WO2002005409A1 - Dc electric motor with two commutators and permanent magnet rotor - Google Patents

Dc electric motor with two commutators and permanent magnet rotor Download PDF

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Publication number
WO2002005409A1
WO2002005409A1 PCT/DK2001/000471 DK0100471W WO0205409A1 WO 2002005409 A1 WO2002005409 A1 WO 2002005409A1 DK 0100471 W DK0100471 W DK 0100471W WO 0205409 A1 WO0205409 A1 WO 0205409A1
Authority
WO
WIPO (PCT)
Prior art keywords
coils
contact
contact surfaces
coil
rotor
Prior art date
Application number
PCT/DK2001/000471
Other languages
French (fr)
Inventor
Kaj Børge HANSEN
Original Assignee
Kirk Acoustics A/S
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Kirk Acoustics A/S filed Critical Kirk Acoustics A/S
Priority to AU2001272358A priority Critical patent/AU2001272358A1/en
Publication of WO2002005409A1 publication Critical patent/WO2002005409A1/en

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Classifications

    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02K—DYNAMO-ELECTRIC MACHINES
    • H02K7/00—Arrangements for handling mechanical energy structurally associated with dynamo-electric machines, e.g. structural association with mechanical driving motors or auxiliary dynamo-electric machines
    • H02K7/06—Means for converting reciprocating motion into rotary motion or vice versa
    • H02K7/061—Means for converting reciprocating motion into rotary motion or vice versa using rotary unbalanced masses
    • 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
    • H02K—DYNAMO-ELECTRIC MACHINES
    • H02K23/00—DC commutator motors or generators having mechanical commutator; Universal AC/DC commutator motors
    • H02K23/62—Motors or generators with stationary armatures and rotating excitation field

Definitions

  • the invention relates to electric motors, and in particular to miniature DC motors.
  • Such motors are useful eg in mobile telephones where such a motor can have a mass mounted eccentrically on the motor shaft.
  • incoming calls can thereby be signalled by vibrations generated by the motor rotating.
  • Signal- ling by means of vibrations is preferably not audible but can be sensed by a user carrying the mobile telephone eg in a pocket.
  • WO 00/41289 discloses a miniature DC-motor with a single set of coils and a single commutator brush commutating the total current from one coil to another.
  • the current path includes two coils, one from each set of coils, in series. The current is maintained in one of the coils in series and only switched in the other.
  • electric noise and electromagnetic interference EMI is reduced, and the motor has a higher torque for the same consumed electric power - or a lower power consumption for the same torque, and the motor can be made very compact.
  • Figure 1 is a longitudinal section through a motor in a preferred embodiment of the invention
  • Figure 2 is a schematic drawing illustrating the contacting of the motor in figure 1
  • Figure 3 shows schematically the structure of the coils of the motor in figure 1
  • Figure 4 shows schematically a cross section through the motor in figure 1 and illustrates the contacting of the motor.
  • Figure 1 shows a motor with a stator 1.
  • the stator is tubular and is made of a soft magnetic material.
  • a flexible sheet 2 with coils formed on one side.
  • the coils are indicated at 2a.
  • the coils can also be formed on both sides of the sheet 2.
  • conventional wound coils may also be used.
  • At the ends of the tubular stator 2 there are a first bearing 4 and a second bearing 4a respectively, which receive the opposite ends of a shaft 6 of an electrically conductive material.
  • the shaft 6 carries a magnet 3, which is magnetised in the direction of its diameter, ie transversally to the motor axis.
  • the two bearings 4 and 4a are preferably identical and have a first set of contactors CI and a second set of contactors C2 respectively, which are formed as flat surfaces perpendicular to the motor axis and facing inwards in the stator.
  • the shaft 6 has contact springs 5 and 5a respectively, which are made of a resilient, electrically conductive metal wire.
  • the contact springs 5 and 5a have a narrow end and a wider portion with a free end.
  • the contact springs are secured to the shaft and electrically connected to the shaft at their arrow ends. Each of the free ends of the contact springs is in electrical contact with a contact surface of respective ones of the bearings.
  • the shaft protrudes beyond the bearing, and the protruding end of the shaft carries an eccentrically mounted mass 7.
  • Figure 2 shows a first set of coils SI, S3 and S5.
  • Each of the coils SI, S3 and S5 in the first set has one coil wire end connected to a first terminal TI of the motor, and the other coil wire ends are connected to respective ones of the contactors Cla, Clb and Clc of the first set of contactors CI situated at the first bearing 4.
  • Figure 2 also shows a second set of coils S2, S4 and S6.
  • Each of the coils S2, S4 and S6 in the second set has one coil wire end connected to a second terminal T2 of the motor, and the other coil wire ends are connected to re- spective ones of the contactors C2a, C2b and C2c of the second set of contactors C2 situated at the second bearing 4a.
  • the rotor with the motor shaft 6 and contact springs 5 and 5a is for illustrative purposes indicated by a circle.
  • the structure in figure 2 is shown "folded out". In the motor the shown structure is cylindrical, and in each set of coils the coils are spaced 120 degrees apart. In each set of contactors the three contactors are also spaced 120 degrees apart. Each contactor extends for slightly less than 120 degrees so that a small gap exists between neighbouring contactors. .
  • the first set of coils and the first set of contactors are angularly offset 60 degrees relative to the second set of coils and the second set of contactors.
  • the terminals TI and T2 are connected to a DC power source
  • an electric current path is established from the first terminal TI through the coil S5 of the first set of coils, the contactor Clc of the first set of contactors, the first contact spring 5, the shaft 6, the second contact spring 5a, the contactor C2c of the second set of contactors, the coil S4 of the second set of coils and the second terminal T2.
  • the shaft 6 with contact springs 5, 5a shown schematically in figure 2 will move from the position shown to a position where the current path is maintained in the coil in one set of coils, whereas the current in the coil in the other set of coils is shifted to another coil in the same set of coils.
  • the current path thus always includes one coil in one set of coils and one coil in the other set of coils connected in series, and upon rotation of the rotor switching of the current path is done alternatingly between the first set of coils and the second set of coils. Each switching operation thus only switches half of the current path and half of the coils, while the other half of the current path and the other half of the coils is switched subsequently.
  • FIG 3 shows schematically the layout of the coils on the flexible sheet.
  • the sheet will be rolled and placed inside the tubular stator near its cylindrical inner surface, where it will be held in place by means of the two bearings. It is seen that each coil has a lateral extension corresponding to 180 degrees when placed in the stator, and that the coils are spaced apart corresponding to 60 degrees.
  • Figure 4 shows a schematical cross section through the motor.
  • the outermost structure is the rolled sheet with the coils.
  • the two sets of contactors where, for illustrative purposes, the first set of contactors Cla, Clb and Clc are shown having a larger diameter than the second set of contactors C2a, C2b and C2c.
  • a contact brush Cbr illustrating the shaft with the two contact springs .
  • the contact brush Cbr is shown bridging contactors in the two sets, in this case contactor Clc in the first set and contactor C2b in the second set.

Landscapes

  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Dc Machiner (AREA)
  • Motor Or Generator Frames (AREA)

Abstract

An electric motor with two sets of stator coils (51, 53, 55 and 52, 54, 56), where the coils in each set are coupled in a star configuration. The motor has two sets of contactors with two rotor brushes. The electric current path always comprises two coils, namely one coil in each set connected in series through the two brushes. The current path is switched from one coil to another in only one set of coils at a time, so that the switching is done alternatingly between the first set of coils and the second set of coils.

Description

DC ELECTRIC MOTOR WITH TWO COMMUTATORS AND PERMANENT MAGNET ROTOR
The invention relates to electric motors, and in particular to miniature DC motors. Such motors are useful eg in mobile telephones where such a motor can have a mass mounted eccentrically on the motor shaft. In addition to being acoustically signalled, or as an alternative thereto, incoming calls can thereby be signalled by vibrations generated by the motor rotating. Signal- ling by means of vibrations is preferably not audible but can be sensed by a user carrying the mobile telephone eg in a pocket.
In mobile phones power consumption of the various com- ponents is of great interest. It is therefore important that all components have low power consumption for the desired function. It is thus desirable to a motor, which can be used as vibrator motor in mobile phones, and which has low power consumption and yields a high torque both at start-up and when running. Furthermore the motor should generate minimum possible electric noise and have a long expected lifetime. The motor according to the invention achieves these goals.
WO 00/41289 discloses a miniature DC-motor with a single set of coils and a single commutator brush commutating the total current from one coil to another. With the arrangement of the invention the current path includes two coils, one from each set of coils, in series. The current is maintained in one of the coils in series and only switched in the other. Hereby electric noise and electromagnetic interference (EMI) is reduced, and the motor has a higher torque for the same consumed electric power - or a lower power consumption for the same torque, and the motor can be made very compact.
In the following the invention will be described with reference to the drawings, in which
Figure 1 is a longitudinal section through a motor in a preferred embodiment of the invention,
Figure 2 is a schematic drawing illustrating the contacting of the motor in figure 1,
Figure 3 shows schematically the structure of the coils of the motor in figure 1, and
Figure 4 shows schematically a cross section through the motor in figure 1 and illustrates the contacting of the motor.
Figure 1 shows a motor with a stator 1. In this embodiment the stator is tubular and is made of a soft magnetic material. Inside the tubular stator 1 is a flexible sheet 2 with coils formed on one side. The coils are indicated at 2a. The coils can also be formed on both sides of the sheet 2. Alternatively, conventional wound coils may also be used. At the ends of the tubular stator 2 there are a first bearing 4 and a second bearing 4a respectively, which receive the opposite ends of a shaft 6 of an electrically conductive material. The shaft 6 carries a magnet 3, which is magnetised in the direction of its diameter, ie transversally to the motor axis. The two bearings 4 and 4a are preferably identical and have a first set of contactors CI and a second set of contactors C2 respectively, which are formed as flat surfaces perpendicular to the motor axis and facing inwards in the stator. At both sides of the magnet 3 the shaft 6 has contact springs 5 and 5a respectively, which are made of a resilient, electrically conductive metal wire. The contact springs 5 and 5a have a narrow end and a wider portion with a free end. The contact springs are secured to the shaft and electrically connected to the shaft at their arrow ends. Each of the free ends of the contact springs is in electrical contact with a contact surface of respective ones of the bearings. At the bearing 4a the shaft protrudes beyond the bearing, and the protruding end of the shaft carries an eccentrically mounted mass 7.
Figure 2 shows a first set of coils SI, S3 and S5. Each of the coils SI, S3 and S5 in the first set has one coil wire end connected to a first terminal TI of the motor, and the other coil wire ends are connected to respective ones of the contactors Cla, Clb and Clc of the first set of contactors CI situated at the first bearing 4. Figure 2 also shows a second set of coils S2, S4 and S6. Each of the coils S2, S4 and S6 in the second set has one coil wire end connected to a second terminal T2 of the motor, and the other coil wire ends are connected to re- spective ones of the contactors C2a, C2b and C2c of the second set of contactors C2 situated at the second bearing 4a. The rotor with the motor shaft 6 and contact springs 5 and 5a is for illustrative purposes indicated by a circle. The structure in figure 2 is shown "folded out". In the motor the shown structure is cylindrical, and in each set of coils the coils are spaced 120 degrees apart. In each set of contactors the three contactors are also spaced 120 degrees apart. Each contactor extends for slightly less than 120 degrees so that a small gap exists between neighbouring contactors. .The first set of coils and the first set of contactors are angularly offset 60 degrees relative to the second set of coils and the second set of contactors.
In operation the terminals TI and T2 are connected to a DC power source In the shown position of the motor shaft an electric current path is established from the first terminal TI through the coil S5 of the first set of coils, the contactor Clc of the first set of contactors, the first contact spring 5, the shaft 6, the second contact spring 5a, the contactor C2c of the second set of contactors, the coil S4 of the second set of coils and the second terminal T2. The electric current in the coils S5 and S4.generates a magnetic field, which interacts with the rotor magnet 3 and causes the rotor to rotate. Upon rotation of the rotor the shaft 6 with contact springs 5, 5a shown schematically in figure 2 will move from the position shown to a position where the current path is maintained in the coil in one set of coils, whereas the current in the coil in the other set of coils is shifted to another coil in the same set of coils. The current path thus always includes one coil in one set of coils and one coil in the other set of coils connected in series, and upon rotation of the rotor switching of the current path is done alternatingly between the first set of coils and the second set of coils. Each switching operation thus only switches half of the current path and half of the coils, while the other half of the current path and the other half of the coils is switched subsequently.
Figure 3 shows schematically the layout of the coils on the flexible sheet. The sheet will be rolled and placed inside the tubular stator near its cylindrical inner surface, where it will be held in place by means of the two bearings. It is seen that each coil has a lateral extension corresponding to 180 degrees when placed in the stator, and that the coils are spaced apart corresponding to 60 degrees.
Figure 4 shows a schematical cross section through the motor. The outermost structure is the rolled sheet with the coils. Also shown are the two sets of contactors, where, for illustrative purposes, the first set of contactors Cla, Clb and Clc are shown having a larger diameter than the second set of contactors C2a, C2b and C2c. Also shown is a contact brush Cbr illustrating the shaft with the two contact springs . The contact brush Cbr is shown bridging contactors in the two sets, in this case contactor Clc in the first set and contactor C2b in the second set.

Claims

Claims :
1. An electric motor having a stator and a rotor ro- tatably received in the stator, wherein
the stator includes a first set of a plurality of coils of electrically conductive wire arranged in a star configuration where each coil in the first set has a first coil wire end connected to a first termi- nal of the stator, and each coil in the first set has a second coil wire end connected to respective ones of a first set of contact surfaces on the stator,
and wherein the rotor has an axis and a magnet magnet- ised transversely to the axis and a first contact brush, which, upon rotation of the rotor, alternatingly contacts the contact surfaces of the first set of contact surfaces, whereby an electric current path through the first contact brush is established alternatingly through the coils of the first set of coils to the first terminal,
c h a r a c t e r i z e d in that
the stator includes a second set of a plurality of coils of electrically conductive wire arranged in a star configuration where each coil in the second set has a first coil wire end connected to a second terminal of the stator, and each coil has a second coil wire end connected to respective ones of a second set of contact surfaces on the stator,
the rotor has a second contact brush electrically connected to the first brush, which upon rotation of the rotor alternatingly contacts the contact surfaces of the second set of contact surfaces, whereby an electric current path through the second contact brush is established alternatingly through the coils of the second set of coils to the second terminal, and
the first contact brush and the first set of contact surfaces are so arranged relative to the second contact brush and the second set of contact surfaces that, upon rotation of the rotor, the current path switches from one coil to another in only one set of coils at a time, and that such switching is done alternatingly between the first set of coils and the second set of coils.
2. Motor according to claim 1 c h a r a c t e r i z e d in that the first set of contact surfaces and the second set of contact surfaces are situated at opposite sides of the rotor.
3. Motor according to claim 2 c h a r a c t e r i z e d in that each set of contact surfaces defines a substantially flat surface perpendicular to the axis .
4. Motor according to claim 1 c h a r a c t e r i z e d in that the contact brushes have a heli- coidal form and are made of a resilient, electrically conductive metal wire.
5. Motor according to claim 4 c h a r a c t e r i z e d in that the helicoidal contact brushes have a narrow end portion and are secured to the rotor shaft by means of that portion, and that the rotor shaft is electrically conductive.
6. Motor according to claim 5 c h a r a c t e r i z e d in that the helicoidal contact brushes each have a wide end portion opposite the narrow end portion with a free end of the wire contacting the respective contact surfaces.
PCT/DK2001/000471 2000-07-07 2001-07-06 Dc electric motor with two commutators and permanent magnet rotor WO2002005409A1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AU2001272358A AU2001272358A1 (en) 2000-07-07 2001-07-06 Dc electric motor with two commutators and permanent magnet rotor

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DK200001064A DK173719B1 (en) 2000-07-07 2000-07-07 Electric motor
DKPA200001064 2000-07-07

Publications (1)

Publication Number Publication Date
WO2002005409A1 true WO2002005409A1 (en) 2002-01-17

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ID=8159608

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/DK2001/000471 WO2002005409A1 (en) 2000-07-07 2001-07-06 Dc electric motor with two commutators and permanent magnet rotor

Country Status (3)

Country Link
AU (1) AU2001272358A1 (en)
DK (1) DK173719B1 (en)
WO (1) WO2002005409A1 (en)

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE293044C (en) *
CH415815A (en) * 1959-09-22 1966-06-30 Heemaf Nv Equipment with direct current motor for high supply voltage
DE1538749A1 (en) * 1966-12-03 1970-01-29 Buehler Gmbh Nachf Geb DC motor for the direct drive of a capstan or the like.
JPS60162463A (en) * 1984-02-03 1985-08-24 Matsushita Electric Ind Co Ltd Revolving-field type dc motor
WO1998043317A1 (en) * 1997-03-26 1998-10-01 Kirk Acoustics A/S A contact device and a tool for handling it

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE293044C (en) *
CH415815A (en) * 1959-09-22 1966-06-30 Heemaf Nv Equipment with direct current motor for high supply voltage
DE1538749A1 (en) * 1966-12-03 1970-01-29 Buehler Gmbh Nachf Geb DC motor for the direct drive of a capstan or the like.
JPS60162463A (en) * 1984-02-03 1985-08-24 Matsushita Electric Ind Co Ltd Revolving-field type dc motor
WO1998043317A1 (en) * 1997-03-26 1998-10-01 Kirk Acoustics A/S A contact device and a tool for handling it

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
PATENT ABSTRACTS OF JAPAN vol. 009, no. 332 (E - 370) 26 December 1985 (1985-12-26) *

Also Published As

Publication number Publication date
DK200001064A (en) 2001-07-23
AU2001272358A1 (en) 2002-01-21
DK173719B1 (en) 2001-07-23

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