WO1994011941A1 - Moteur electrique - Google Patents

Moteur electrique Download PDF

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Publication number
WO1994011941A1
WO1994011941A1 PCT/GB1993/002291 GB9302291W WO9411941A1 WO 1994011941 A1 WO1994011941 A1 WO 1994011941A1 GB 9302291 W GB9302291 W GB 9302291W WO 9411941 A1 WO9411941 A1 WO 9411941A1
Authority
WO
WIPO (PCT)
Prior art keywords
motor
armature
turns
coils
parts
Prior art date
Application number
PCT/GB1993/002291
Other languages
English (en)
Inventor
Colin Edward Cartwright
Original Assignee
Emerson International Limited
Johnson, Terence, Leslie
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 GB939318576A external-priority patent/GB9318576D0/en
Application filed by Emerson International Limited, Johnson, Terence, Leslie filed Critical Emerson International Limited
Priority to AU54275/94A priority Critical patent/AU5427594A/en
Priority to AU67178/94A priority patent/AU6717894A/en
Priority to PCT/AU1994/000257 priority patent/WO1994028613A1/fr
Publication of WO1994011941A1 publication Critical patent/WO1994011941A1/fr

Links

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
    • H01—ELECTRIC ELEMENTS
    • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H9/00—Details of switching devices, not covered by groups H01H1/00 - H01H7/00
    • H01H9/02—Bases, casings, or covers
    • H01H9/06—Casing of switch constituted by a handle serving a purpose other than the actuation of the switch, e.g. by the handle of a vacuum cleaner
    • H01H9/063—Casing of switch constituted by a handle serving a purpose other than the actuation of the switch, e.g. by the handle of a vacuum cleaner enclosing a reversing switch

Definitions

  • This invention relates to a motor, particularly a D.C. electrical motor, for example a small direct current electric motor, although the applicability of the invention 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 teeth established by reason of a laminated ferromagnetic core and insulated wire wound around, as a coil, each of the teeth 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.
  • D.C. permanent magnet direct current
  • Such motors are generally used in battery powered hand-held tools such as screwdrivers and drills; or propulsion vehicles that are powered by Solar Cells, batteries or a combination or 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 armature coils.
  • Such motors are known as permanent magnet direct current motors.
  • an electrical motor comprising two parts 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, the first one of the parts including a plurality of coils of electrically conducting insulated wire aroimd a motor, and a second one of the parts has a magnetic field adapted to interact with the magneto motive force from the coils, characterised by the number of turns of windings around the former for each of the coils on the first one of the parts being such that a relatively high output torque per unit armature current input is obtained.
  • the motor may comprise a direct current flow motor, suitably a permanent magnet motor.
  • the plurality of coils may be wound upon the rotor to provide an magneto motive forces for providing a torque between the permanent magnetic field and the electromagnetic field, and the coils providing the electromagnetic field may be wound such that when the motor's rated voltage is applied thereto, and the motor is loaded sufficiently for the speed to fall to a small fraction of the no-load speed, the percentage drop in battery voltage from the open circuit voltage is relatively small and the armature reaction in the motor is insufficient to cause appreciable reduction in the motor's torque per armature current.
  • the coils and core may be in the form bf an armature. This is a relatively simple construction.
  • a tool characterised by an electric motor as hereinbefore defined, particularly a hand-held tool.
  • the tool may be characterised by a gear box with selectable gear ratios whereby the difference between ratios is N, suitably 2.
  • the armature has a core which may comprise a ferromagnetic material.
  • each coil is formed from wire having a gauge which enables the number of turns and hence total length of wire to be high, thereby offering substantial resistance to current flowing therethrough at the motors rated voltage.
  • each of the coils of the armature may have a resistance such that the resistance across the brushes is no less than about 1.2 ohms.
  • the motor is connected to an electric power supply with a voltage which is the motors rated voltage.
  • the motor may be 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 may be a battery or a solar cell.
  • the battery may suitably comprise at least one Nickel Cadmium battery cell, suitably one which may have an internal resistance of less than 250 milli Ohms per cell.
  • the tool may comprise portable power tools such as a drill or screwdriver, or alternatively in a propulsion vehicle.
  • Each individual coil between two armature commutator segments may have between 75 to 200 turns.
  • Each individual coil between two armature commutator segments may have between 100 to 200 turns.
  • Each individual coil between two armature commutator segments may have between 125 to 200 turns.
  • Each individual coil between two armature commutator segments may have between 75 to 175 turns.
  • Each individual coil between two armature commutator segments may have between 100 to 175 turns.
  • Each individual coil between two armature commutator segments may have between 125 to 175 turns.
  • Each individual coil between two armature commutator segments may have between 75 to 150 turns.
  • Each individual coil between two armature commutator segments may have between 100 to 150 turns.
  • Each individual coil between two armature commutator segments may have between 105 to 150 turns.
  • Each individual coil between two armature commutator segments may have between 110 to 150 turns.
  • Each individual coil between two armature commutator segments may have between 115 to 150 turns.
  • Each individual coil between two armature commutator segments may have between 120 to 150 turns.
  • Each individual coil between two armature commutator segments may have between 100 to 125 turns.
  • Each individual coil between two armature commutator segments may have between 100 to 120 turns.
  • Each individual coil between two armature commutator segments may have between 105 to 120 turns.
  • Each individual coil between two armature commutator segments may have between 100 to 105 turns.
  • Each individual coil between two armature commutator segments may have between 105 to 115 turns.
  • Each individual coil between two armature commutator segments may have between 110 to 115 turns.
  • a motor embodying the invention is hereinafter described, by way of example, with reference to the accompanying drawings, together with the performance criteria compared with motors previously wound according to conventional winding formulas.
  • Fig.l (a,b,c,d) to Fig.15 (a,b,c,d) illustrate the chara ⁇ eristics discovered by increasing the number of windings of an armature
  • Fig.16 is a comparison of the number of turns per coil and the current required to provide a torque of 1 Newton metre at stall.
  • Fig. 17 illustrates a standard magnetization curve
  • Fig.18 illustrates the circuitry used to obtain the test results
  • Figs. 19A to 19C show graph results for a test motor in relation to the number of turns of its coil.
  • Figs. 21 & 22 respectively show a 3 pole-piece and a 7 pole-piece direct current permanent magnetic motor at stall.
  • 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. 1 to lb were obtained using the same motor and rewinding the armature with the different number of turns and wire gauges.
  • Fig. 1 (a,b,c,d) relates to a 32 turn per coil wound Johnson 50274 motor, each of the wound poles having a 0.75mm diameter wire of 0.2 ohms across the brushes
  • Fig. 5 (a,b,c,d) has relates to the same motor wound with 110 turns per coil of 0.34mm diameter 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).
  • a,b,c,d 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 lower armature resistance. Accordingly, this can rapidly discharge the battery, or reduce the effectiveness of the supply. Furthermore, it may also damage the supply.
  • the increase in the number of turns preferably reduces the possibility of damage occurring to the supply.
  • a preferable feature is that the motor's armature resistance is at least 80% of that of the internal resistance of the supply. For example, if 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, and the motor's armature resistance should be at least 4.8 Ohms.
  • the characteristics (even when taking into account gearing) where high turns per armature coil with smaller wire diameter are used provides an improved performance, taking into account the current required to achieve a specific torque, over the standard type of motor of Fig. 1 (a,b,c,d).
  • the results for the Johnson 50274 show (Fig. 16) that at approximately 100 to 110 turns per coil of 0.34mm wire diameter an optimum occurs for a required torque output (note a different optimum number of turns may result for a different permanent magnet motor).
  • the optimum number of turns can be determined by non inventive experimentation.
  • the number of turns is limited by the physical dimensions of the armature and slots.
  • the armature magneto motive force at or near stall conditions is reduced so that the armature reaction is lessened and reductions in torque per armature turn minimised.
  • a 3 tooth direct current permanent magnet motor having the approximate dimension:
  • Adopting a number of turns per coil that is significantly higher than usual is beneficial for screw-driver motors. Trying to maintain speeds by reducing the combined gear ratio is generally not feasible due to the resulting impact on torque. Adopting a higher battery voltage will reduce somewhat the impact on speeds of the increased turns per coil.
  • a battery with a higher voltage and lower current capacity could be similar in size, weight and cost to the original. Since the modified motor operates with lower output and input powers, battery life is improved particularly when operation near motor stall occurs regularly, as is the case with screw-driver applications. This is because in operation the gross battery over-loading and severe armature reaction effects that occur with an unmodified motor is eliminated.
  • the motor has lower I 2 R losses under heavy load conditions which is beneficial on a battery's life when heavy loads are frequent.

Landscapes

  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Dc Machiner (AREA)

Abstract

Cette invention concerne un moteur à aimant permanent à courant continu du type Johnson 50274 comprenant un induit à 3 et 7 dents. Les figures 1 (a, b, c, d) représentent un moteur Johnson 50274 classique bobiné à 32 spires par bobine dans lequel chaque pôle bobiné comporte un fil d'un diamètre de 0,75 mm de 0,2 ohms au niveau des balais, et les figures 5 (a, b,c, d) représentent le même enroulement du moteur de cette invention comportant 110 spires par bobine d'un diamètre de 0,34 mm et d'une résistance de 1,4 ohms au niveau des balais. Ces moteurs possèdent donc des bobines ayant plus de spires que les bobines de l'art antérieur et par conséquent ils peuvent produire des couples de sortie pour une entrée de donnée qui sont supérieurs à ceux produits par des moteurs classiques ayant des caractéristiques apparentes similaires et ils peuvent globalement être plus efficaces dans des conditions de fortes charges.
PCT/GB1993/002291 1992-11-06 1993-11-08 Moteur electrique WO1994011941A1 (fr)

Priority Applications (3)

Application Number Priority Date Filing Date Title
AU54275/94A AU5427594A (en) 1992-11-06 1993-11-08 An electrical motor
AU67178/94A AU6717894A (en) 1993-05-20 1994-05-19 Battery powered permanent magnet direct current motor
PCT/AU1994/000257 WO1994028613A1 (fr) 1993-05-20 1994-05-19 Moteur cc a aimants permanents alimente par batterie

Applications Claiming Priority (6)

Application Number Priority Date Filing Date Title
AUPL571792 1992-11-06
AUPL571692 1992-11-06
AUPL5717 1992-11-06
AUPL5716 1992-11-06
GB939318576A GB9318576D0 (en) 1993-09-08 1993-09-08 A motor
GB9318576.7 1993-09-08

Publications (1)

Publication Number Publication Date
WO1994011941A1 true WO1994011941A1 (fr) 1994-05-26

Family

ID=27157696

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/GB1993/002291 WO1994011941A1 (fr) 1992-11-06 1993-11-08 Moteur electrique

Country Status (1)

Country Link
WO (1) WO1994011941A1 (fr)

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR490292A (fr) * 1918-05-29 1919-04-15 Howard Austin Whiteside Perfectionnements aux moteurs électriques
FR2070072A1 (fr) * 1969-08-28 1971-09-10 Chouinard Romeo
US4876472A (en) * 1987-09-30 1989-10-24 Shicoh Engineering Co., Ltd. Five-phase dc motor with non-overlapping armature windings

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR490292A (fr) * 1918-05-29 1919-04-15 Howard Austin Whiteside Perfectionnements aux moteurs électriques
FR2070072A1 (fr) * 1969-08-28 1971-09-10 Chouinard Romeo
US4876472A (en) * 1987-09-30 1989-10-24 Shicoh Engineering Co., Ltd. Five-phase dc motor with non-overlapping armature windings

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
E. PORTER: "d-c motors", MACHINE DESIGN, vol. 44, no. 9, 13 April 1972 (1972-04-13), CLEVELAND US, pages 10 - 12 *

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