FR3084959A1 - MAGNETIC CIRCUIT COMPRISING AN INTERNAL CABLE ROUTING CONDUIT - Google Patents

Abstract

The invention provides a magnetic circuit comprising an annular stack (22) of sheets (12), each sheet (12) comprises a ring (14) a plurality of branches (16), characterized in that the stack of sheets comprises: - A group of primary sheets (52) including a connecting branch (16) is generally L-shaped which extends axially in a first direction); and - a group of secondary sheets (54) of which a connecting branch (16) is U-shaped or L-shaped which extends axially in a second direction opposite to said first direction.

Description

MAGNETIC CIRCUIT COMPRISING AN INTERNAL CABLE ROUTING CONDUIT

DESCRIPTION

TECHNICAL AREA

The invention relates to a magnetic circuit for an electric machine such as a rotary transformer or a linear actuator comprising an arrangement allowing the passage of electrical wires through the magnetic circuit.

This arrangement consists in forming a conduit which does not break the magnetic flux in the magnetic circuit.

PRIOR STATE OF THE ART

Some electrical machines include a magnetic circuit delimiting one or more annular housings, in each of which a coil is arranged.

The magnetic circuit consists of an element of revolution formed by a stack of sheets.

A tubular magnetic circuit consists of an annular stack of sheets parallel to the main axis of the magnetic circuit, that is to say that the sheets are stacked tangentially to the main axis.

Each sheet is made in one piece and comprises an alternation of portions partially delimiting one or more annular housings open radially with respect to the main axis.

Each winding arranged in the annular housings comprises electrical wires intended for its electrical connection to other windings or to a supply device.

According to a known embodiment, a conduit allowing the passage of the wires radially or axially through the magnetic circuit is formed by cutting out several adjacent sheets.

For manufacturing reasons, this conduit opens into the air gap, creating a discontinuity at the level of the active surface. It is possible to close the duct at the air gap, but this delicate operation reduces the strength and mechanical rigidity of the machine.

Also, such a conduit creates a surface region, where the induction is very reduced or even zero at its center. In the case of a rotating transformer, the flux varies suddenly when a notch in the stator coincides with that of the rotor, creating a voltage peak which is added to the voltage transmitted by the transformer. In addition, the relative displacement of this surface region of reduced induction can create additional iron losses.

The object of the invention is to propose a magnetic circuit comprising a passage of wires which does not produce a break in the passage of the magnetic flux through the magnetic circuit.

STATEMENT OF THE INVENTION

The invention provides a magnetic circuit for a rotary transformer or a linear actuator comprising an annular stack of sheets centered on a main axis of the magnetic circuit, in which each sheet extends in a radial plane relative to the main axis and comprises a ring extending parallel to the main axis of the magnetic circuit and a plurality of branches extending radially from the same edge of the ring, characterized in that the stack of sheets comprises:

a group of primary sheets joined to one another, one branch of connection of each primary sheet is generally L-shaped comprising a primary radial arm connected to the crown and a primary base which extends axially in a first direction from from the free radial end of the primary radial arm; and a group of secondary sheets joined to one another and which is joined to the group of primary sheets, including a connecting branch of each secondary sheet, which is located in the same axial position as said connecting branch of each primary sheet, is U-shaped or L-shaped, comprising at least one secondary radial arm connected to the crown, which is axially offset with respect to said primary radial arm and a secondary base which is located in the same axial position as said primary base of the connecting branch of each sheet of the group of primary sheets and which extends axially in a second direction opposite to said first direction from the free radial end of the secondary radial arm.

The realization of the connecting branches in an L or U shape makes it possible to delimit conduits communicating with each other, without inducing in the stack of sheets a local rupture of the axial path of the magnetic flux.

Preferably, the connecting branch of each sheet of the group of secondary sheets is U-shaped comprising a first secondary radial arm which is offset axially with respect to said primary radial arm, a second secondary radial arm which is located axially at a distance from the first secondary radial arm which is situated in the same axial position as the primary radial arm and a secondary base which extends axially from the free radial end of the first secondary radial arm to the free radial end of the second secondary radial arm .

Preferably, the crown comprises a radial cutout which opens radially between the two radial arms of the connection branch of each sheet of the group of secondary sheets.

Preferably, the connecting branches of the group of primary sheets delimit a primary duct and the connecting branches of the group of secondary sheets delimit a secondary duct, and in that the internal volume of the primary duct and the internal volume of the secondary duct are communicating depending on the stacking direction.

Preferably, the primary conduit opens axially in the first direction.

Preferably, the secondary conduit opens axially in the second direction opposite to the first direction.

Preferably, the secondary duct opens out radially at an edge of each base which is opposite to the edge of the base from which the branches extend.

Preferably, the magnetic circuit comprises at least one electrical conductor which passes through the stack of sheets extending through the primary conduit and through the secondary conduit.

Preferably, the magnetic circuit comprises elementary sheets which are stacked on either side of the assembly formed by the group of primary sheets and the group of secondary sheets, each elementary sheet comprising a connection branch comprising at least one base. whose axial dimension of said base is substantially equal to the axial dimension of the primary and secondary bases, and which is located in the same axial position as the primary and secondary bases.

The invention also relates to a method of assembling and connecting a magnetic circuit according to any one of the preceding claims, characterized in that it comprises:

a step of stacking the primary sheets;

a step of stacking the secondary sheets;

a step of introducing a conductor into a primary conduit delimited by the connecting branches of the primary sheets, in a direction opposite to the first direction;

a step of bending the conductor so that it is parallel to the stacking direction;

a step of introducing the conductor into the secondary conduit delimited by the connecting branches of the secondary sheets in the stacking direction;

a step of bending the conductor so that it is perpendicular to the stacking direction; and a step of passing the conductor through the secondary conduit to lead out of it.

BRIEF DESCRIPTION OF THE DRAWINGS

- Figure 1 is a schematic perspective representation of an annular stack intended to form a magnetic circuit according to the invention;

- Figure 2 is a plan view of a sheet forming the annular stack shown in Figure 1;

- Figure 3 is a plan view showing a first sheet and a second sheet having connecting branches made according to a first aspect of the invention;

- Figure 4 is a schematic representation showing several levels of stacking of sheets shown in Figure 3, illustrating the routing of a cable in the conduit formed by the notches in the sheets

FIG. 5 is a view similar to that of FIG. 3, showing the notches according to a second aspect of the invention,

- Figure 6 is a schematic representation showing several levels of stacking of sheets shown in Figure 5, illustrating the routing of a cable in the conduit formed by the notches in the sheets.

DETAILED PRESENTATION OF PARTICULAR EMBODIMENTS

FIG. 1 shows an annular stack 22 of flat sheets 12 intended to be mounted in a magnetic circuit for an electric machine such as for example a rotary transformer.

The stack of sheets 22 is of annular shape and has a main axis A.

Each sheet 12 extends in a radial plane with respect to the main axis A and it is joined to another sheet 12 in a tangential direction with reference to the main axis A, that is to say along a direction perpendicular to the radial plane of the sheet 12.

As can be seen in Figure 2, each sheet 12 is of main orientation parallel to the main axis A and has a portion 14 extending in a direction parallel to the main axis A, which will be designated by the crown suite and a plurality of portions 16 extending radially from an axial edge of the crown 14, which will hereinafter be designated branches.

Here, the branches 16 extend radially inwards, that is to say in the direction of the main axis A from an edge 18 of internal radial end of the crown 14. It will be understood that the invention does not is not limited to this embodiment and according to a second embodiment not shown, the branches 16 can also extend radially outward, that is to say away from the main axis A from an edge 20 of the outer radial end of the crown 14

All of the sheets 12 attached to each other delimit annular housings 24 of the magnetic circuit in each of which an annular winding (not shown) is intended to be installed.

According to the embodiment shown in the figures, the annular housings 24 are formed in the radially internal part of the annular stack 22 of sheets 12. Thus, each coil is formed by winding a conductor inside the ring formed through the crowns 14.

According to the second embodiment, the annular housings 24 are formed in the radially external part of the annular stack 22 of sheets 12, that is to say that each winding is formed by winding a conductor around the ring formed by the crowns 14.

In the description which follows, reference will be made to the embodiment shown in the figures for which the arms 16 extend radially inwards from the internal edge 18 of the crown 14. The description of the second embodiment for which the branches extend radially outward from the outer edge 20 of the crown is effected by symmetry.

Each winding is intended to be electrically connected either to an adjacent winding, or to a device for its electrical supply.

To allow this connection, the stack of sheets 22 is traversed by several conduits, each conduit of which connects each annular housing 24 with an annular housing 24 which is adjacent to it or else with the outside of the annular stack 22.

These conduits are formed by making cuts in certain sheets 12.

In order not to produce a break in the passage of the magnetic flux at these cutouts, the branches 16 are made in the form of L or in the form of U, so that each sheet 12 remains formed in a single part.

This embodiment of the branches 16 also makes it possible to maintain a continuity of axial path of the magnetic flux through the magnetic circuit.

As mentioned above, each coil is intended to be electrically tuned to a component located outside the magnetic circuit or to another coil located in an adjacent annular housing 24.

For this, the conduits are made either to pass through a stack of branches 16 in a mainly axial direction, or to pass through the annular stack 22 in a mainly radial direction.

In the description which follows, reference will be made to the branches 16 of the sheets 12 which are located at the same axial position along the main axis A, and therefore which are stacked on top of each other. These branches will be called connecting branches.

There is shown in Figures 3 and 4 a first embodiment of the connecting branches 16 which are formed to pass axially through the annular stack 22. According to this embodiment, the connecting branches 16 are located between two annular housings 24, c that is to say for the connection of two adjacent windings. It will be understood that this embodiment also applies to axially connecting an annular housing 24 located at an axial end of the stack of sheets 22 with the outside.

To form such a conduit, the stack of sheets 22 comprises a first group of sheets which will be called primary sheets 52 and a second group of sheets, which will be called secondary sheets 54.

In the following description, to differentiate the parts of the primary sheets from similar parts of the secondary sheets, either the primary term or the secondary term will be used.

The connecting branch 16 of each primary sheet 52 is L-shaped oriented in a first direction, here to the left, it thus comprises a primary radial arm 26 which extends radially inward from the inner edge 18 of the ring 14 and a primary base 28 which extends axially in the first direction, that is to say here to the left, from the free radial end edge of the primary radial arm 26.

The set of connecting branches 16 formed by the stack of primary sheets 52 thus defines a primary conduit 30 which is open axially in the first direction, that is to say here to the left.

The connecting branch 16 of each secondary sheet 54 is here also in the shape of an L, but this L is oriented in a direction opposite to the first direction, that is to say here to the right. It comprises a secondary radial arm 32 which extends radially inwards from the internal edge 18 of the crown 14 and a secondary base 34 which extends axially in a second direction opposite to the first direction, that is to say here say to the right, from the free radial end edge of the secondary radial arm 32.

The set of connecting branches 16 formed by the stack of secondary sheets 54 thus delimits a secondary duct 36 which is open axially in the second direction, that is to say here to the right.

The axial position of the secondary base 34 is the same as the axial position of the primary base 28. Thus, when the stack of sheets 22 is formed, the primary bases 28 and the secondary bases 34 overlap each other.

The secondary radial arm 32 is axially offset in the first direction relative to the primary radial arm 26, that is to say here to the left. This axial offset is made so that the primary radial arm 26 and the secondary radial arm 32 are not overlapping one another when the stack of sheets 22 is formed.

Thus, as can be seen in FIG. 3, the primary radial arm 26 has a radial edge 26A, which delimits the axial bottom of the primary conduit 30, the secondary radial arm 32 has a radial edge 32A, which delimits the axial bottom of the secondary duct 36. The radial edge 32A of the secondary radial arm 32 is axially offset in the first direction, that is to say here to the left with respect to the radial edge 26A of the primary radial arm 26.

The axial dimension of the axial clearance 38 thus formed between the radial edge 32A of the secondary radial arm 32 and the radial edge 26A of the primary radial arm 26 is defined to allow the passage of one or more conductors 42 intended to pass through the annular stack 22 in the axial direction.

By way of nonlimiting example, the axial dimensions of the arms 26, 32 and of the axial clearance 38 are substantially equal to one another and to 1/3 of the axial dimension of the primary or secondary base 28, 34. According to another nonlimiting example, the axial dimension of each arm 26, 32 is substantially equal to 1/4 of the axial dimension the primary or secondary base 28, 34 and the axial dimension of the axial clearance 38 is substantially equal to 1/2 of the dimension axial of the primary or secondary base 28, 34.

The group of primary sheets 52 and the group of secondary sheets 54 are stacked on top of each other. The presence of the axial clearance 38 between the primary and secondary radial arms 26, 32 allows the primary conduit 30 to communicate with the secondary conduit 36 in the stacking direction, thus allowing the passage of a conductor 42.

The two groups of primary sheets 52 and secondary sheets 54 are interposed between two groups of general sheets 40 (shown in Figure 4) for each of which the connecting branch 16 has a base whose axial dimension is substantially equal to the axial dimension primary and secondary bases 28, 34 and which is located axially in the same position as the primary and secondary bases.

Referring to FIG. 4, the assembly and connection of the magnetic circuit, at the level of the connection branches 16, by the passage of one or more conductors 42 through the stack of sheets 22, is carried out, first by stacking a first group of general sheets 40.

Then, as can be seen in the second view of this FIG. 4, the group of primary sheets 52 is stacked on this first group of general sheets 40. As said previously, each of the primary sheets 52 comprises a branch of connection 16 L-shaped oriented in the first direction, that is to say here to the left, so that the group of primary sheets 52 defines a conduit 30 open in the first direction, here to the left.

Then, as can be seen in the third view of FIG. 4, the group of secondary sheets 54 is stacked on the group of primary sheets 52.

As mentioned above, each of the secondary sheets 54 has an L-shaped connecting branch 16 oriented in the second direction, that is to say here to the right, so that the group of secondary sheets 54 delimits a secondary duct 36 open in the second direction, here to the right.

Finally, as can be seen in the fourth view of FIG. 4, a second group of general sheets 40 is stacked on the group of secondary sheets 54.

When making the connections between the coils (or the wire outlet), the conductor 42 is introduced into the conduit 30 formed in the connecting branches 16 of the group of primary sheets 52, in the axial direction, then it is bent to extend in the stacking direction, it is then introduced into the secondary conduit 36 delimited by the sheets of the group of secondary sheets 54, it is then bent to be oriented axially in the second direction, that is to say to the right.

FIGS. 5 and 6 show a second embodiment of the connecting branches 16 which are formed to radially pass through the annular stack 22. According to this embodiment, the connecting branches 16 are located between two annular housings 24, and they allow the connection of one of the two adjacent windings, here that located to the left of the connecting branches 16, with the outside of the annular stack.

Here too, to form such a conduit, the stack comprises a first group of sheets which will be called primary sheets 52 and a second group of sheets, which will be called secondary sheets 54.

Similarly to the description of the first embodiment shown in FIGS. 3 and 4, in the description which follows, in order to differentiate the parts of the primary sheets from similar parts of the secondary sheets, either the term primary or the term secondary will be used.

The connecting branch 16 of each primary sheet 52 is L-shaped oriented in a first direction, here to the left, it thus comprises a primary radial arm 26 which extends radially inward from the inner edge 18 of the ring 14 and a primary base 28 which extends axially in the first direction, that is to say here to the left, from the free radial end edge of the primary radial arm 26.

The set of connecting branches 16 formed by the stack of primary sheets 52 thus defines a primary conduit 30 which is open axially in the first direction, that is to say here to the left.

The connecting branch 16 of each secondary sheet 54 is here in the form of a U open radially in the direction of the ring 14, that is to say here outwards.

The crown 14 has a radial cutout 44 which extends radially the groove 46 delimited by the U of the connecting branch 16.

The connecting branch 16 of each secondary plate 54 comprises a first secondary radial arm 48 which extends radially inwards from the internal edge 18 of the ring 14, a second secondary radial arm 50 which extends radially towards the inside from the inner edge 18 of the crown 14 and which is axially offset relative to the first secondary radial arm 48 and a secondary base 56 which extends axially from the free radial end of the first secondary radial arm 48 to the free radial end of the second secondary radial arm 50.

The axial position of the secondary base 56 is the same as the axial position of the primary base 28. Thus, when the stack of sheets 22 is formed, the primary bases 28 and the secondary bases 56 overlap each other.

The first secondary radial arm 48 is axially offset in the first direction relative to the primary radial arm 26, that is to say here to the left. The second secondary radial arm 50 is located at the same axial position as the primary radial arm 26. Thus, when the stack of sheets 22 is formed, the primary radial arms 26 and the second secondary radial arms 50 overlap stacked one on the other. others.

The first secondary radial arm 48 is also offset axially in the first direction relative to the second secondary radial arm 50.

The set of connecting branches 16 formed by the stack of secondary sheets 54 thus delimits a groove 46 which is open radially outwards, that is to say here towards the ring 14.

The axial dimension of the groove 46 formed between the first secondary radial arm 48 and the second secondary radial arm 50 is defined to allow the passage of the conductor 42 intended to pass radially through the annular stack 22.

By way of nonlimiting example, the axial dimensions of the secondary radial arms 48, 50 and of the groove 46 are substantially equal to one another and to 1/3 of the total axial dimension of the connecting branch 16. According to another nonlimiting example, the axial dimension of each secondary radial arm 48, 50 is substantially equal to 1/4 of the axial dimension of the connecting branch 16 and the axial dimension of the groove 46 is substantially equal to 1/2 of the dimension axial of the connecting branch 16.

The radial cut 44 formed in the crown 14 extends radially the groove 46, the axial dimension of this radial cut 44 is therefore substantially equal to the axial dimension of the groove 46.

Together, the groove 46 and the radial cut 44 form a secondary conduit 58 which extends radially and which opens into the edge 20 of the outer radial end of the crown 14.

The group of primary sheets 52 and the group of secondary sheets 54 are stacked on top of each other. The presence of the groove 46 between the secondary radial arms 48, 50 allows the primary conduit 30 to communicate with the secondary conduit 58 in the stacking direction, thus allowing the passage of a conductor 42.

The two groups of primary sheets 52 and secondary sheets 54 are interposed between two groups of general sheets 40 for each of which the connecting branch 16 has a base whose axial dimension is substantially equal to the axial dimension of the primary and secondary bases 28, 56 and which is situated in the same axial position as the primary and secondary bases 28, 56.

Referring to FIG. 6, the assembly of the magnetic circuit, at the level of the connecting branches 16, by the radial passage of one or more conductors 42 through the stack of sheets 22, is carried out, in a first step by stacking a first group of general sheets 40.

Then, as can be seen in the second view of this FIG. 6, the group of primary sheets 52 is stacked on this first group of general sheets 40. As said previously, each of the primary sheets 52 comprises a branch of connection 16 L-shaped oriented in the first direction, that is to say here to the left, so that the group of primary sheets 52 defines a conduit 30 open in the first direction, here to the left.

Each conductor 42 is then introduced into this conduit 30 then it is bent to be oriented in the stacking direction.

Then, as can be seen in the third view of FIG. 6, the group of secondary sheets 54 is stacked on the group of primary sheets 52.

As mentioned above, each of the secondary sheets 54 has a U-shaped connecting branch 16 open radially towards the crown 14, which delimits a radial groove 46 extended radially by a cutout formed in the crown 14, so that the group of secondary sheets 54 delimits a secondary duct 58 open radially, here outwards.

Finally, as can be seen in the fourth view of FIG. 6, a second group of general sheets 40 is stacked on the group of secondary sheets 54 until the stack of sheets 22 is completed.

When making the wire outlet, for the electrical connection of the magnetic circuit, the conductor 42 is introduced into the conduit 30 formed in the connecting branches 16 of the group of primary sheets 52, in the axial direction, then it is bent to extend in the stacking direction, it is then introduced into the secondary duct 58 delimited by the sheets of the group of secondary sheets 54, it is then curved to extend in the radial direction and to exit radially out of the secondary duct 58 and therefore out of the stack of sheets 22.

Claims (10)

1, Magnetic circuit for a rotary transformer or a linear actuator comprising an annular stack (22) of sheets (12) centered on a main axis (A) of the magnetic circuit, in which each sheet (12) extends in a radial plane relative to the main axis (A) and comprises a ring (14) extending parallel to the main axis (A) of the magnetic circuit and a plurality of branches (16) extending radially from the same edge (18, 20) of the crown (14), characterized in that the stack of sheets comprises: a group of primary sheets (52) placed side by side, of which a connecting branch (16) of each primary sheet (52) is generally L-shaped comprising a primary radial arm (26) connected to the crown (14) and a primary base (28) which extends axially in a first direction from the free radial end of the primary radial arm (26); and a group of secondary sheets (54) joined to each other and which is joined to the group of primary sheets (52), including a connecting branch (16) of each secondary sheet (34), which is located in the same position axial that said connecting branch (16) of each primary sheet, is U-shaped or L-shaped, comprising at least one secondary radial arm (32, 48) connected to the crown (14), which is axially offset by relative to said primary radial arm (26) and a secondary base (34, 56) which is situated in the same axial position as said primary base (28) of the connecting branch (16) of each sheet (12) of the group of sheets primary (52) and which extends axially in a second direction opposite to said first direction from the free radial end of the secondary radial arm (32,48), 2. Magnetic circuit according to the preceding claim, characterized in that the connecting branch (16) of each sheet (12) of the group of secondary sheets (54) is U-shaped comprising a first secondary radial arm (48) which is offset axially with respect to said primary radial arm (26), a second secondary radiating arm (50) which is located axially at a distance from the first secondary radiating arm (48) and which is situated in the same axial® position as the primary radial arm ( 26) and a secondary base (56) which extends axially from the free radiated end of the first secondary radial arm (43) to the free radial end of the second secondary radial arm (50). 3. Magnetic circuit according to the preceding claim, characterized in that the crown (14) has a radial cutout (44) which opens radially between the two radial arms of the connecting branch (16) of each 10 sheet (12) from the group of secondary sheets (54). 4. Magnetic circuit according to any one of the preceding claims, characterized in that the connecting branches (16) of the group of primary sheets (52) delimit a primary conduit (30) and the branches of 15 connection (16) of the group of secondary sheets (54) delimit a secondary conduit (38, 58), and in that the internal volume of the primary conduit (30) and the internal volume of the secondary conduit (36, 58) are communicating depending on the stacking direction. 5. Magnetic circuit according to claim 4, characterized in that the primary conduit (30) opens axially in the first direction 6. Magnetic circuit according to any one of claims 4 or 5, characterized in that the secondary conduit (36) opens axially in the second direction opposite to the first direction 7. Magnetic circuit according to any one of claims 4 to 6, characterized in that the secondary conduit (58) opens radially at an edge (2D of each base (14) which is opposite the edge (18) from the base (14) from which the branches (16) extend. 8. Magnetic circuit according to any one of claims 4 to 7, characterized in that it comprises at least one electrical conductor which crosses the stack of sheets (22) extending through the primary conduit (30) and through the secondary duct (38,58). 9, magnetic circuit according to any one of the preceding claims, characterized in that! comprises elementary sheets (40) which are stacked on either side of the assembly formed by the group of primary sheets (52) and the group of secondary sheets (54), each elementary sheet having a connecting branch (16 ) which has at least one base whose axial dimension of said base is substantially equal to the axial dimension of the primary and secondary bases (28, 34, 56) and which is located in the same axial position as the primary and secondary bases. 10. A method of assembling and connecting a magnetic circuit according to any one of the preceding claims, characterized in that it comprises: a step of stacking the primary sheets; a step of stacking the secondary sheets; a step of introducing a conductor into a primary conduit delimited by the connecting branches (16) of the primary sheets (52), in a direction opposite to the first direction; a step of bending the conductor so that it is parallel to the stacking direction a step of introducing the conductor into the secondary conduit (36, 58) delimited by the connecting branches (16) of the secondary sheets (54 ) according to the stacking direction; a step of bending the conductor so that it is perpendicular to the stacking direction; and a step consisting in passing the conductor through the secondary conduit in order to lead out of it,