Classifications

• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61C—DENTISTRY; APPARATUS OR METHODS FOR ORAL OR DENTAL HYGIENE
  • A61C17/00—Devices for cleaning, polishing, rinsing or drying teeth, teeth cavities or prostheses; Saliva removers; Dental appliances for receiving spittle
  • A61C17/16—Power-driven cleaning or polishing devices
  • A61C17/22—Power-driven cleaning or polishing devices with brushes, cushions, cups, or the like
  • A61C17/32—Power-driven cleaning or polishing devices with brushes, cushions, cups, or the like reciprocating or oscillating
  • A61C17/34—Power-driven cleaning or polishing devices with brushes, cushions, cups, or the like reciprocating or oscillating driven by electric motor
• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02K—DYNAMO-ELECTRIC MACHINES
  • H02K33/00—Motors with reciprocating, oscillating or vibrating magnet, armature or coil system
  • H02K33/02—Motors with reciprocating, oscillating or vibrating magnet, armature or coil system with armatures moved one way by energisation of a single coil system and returned by mechanical force, e.g. by springs
  • H02K33/04—Motors with reciprocating, oscillating or vibrating magnet, armature or coil system with armatures moved one way by energisation of a single coil system and returned by mechanical force, e.g. by springs wherein the frequency of operation is determined by the frequency of uninterrupted AC energisation
  • H02K33/06—Motors with reciprocating, oscillating or vibrating magnet, armature or coil system with armatures moved one way by energisation of a single coil system and returned by mechanical force, e.g. by springs wherein the frequency of operation is determined by the frequency of uninterrupted AC energisation with polarised armatures

Definitions

• the invention relates to an AC small motor with an oscillating permanent-magnet rotor, in particular for the oscillating drive of a toothbrush attached to the rotor shaft, with a cylindrical, diametrically magnetized permanent magnet as a rotor and with a fixed coil.
• Known AC motors of this type (FR-PS 1 470 893) have rather complicated stator structures with a plurality of stator parts in double T or Z shape, the inner beams forming curved poles and the radially oriented central parts being surrounded by the stator coils.
• the motor In a known electric toothbrush (DE-PS 1119819), the motor is mounted in a housing-like handle and has a rotor that vibrates at the frequency of the supply voltage and on the shaft of which an interchangeable plug-in toothbrush can be placed. When connecting the motor to the AC network the toothbrush swings at the mains frequency around the brush axis.
• the oscillating armature of this known AC motor is designed in the form of a salient pole rotor which has a permanent magnet with soft iron pole shoes and is held in its rest position by a return spring.
• the stand has two pole-forming, winding-free pole shafts which are oriented in the longitudinal direction of the housing and are diametrically opposite one another; the pole shafts have legs which are extended beyond the area of the oscillating armature in the direction of the rear end of the housing and which are connected by a transverse yoke which carries the stator winding.
• the invention has for its object to improve the engine efficiency compared to known AC motors with an oscillating rotor in such a way that either approximately the same torque with reduced power consumption or a higher torque can be achieved with approximately the same power consumption, and furthermore the structure of the motor is particularly compact and simple to design.
• the higher efficiency makes it possible, in particular, to operate the motor with low voltage, for example with 20 V, which is particularly advantageous for safety reasons, particularly in the case of electric toothbrushes or massage devices.
• Such a handheld device can then preferably be fed from the network via a transformer and does not have to meet any strict regulations with regard to its electrical insulation.
• this object is achieved in that the coil is oriented with its axis perpendicular to the rotor axis and surrounds the permanent magnet, wherein their turns are substantially rectangular, and that the stator is a tubular, coaxial to the rotor axis housing part made of magnetizable material, which encloses the coil.
• the coil can preferably be composed of two essentially identical partial coils, the contact plane of which passes through the rotor axis and which, depending on the supply voltage used, can be connected in series or in parallel.
• the stand has a rectangular cross section with a long and with a short side surface pair, the long side surfaces forming preferred poles and thus a geometry with a variable reluctance depending on the position of the rotor, without special pole shoes or differently shaped projecting poles being provided .
• the torque exerted by the magnetic coil field on the rotor by means of the rectangular stator geo
• the resulting static torque is amplified, which tries to rotate the rotor so that the magnetization direction of the permanent magnet is parallel to the short side surfaces of the stator.
• the coil axis must be oriented perpendicular to the long side surfaces of the stator and the rotor in its rest position must be held in a position in which the direction of the diametrical rotor magnetic field perpendicular to the coil axis by means of suitable return means, for example a return spring and is therefore parallel to the long side surfaces of the stand.
• suitable return means for example a return spring and is therefore parallel to the long side surfaces of the stand.
• a similarly effective effect is provided by an octagonal cross-section with a pair of opposite side faces that are larger than the other side faces.
• the same effect can also be achieved by choosing a cylindrical stator housing with two projecting stator poles diametrically opposite on its inner circumference.
• the stator is merely a cylindrical sleeve without projecting poles, and because of the symmetrical stator geometry, no additional static torque acts on the rotor.
• FIG. 1 is a perspective view of a first embodiment with a rectangular stator housing in an exploded arrangement of the individual parts
• FIG. 6 is a perspective view of a second embodiment with a cylindrical stator housing in an exploded arrangement of the individual parts
• FIG. 7 shows the assembled motor according to FIG. 6, but with the stand cut open
• FIG. 11 shows a cross section through an octagonal, two-part stand of a third embodiment.
• the stator 1 of the AC motor consists of a tubular housing part with right corner-shaped cross section, which consists of magnetizable material and has the long or large side surfaces la and the short or small side surfaces 1b.
• the rotor attached to the rotor shaft 5 consists of a cylindrical permanent magnet 4 with diametrical magnetization. The poles are indicated in Fig. 1 by the letters N and S.
• the rotor shaft 5 can consist of magnetic material.
• the permanent magnet 4 is surrounded over its entire length by a coil consisting of two partial coils 2 and 3, the axis of which runs perpendicular to the rotor shaft 5 and perpendicular to the long side faces la of the stator 1 and whose winding direction is indicated in FIG. 2 by arrows.
• the turns are essentially rectangular and are adapted to the longitudinal section through the axis of the cylindrical permanent magnet 4.
• the partial coils 2 and 3 are constructed identically and lie with their inwardly facing surfaces oriented parallel to their winding planes in a plane passing through the rotor axis; the edges of the partial bobbin running diametrically to the rotor have approximately semicircular recesses 2a, 2b and 3a, 3b in the middle, which in the assembled state complement each other to provide openings for the passage of the rotor shaft 5.
• the outer circumference of the two partial coils 2 and 3 is adapted to the inner circumference of the rectangular stator 1, which in this way holds the coil essentially in a form-fitting manner, the rectangular coil openings 2c and 3c lying in front of the long stator side surfaces la.
• the inner circumference of the partial coils 2 and 3 is adapted to the cylindrical shape of the permanent magnet 4.
• the permanent magnet 4 of the shell-shaped partial coils 2 and 3 is complete and with only little play surrounded, the free space between the rotor and the stand is practically completely filled by the coil turns.
• the coil arrangement can also be designed such that it only partially fills the free space within the stator.
• stator 1 The end faces of the stator 1 are closed by two rectangular flanges 6 and 7 which are adapted to the stator opening cross section and which have bearing openings 8 and 9 in the middle for the passage of the rotor shaft 5 and which can optionally consist of magnetic material.
• the motor described can typically have an axial length of approximately 55 mm, a height of approximately 20 mm and a width of approximately 15 mm.
• the power consumption when operating at 50 Hz or at 60 Hz can typically be between 1.3 and 1.6 W.
• the motor described works as follows: by means of a restoring means, for example a restoring spring 20 indicated in FIG. 2 and surrounding the rotor shaft 5, the permanent magnet rotor 4 is forced into a position in the rest position, which is shown in FIG. 2 and in which the direction of the diametrical rotor magnetic field is perpendicular to the coil axis.
• a restoring means for example a restoring spring 20 indicated in FIG. 2 and surrounding the rotor shaft 5
• the permanent magnet rotor 4 is forced into a position in the rest position, which is shown in FIG. 2 and in which the direction of the diametrical rotor magnetic field is perpendicular to the coil axis.
• stator housing 1 now has two additional advantageous effects.
• this stator geometry allows, for a given amount of copper in the coil wire, the generation of a relatively high field in the axial direction of the coil.
• the magnetic circuit has a reluctance which is relatively strongly dependent on the angle between the magnetization axis of the rotor magnet 4 and the large axis of symmetry of the stator rectangular cross section, since the two long or large side surfaces la of the stator 1 have the function of preferred poles.
• the effect of this variable reluctance is as follows: If the rotor is deflected a little from its rest position shown in FIG.
• the size of the vibration angle of the rotor depends on the external load and on the coordination of the mechanical vibration system, i.e. on the mass of the rotor and the object attached to it, on the characteristic of the restoring means and on the damping or Friction. Under certain circumstances, this angle can be 180 and possibly even exceed this value. If no measures are provided to limit the angle of the rotor and the rotor is therefore free, the motor can behave like a rotating, single-phase synchronous motor. For the special application of the motor to the drive of a toothbrush, however, the oscillation angle of the rotor and thus the oscillation movement of the toothbrush about the brush axis is limited to an angle of approximately 60 or less.
• the second exemplary embodiment of an engine according to the invention according to FIGS. 6 to 10 differs from the first embodiment in that the stator 11 consists of a cylindrical sleeve, that accordingly the outer circumference of the coil, which in turn is formed from two identical partial coils 12 and 13, is cylindrical in adaptation to the stator inner circumference and that the end flanges 16 and 17, the again have bearing openings 18 and 19 for the passage of the rotor shaft 5, are circular to match the opening cross section of the stator 11.
• the rotor in turn, as in the first embodiment, consists of a cylindrical permanent magnet 4 with diametrical magnetization fastened to the rotor shaft 5.
• the two partial coils 12 and 13 are constructed, oriented and arranged in the stator 11 in exactly the same way as in the first exemplary embodiment.
• stator pole pieces 14 and 15 made of magnetizable material are provided in the second exemplary embodiment according to FIG. which are diametrically opposed to one another and rest against the inner circumference of the stand 11 or are fastened there.
• these two stator pole pieces 14 and 15 have the shape of hollow cylinder segments and are adapted to the shape of the openings 12c and 13c of the partial coils 12 and 13, respectively, so that they engage in these coil openings in the assembled state of the motor.
• stator poles 14 and 15 which can also be designed in any other way or can be fastened or molded onto the inner circumference of the stator, effect practically the same static torque effect, which was described with reference to the first exemplary embodiment and which has the consequence that the rotor magnet 4, as soon as it is deflected somewhat from its rest position shown in FIG. 7, experiences a torque which causes it to move 90 out of its rest position seeks to rotate and which overlaps the torque generated by the coil field.
• the projecting stator poles increase the coil field.
• an AC motor according to the invention can also have a stator which only consists of a cylindrical housing 11 (FIG. 6) and has no projecting stator poles.
• This construction of a motor is particularly simple and has the advantage of an indifferent balance with respect to the rotation of the rotor.
• FIG 11 shows the octagonal stator 21 in cross section of a further embodiment of a motor according to the invention, in which, analogously to the example according to Figure 1, the two coil halves (not shown) are adapted with their outer circumference to the octagonal stator inner circumference and advantageously practically the entire free space between the stator and take runners.
• two identical shell-shaped stator halves 21 'and 21 "are provided in the example according to FIG with the help of flanges adapted to the octagonal column cross section can happen, which, like the flanges 6 and 7 of Figure 1, form the stator end faces.
• the two opposite side surfaces 21a of the stand 21 are larger than the other side surfaces, and the coil axis is oriented perpendicular to these large side surfaces, so that there are very similar advantageous effects as for the rectangular stand 1 according to FIG. 1 with its long side surface pair la and its short side surface pair 1b.
• the distance between the side faces oriented perpendicular to the large side faces 21a can generally be between 10 and 50%, preferably about 30% larger than the distance between the large side faces 21a. This also applies to the dimensions of the rectangular stand according to FIG. 1.
• An octagonal stator shape according to FIG. 11 has the additional advantages that the motor can be accommodated particularly well and in a space-saving manner in a handle-like housing with an oval cross section, as is typically used for electric toothbrushes, and that the maximum radial distance between the rotor and the stator sleeve compared to the diagonal dimensions of a rectangular stand is reduced; this reduces the volume of air or copper within the magnetic circuit and thus increases the field.
• a more favorable characteristic curve of the torque is obtained as a function of the rotor angle.
• the stands 1 and 11 can each be composed of two halves, analogously to the stand 21 according to FIG. 11.
• the preferred application of the AC motor according to the invention is the installation in the handle-like housing of an electric toothbrush with interchangeable toothbrushes; Due to the relatively low power consumption, such an electric toothbrush can then be supplied with low voltage via a transformer from the network, so that practically no problems with the electrical insulation occur.
• the motor according to the invention is also suitable for other purposes, for example for massage devices and for all applications in technical fields in which a rapid periodic movement plays a role, such as in small pumps.
• the invention is not limited to the exemplary embodiments described, but allows multiple variants with regard to the design and assembly of the individual parts, in particular with regard to the stator cross section, which can also be oval, square or generally polygonal, and with regard to the coils.

Landscapes

• Health & Medical Sciences (AREA)
• Dentistry (AREA)
• Epidemiology (AREA)
• Life Sciences & Earth Sciences (AREA)
• Animal Behavior & Ethology (AREA)
• General Health & Medical Sciences (AREA)
• Public Health (AREA)
• Veterinary Medicine (AREA)
• Engineering & Computer Science (AREA)
• Power Engineering (AREA)
• Reciprocating, Oscillating Or Vibrating Motors (AREA)
• Brushes (AREA)

Priority Applications (1)

Applications Claiming Priority (2)

Publications (1)

Family

ID=4309811

Family Applications (1)

Country Status (7)

Cited By (2)

Families Citing this family (23)

Citations (5)

Family Cites Families (16)

• 1979
  • 1979-07-11 CH CH644979A patent/CH646554A5/de not_active IP Right Cessation
• 1980
  • 1980-07-07 DE DE19803025675 patent/DE3025675A1/de active Granted
  • 1980-07-08 WO PCT/CH1980/000083 patent/WO1981000331A1/de unknown
  • 1980-07-08 FR FR8015150A patent/FR2461393A1/fr active Granted
  • 1980-07-08 JP JP55501420A patent/JPH0526424B2/ja not_active Expired - Lifetime
  • 1980-07-08 BR BR8008733A patent/BR8008733A/pt unknown
• 1985
  • 1985-06-13 US US06/744,642 patent/US4595849A/en not_active Expired - Lifetime

Patent Citations (5)

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