for example in commercially available power tools. With such tools the excessive currents required by the armature and physical size capacitor constraints do not readily allow for such capacitors to be connected across each pole winding.
  • FIGs 3 to 18 the motor used to obtain these results was a Johnson 50274 D.C. permanent magnet motor having a 3- tooth armature.
  • the results of FIGs 3 to 18 were obtained using the same motor and rewinding the armature with the different number of turns and wire gauges.
  • FIG 3 (a,b,c,d) relates to a 32 turn per pole wound Johnson 50274 motor, each of the wound poles having a 0.75 gauge wire of 0.2 ohms across the brushes
  • FIG 7 (a,b,c,d) has relates to the same motor wound with 110 turns of 0.34 wire gauge having a resistance of 1.4 ohms across the brushes.
  • a conventionally wound motor usually has approximately 32 turns of relatively thick wire gauge (eg. 0.75).
  • stall armature currents that are above the current rating of the supply (battery, solar cell or other similar supplies) may result (typically substantially greater than 110% of the battery's current rating) due to the reduced back electro motive force (emf) effects. Accordingly, this can rapidly discharge the battery, or reduce the effectiveness of the supply. Furthermore, it may also damage the supply.
  • SUBSTTTUTE SHEET (Rule 26) solar cell technology) and have not addressed the issue of increasing the number of turns to decrease the voltage reduction under load whilst providing a motor with suitable torque characteristics.
  • This increase in the number of turns reduces the current drain from the supply and therefore it is desirable but not essential to operate below the supply's current rating when the motor is at or near stall (a preferable range is between 110% to 65% of the supply's current rating).
  • the increase in the number of turns preferably reduces the possibility of damage occurring to the supply.
  • a preferable feature is that the resistance across supply is at least 20% of that of the internal resistance of the supply.
  • the supply is a Nickel Cadmium battery of 250 milli Ohms per cell then for a 24 volt battery the internal resistance is 6 Ohms, therefore preferably the resistance of the armature should be at least 1.2 Ohms.
  • Johnson 50274 show (FIG 18) that at approximately 100 to 110 turns per pole of 0.34 wire gauge an optimum occurs for a required torque output (note a different optimum number of turns may result for a different permanent magnet motor). Hence, upon deciding upon a required torque output and a wire gauge then the optimum number of turns can be determined by non inventive experimentation. However, it should be noted that the number of turns is limited by the physical dimensions of the armature and air gap.
  • the motor under high loads (or at stall) is magnetically saturated. That is it is operating above the knee point in the area of the magnetization curve known as the non linear portion of the curve.
  • SUBSTTTUTE SHEET (Rule 26) standard theoretical magnetization curve is illustrated in FIG. 19. This shows the three commonly known parts of the magnetization curve: the instep, knee point and the non linear portion.
  • the flux density limit (saturation) of Gauss is shown by Bs and the non linear portion can be approximately defined by Frohlic's equation:
  • the increased Gauss attributable to non linear portion of the magnetization curve results from the combination of the number of turns and the current therethrough. Accordingly, by increasing the number of turns of the armature coils this increase in Gauss can result. However, there is a limit to this as shown in FIG 13b which shows a reduced Gauss at stall.
  • SUBSTTTUTE SHEET (Rule 26) 105 turns per pole armature the flux density at stall is 860 Gauss (see FIG 6b) and for the 110 turns per pole armature (see FIG 7b) the flux density at stall is 900 Gauss.
  • the Flux density (useful flux) of the permanent magnet was measured to be 900 Gauss (see FIG 21 ). Hence, when comparing the results as illustrated in FIG 18, and the corresponding Gauss measurements, it is apparent that there is an optimum in the motor's performance. This occurs when flux density of the armature's magnetic field (or fields) is substantially identical to the flux density of the permanent magnetic field or fields when the motor is at stall.
  • an improved motor performance can be achieved when the the substantially identical matching is not accurately achieved but is within specified limits. These limits being preferably no greater than a 20% difference.
  • the results conducted on the Johnson 50274 D.C. permanent magnet motor illustate this difference (for this motor) is 180 Gauss, therefore when the armature's flux density is below 720 Gauss or above 1080 Gauss there is a considerable reduction in the motor's performance.
  • the Gauss at stall is 998 (11 % difference) and provides an improved performance over what has perviously been known.
  • the 100 turn armature has a Gauss at stall of 763 (15% difference) and provides an improved performance over what has perviously been known. Terpolating these results it is estimated that at approximately 20% difference the improvements over previously known D.C. permanent magnet motors is not substantially significant.
  • the values of flux densisty and the corresponding percentage difference values preferably relate to the useful flux as illustrated in FIG 21. Furthermore, the above results were obtained by using the circuit as illustrated in FIG. 20. it should be noted that the Torque measurements were taken with the same Torque meter and therefore any errors in the accuracy of this meter are common to all the results. To emulate the supply (battery, solar cell or otherwise) two variacs VRI and VR2 were used to model the internal resistance of the supply. The ammeter Am measured the armature current la, the Torque was measured with the Torque meter Tm and the tachometer Rm measured the speed of the motor's shaft under different loads from free running to stall.
  • FIG. 22 there is illustrated a self contained power tool 1 having a push button switch 3, ten 1.2 volt rechargeable batteries 12, recharged via the recharging socket 4.
  • the motor 5 drives the gearbox 6 which turns the chuck 7.
  • the chuck is attached to a spindle and the chuck can be removed from the spindle such that a screwdriver means can be inserted directly into the spindle as opposed to the screwdriver means being gripped by the chuck 7.
  • the push button switch 3 is adapted to move within the slot 34.
  • the push button switch 3 is in the centre of the slot 34, as shown in FIG. 22, no power can be applied to the motor 5 by depressing the push button switch 3.
  • the push button switch 3 when the push button switch 3 is in its top position within the slot 34 the motor 5 turns in a clockwise direction.
  • the push button switch 3 is in the down position within the slot 34 the motor 5 will turn in an anticlockwise direction.
  • the self contained power tool 1 is shown inserted in the attachment means 2.
  • the interlock 16 is pulled downwards by
  • the attachment means further has a hollow handle 18 within which are located ten 1.2 volt batteries 17 that are adapted to be recharged via the socket 35.
  • FIG. 24 and FIG. 25 there is illustrated the switch mechanism and the electrical circuitry of both the self contained power tool 1 and attachment means 2.
  • the turning handle 8 is adapted to rotate the inner body 9 such that push button switch 3 will be activated by either the cam 32 or cam 33 of the interlock 16. This therefore connects the spring means 24 to the positive of the battery 12.
  • both the spring means 23 and 24 are mechanically connected to the inner body 9, therefore when the turning handle 8 is pushed clockwise the spring means 23 makes contact with the pin 22 and the spring means 24 makes contact with the pin 21. Note if the turning handle 8 was pushed in an anticlockwise direction then the spring means 23 would be connected to pin 21 and the spring means 24 would be connected to the pin 22. This provides a simple mechanism for reversing the direction of the motor 5 which is electrically connected to the pins 21 and 22.
  • the push button switch 3 Upon the turning handle 8 being pushed either clockwise or anticlockwise the push button switch 3 will close its contacts by either being activated by the cam 32 or the cam 33. However, the motor 5 will not turn until the switch 13, located upon the handle 18, is closed.
  • the switch 13 is inserted into the circuit by the circuit modification means 20 which includes a jack plug 10 having an inner conductor 31 surrounded by an insulator 30 and an outer conductor 29.
  • the circuit modification means 20 which includes a jack plug 10 having an inner conductor 31 surrounded by an insulator 30 and an outer conductor 29.
  • an electrical circuit is completed at the circuit modification means 20 by the cylindrical conductor 26 making contact with the cylindrical conducting piston 27 which is spring loaded by the conducting spring 28.
  • an electrical circuit is made via the negative of the battery 12 through the conducting spring 28, through the cylindrical conducting piston 27 and the cylindrical conductor 26 to the spring means 23.
  • the cylindrical conducting piston 27 is pushed away from the cylindrical conductor 26 which therefore breaks their direct electrical contact between the negative of battery 12 and the spring means 23.
  • the outer conductor 29 of the jack plug 10 is connected to the switch 13.
  • the other side of the switch 13 is connected to the negative of the battery 17 and the positive of the battery 17 is connected to the inner conductor 31 of jack plug 10.
  • the inner conductor 31 makes electrical contact with the cylindrical conducting piston 27 and the outer conductor 29 makes contact with the cylindrical conductor 26.
  • the insertion of the jack plug 10 reconfigures the circuit such that the battery 12 and battery 17 are in series and power can only be supplied to the motor when both the contacts of the push button 3 and switch 13 are closed.
  • the motor preferably embodies at least one of the improvements described herein for direct current electric motors.
  • the particular forms described above with reference to FIGs 1 to 21 may be especially mentioned. Attention is also directed to the associated discussions of "Theory” and “Results”.
  • motors of improved efficiencies can be designed and manufactured by determining an output speed of the motor which is preferably less than the desired application for which the motor is to be used.
  • the output speed is proportional to 1/n, hence this determines the number of windings (turns) per armature pole-piece.
  • n it is preferable to select the thickest wire gauge that can be wound upon the armature.
  • the Force or Torque is proportional to n.l (until
  • the more turns per pole-piece will improve the motors efficiency. This is basically because the generated magnetic field is proportional to the number of turns for a given current. That is the more turns, the smaller the battery current drain required to produce a given torque. Also, the smaller this current, the smaller the power inefficiency losses from the internal resistance of the battery and resistive losses of the brushes, armature and conductors feeding the motor via the switch. However, there is a limit to the number of turns providing improved efficiencies. This related to the insulation of the wires in which the insulation affects the flux within the armature and therefore there is a range of turns which are suitable for a specific application.
  • FIGS. 22-25 there is illustrated a multi purpose tool which can be powered by either a 12 volt battery supply or 24 volt battery supply. It should be noted that other battery voltages can be used and variations of the embodiments described can be substituted without diverting from the invention. Throughout this specification various indications have been given to the scope of the invention but the invention is not limited to any one of these indications.

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  • Power Engineering (AREA)
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Abstract

Moteur CC (5) à aimants permanents, et batterie (12) alimentant ledit moteur en courant électrique, la résistance dudit moteur étant sensiblement supérieure à la résistance de ladite batterie. Le moteur électrique comporte un ou plusieurs champs magnétiques et plusieurs bobines enroulées autour d'un ou de plusieurs gabarits et engendrant un champ électromagnétique de façon à produire un mouvement mécanique relatif entre le champ magnétique permanent et le susdit champ électromagnétique. Les bobines engendrant le champ électromagnétique sont enroulées de façon que le courant de la source de CC les alimentant soit tel que la densité du flux du champ électromagnétique et de ses gabarits associés présente une valeur similaire à celle du (des) champ(s) magnétique(s) permanent(s) lorsque le moteur est bloqué.
PCT/AU1994/000257 1993-05-20 1994-05-19 Moteur cc a aimants permanents alimente par batterie WO1994028613A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AU67178/94A AU6717894A (en) 1993-05-20 1994-05-19 Battery powered permanent magnet direct current motor

Applications Claiming Priority (7)

Application Number Priority Date Filing Date Title
AUPL890293 1993-05-20
AUPL890393 1993-05-20
AUPM224193 1993-11-08
PCT/GB1993/002291 WO1994011941A1 (fr) 1992-11-06 1993-11-08 Moteur electrique
AUPM224293 1993-11-08
PCT/GB1993/002293 WO1994011162A1 (fr) 1992-11-06 1993-11-08 Outil a moteur
US17091393A 1993-12-17 1993-12-17

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Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0111740A1 (fr) * 1982-11-13 1984-06-27 Hitachi, Ltd. Machine à courant continu du type à champ à aimant permanent
EP0237935A2 (fr) * 1986-03-17 1987-09-23 Hitachi, Ltd. Machine à courant continu avec champ magnétique permanent
EP0312290A2 (fr) * 1987-10-13 1989-04-19 Magneti Marelli Electrical Limited Machines dynamo-électriques rotatives à aimants permanents
EP0339584A1 (fr) * 1988-04-25 1989-11-02 Hitachi, Ltd. Machine électrique rotative à courant continu du type à champ à aimant permanent
US5175460A (en) * 1991-01-29 1992-12-29 Asmo Co., Ltd. Flat yoke type DC machine

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0111740A1 (fr) * 1982-11-13 1984-06-27 Hitachi, Ltd. Machine à courant continu du type à champ à aimant permanent
EP0237935A2 (fr) * 1986-03-17 1987-09-23 Hitachi, Ltd. Machine à courant continu avec champ magnétique permanent
EP0312290A2 (fr) * 1987-10-13 1989-04-19 Magneti Marelli Electrical Limited Machines dynamo-électriques rotatives à aimants permanents
EP0339584A1 (fr) * 1988-04-25 1989-11-02 Hitachi, Ltd. Machine électrique rotative à courant continu du type à champ à aimant permanent
US5175460A (en) * 1991-01-29 1992-12-29 Asmo Co., Ltd. Flat yoke type DC machine

Non-Patent Citations (4)

* Cited by examiner, † Cited by third party
Title
(JAMES R. IRELAND), "Ceramic Permanent Magnet Motors", Published 1968, by MCGRAW HILL BOOK COMPANY (NEW YORK), pages 38-47, 52-56. *
(M.G. SAY et al.), "Direct Current Machines", Published 1980, by PITMAN PUBLISHING LTD (LONDON), pages 345-348. *
(T. KENJO et al.), "Permanent Magnet and Brushless DC Motors", Published 1985, by OXFORD UNIVERSITY PRESS (OXFORD et al.), pages 25-31. *
PROCEEDINGS OF THE 34TH INTERNATIONAL POWER SOURCES SYMPOSIUM, 25-28 June 1990, Sponsored by the Industry Applications Society of the Institute of Electrial and Electronics Engineers, HARVEY N. SEIGER, "Lithium/Cobalt Sulfide Pulse Power Battery", pages 334-338. *

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