FR3083027A1 - INSULATING PAPER FOR VARNISH IMPREGNATED NOTCHES - Google Patents

Abstract

Insulating paper 4 for insulating conductors in a slot comprising: -an internal portion 41, -two external portions 42, -a total axial length along a direction of a longitudinal axis X of the paper 4, equal to the sum of a length internal axial length of the internal portion 41 and two external axial lengths of the two external portions, the internal axial length being equal to at least eighty percent of the total axial length of the paper 4, in which the internal portion 41 comprises a central zone 410 whose axial middle is the middle of the internal portion, the central zone 410 having - a central axial length equal to at least 50% of the internal axial length, - transfer holes 43 located over all the central axial length, each transfer hole having a surface area of at least 0.02mm2, and in that each of the outer portions 42 each comprises at least one insulating zone 421 over an axial length of at least 2 mm devoid of holes having a surface greater than 0.01 mm2, each of the insulating zones 421 extending from one end of the internal portion 41.

Description

Insulation paper for notches impregnated with varnish

TECHNICAL AREA

The present invention relates to an insulating paper for notches of an armature of a rotating electric machine comprising pins in the notches of the armature to form an electric coil.

The invention also relates to the armature, or a rotor comprising the armature as well as an electric machine comprising such a rotor.

The invention relates for example to a motor vehicle starter comprising such an electric machine.

STATE OF THE ART

In known manner, rotary electrical machines comprise a rotor and a stator each comprising an electrical winding or magnets.

As is known, a starter comprises an induced rotor and an inductor stator mounted coaxially.

The rotor is integral with a shaft which is itself integral with a movement transmission member, such as a pinion, to mesh with a toothed crown integral in rotation with the crankshaft of a heat engine, for example the heat engine of a motor vehicle.

This rotor comprises at least one induced winding and a body comprising an axis formed from a pack of sheets carrying the induced winding.

The stator can either be wound around a pole or be without winding and include only magnets.

The rotor body includes a plurality of sheets stacked together axially.

The rotor body comprises on its outer periphery notches extending axially, angularly distributed around the axis of the rotor. These notches are open on either side of the rotor.

Each sheet of the sheet pack therefore includes on its outer periphery notches distributed angularly.

The armature winding comprises pins each comprising two arms each comprising an internal portion in the notches. Each portion extends axially from one end to the other of the rotor body.

The pins each further comprise a junction part connecting the two internal portions of the arms. Each arm further comprises two free portions each extending from an internal portion axially opposite with respect to the junction part. These free portions include a connection zone in contact with a collector.

There may be several internal portions of different pins in a single notch.

In order to ensure optimal operation of the rotating electrical machine, it is preferable that the browns constitute a sufficiently rigid block with the sheet metal package, in particular to limit vibrations and noise and thus resist during the entire period of use of the rotating electric machine.

A known manufacturing method consists in carrying out an impregnation by adding a resin in the notches, with the aim of stiffening and binding the internal portions in the notches.

Impregnation can be obtained by immersing the stator in a resin bath which may be a varnish, or by pouring the varnish into the notches.

In order to reduce the risk of short circuit between the pins and the metal body of the rotor, it is known to interpose a sheet of electrical insulating material between each wall or surface delimiting each notch. The internal portions of the conductors are therefore housed in this paper housed in this notch. The notch therefore comprises a volume of pin housing delimited inside the U-shaped insulating paper and a volume of insulator delimited between the included paper and the sheet metal package.

To ensure good mechanical and vibratory resistance of the winding relative to the sheet metal package, it is preferable that the sheet of paper is immobilized relative to the body of the rotor, that is to say mechanically linked to the wall defining the notch and also to the internal portions with which the sheet of paper is in contact.

For this purpose, it is known to use a paper of porous insulating material so as to allow the passage of the varnish so that it infiltrates between the wall defining the notch and the sheet of insulating material. The paper then includes holes on the order of 0.05 to 0.1mm in diameter. It is notably known porous insulating sheets in notches of alternator stators comprising holes less than 0.15mm along the entire length of the paper to allow the sheet to be kept at the notch through the varnish to pass from the housing volume pin to the volume of insulation.

The hardening of the varnish therefore causes the sheet of insulating material to immobilize with respect to the pins of the rotor with which the sheet is in contact and with respect to the notch.

FIG. 1 represents a sectional view of an example of a portion of an armature 1 of a starter. In Figure 1 we can see a portion of the sheet 2 of the sheet package comprising two teeth 21 and a notch 22 between the two teeth 21. In this case three notches 22 are visible in Figure 1. The armature comprises in the notches 22 two pins 3, a paper 4 and a resin 5. As can be seen, in this section, air bubbles 6 are located in each notch 22. In this case it can be seen that in two notches, an air bubble 5 is located at the bottom of the notch 22 between the paper 4 and the pins 3. It can also be seen that in each of the notches an air bubble is formed between the paper and a tooth of the sheet metal package . More precisely, it can be seen that each of these three air bubbles are located in the angle of the tooth head of tooth 21. In fact, the air remains trapped in this area due to the tooth foot and paper.

These air bubbles decrease the vibration resistance and heat transfer from the pins to the sheet package.

An electric machine such as a starter operates for a very short time, around 1 second but this can go up to 15 or even 20 seconds. This allows for a very small electric machine with a very large current draw around 400A when the battery voltage is low to achieve the speed and torque required to start the engine.

The current flows through the rotor through the pins, which causes the rotor to heat up considerably. Due to the stop-start operating mode known under the name “stop-start” in English, the starter can restart several times in a row without having had time to cool down between two restarts. There is therefore a risk of overheating which exceeds a safety temperature threshold. The varnish allows the transfer of calories (amount of heat) due in particular to the joule losses of the current passing through the pins, towards the sheet pack which makes it possible to dissipate the heat and therefore cool the armature. Indeed the varnish has a better coefficient of heat transfer than air.

Too small holes entail a risk that the varnish does not pass through the paper and therefore a risk that an area in the notch is devoid of varnish resulting in a reduction of heat dissipation in the pins and therefore a risk that the temperature goes above the maximum safety temperature.

In addition, there is a risk of short circuit between the pins and the sheet pack by having contact through the holes in the paper when these are too large.

SUMMARY OF THE INVENTION

It is noted that there is a need to provide for improvement of cooling of an armature while ensuring electrical isolation between the pins and the sheet package.

According to the invention, there is a tendency to satisfy this need by providing an insulating paper comprising:

an inner portion, two outer portions, the inner portion being located between the two outer portions, the paper comprising a total axial length along a direction of a longitudinal axis of the paper, the total axial length being equal to the sum of a length internal axial along the longitudinal axis of the internal portion and two external axial lengths along the longitudinal axis of the two external portions, the internal axial length being equal to at least eighty percent of the total axial length of the paper, in which the internal portion comprises a central zone whose center along the longitudinal axis is the center along the longitudinal axis of the paper and of the internal portion, the central zone having

- a central axial length equal to at least 50% of the internal axial length,

- transfer holes located over the entire central axial length, each transfer hole having a surface of at least 0.02mm2, and in that each of the external portions each comprises an insulating zone having at least an axial length of 2 mm without holes greater than an area of 0.01 mm2, each of the insulating zones extending from one end of the internal portion.

Thus, the pin of an armature can have a portion bearing on an insulating zone of the paper devoid of hole larger than 0.01 mm2 to ensure good electrical insulation, this insulating zone devoid of hole larger than 0.01 mm2 being intended to be located on one end of the notch (part of the area in the notch another part outside the notch).

In other words, the insulating zone is either completely waterproof (non-porous) or porous comprising insulating holes whose surface of each hole is less than 0.01 mm 2 making it possible to ensure that there is no electrical contact between the pins and the package of sheets.

Indeed, we have realized that holes with an area of less than 0.01 mm2 allow good insulation. The pins positioned in the notches are supported on the first and last sheets of the sheet pack by means of the paper. The electrical insulation function of the paper is therefore provided by the insulating portions.

In addition, the paper comprises over its entire central zone corresponding to the center of the notch, transfer holes having a surface large enough to ensure that the varnish passes through the paper. This reduces the risk of air bubbles in the insulating volume (between the paper included and the sheet package). Indeed, it has been noticed that from 0.02 mm 2, the resin passes through the paper and that with a prior art paper having holes having a surface area less than 0.02 m 2, the risk of air bubbles in the The notch was mainly in the central area of the notch. Indeed, on the ends of the notch, the resin or varnish can flow more easily due to the axial openings of the notch allowing the air to be evacuated in the notch. Thus, the invention decreases the number of air bubbles in the notch and therefore increases the transfer of heat from the pins to the sheet pack by means of the resin which can be a varnish.

The invention therefore makes it possible to have a paper suitable for reducing air bubbles by increasing the transfer of the resin through the paper in the notch, whether it is from the volume of insulation to the volume of pin housing or either pin housing volume to the insulation volume for good heat dissipation from the pins to the sheet metal package and good insulation by having two insulating zones at the axial ends of the notch serving as support for the pins.

According to one embodiment, the transfer holes over the entire central axial length each have an area between 0.02mm2 and 1.77mm2.

In fact, beyond 1.77 mm 2, there has been a risk of tearing and folding of the paper in the notch during the manufacturing process, in particular during the process of inserting the paper into the notch.

According to an exemplary embodiment, the transfer holes each have a surface greater than or equal to 0.04mm2, in particular between 0.04mm2 and 1mm2.

It has been noticed a decrease in the number of air bubbles in the notch with holes of at least 0.04mm2 and less risk of defective torn or folded paper with holes less than 1mm2.

According to an exemplary embodiment, all the holes in the central zone have the same surface. As the paper punch tool is simpler, this increases the productivity of making paper, and therefore less expensive paper.

According to another exemplary embodiment, the closer the holes are to the center, the larger the holes have. In other words, the holes in the central zone closest to the insulating zone have a surface smaller than the holes closest to the center of the paper. Thus, the closer we are to the axial or longitudinal center of the notch, the more the resin or varnish spreads through the transfer holes.

In one embodiment, the central zone has an axial length at least equal to 80% of the internal axial length. In other words the central zone makes at least 80% of the internal part which itself makes at least 80% of the paper.

This reduces the risk of air bubbles in the insulating volume and in the pin housing volume.

In one embodiment, the central axial length corresponds to the internal axial length.

This further reduces the risk of air bubbles in the notch.

In one embodiment, the external portions are devoid of all their lengths of holes.

This allows paper to be produced more easily without reducing the effectiveness of the paper since the rest of the external portions (part of the external portion without the insulating zone) is intended to be outside the notches.

In one embodiment, the paper comprises a width and in that the holes greater than 0.02 mm 2 are located over the entire width of the paper.

This reduces the risk of air bubbles over the entire depth of the notch. In particular, this reduces the risk of air bubbles under the conductors but also under the projections of the T-shaped tooth heads in the case of T-shaped tooth forming a narrowing at the radial opening on all along the notch. Indeed, the resin can also flow, cross, from the insulating volume to the pin housing volume or vice versa.

According to another embodiment, the paper comprises a total width and a perforated width and in that the holes greater than 0.02 mm 2 are located on the perforated width of the paper, an axial strip of at least 2 mm is devoid of holes greater than 0.02mm2.

This allows, for the manufacturing process to facilitate the cutting of a sheet of paper in this axial strip to produce several strips of paper of total width. The paper is also cut crosswise between two external parts of the paper.

In one embodiment, the holes each have an oblong shape, the length of which is in the direction of the axial length.

This will reduce the risk of wrinkling the paper.

In one embodiment, the holes are aligned axially forming a column and in width forming rows.

According to one embodiment, the holes are regularly distributed.

According to an example of these two combined embodiments, each column is offset from its neighbor so that each row includes holes in every second column.

This increases the resistance to folding while increasing the dispersion of the holes for the uniformity of the transfer of the resin or varnish through the holes in the paper.

The invention also relates to an armature comprising:

an axis, a packet of sheets stacked axially, the packet of sheets comprising notches extending axially and being open at each of the axial ends of the packet of sheets, at least one paper described above with or without the various embodiments described, the paper being folded in the shape of a U forming two lateral edges and a bottom, and being located in one of the notches of the sheet pack, the notch comprising a pin housing volume between these two lateral edges and the bottom and a volume of insulation between the paper included and the sheet pack, at least one pin located in the pin housing volume resting on at least one insulating zone of the paper, a resin in the insulation volume and in the housing volume d 'pin.

According to an example, each of the insulating zones comprises a part situated inside the notch and another part is situated outside the notch.

According to one embodiment, the armature comprises a paper as described above by notch and a plurality of pins and in that each of the notches accommodates a paper and in that at least one pin is located in each volume of pin housing of the papers.

According to an example of this embodiment, the armature comprises two pins per notch, at least one of which is in contact with an insulating zone of the paper.

According to one embodiment, the pins are made of copper.

According to another embodiment, the pins are made of aluminum.

According to one embodiment, the armature is a rotor comprising a shaft and in that the notches are located on the outer periphery of the sheet pack.

Another aspect of the invention relates to a rotor comprising the armature described above with or without the various embodiments described.

According to one embodiment, the sheet pack comprises teeth each having a tooth base and a tooth head forming the part furthest from the axis X of the tooth head, the notches of the sheet pack are formed between two consecutive teeth of the sheet pack and in that two consecutive feet of teeth form the bottom of the notch, and in which the distance between two heads of teeth is less than the diameter of a pin in the notch. The two tooth heads form between them the radial opening of the notch which extends along the longitudinal axis over the entire length of the sheet metal package.

This allows a stop holding the pin (s) in the notch with the paper and the resin to come out radially by centrifugal effect when the rotor.

In addition, such a rotor involves inserting the pins axially into the notch. Such an axial insertion involves a risk of tearing of the paper and scratching by friction of the pin.

The fact that the paper has no transfer hole in the insulation zone makes it possible to insert the pin by resting on this insulating zone which is an area less prone to tearing than the central zone comprising transfer holes.

Another aspect of the invention relates to an electric machine comprising a stator and a rotor described above.

The invention also relates to a device comprising the electric machine described above and in that the device comprises a starter mode for starting a heat engine of a vehicle.

According to one embodiment, the device is a thermal engine starter for a motor vehicle.

The device according to the invention may also have one or more of the characteristics below, considered individually or in all the technically possible combinations:

BRIEF DESCRIPTION OF THE FIGURES

Other characteristics and advantages of the invention will emerge clearly from the description which is given below thereof, by way of indication and in no way limiting, with reference to the appended figures, among which:

- Figure 1 shows a radial sectional view of a portion of a sheet metal package of the prior art.

- Figure 2 shows an insulating paper according to an example of an embodiment of the invention.

- Figure 3 shows a view of a paper according to another example of the previous embodiment.

- Figure 4 schematically shows an axial section of a portion of a package of sheets in a notch.

For the sake of clarity, identical or similar elements are identified by identical reference signs in all of the figures.

DETAILED DESCRIPTION OF AT LEAST ONE EMBODIMENT

FIG. 2 represents an example of an embodiment of an insulating paper 4 for insulating conductors in a notch according to the invention. The paper 4 comprises a longitudinal axis X and a transverse axis Y, the longitudinal and transverse axis passing through the middle of the rectangle. In this case the paper is rectangular and therefore the two axes X and Y are bisectors of the rectangle.

The paper comprises an internal portion 41 and two external portions 42. The internal portion 41 being located between the two external portions.

The inner portion of the paper is intended to be in the notch while the outer portions are intended to be outside the notch.

The paper 4 comprises a total longitudinal length, also called the total axial length, along the direction of the longitudinal axis X of the paper 4, the total axial length being equal to the sum of an internal longitudinal or internal axial length of the internal portion 41 and two external axial or longitudinal lengths of the two external portions 42.

In this embodiment, the internal axial length being equal to three quarters of the total axial length of the paper 4. In other words, three quarters of the paper is used for the notch.

Of course, the internal portion 41 can correspond to 90% of the paper.

The internal portion 41 includes a central zone 410, the middle of which along the longitudinal axis X is the middle of the internal portion 41. The transverse axis Y of the paper passes through this medium. In this case, the middle of the central area 410 is the middle of the paper 4. In this example, the central area corresponds to 11/13 of the internal portion but may be between 100% and 50% of the internal portion 410.

As can be seen, the central zone comprises transfer holes 43 located over all the central longitudinal length of the central zone 410. Each transfer hole 43 comprises an area of at least 0.02mm2. In Figure 2, the transfer holes are shown schematically to identify them.

In this example, the holes have the shape of an ellipse.

We can see in this example that the internal part comprises on an area between one of the two external parts and the central area of the insulating holes 44 smaller than the transfer holes. In this example, these insulating holes have an area of 0.01 mm2. These holes are also shown diagrammatically to identify them. The transfer holes or the insulating holes can have different shapes, in particular of oblong shape. These insulating holes having a surface or volume smaller than that of the transfer holes, allow better electrical insulation. Indeed, due to the thickness of the paper, for example 0.5 mm and the surface of this insulating hole 44, makes it possible to limit a risk of electrical contact between the conductors and the sheet pack with respect to the transfer holes. The paper has a thickness between 0.1mm and 0.8mm, in this case the paper 4 has a thickness of 0.5mm. Of course, on the side of the other external part, it could also have in this internal part insulating holes or through holes.

The external portions 42 comprise an insulating zone 421 over an axial length of at least 2 mm devoid of holes greater than an area of 0.01 mm2. In this case in this example shown in Figure 2, there are no holes in this insulating zone 421. In this case there are no holes on the entire outer portion. The insulating zones 421 extend from one end of the internal portion towards the end of the paper.

In this example of this paper shown in Figure 2, the transfer holes 43 are over the entire width of the paper. Thus, this allows a transfer of the resin over the entire width of the paper.

FIG. 3 represents another embodiment of paper 4, in which the external part comprises, between the end of the paper and the insulating zone, insulating holes 44. Furthermore in this example, the central zone 410 corresponds to 50% of the internal part 41. The internal part 41 comprises an intermediate zone between the central zone 410 and the insulating zone 421, comprising insulating holes 44. In this example the insulating holes are aligned forming a line parallel to the transverse axis.

The space between two lines of insulating holes 44 corresponds in this example to at least the width, measured in the direction of the longitudinal axis, of the insulating zone. Thus, this makes it easy to make the insulating holes on the paper.

To make the papers 4, it is possible to have a strip of papers having a width corresponding to the total length of the paper 4 and in that holes are made along the length of the strip over a width corresponding at least to the length of the central area of a paper 4.

Such a band 40 of papers is shown in FIG. 4. The band 40 of papers shown comprises 3 papers but of course can include many more, thirty for example.

The strip of paper is then cut along the black lines 400 to form the longitudinal edges of the papers.

The cutout may fall on transfer holes, as is the case in the example shown in Figure 4.

In addition, a paper plate, not shown, may have several strips of paper. In this case the cutting is carried out between two strips of paper forming the transverse edges of the papers of the external parts of the paper.

FIG. 5a schematically represents a part of a sheet metal package cut along the longitudinal axis and FIG. 5b schematically represents a part of the armature seen from above. To simplify the representation, the resin is not shown.

The armature comprises a pack of sheets 9 comprising sheets 91 stacked axially along a longitudinal axis X ′ parallel to that of the paper. The sheet pack 91 includes notches 92 extending axially and each include two axial openings at each of the axial ends of the sheet pack 9 and a radial opening on the outer periphery of the armature extending along the axis X ' longitudinal. Each notch 92 therefore comprises two lateral edges 921 (only one of which is visible in FIG. 5a) and a bottom for receiving the paper 4 and an axial opening over the entire length of the notch and two radial openings of pat and other of the notch. The paper 4 described above is therefore folded in a U shape. In FIG. 5a, the bottom of the U shape of the paper 4 can be seen.

The paper 4 folded into a U therefore also comprises two lateral flanks 44 extending axially and the bottom 410 extending axially. Thus the paper in the notch forms a volume of pin housing inside the U-shape, that is to say between the lateral flanks and the bottom of the paper 4. The paper also forms a volume of insulator between the paper 4 included and the surfaces of the sheet pack of the notch 92, that is to say between the two lateral edges 921 and the bottom of the notch.

The armature further comprises conductors, in this case pins 8 are shown diagrammatically which may be made of aluminum or copper. These pins include straight branches, called active branches, inside the notch 92. During the process of inserting the pins into the notch, it is difficult to position them parallel to the X axis and are therefore slightly inclined in the notch. Thus, the active branches of each of the conductors 8 are supported on the sheet metal package by means of the paper at their ends (on either side of the notch 92). The fact that the paper 4 does not include holes or holes smaller than 0.01 mm2 in its insulation zone, in this case without a hole, the paper 4 provides good insulation in this zone which is the zone most subject to risk of short-circuiting the notch. The length of the sheet metal packet 4 along the X axis, therefore the longitudinal length of the notch is equal to the sum of the longitudinal length 41 of the paper and at least the longitudinal length of part of the two insulating zones of the part outer of the paper. In fact, according to the tolerances of the method of inserting paper and keeping the paper in the notch during the insertion of the conductors, it is therefore necessary for the insulating zone to protrude on either side of the notch while having a part inside to ensure the insulation function. In other words, the insulating zone passes through an axial opening of the notch. For example, if the axial displacement tolerance of the paper 4 in the notch 92 is two millimeters axially, the longitudinal length (therefore measured along the X axis) of each insulation zone must be greater than 2mm to ensure that d 'one side of the notch part of the insulation area is in the notch.

In addition, because of the openings on either side of the notch, the resin spreads more easily than in the middle of the notch.

The sheets comprise teeth 910 forming between them the notches 92. Each of the teeth in this example comprise t-shaped teeth heads 9100. In this case, the radial opening of the notch has a narrower width than the bottom of the notch due to the two projections of the T-shaped tooth heads

Each notch 92 therefore comprises a narrowing at the radial opening due to the projections of the T-shaped tooth heads.

In FIG. 5b, it can be seen that in this example, the pins have a diameter larger than the width of the radial opening of the notch.

In addition, due to the shape of the projections of the T-shaped tooth heads, the paper 4 comprises, on each of the longitudinal ends of these longitudinal flanks 44, a curved flank 45, which may be straight or curved. Thus the longitudinal edges of the paper face towards each other closing the housing volume.

FIG. 7a represents such a folded paper seen axially on an edge of the external part of the paper 4. The folds of the paper 4 can be pre-folded before the insertion of the paper into the notch 92 or can fold during the insertion paper in the notch.

According to another embodiment, shown in FIG. 7B, seen axially the paper further comprises two opening flanks 46 extending from curved flanks 45 outside the radial opening of the notch. These sides are then folded inside the notch to completely close the volume of the paper pin housing.

Figure 6 shows a view in cross section of a portion of the armature according to the invention.

In the embodiment represented in this FIG. 6, the paper 4 is folded by inserting it into a notch 92. In this FIG. 6 it can be seen that a resin, in this case a varnish is located in the notch and fills both the volume of insulation, including the paper holes and the volume of pin housing around the conductors

8.

The invention relates in particular to an electric machine comprising a rotor 5 comprising the armature as described and a collector, the pins 8 each comprise two arms each comprising the straight branch, called active branches in the notches 8. The pins 8 further comprise each a junction part connecting the two internal portions of the arms. Each arm further comprises two free portions each extending from an internal portion axially opposite with respect to the joining part. These free portions include a connection zone in contact with the collector.

Claims (10)

1. Insulating paper (4) for insulating conductors (8) in a notch (92) comprising: an internal portion (41), two external portions (42), the internal portion (41) being located between the two external portions (41), a total axial length along a direction of a longitudinal axis (X) of the paper (4), the total axial length being equal to the sum of an internal axial length measured along the longitudinal axis (X) of the internal portion (41) and of two external axial lengths along the longitudinal axis (X) of the two external portions (42), the internal axial length being equal to at least eighty percent of the total axial length of the paper (4), in which the internal portion (41) comprises a central zone (410) whose center along the longitudinal axis is the center along the longitudinal axis of the paper (4), the central zone (410) having - a central axial length along the longitudinal axis (X) equal to at least 50% of the internal axial length, - transfer holes (43) located over the entire central axial length, each transfer hole having a surface of at least 0.02mm2, and in that each of the external portions (42) comprises an insulating zone (421) having at minus an axial length of 2 mm devoid of holes having a surface greater than 0.01 mm 2, each of the insulating zones (421) extending from one end of the internal portion (41). 2. Paper according to claim 1, wherein the transfer holes (43) each have an area between 0.04mm2 and 1.77mm2. 3. Paper according to claim 1 or 2, wherein the central zone (410) has an axial length of at least 80% of the internal axial length. 4. Paper according to any one of the preceding claims, comprising a width measured perpendicular to the longitudinal axis and in that the transfer holes (43) are located over the entire width of the paper (4). 5. Armature comprising: - an axis (X ’), - a pack of sheets (9) stacked axially along the axis (X '), the pack of sheets (9) comprising notches (92) extending axially and being open at each of the axial ends of the pack of sheets (9 ) - at least one paper (4) according to any one of the preceding claims, the paper (4) being folded into a U-shape forming at least two lateral edges (44) and a bottom (410), and being located in one of the notches (92) of the sheet pack (9), the notch (92) comprising a volume of pin housing between the two lateral edges (44) and the bottom (410) and a volume of insulation between the paper ( 4) including and the surfaces of the sheet pack (9) delimiting the notch (92), - at least one pin (8) located in the pin housing volume resting on at least one insulating zone (421) of the paper (4), - a resin (7) located in the insulator volume and in the pin housing volume. 6. Armature according to the preceding claim, wherein each of the insulating zones (421) comprises a part located inside the notch (92) and another part located outside the notch (92). 7. Armature according to one of the two preceding claims comprising two pins (8) by notch (92) at least one of which is in contact with an insulating zone (421) of the paper (4). 8. Rotor comprising an armature according to one of the three preceding claims, in which the sheet metal package (9) comprises teeth (91) each having a tooth foot and a tooth head (910) forming the most distant part of the axis (X ') of the tooth (91), the notches (92) of the sheet pack (9) are formed between two consecutive teeth (91) of the sheet pack (9) and in that two feet consecutive teeth form the bottom of the notch (92), and in which the distance between two tooth heads (910) is less than the diameter of a pin (8) in the notch (92). 9. Electric machine comprising a stator and a rotor according to the preceding claim. 5 10. Starter comprising an electric machine according to the preceding claim.