FR2519206A1 - ELECTRIC MOTOR WITH INTERIOR PROTECTED FROM FOREIGN MATTER - Google Patents

Abstract

THE INVENTION RELATES TO AN ELECTRIC MOTOR WHICH INCLUDES A CYLINDRICAL CYLINDRICAL CYLINDRICAL CYLINDRICAL, A NUMBER OF PAIRS OF MAGNETIC POLES IN A PERMANENT FERRITE MAGNET AND WHICH ARE FIXED SOLIDLY AT EQUAL ANGULAR INTERVALS PREDETERMINED ON A PERIPHERAL SURFACE AND INTERNAL CELLS, AND THE INTERNAL PERIPHERAL SURFACE. MOVING AXIALLY THROUGH THE CYLINDER HEAD AND THROUGH IT RADIALLY SO AS TO BE PLACED ON THE AXES OF THE MAGNETIC POLES DUE TO ONE FOR EACH POLE. ACCORDING TO THE INVENTION, A PROTECTIVE TUBE 18 OF A HEAT-SHRINKABLE MATERIAL IS ADJUSTED TO THE HEAT ON AN EXTERNAL PERIPHERAL SURFACE OF THE CYLINDER HEAD 12 TO COVER THE SLOTS 16. THE INVENTION APPLIES IN PARTICULAR TO ELECTRIC MOTORS.

Description

The present invention relates to an electric motor, and more

  particularly to improvements to an electric motor comprising a cylindrical yoke, a number of pairs of magnetic poles formed of a ferrite permanent magnet and which are securely attached to the yoke and a number of slots disposed

  on the cylinder head to interrupt the magnetic flux that I 6: -

  the through the bolt due to a reinforcement reaction,

  at the rate of one for each magnetic pole.

  A conventional electric motor of the type

  that includes a cylinder head formed of sheet metal

  two pairs of magnetic poles which are

  in a permanent magnet of ferrite and which are fixed

  solidly at equal angular intervals on the surface

  this internal device of the breech by an agent of rush-

  four slots, each of which is arranged on the cul-

  on the axis of the magnetic pole associated to interrupt the magnetic flux flowing through the cylinder head

made of a frame reaction.

  Conventional electric motors such as that described above are disadvantageous because foreign materials such as water, dust and the like intrude inside the cylinder head through the slots,

  to contaminate the latter, resulting in a

improved reliability.

  Accordingly, the present invention obtains

  a new and improved electric motor of the

  diqué, including a breech whose interior can not

  to be contaminated by foreign matter.

  The present invention relates to an electric motor

  which comprises a cylindrical yoke, a number of pairs of magnetic poles made of a permanent magnet of ferrite and which are fixed firmly at equal and predetermined intervals on the inner peripheral surface

  of the breech, a number of slots running axially

  the yoke and extending radially therethrough, to be placed on the axes of the magnetic poles, one for each magnetic pole, and a protective tube of a heat-shrinkable material fitting on the outer peripheral surface of the breech to cover the various slots. The invention will be better understood, and other purposes,

  characteristics, details and advantages of it

  will become clearer in the course of the description

  following diagram made with reference to the schematic drawings

  annexed issues given solely by way of illustrative

  an embodiment of the invention and in which: FIG. 1 is a cross-sectional view

  of an embodiment of the electric motor according to the invention.

  tion, parts being omitted; and Fig. 2 is a fragmentary longitudinal sectional view of the arrangement of Fig. 1, looking at

  along the line II-II of Figure 1.

  Referring now to Figure 1 of the

  we can see an embodiment of the electric motor

  The illustrated arrangement comprises a field device for a DC motor generally designated by the reference numeral 10.

  consists of a cylindrical yoke 12 which is produced

  by pressing a steel sheet and a number of pairs of magnetic poles that are formed into segments

  of a permanent magnet of ferrite and which are fixed solid-

  at equal, predetermined angular intervals on the inner peripheral surface of the yoke 12 by a jointing agent (not shown) The magnetic poles 14 are identical to each other and comprise coaxially radially outer and inner surfaces with

  the inner peripheral surface of the breech 12 In the exei-

  In FIG. 2, two pairs of the four magnetic poles 14 are arranged at equal angular intervals of 900 on the inner peripheral surface of the yoke 12, so that the magnetic poles 14 of each pair are diametrically

  Opposites An axial slot 16 runs axially through the cul-

  12 and extends radially through it, on the axis of

each magnetic pole 14.

  When an armature (not shown) is exterior

  When excited to be rotated with the magnetic excitation of the field device 10, the energized armature exerts a reaction on the cylinder head 12, having a low reluctance, to cause the flow of a magnetic flux through the coil. The slits 16 are intended to interrupt the flow of this magnetic flux to

through the breech.

  The part of the arrangement that has just been described

  re represents the conventional structure and is disadvantageous

  because foreign matter such as water, dust and other intrusions into the interior of the

  12 by the slots 16, with the result that

deterioration of reliability.

  The present invention aims to eliminate disadvantages such as those described above, in

  providing means for closing slots 16.

  As shown in Figures 1 and 2, a tube

  protection device 18 fits on the peripheral surface ex-

  dull of the cylinder head 12 The protection tube 18 is formed

  in a heat-shrinkable material selected from the group con-

  polyvinylchloride, polyesters and polyvinylchloride

  léfines, and marketed under the names "HISHI TUBE" (denominated

  mha Uicncmenia ,, "TERE TUBE" (trade name) or SUMI TUBE "(trade name) by Mitsubishi Jushi

  firm, Teijin Kasei firm or Sumitomo Denko firm respec-

tively.

  After being placed on the peripheral surface

  external cylinder 12, the protective tube 18

  is shrunk by heating until it closes completely.

Slots 16.

  It has been found that when breech 12 has a diameter

  outer 70 to 80 mm and a thickness of 1.8 to 2.2 mm, a protective tube 18 of 0.1 mm thick gives

satisfactory results.

  It can be seen from the above that according to the invention the protective tube fits on the cylinder head and is shrunk by heating to close the

  slots in order to suppress a reaction.

  Thus, the protective tube is effective to prevent foreign matter such as water, dust and the like from intruding into the breech through the slots, resulting in an impermeable structure. the resulting device is impermeable and prevents the inside of the cylinder head from rusting and this also prevents the presence of objections such as deterioration of the binding agent

  the magnetic poles at the breech and others

  terms, the field device according to the invention has

  its inner part which can not be contaminated with the ex-

  TER AL. The present invention has been described with reference to a yoke having two pairs of magnetic poles which are formed of a ferrite permanent magnet and which are firmly attached to its inner peripheral surface, but it will be understood that this is unrestricted and that The invention also applies to electric motors

  having a breech provided with slots to prevent a reaction

  In the same way, the breech may include an amount other than two pairs of poles.

  magnetic fields, and therefore a quantity other than

to be slits.

Claims (2)

R E V E N D I C A T I 0 N S   1 Electric motor of the type comprising a   cylindrical sleeve, a number of pairs of magnetic poles into a permanent magnet of ferrite and which are fixed firmly at equal and predetermined angular intervals on an inner peripheral surface of the   so-called breech, a number of axially traversing slots   said cylinder head and crossing it radially,   to be placed on the axes of said magnetic poles.   one for each pole, characterized by a protective tube (18) of heat-shrinkable material, which is heat-fitted to an outer peripheral surface of said yoke (12) to cover said slots (16).   Electric motor according to Claim 1, characterized in that the heat-shrinkable material mentioned above   is selected from the group consisting of polyvinyl chlorides nyl, polyesters and polyolefins.