FR2631755A1 - METHOD FOR PRODUCING A MAGNETIC CIRCUIT FOR A STATOR OF ROTARY ELECTRIC MACHINES OR A MAGNETIC CIRCUIT FOR TRANSFORMERS, AND MAGNETIC CIRCUIT THUS OBTAINED - Google Patents

Abstract

The invention relates to the field of construction techniques for magnetic circuits of electric machines. In particular, the method provides for the formation of packets of cut magnetic sheets which are brought together and united in correspondence of their joining sides. The joining of the bundles can take place by welding of the closely joined sides or by a male-female interlocking system of the sheets of one pack in the sheets of the adjacent pack.

Description

PROCESS FOR THE REALIZATION 0 OF A MAGNETIC CIRCUIT OF STATOR XE

  ROTARY ELECTRICAL OR MKAGNETIC CIRCUIT MACHINES

  TRANSFOMATORS, AND MAGNETIC CIRCUIT THUS OBTAINED

  The present invention relates to a method for producing a magnetic stator circuit of a rotary electric machine or an electric circuit for transformers, and the magnetic circuit

thus obtained.

  Currently, for the formation of packages of stators of rotary electrical machines, the sheets are first cut, which will then be packaged to form the magnetic circuit of the machine. When it comes to electric alternator stators, in most cases the rings are cut from a strip or a ribbon and this results in a remarkable quantity of unusable waste. In order to reduce the quantity of this waste, we have already considered the possibility of cutting the sheets in the form of ring arcs which will then be placed side by side for the formation.

of a complete ring.

  For the formation of the bundle, we stack a certain number of rings where the junctions of the arcs are offset and we then perform

  racking of the package which must be kept compact.

  In practice, sheets are produced having the shape of a circular crown arc whose angle at the center is 120 'so that the bringing together of three sheets makes it possible to form a complete circular crown. The sheets of one layer are offset by 45 relative to those of the next layer. The sheets are further provided with through holes through which rivets or pins are introduced which are riveted in order to keep the sheets united after the formation of the

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  package. The technique described above has several drawbacks among which it is necessary to remember the high scrap of sheet metal during the step of cutting the strip and the loss of a lot of time for the formation and assembly of the package. = The final precision is also low and the tolerances are

  high, of the order of a few tenths of a millimeter.

  Another known technique provides for the cutting of rectilinear pieces having a length equal to the extension of the complete circular crown. This technique minimizes cutting waste but there is a lot of waste during the formation of the final package, because there are many difficulties when you have to

bend the straight pieces.

  According to another known technique, quite expensive and difficult, the sheets are cut in a spiral. This technique is very expensive with regard to installations and this has repercussions on

the cost price of the product.

  When it comes to small motors whose stator is of substantially rectangular or square shape, the sheet metal is cut in one

  piece and in this case too there is a lot of unusable waste.

  This also applies to the formation of magnetic circuits

of various type transformers.

  The present invention aims to remarkably reduce the waste resulting from the cutting operation of the sheets obtained from a

tape or ribbon.

  Another object is to carry out the assembly of the parts or packets of sheets making up the final magnetic circuit of the machine, in a very rapid and precise manner, capable of not influencing the flux lines of the magnetic field which pass through the circuit. magnetic itself. Yet another object of the invention is to obtain circuits

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  magnetic with a minimum tolerance of a few hundredths of a millimeter. These and other objects are achieved by the method for producing a magnetic circuit of a stator of rotary electric machines or a magnetic circuit for transformers, such as

  that it is characterized in the claims which follow.

  The magnetic circuit obtained by the above process, as it is

  defined in the claims which follow, represents another

  characteristic of the present invention.

  The features in question and more will emerge more

  clearly from the following description of the two embodiments

  preferred, but not exclusive, illustrated by way of example

  not limiting in the accompanying drawings, in which.

  - Figure 1 is a perspective view of a magnetic circuit obtained using the method of the invention for a motor of small dimensions; - Figure 2 shows in perspective the stator of an electric generator also obtained using the method of the invention; - Figure 3 is a perspective view of the magnetic circuit obtained

  according to a possible variant of the process of the invention.

  Referring to FIG. 1, the magnetic stator circuit of a small motor is indicated at 1. The magnetic circuit consists of two

sheet packages 2 and 3.

  The package 2 is formed by superimposing sheets having an interlocking portion m & le 5 provided on the upper cross member 4 on which

  the winding of the stator, not shown, is adapted.

  Package 3 is formed by superimposing sheets having a portion

  female socket 7 provided on a vertical column 6.

  We will now describe the process for obtaining the magnetic circuit

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  illustrated. We start with a ribbon or strip of continuous sheet metal and we first cut the sheets provided with a portion of embo. male 5 obtained during the forming step. A pack of these sheets is then formed using a plurality of these until the desired and final thickness of the magnetic circuit is reached. Said package is welded along lines 8 in order to maintain the sheets forming the

united and compact package.

  Then, from a continuous strip, the sheets are cut having a female interlocking portion 7 and we form

  then a package provided with welds 8 of union of the sheets.

  To obtain the final magnetic circuit, it suffices to introduce the male nesting portion 5 of the pack 2 into the female nesting portion 7 of the pack 3 and to slide the two pieces nested along the straight line 9 ; we

  will thus be able to obtain the perfect and stable junction of the two packages.

  By the process described we have remarkable reductions in waste and at the same time we significantly reduce the time

  assembly and assembly of electrical machines.

  Indeed, the nesting of the two male and female parts allows the rapid insertion of the electric circuit of the stator, in the form of a coil, on the cross-member 4 and its final blocking by the union of the

two packages.

  Referring to Figure 2, there is shown a magnetic stator circuit 10 of circular shape, capable of being used, for example

for an electric alternator.

  For the formation of the sheet pack making up the magnetic stator circuit 10, the sheets are cut first in the form of arcs of a circle of 90 (11) provided with a male interlocking portion 12 and a portion female socket 13 arranged on the two opposite sides. There is then the formation of bundles of sheets of a desired height, then the bundles are assembled together by simple

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  displacement of a package compared to the other along lines

parallel lines 14.

  Referring to Figure 3, we will describe the embodiment of a magnetic stator circuit according to a possible alternative form of the method. In 21, the magnetic circuit of the stator of a current alternator has been indicated, in particular for vehicles. The circuit consists of six packets of sheets 22 in the shape of a circular crown arc. Each sheet is provided with a chamfer on its side 24 defining the width of the crown. By joining the packets we create a channel

  inside duque] a weld can be made 25.

  The stator magnetic circuit described above is made on the

basis of the process which follows.

  Sheet metal is cut in the shape of a circular crown arc whose angle at the center is less than or equal to 90, in the case shown the angle at the center being 60 '. Each sheet is provided with a chamfer 23, on its outer edge and on each of its sides,

  indicated at 24, defining the width of the crown.

  The sheets thus obtained are formed into bundles which must be at least four, until reaching the desired thickness, by simple

  superimposition of a plurality of sheets.

  By] .e bringing together the packages thus formed, which must be at least four, we will create a complete circular crown, like that shown in Figure 3. We will then perform the welding of the packages (four or more than four) brought together on their sides joints, inside the chamfers, so as to obtain, by solder 25, a stable union of the packets and therefore of the magnetic circuit

of the stator.

  Preferably, the formation of bundles of sheets will be carried out using sheets in the shape of an arc of circular crown having an angle at the center of 60 ', so as to use six packs of sheets

  to get a full crown.

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  R VF N n TCAT JLS 1. Method for producing a magnetic circuit of a stator of rotary electrical machines or a magnetic circuit for transformers by means of the formation of previously cut magnetic sheet bundles, characterized in that it provides for the bringing together the packets to form the desired magnetic circuit and the union of the sheet packets in correspondence of their joining sides

of reconciliation.

  2. Method according to claim 1, characterized in that it provides the following steps: - sheet metal cutting] are provided with a mailing nesting portion

- (5; 12);

  - cutting of sheets provided with a female interlocking portion (7; 13); - Union by welding of sheets having the same type of socket, so as to form a packet of the desired final dimensions; - introduction of the male interlocking portion into the portion

  female interlocking by simply sliding one into the other.

  3. Method according to claim 2, characterized in that during the step of cutting the sheets is provided a fitting portion

  male (12) and a female socket portion (13) opposite.

  4. Method according to claim 2, characterized in that it comprises a step of cutting the sheets during which one obtains two female socket portions (13) opposite and a step of cutting

  other sheets having two opposite male fitting portions (12).

  5. Method according to claim 2, characterized in that during the step of cutting the sheets each sheet and therefore each package (6, 11) obtained by superposing sheets is provided with a fitting portion m & âle and / or female , or two interlocking portions

opposite male and female.

  6. Magnetic circuit obtained according to the method of claim 1,

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  characterized in that it comprises at least one pack of sheets provided with a male interlocking portion and at least one packet of sheets provided with a female interlocking portion, these male and female fitting portions being suitable & penetrate one into

  the other by simple translation of the packages.

  7. Method according to claim 1, characterized in that it comprises the following stages: - cutting of sheets in the form of a circular crown arc whose angle in the center is less than or equal to 90 '; - Formation of at least four packages (22) of-sheets, each of which is formed by simple superposition of a plurality of sheets obtained according to the previous step, until reaching the desired thickness of the package; bringing the packets together (four or more) so as to form a complete circular ring (21); - formation of a weld (25) between the packages (four or more) in

  correspondence of their joining sides of reconciliation.

  8. Method according to claim 7, characterized in that during the first cutting step, sheets are produced in the form of a circular crown arc whose angle at the center is equal to 60 'and for

  in the second stage, six bundles of sheets are formed.

  9. Method according to claim 7, characterized in that during the first step of cutting the sheets, chamfers (23) are made on the outer edge of these, on each side defining the width of the rings and in that the welding packets takes place at

inside the chamfers.

  10. Magnetic stator circuit of a current generator in the shape of a circular crown, characterized in that it comprises at least four packets of teles joined to one another by a weld housed in

  a chamfer along the generatrix of the circular crown.

  11. Magnetic circuit according to claim 10, characterized in that it comprises six packets of sheets joined to one another by a weld housed in a chamfer along the generatrix of the circular crown,