EP3061103B1 - Electromagnetic actuator and method for producing such an actuator - Google Patents

Description

The present invention relates to an electromagnetic actuator. The actuator comprises a ferromagnetic carcass, extending in a longitudinal direction and having a height in a vertical direction perpendicular to the longitudinal direction. The actuator comprises two electromagnetic coils disposed inside the carcass, each comprising at least one winding around the longitudinal direction.

The actuator also comprises a ferromagnetic member disposed between the coils and a ferromagnetic plunger subjected to a magnetic field generated by the coils, the ferromagnetic plunger being movable in the longitudinal direction and able to be immobilized according to three distinct longitudinal positions depending on the field generated. by the coils.

The invention also relates to a method of manufacturing such an electromagnetic actuator.

We know of the document EP 2 250 651 an electromagnetic actuator comprising two coils, a plunger adapted to be immobilized in three positions, namely two extreme positions facing the coils and an intermediate position between the coils.

The plunger comprises a magnet and two members for guiding the flow of the magnet to the carcass, in order to stabilize the plunger in its intermediate position. The actuator has an additional coil for compensating the field of the magnet when the plunger is in a position other than its intermediate position.

However, such an actuator is relatively complex, since it involves the presence of a magnet and an additional coil to allow better stability of the intermediate position.

The document US 3,784,943 discloses an electromagnetic actuator according to the preamble of claim 1. The object of the invention is therefore to provide a three-position actuator having a reduced cost and volume.

• chaque bobine électromagnétique comporte une armature, le ou chaque enroulement étant fixé à l'armature correspondante, et l'organe ferromagnétique est fixé aux deux armatures ;
• l'organe ferromagnétique comporte suivant la direction longitudinale un évidement de passage du plongeur ;
• l'organe ferromagnétique s'étend depuis l'évidement jusqu'à la carcasse ;
• l'évidement présente un bord périphérique, et l'organe ferromagnétique comporte au moins un rebord s'étendant à partir dudit bord périphérique ;
• le rebord s'étend suivant la direction longitudinale ;
• l'organe ferromagnétique comporte au moins une saillie extérieure, la ou chaque saillie extérieure étant disposée à l'extérieur de la carcasse et au moins partiellement en contact avec la carcasse ;
• l'organe ferromagnétique comporte au moins une saillie intérieure, la ou chaque saillie intérieure étant disposée à l'intérieur de la carcasse et au moins partiellement en contact avec la carcasse ; et
• les saillies sont orientées selon la direction longitudinale.

For this purpose, the subject of the invention is an electromagnetic actuator according to claim 1. According to other advantageous aspects, the electromagnetic actuator comprises one or more of the following characteristics, taken individually or in any technically possible combination:

• each electromagnetic coil comprises an armature, the or each winding being fixed to the corresponding armature, and the ferromagnetic member is fixed to the two armatures;
• the ferromagnetic member comprises in the longitudinal direction a passage recess of the plunger;
• the ferromagnetic member extends from the recess to the carcass;
• the recess has a peripheral edge, and the ferromagnetic member has at least one flange extending from said peripheral edge;
• the flange extends in the longitudinal direction;
• the ferromagnetic member comprises at least one outer projection, the or each outer projection being disposed outside the carcass and at least partially in contact with the carcass;
• the ferromagnetic member comprises at least one inner projection, the or each inner projection being disposed inside the carcass and at least partially in contact with the carcass; and
• the projections are oriented in the longitudinal direction.

The invention also relates to a method of manufacturing an actuator according to claim 10.

According to another advantageous aspect, the manufacturing method comprises the following characteristic: during step c), the ferromagnetic member is fixed by laser welding to the carcass.

• la figure 1 est une vue en perspective d'un actionneur selon l'invention, comprenant une carcasse ferromagnétique, deux bobines électromagnétiques, un plongeur ferromagnétique mobile en translation et un organe de guidage d'un flux magnétique généré par les bobines,
• la figure 2 est une vue en perspective éclatée de l'actionneur de la figure 1,
• la figure 3 est une vue en perspective de l'organe de guidage du flux de la figure 1, et
• la figure 4 est un organigramme d'un procédé de fabrication selon l'invention.

These features and advantages of the invention will become apparent on reading the description which follows, given solely by way of nonlimiting example, and with reference to the appended drawings, in which:

• the figure 1 is a perspective view of an actuator according to the invention, comprising a ferromagnetic carcass, two electromagnetic coils, a ferromagnetic plunger movable in translation and a guide member for a magnetic flux generated by the coils,
• the figure 2 is an exploded perspective view of the actuator of the figure 1 ,
• the figure 3 is a perspective view of the flow guide member of the figure 1 , and
• the figure 4 is a flowchart of a manufacturing method according to the invention.

On the Figures 1 and 2 , an electromagnetic actuator 10 comprises a carcass 12, two electromagnetic coils 14, 16, two armatures 18, 20, a plunger 22, a member 24 for guiding a magnetic field generated by the coils 14, 16.

In addition, the electromagnetic actuator 10 comprises a rod 26 for guiding the plunger.

The electromagnetic actuator 10 is for example used to establish or section a current. It is used in particular to control the direction of rotation of an electric motor.

The carcass 12 extends in a longitudinal direction X and has a generally cubic shape with rounded edges. This carcass 12 is preferably made of a ferromagnetic material. The carcass 12 comprises two U-shaped portions 28, 30 and two magnetic tips 32, 34.

The carcass 12 has a first height H1 in a vertical direction Z perpendicular to the longitudinal direction X.

The two electromagnetic coils 14, 16 are disposed inside the carcass 12. The two coils 14, 16 are, for example, coaxial with respect to an axis in the longitudinal direction X. Each electromagnetic coil 14, 16 comprises a respective winding 36, 38.

The two coils 14, 16 are spaced from one another by a spacing E in the longitudinal direction X, as shown in FIGS. Figures 1 and 2 .

The two armatures 18, 20 each hold a respective winding 36, 38 and fix the coils 14, 16 to the carcass 12. The armatures 18, 20 are preferably made of plastic. In the example of Figures 1 and 2 the reinforcements 18, 20 preferably form one and the same plastic part around which are wound two copper wires to form the respective windings 36, 38.

Each armature 18, 20 is of revolution about the axis of the coils 14, 16 and has a U-shaped section open towards the outside in a vertical plane containing the axis of the coils, as visible on the Figures 1 and 2 . The armatures 18, 20 are then able to receive the windings 36, 38. The armatures 18, 20 are fixed relative to the carcass 12.

Each armature 18, 20 forms at its center a substantially cylindrical tube 39 and extending in the longitudinal direction X, and inside which the plunger 22 is slidable, as shown in FIGS. Figures 1 and 2 .

The plunger 22 is subjected to a magnetic field generated by the coils 14, 16. This plunger 22 is movable in translation along the axis of the coils 14, 16. The plunger 22 comprises a ferromagnetic material, and is preferably made of said ferromagnetic material .

The plunger 22 is of revolution about the longitudinal direction X, and is arranged around the guide rod 26.

The plunger 22 has a cylindrical shape in its median portion in the longitudinal direction X and two convex conical shapes at each of its ends in the longitudinal direction X, as shown in FIGS. Figures 1 and 2 .

The plunger 22 is able to be immobilized according to three distinct longitudinal positions, namely two extreme positions facing the coils 14, 16 and an intermediate position between the coils 14, 16. The intermediate position of the plunger 22 belongs for example to a median plane perpendicular to the longitudinal direction X and situated midway between the two coils 14, 16.

The guide member 24 is disposed between the coils 14, 16 and is fixed relative to the carcass 12. The guide member 24 preferably passes through the carcass 12 to be fixed thereto.

The guide member 24 has, in the vertical direction Z, a second height H2 greater than one sixth of the first height H1 of the carcass 12, preferably greater than one quarter of said first height H1, more preferably greater than one third of said first height H1.

In the embodiment described, the second height H2 of the guide member 24 is greater than the first height H1 of the carcass 12, as shown in FIGS. Figures 1 and 2 .

The guiding member 24, as visible on the figure 3 , comprises a main portion 40, a recess 42, first 44A and second 44B edges. The guide member 24 has upper outer projections 46A and lower 46B, and inner projections 48. The outer outer projection 46A is intended to be disposed outside and above the carcass 12 in a perpendicular vertical direction Z in the longitudinal direction X, and the lower outer projection 46B is intended to be disposed outside and below the carcass 12. The inner projections 48 are intended to be disposed inside the carcass 12.

The guide member 24 is made of a ferromagnetic material, and is capable of guiding the magnetic flux generated by the coils 14, 16.

The guide member 24 is, for example, in the form of a ferromagnetic plate disposed in a plane substantially perpendicular to the longitudinal direction X. The plane of the guide member 24 is located, in the longitudinal direction X, at a distance of distance less than a quarter of the distance E with respect to a median plane P perpendicular to the longitudinal direction and located midway between the two coils 14, 16.

In the embodiment described, the plane of the guide member 24 coincides with the median plane P. In other words, the guide member 24 is disposed at the intermediate position of the plunger 22 in the direction longitudinal X.

The guide rod 26, visible on the figure 2 is, for example, plastic. It traverses the plunger 22 from one side to the other in the longitudinal direction X. The guide rod 26 is, for example, fixed integrally to the plunger 22. The guide rod 26 has a substantially cylindrical shape.

The guide rod 26 is able to guide the plunger 22, so that it moves only axially in the longitudinal direction X. In addition, the guide rod 26 guides the plunger 22 so that it does not touch the inner wall of the tube 39 formed by the frames 18, 20, to reduce friction.

Each U-shaped portion 28 has 30 walls, namely a first transverse wall 50 perpendicular to the longitudinal direction X, an upper longitudinal wall 52 and a lower longitudinal wall 54. Each transverse wall 50 has a hole 56 for passing through. a tip 32, 34 corresponding.

Together, the two U-shaped portions 28, 30 form, when they are assembled, a fixed frame. This frame forms a support for fixing the other elements of the electromagnetic actuator 10.

The end pieces 32, 34 of the carcass 12 are positioned at the longitudinal ends of the tube 39 formed by the armatures 18, 20. These end pieces 32, 34 make it possible to limit the displacement of the plunger 22 when it is in one of its positions. extremes facing one of the coils 14, 16. These tips 32, 34 and form stops. These tips 32, 34 are coaxial with the axis of the coils 14, 16, which is also the axis of translation of the plunger 22.

Each end piece 32, 34 has a concave conical shape oriented towards the inside of the actuator 10 in the longitudinal direction X. Otherwise, the concave shape of the end pieces 32, 34 is oriented towards the plunger 22. These conical shapes are complementary to the surfaces. convex cones of the plunger 22, as shown in Figures 1 and 2 .

The end pieces 32, 34 preferably comprise at least one ferromagnetic part, in order to better guide a magnetic flux produced by the coils 14, 16.

Each endpiece 32, 34 has a through-hole 57 which is longitudinal to permit the sliding of the guide rod 26, and to limit the substantially radial displacements of the guide rod 26 as shown in FIG. figure 2 .

The main part 40 forms the central part of the member 24. It is preferably flat and in the longitudinal direction X. It extends from the recess 42, between the two frames 18, 20 to the ends of the carcass 12.

The recess 42 has a peripheral edge 58 in the plane of the guide member 24 perpendicular to the longitudinal direction X.

The recess 42 is formed in the main part 40. It is sufficiently wide in a radial direction perpendicular to a longitudinal direction X to allow the passage of the plunger 22. This recess 42 is oriented in the longitudinal direction X.

The recess 42 has, in the radial direction, an internal diameter D1 fitted to the outer diameter D2 of the plunger 22 in this radial direction and to a mechanical tolerance close to allow the plunger 22 to slide as shown in FIG. figure 2 .

Each rim 44A, 44B extends from the peripheral edge 58 of the recess, the first rim 44A in one direction and the second rim 44B in the other direction, in the longitudinal direction X, as visible on the figure 3 .

In the example of Figures 1 and 2 , the flanges 44A, 44B fit into the two plates 18, 20 in the longitudinal extension of the tube 39, so that the plunger 22 slides easily inside the tube 39, the recess 42 and the flanges 44A, 44B.

The outer projections 46A, 46B are disposed outside the carcass 12 and at least partially in contact with the carcass 12. The guide member 22 preferably comprises two outer projections 46A, 46B, namely the outer outer projection 46A and the lower outer projection 46B.

The outer projections 46A, 46B are oriented in the longitudinal direction X and in both directions, as can be seen in FIG. figure 3 . In other words, each outer projection 46A, 46B is adapted to be in contact with each of the two parts 28, 30 forming the carcass 12.

Each outer projection 46A, 46B is, for example, in the form of a flat strip fixed perpendicularly to the longitudinal direction, pressed against the outer surface of the carcass 12, as shown in FIG. figure 1 .

The inner projections 48 are disposed within the carcass 12 and at least partially in contact with the carcass 12. There are preferably two inner projections 48, one upper and one lower. These projections are oriented in the longitudinal direction X as is visible on the figure 3 .

Each inner projection 48 is, for example, in the form of a lug intended to be in contact with the inner surface of the carcass 12.

The outer projections 46A, 46B and the inner projections 48 are, for example, arranged to take the carcass 12 sandwiched. The member 24 is then in contact with both the inner face and the outer face of the carcass 12.

The method of manufacturing the electromagnetic actuator 10 will now be described using the flowchart of the figure 4 .

The initial step 100 consists in arranging the guiding member 24, provided with its flanges 44A, 44B, with its external projections 46A, 46B and its internal projections 48. The member 24 is disposed at the median plane perpendicular to the axis of the coils 14, 16. The guide member 24 is preferably a ferromagnetic plate that is arranged perpendicularly to the longitudinal direction X.

The flow guiding member 24 is formed, for example, by sintering two pieces, each U-shaped in the longitudinal direction X, and the U-shaped pieces being oriented in opposite directions to form a general shape in an H extending in the longitudinal direction X.

The following step 110 consists in arranging the electromagnetic coils 14, 16, by fixing them to the member 24.

The armatures 18, 20 of the electromagnetic coils are then overmolded around the flux guiding member 24. The armatures 18, 20 preferably form a single plastic part overmolded around the guiding member 24. In this case, during the initial step 100, the guide member 24 is placed in a central position in a mold which then serves to overmold the reinforcements 18, 20.

The windings 36, 38 are then made by winding copper wires around the reinforcements 18, 20, the latter having been previously fixed to the guide member 24.

Then, during step 120, the guide rod 26 is placed in the ferromagnetic plunger 22 and then the guide rod 26 - plunger 22 assembly in the tube 39 formed by the armatures 18, 20.

Finally, in step 130, the carcass 12 is made by placing the magnetic tips 32, 34, which slide the guide rod 26, in the U-shaped portions 28, 30, which fit together to form the carcass. 12.

The parts 28, 30 are during their assembly, sandwiched by the guide member 24 by means of the outer projections 46A, 46B and inner 48.

The guide member 24 is then fixed to the carcass 12 by laser welding. The magnetic tips 32, 34 are attached to the U-shaped portions 28, also by laser welding.

The operation of the electromagnetic actuator 10 will now be described.

To move the plunger 22 towards one of its two extreme positions, one of the two electromagnetic coils 14, 16 is electrically energized so as to generate a magnetic field of attraction of the plunger 22. The other electromagnetic coil 14, 16 is not electrically powered or is electrically powered to generate a repulsive magnetic field of the plunger 22.

The generated magnetic field or fields produce a magnetic flux which is guided by the ferromagnetic parts of the electromagnetic actuator 10, that is to say by the carcass 12, the plunger 22 and the guide member 24. This arrangement minimizes the leakage flow and improves the efficiency of the electromagnetic actuator 10.

The displacement of the plunger 22 towards its intermediate position is for example ensured by a return spring, not shown. The use of a return spring avoids feeding the electromagnetic coils 14, 16 to move the plunger 22 to its intermediate position.

As a variant, the displacement of the plunger 22 towards its intermediate position is obtained by the generation of repulsive magnetic fields or fields of attraction of the plunger 22, these fields of repulsion or attraction being generated by the two electromagnetic coils 14, 16 which are then electrically powered.

The plunger 22 then moves inside the tube 39, the recess 42 and the flanges 44A, 44B, while being guided by the sliding of the guide rod 26 inside the end pieces 32, 34.

The guide member 24 according to the invention then makes it possible to ensure a better mechanical stability of the plunger 22 in its intermediate position, the guide member 24 improving the guidance of the magnetic flux towards the carcass 12 from the coils 14, 16.

The flanges 44A, 44B advantageously improve the stability of the plunger 22 in its intermediate position by guiding more the flows from the coils 14, 16 to the carcass 12. The orientation of the flanges 44A, 44B parallel to the translation axis of the plunger 22, that is to say in the longitudinal direction X, further improves this flow guidance by minimizing the reluctance between the plunger 22 and the main portion 40 of the guide member.

The outer projections 46A, 46B further improve the stability of the plunger 22 in its intermediate position by improving the flow guidance. The arrangement of the outer projections 46A, 46B in the longitudinal direction X parallel to the longitudinal walls of the carcass 12 further improves this flow guidance by minimizing the reluctance between the carcass 12 and the main portion 40 of the guide member.

Thus, the ferromagnetic member 24 allows, by its large radial dimensions and by its arrangement between the two electromagnetic coils 14, 16, to best guide the magnetic flux produced by the coils 14, 16, the plunger 22 is attracted to its position intermediate. This thus improves the stability of the intermediate position of the plunger 22 without resorting to other devices, such as the magnet and the additional coil of the actuator of the state of the art.

The ferromagnetic armatures 18, 20 make it possible to fix the coils 14, 16 so that they each exert a magnetic field for controlling the position of the plunger 22.

The overmolding of the reinforcements 18, 20 allows a better coaxial positioning of the coils 14, 16 with respect to the translation axis of the plunger 22 in the longitudinal direction X.

The shape of the plunger 22 with its two convex conical shapes at each of its ends in the longitudinal direction X makes it possible to reduce the ferromagnetic mass embedded in the actuator 10, and also to reduce a resistance force diagram.

The complementarity of the conical shapes of the plunger 22 with the respective conical shapes of the magnetic tips 32, 34 allows a coaxial geometric repositioning, while avoiding, via the guide rod 26, a bonding between said conical shapes.

In addition, the fact that the ferromagnetic member 24 extends from the recess 42 to the carcass 12, makes it possible to best guide the magnetic flux to the carcass, and reduces the magnetic reluctance of the whole assembly. the electromagnetic actuator 10.

It is thus conceivable that the electromagnetic actuator 10 according to the invention makes it possible to improve the stability of the intermediate position of the plunger 22 while presenting a reduced cost and volume compared to the electromagnetic actuator of the state of the art.

Claims (11)

1. Electromagnetic actuator (10) comprising:

   - a ferromagnetic frame (12) extending along a longitudinal direction (X) and having a height (H1) along a vertical direction (Z) perpendicular to the longitudinal direction (X),

   - two electromagnetic coils (14, 16) disposed inside the frame (12), each comprising at least one winding (36, 38) around the longitudinal direction (X),

   - a ferromagnetic member (24) arranged between the coils (14, 16),

   - a ferromagnetic plunger (22) subject to a magnetic field generated by the coils (14, 16), the plunger (22) being movable along the longitudinal direction (X) and capable of being immobilized in three different longitudinal positions depending on the field generated by the coils (14, 16),

   wherein the ferromagnetic member (24) is integral with the frame (12) and has, along the vertical direction (Z), a dimension (H2) greater than one sixth of the height (H1) of the frame (12), preferably greater than one fourth of said height (H1), even more preferably greater than one third of said height (H1), the ferromagnetic member (24) being situated at a distance of less than one fourth of a space (E) along the longitudinal direction (X) between the two coils (14, 16), with respect to the median plane (P) perpendicular to the longitudinal direction and situated halfway between the two coils (14, 16), so as to guide the magnetic flow created by the coils (14, 16) towards the frame (12), characterized in that the ferromagnetic member (24) comprises at least one projection (46A, 46B, 48), the or each projection (46A, 46B, 48) being at least partially in contact with the frame (12).
2. Actuator (10) according to claim 1, wherein each electromagnetic coil (14, 16) comprises an armature (18, 20), the or each winding (36, 38) being secured to the respective armature (18, 20), and the ferromagnetic member (24) is secured to the two armatures (18, 20).
3. Actuator (10) according to claim 1 or 2, wherein the ferromagnetic member (24) comprises, along the longitudinal direction (X), a recess (42) for passage of the plunger (22)
4. Actuator (10) according to claim 3, wherein the ferromagnetic member (24) extends from the recess (42) to the frame (12).
5. Actuator (10) [according to] claim 3 or 4, wherein the recess (42) has a peripheral edge (58), and the ferromagnetic member (24) comprises at least one flange (44A, 44B) extending from said peripheral edge (58).
6. Actuator (10) according to claim 5, wherein the flange (44A, 44B) extends along the longitudinal direction (X).
7. Actuator (10) according to any one of the preceding claims, wherein at least one of the or each projection is an exterior projection (46A, 46B), the or each exterior projection (46A, 46B) being disposed outside of the frame (12).
8. Actuator (10) according to any one of the preceding claims, wherein at least one of the or each projection is an interior projection (48), the or each interior projection (48) being disposed inside of the frame (12).
9. Actuator (10) according to any one of the preceding claims, wherein the projections (46A, 46B, 48) are oriented along the longitudinal direction (X).
10. Method of manufacturing an electromagnetic actuator (10), the method comprising the steps consisting of:

    a) producing a ferromagnetic frame (12) extending along a longitudinal direction (X) and having a height (H1) along a vertical direction (Z) perpendicular to the longitudinal direction (X),

    b) placing two electromagnetic coils (14, 16) inside the frame (12), each coil (14, 16) comprising at least one winding (36, 38) around the longitudinal direction (X),

    c) placing a ferromagnetic member (24) between the coils (14, 16),

    d) placing a ferromagnetic plunger (22) in a magnetic field generated by the coils (14, 16), the plunger (22) being movable along the longitudinal direction (X) and capable of being immobilized in three different longitudinal positions depending on the field generated by the coils (14, 16),

    wherein, during the step c) the ferromagnetic member (24) is integral with the frame (12) and has, along the vertical direction (Z), a dimension (H2) greater than one sixth of the height (H1) of the frame (12), preferably greater than one fourth of said height (H1), even more preferably greater than one third of said height (H1), the ferromagnetic member (24) being situated at a distance of less than one fourth of a space (E) along the longitudinal direction (X) between the two coils (14, 16), with respect to the median plane (P) perpendicular to the longitudinal direction and situated halfway between the two coils (14, 16), so as to guide the magnetic flow created by the coils (14, 16) towards the frame (12), characterized in that during the step c) the ferromagnetic member (24) comprises at least one projection (46A, 46B, 48), the or each projection (46A, 46B, 48) being at least partially in contact with the frame (12).
11. Method according to claim 10, wherein, during the step c), the ferromagnetic member (24) is secured to the frame (12) by laser welding.

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