EP3764383A9 - Electromechanical relay with reduced dispersion of overtravel, and method for manufacturing same - Google Patents

Abstract

Electromechanical relay comprising a control coil (5), a magnetic core (2), a movable armature (3) having an active face oriented opposite one end of the magnetic core, having a fixing face opposite the active face, and having a first end (31) articulated according to a fixed hinge to allow the rotation of the movable frame (3) between a working state and a resting state towards which it is returned by elastic return means (9). The movable armature (3) is attracted by the magnetic core (2) when the latter conducts the magnetic field generated by the powered control coil (5). The magnetic core (2) is fixed along its side surface to an attachment surface (1d) of the movable frame (1) by laser welding (23).

Description

TECHNICAL FIELD OF THE INVENTION

The present invention relates to electromechanical relays, in particular those used in motor vehicles, to fulfill various control or safety functions.

An electromechanical relay generally comprises a control coil, consisting of the winding of an electrical conductor intended to be supplied according to a nominal control voltage by a voltage or electric current source, a magnetic core placed in an axial passage of the coil and intended to conduct a magnetic field generated by an electric current flowing through the conductor of the control coil, and a movable armature.

A first end of the movable frame is articulated according to a fixed hinge, so that the movable frame is movable by rotation around the hinge between a rest state and a working state. The movable armature comprises an intermediate section of the movable armature, which is located opposite one end of the magnetic core, and which is made of a material capable of being attracted by the magnetic core when the coil is supplied with energy. electric. The mobile armature comprises a movable armature contact section, which extends to a contact free end, provided with a contact pad facing a fixed working contact, and optionally provided with a pad idle face facing a fixed idle contact. Elastic return means urge the movable armature to bring it back to the rest state.

When the control coil is not supplied with electrical energy, the movable armature is in its rest state, in which the intermediate section of the movable armature is away from the magnetic core, and in which the end free of the contact section is supported by the rest pad against the fixed rest contact. The movable frame is maintained in this state of rest by the elastic return means. When the control coil is supplied with electrical energy according to a sufficient excitation electrical voltage, at least equal to a voltage which is designated by the expression switching voltage, the intermediate section of the movable armature is attracted by the magnetic core and the movable armature pivot around the hinge against the elastic return means and come into its working state, in which the intermediate section of the armature mobile is near or in contact with the magnetic core, and in which the free end of the contact section is supported by the contact pad against the fixed working contact with an appropriate working force. The working force is used to avoid any rebounds when the electromechanical relay is activated, to avoid any untimely electrical trips under the effect of vibrations, and to guarantee the achievement of a low contact resistance.

The switching voltage is a characteristic specific to the electromechanical relay considered. It depends on a fairly large number of factors, including the relative position of the magnetic core, the number of turns of the electrical conductor constituting the coil winding, the dimensional, structural and relative positional characteristics of the magnetic core, the strength of the conductors. elastic return means of the mobile armature, the distance between the hinge and the magnetic core, the length and the bending elasticity of the contact section, etc.

In a mass production of a large number of electromechanical relays, basic components are used such as metal bands to be fed and formed to constitute the movable armature, the elastic return means as well as the contact sections; contact pads and work contacts are stamped parts drawn from metal blocks. The assembly of the components, in particular the assembly of the magnetic core on the fixed armature, is generally carried out by stamping or by force engagement.

We note that the assembly of these components, even when it is carried out with care, leads to the production of electromechanical relays whose switching voltages can vary appreciably from one relay to another, and especially from one series. relay to another series of relays when using different sets of base components.

Until now, care has been taken that disparities in the switching voltages of electromechanical relays do not cause the relays to malfunction during their use. For this, a number of coil turns is chosen such that the highest switching voltage of all electromechanical relays in series production is lower than the nominal control voltage of the coils.

During the operation of a motor vehicle, an electromechanical relay, installed in this vehicle to fulfill its control or safety functions, is normally in the engaged state, so that the control coil must be supplied with electrical energy under the nominal control voltage. In this state, the control coil is a resistive element, traversed by a current electric proportional to the electric voltage applied to its terminals. It is then understood that the electric energy expended in the coil, which is itself proportional to the square of the electric current, is oversized, already when the nominal control voltage is only a little higher than the switching voltage of the relay. electromechanical, that is to say in the case of a relay having a switching voltage higher than those of the relays of the series production, but especially when the nominal control voltage is much higher than the voltage of switching on of the electromechanical relay, i.e. in the case of a relay with a lower switching voltage than the maximum switching voltage of the electromechanical relays of series production. This results in significant energy losses in most electromechanical relays in series production, and a corresponding increase in heating unnecessarily produced by electromechanical relays during their use. The greater the disparity in the switching voltages of electromechanical relays, the greater the unnecessary energy losses.

However, there is a permanent need for energy savings in motor vehicles, and an increasingly sensitive need to avoid or reduce the heating of electronic components used in motor vehicles in the vicinity of electromechanical relays.

The document US 5,220,720 teaches to compensate for the switching voltage dispersions due to the inevitable tolerances of the parts to be assembled by adjusting the position of the core in the fixed armature after having assembled all the parts of the relay. For this, provision is made for a provisional positioning of the core by force-fitting the core in the coil and in a reduced-diameter hole in the fixed armature, then complete assembly of the relay including the movable armature, then complete the positioning of the core by applying to the movable armature and to the core a driving force moving the core and the movable armature according to an overtravel beyond the position of electrical contact detected by a sensor. A laser welding can then complete the fixing of the core in the fixed frame, before releasing the driving force.

Despite some improvement, there is still an unacceptable residual dispersion of the pick-up voltages of electromechanical relays in series production, and there still remains a need to reduce this residual dispersion of the pick-up voltages of electromechanical relays, so as to reduce further energy consumption of electromechanical relays, and further reduce the inevitable heating that results.

The document JP H07 176254 teaches to force-engage two pieces of the fixed armature on a control coil by effecting the axial force engagement of a lug of the first part in a hole of the second part, until the two parts come into abutment on the shoulders or on the flanges of the control coil. The fixing is then completed by laser welding carried out along the line of contact between the edge of the hole and the protruding part of the lug. A notch made in the vicinity of the engagement hole prevents the force exerted on the two parts for the force engagement from deforming the parts. Laser welding makes it possible to avoid the subsequent relative displacement of the two parts with respect to each other and with respect to the control coil, in the case where the pin has a section smaller than the hole.

The document JP H05 274977 teaches assembling two parts of the fixed armature of an electromechanical relay by providing an engagement with play between the end of a first part and a hole made in the other part, then ensuring the fixing by laser welding. The engagement with clearance is used for an orientation and transverse position adjustment of a part relative to the other to ensure parallelism of the two poles of the fixed reinforcement. There is no provision for longitudinal sliding or adjustment of the longitudinal position of one part relative to the other before welding.

The document JP H05 47283 teaches the assembly of two pieces of the fixed armature of an electromechanical relay by providing for the nesting of a core in a hole of the fixed armature, then carrying out an internal laser welding at the interface between the fixed armature and the core. A wide air gap area is provided to ensure a constant weld depth. There is no provision for longitudinal sliding or adjustment of the longitudinal position of the core relative to the fixed reinforcement before welding.

DISCLOSURE OF THE INVENTION

A problem proposed by the present invention is to significantly reduce the energy losses generated in an electromechanical relay integrated in a motor vehicle.

Another problem proposed by the present invention is to design means for appreciably reducing the residual dispersion of the switching voltage values of the various electromechanical relays produced in series production, a dispersion which has not been sufficiently compensated by the adjustment of the overtravel during the force positioning of the core in the fixed frame.

The idea which is the basis of the invention is that, when the core is positioned in force in the fixed reinforcement, the driving forces are high and vary according to the tolerances of the parts. When the driving force is released, the parts release their deformations due to mechanical stresses and regain a random shape and relative position, which could explain the residual dispersions of the switching voltages.

• une armature fixe, en un matériau apte à conduire un champ magnétique entre une première extrémité et une seconde extrémité, la première extrémité ayant une surface de fixation,
• une bobine de commande, apte à être alimentée par une tension nominale de commande, et comportant un passage axial cylindrique s'étendant selon un axe longitudinal,
• un noyau magnétique, engagé à coulissement dans le passage axial cylindrique de la bobine de commande, apte à conduire un champ magnétique généré par la bobine de commande lorsque celle-ci est alimentée, et ayant un tronçon de seconde extrémité fixé à l'armature fixe par des moyens de fixation comprenant au moins une soudure laser,
• une armature mobile, ayant une face active orientée en regard d'une première extrémité du noyau magnétique, et ayant une première extrémité articulée sur la première extrémité d'armature fixe par des moyens de charnière assurant la conduction du flux magnétique entre l'armature fixe et l'armature mobile et permettant la rotation de l'armature mobile entre un état de travail et un état de repos vers lequel elle est rappelée par des moyens de rappel,
• un tronçon magnétique d'armature mobile, structuré de façon à être attiré par le noyau magnétique lorsque celui-ci conduit le champ magnétique généré par la bobine de commande alimentée,
• un tronçon de contact d'armature mobile, qui est solidaire du tronçon magnétique d'armature mobile, qui s'étend jusqu'à une extrémité libre de contact, et qui fléchit élastiquement lorsque l'armature mobile est dans l'état de travail,
• un contact de travail fixe, en regard de l'extrémité libre de contact,
• la surface de fixation de l'armature fixe étant conformée pour être en contact avec la seconde extrémité du noyau magnétique selon la surface latérale du tronçon de seconde extrémité du noyau magnétique,

dans lequel :

• la surface de fixation de l'armature fixe est conformée de telle sorte que le noyau magnétique peut coulisser axialement sur la surface de fixation en l'absence desdits moyens de fixation,
• ladite au moins une soudure laser est une soudure interne qui assure une liaison métallurgique entre la surface de fixation de l'armature fixe la surface latérale du tronçon de seconde extrémité du noyau magnétique.

To achieve these and other objects, according to a first aspect, the invention proposes a particular structure of an electromechanical relay, in which the electromechanical relay comprises:

• a fixed frame, made of a material capable of conducting a magnetic field between a first end and a second end, the first end having a fixing surface,
• a control coil, capable of being supplied by a nominal control voltage, and comprising a cylindrical axial passage extending along a longitudinal axis,
• a magnetic core, slidably engaged in the cylindrical axial passage of the control coil, capable of conducting a magnetic field generated by the control coil when the latter is energized, and having a second end section fixed to the fixed armature by fixing means comprising at least one laser weld,
• a mobile armature, having an active face oriented opposite a first end of the magnetic core, and having a first end articulated on the first end of the fixed armature by hinge means ensuring the conduction of the magnetic flux between the fixed armature and the movable armature and allowing the rotation of the movable armature between a working state and a resting state towards which it is recalled by return means,
• a magnetic section of movable armature, structured so as to be attracted by the magnetic core when the latter conducts the magnetic field generated by the powered control coil,
• a mobile armature contact section, which is integral with the mobile armature magnetic section, which extends to a contact free end, and which flexes elastically when the mobile armature is in the working state,
• a fixed work contact, facing the contact free end,
• the fixing surface of the fixed frame being shaped to be in contact with the second end of the magnetic core according to the lateral surface of the section of second end of the magnetic core,

in which :

• the fixing surface of the fixed frame is shaped so that the magnetic core can slide axially on the fixing surface in the absence of said fixing means,
• said at least one laser weld is an internal weld which provides a metallurgical connection between the fixing surface of the fixed frame and the lateral surface of the second end section of the magnetic core.

The particular conformation of the fixing surface of the fixed armature, allowing the axial sliding of the core, allows, during the assembly of the electromechanical relay, an adjustment of the overtravel using a low force for driving the core in. the fixed armature, this driving force being sufficiently low so that the core and the fixed armature do not undergo appreciable deformation during the adjustment, the laser welding then ensuring the relative fixation of the core in the fixed armature without the core and the fixed frame do not deform again when the driving force is released.

This effectively compensates for the effect that inevitable variations in the shapes, dimensions and mechanical properties of the basic components from which electromechanical relays are made when going from batch to batch can be effectively compensated for on the cut-in voltage. further supply of basic components in a series production of electromechanical relays.

Finally, the particular attachment of the magnetic core by laser welding produces a metallurgical connection between the magnetic core and the fixed armature, which metallurgical connection makes it possible to eliminate the random air gap which is necessary to allow the sliding of the core during the adjustment of the overtravel, an air gap which would be liable to induce a disparity in the switching voltages of the electromechanical relays, and a loss of efficiency of these electromechanical relays.

Good results have been obtained by providing that the fixing surface of the fixed frame is shaped so as to leave, before carrying out the laser welding, with respect to the corresponding lateral surface of the magnetic core, a clearance of between 0.1 mm and 0.2 mm, preferably close to 0.15 mm. Satisfactory sliding of the magnetic core is thus ensured, that is to say without appreciable deformation of the magnetic core and of the fixed armature during the adjustment of the overtravel, and it facilitates the production of the internal laser welding.

Preferably, said at least one laser weld provides a continuous metallurgical connection along the entire fixing surface of the fixed reinforcement.

In this way, the risks of disparity in the magnetic flux flowing through the magnetic circuit formed by the fixed armature, the mobile armature and the magnetic core are further reduced, and therefore the risks of disparity in the switching voltages of the electromechanical relays. in serial production.

Preferably, the fixing surface of the fixed frame occupies the entire cross section of the fixed frame.

The passage of the magnetic flux between the magnetic core and the fixed armature is thus optimized, so as to increase the performance of the electromechanical relays.

To facilitate the penetration of the internal laser weld to a great depth, that is to say over almost the entire cross section of the fixed reinforcement, it is possible to provide, on the external face receiving the laser beam, a entry chamfer on the magnetic core and / or on the fixed armature, preferably on the magnetic core. The chamfer can advantageously be made over 20% of the length of the magnetic core section penetrating into the fixed frame. In the area of the chamfer, the respective walls of the magnetic core of the fixed armature can advantageously form an angle of approximately 20 °.

• (a) réaliser une ébauche de relais électromécanique comprenant :
  • une bobine de commande, apte à être alimentée par une tension nominale de commande, et comportant un passage axial cylindrique se développant selon un axe longitudinal,
  • une armature fixe, en un matériau apte à conduire un champ magnétique entre une première extrémité et une seconde extrémité, la première extrémité ayant une surface de fixation,
  • un noyau magnétique, apte à conduire un champ magnétique généré par la bobine de commande lorsque celle-ci est alimentée, le noyau magnétique étant engagé à coulissement dans le passage axial cylindrique de la bobine de commande,
  • une armature mobile, ayant une face active orientée en regard d'une première extrémité du noyau magnétique, et ayant une première extrémité articulée sur la seconde extrémité de l'armature fixe par des moyens de charnière assurant la conduction du flux magnétique entre l'armature fixe et l'armature mobile et permettant la rotation de l'armature mobile entre un état de travail et un état de repos vers lequel elle est rappelée par des moyens de rappel,
  • un tronçon magnétique d'armature mobile, structuré de façon à être attiré par le noyau magnétique lorsque celui-ci conduit le champ magnétique généré par la bobine de commande alimentée,
  • un tronçon de contact d'armature mobile, qui est solidaire du tronçon magnétique d'armature mobile, qui s'étend jusqu'à une extrémité libre de contact, et qui est apte à fléchir élastiquement lorsque l'armature mobile est dans l'état de travail,
  • un contact de travail fixe, en regard de l'extrémité libre de contact,
  • la surface de fixation de l'armature fixe étant conformée pour être en regard de la surface latérale du tronçon de seconde extrémité du noyau magnétique,
  • la surface de fixation de l'armature fixe étant conformée de sorte que le noyau magnétique peut coulisser axialement sur la surface de fixation,
• (b) positionner le noyau magnétique de façon que la surface latérale de son tronçon de seconde extrémité soit en regard de la surface de fixation de l'armature fixe,
• (f) fixer le noyau magnétique sur la surface de fixation de l'armature fixe, en réalisant au moins une soudure laser à l'interface entre le noyau magnétique et la surface de fixation de l'armature fixe.

According to a second aspect, the invention proposes a method for producing electromechanical relays in series, comprising the following steps:

• (a) produce an electromechanical relay blank comprising:
  • a control coil, capable of being supplied by a nominal control voltage, and comprising a cylindrical axial passage developing along a longitudinal axis,
  • a fixed frame, made of a material capable of conducting a magnetic field between a first end and a second end, the first end having a fixing surface,
  • a magnetic core, able to conduct a magnetic field generated by the control coil when the latter is supplied, the magnetic core being slidably engaged in the cylindrical axial passage of the control coil,
  • a mobile armature, having an active face oriented opposite a first end of the magnetic core, and having a first end articulated on the second end of the fixed armature by hinge means ensuring the conduction of the magnetic flux between the armature fixed and the movable armature and allowing the rotation of the movable armature between a working state and a resting state towards which it is recalled by return means,
  • a magnetic section of movable armature, structured so as to be attracted by the magnetic core when the latter conducts the magnetic field generated by the control coil powered,
  • a movable armature contact section, which is integral with the mobile armature magnetic section, which extends to a contact free end, and which is able to flex elastically when the movable armature is in the state working,
  • a fixed work contact, facing the contact free end,
  • the fixing surface of the fixed frame being shaped to be facing the lateral surface of the second end section of the magnetic core,
  • the fixing surface of the fixed frame being shaped so that the magnetic core can slide axially on the fixing surface,
• (b) position the magnetic core so that the side surface of its second end section is facing the fixing surface of the fixed frame,
• (f) fixing the magnetic core on the fixing surface of the fixed frame, making at least one laser weld at the interface between the magnetic core and the fixing surface of the fixed frame.

Preferably, the fixing surface of the fixed frame is shaped so as to leave, before step f), with respect to the corresponding lateral surface of the magnetic core, a clearance of between 0.1 mm and 0.2 mm, advantageously of about 0.15 mm.

• (c) en l'absence d'une alimentation de la bobine de commande, l'armature mobile étant dans son état de repos, positionner le noyau magnétique de façon que sa première extrémité soit proche ou au contact de la face active de l'armature mobile,
• (d) appliquer sur l'armature mobile, selon ledit axe longitudinal, une force de réglage la faisant pivoter en direction de son état de travail en repoussant le noyau mobile, jusqu'à ce que l'extrémité libre de contact vienne en appui sur le contact de travail fixe,
• (e) poursuivre l'application de la force de réglage pour faire pivoter l'armature mobile pour repousser ainsi en coulissement le noyau magnétique selon une surcourse dont la longueur est prédéterminée.

Advantageously, to correctly position the magnetic core before it is fixed, the following steps can be carried out:

• (c) in the absence of a power supply to the control coil, the movable armature being in its rest state, position the magnetic core so that its first end is close to or in contact with the active face of the mobile frame,
• (d) applying to the movable armature, along said longitudinal axis, an adjusting force causing it to pivot in the direction of its working state by pushing back the movable core, until the free contact end comes to rest on the fixed work contact,
• (e) continuing to apply the adjustment force to rotate the movable armature to thereby slidably push back the magnetic core by an overtravel whose length is predetermined.

BRIEF DESCRIPTION OF THE DRAWINGS

• [Fig.1] La figure 1 est une vue de côté en coupe selon l'axe de la bobine de commande, illustrant un relais électromécanique selon un mode de réalisation de l'invention, en état de repos ;
• [Fig.2] La figure 2 est une vue de côté en coupe selon l'axe de la bobine de commande, illustrant le relais électromécanique de la figure 1 en état de travail ;
• [Fig.3] La figure 3 est une vue de côté en coupe selon l'axe de la bobine de commande, illustrant le relais électromécanique des figures 1 et 2 dans un état intermédiaire de contact électrique sans force d'appui ;
• [Fig.4] La figure 4 est une vue de côté en coupe selon l'axe de la bobine de commande, illustrant une première étape de positionnement du noyau magnétique ;
• [Fig.5]. La figure 5 est une vue de côté en coupe selon l'axe de la bobine de commande, illustrant une deuxième étape de positionnement du noyau magnétique ; et
• [Fig.6]. La figure 6 est une vue de côté en coupe selon l'axe de la bobine de commande, illustrant une troisième étape de positionnement et de fixation du noyau magnétique.

Other objects, characteristics and advantages of the present invention will emerge from the following description of particular embodiments, given in relation to the accompanying figures, among which:

• [ Fig. 1 ] The figure 1 is a side view in section along the axis of the control coil, illustrating an electromechanical relay according to one embodiment of the invention, in the rest state;
• [ Fig. 2 ] The figure 2 is a side view in section along the axis of the control coil, illustrating the electromechanical relay of the figure 1 in working condition;
• [ Fig. 3 ] The figure 3 is a side view in section along the axis of the control coil, illustrating the electromechanical relay of the figures 1 and 2 in an intermediate state of electrical contact without pressing force;
• [ Fig. 4 ] The figure 4 is a side view in section along the axis of the control coil, illustrating a first step of positioning the magnetic core;
• [ Fig. 5 ]. The figure 5 is a side view in section along the axis of the control coil, illustrating a second step of positioning the magnetic core; and
• [ Fig. 6 ]. The figure 6 is a side view in section along the axis of the control coil, illustrating a third step of positioning and fixing the magnetic core.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

In the figures is schematically illustrated the structure of an electromechanical relay according to an embodiment of the present invention.

The electromechanical relay as illustrated in the figures comprises a fixed armature 1, a magnetic core 2, a movable armature 3, a fixed work contact 4, a control coil 5, a contact section 6 which forms a distal section of the movable armature 3 to a contact free end 7.

The control coil 5 comprises a coil carcass 51, integral with the fixed armature 1, and comprising a cylindrical axial passage 52 developing along a longitudinal axis II and in which the magnetic core 2 is engaged. A coil winding 53, consisting of an electrical conductor wound around the coil casing 51, is intended to be connected to an external source of nominal control voltage not shown in the figures.

A first end 21 of the magnetic core 2 protrudes out of a first end of the axial passage 52 of the control coil 5, and constitutes the attractive pole capable of stressing the movable armature 3. A second end 22 of the magnetic core 2 protrudes out. a second end of the axial passage 52 of the control coil 5, and is fixed to a first end 1a of the fixed armature 1. From its first end 1a, the fixed armature 1 extends radially along a first branch away from the second end 22 of the magnetic core 2, and is connected to a second fixed armature branch 1b which extends parallel to the longitudinal axis II as far as a second fixed armature end 1c against which a first end 31 of the mobile armature 3 bears.

The movable frame 3 comprises, from its first end 31, a magnetic section 32, developing parallel to the first branch 1a of the fixed frame 1, facing the first end 21 of the magnetic core 2, and structured so to be attracted by the magnetic core 2 when the latter conducts a magnetic field generated by the control coil 5 which has been supplied with electrical energy. The magnetic section 32 has the general shape of a bar, having an active face 33 oriented towards the magnetic core 2, and having a fixing face 34 oriented away from the magnetic core 2. The fixing face 34 comprises, in a zone located between the first end 31 of the frame 3 and the first end 21 of the magnetic core 2, a positioning lug 35.

The fixed armature 1 comprises a ferromagnetic material capable of conducting a magnetic field generated by the control coil 5 in the magnetic core 2. The movable armature 3 itself comprises, in its magnetic section 32, a ferromagnetic material, and closes thus the magnetic field generated in the magnetic core 2.

In the illustrated embodiment, constituting an electromechanical relay with a relatively low controlled voltage (from a few volts to a few tens of volts), the contact section 6 extends the magnetic section 32 of the mobile armature 3, and extends to the -beyond the magnetic section 32 of the movable armature 3, away from the first end 31 of the movable armature 3, up to a free contact end 7 which is located opposite the fixed working contact 4, itself integral with the coil casing 51.

The contact section 6, in the illustrated embodiment, comprises a leaf spring 61, in the form of a flat strip made of bronze / beryllium alloy, which has the advantage of good elastic properties and good electrical conduction properties. The leaf spring 61 is fixed, along one of its two main faces, on the fixing face 34 of the movable frame 3, in an intermediate fixing zone located between the first articulated end 31 and the free contact end. 7 of the leaf spring 61. For this, by way of nonlimiting example, in this particular embodiment, the leaf spring 61 comprises a positioning slot 62 in which the positioning lug 35 which protrudes is forcibly engaged. of the fixing face 34 of the movable frame 3.

The leaf spring 61 is extended beyond said intermediate fixing zone, away from the free contact end 7, by an arcuate section 64 followed by a longitudinal section 65 generally parallel to the second branch 1b of the fixed armature 1 and to which it is fixed with the interposition of a common plug 8 forming one of the terminals of the electric power circuit of the electromechanical relay. By this arrangement, the leaf spring 61 constitutes elastic return means 9 of the movable armature 3.

Because of its support by its first end 31 on the second end 1c of the fixed frame 1, and because of its retention by the elastic return means 9, the mobile frame 3 is articulated by its first end 31 according to hinge means constituted by the second end 1c of the fixed frame 1, and can thus pivot between a state of rest illustrated on figure 1 and a working condition illustrated on the figure 2 . The elastic return means 9 ensure the return of the movable armature 3 to its rest state. The hinge means also ensure conduction of the magnetic flux between the fixed armature 1 and the mobile armature 3.

The free contact end 7 of the contact section 6 is provided with a contact pad 71 made of an electrically conductive material and having good anti-wear properties. Likewise, the fixed working contact 4 is formed by a fixed pad 41 made of an electrically conductive material and having good anti-wear properties. The fixed pad 41 is secured to a work plug 10 constituting the second connection terminal of the power circuit of the electromechanical relay.

In the illustrated embodiment, a rest stop 11 limits the movement of the free contact end 7 away from the fixed working contact 4.

We now consider more specifically the means for fixing the magnetic core 2 on the fixed armature 1. In this regard, as illustrated in the figures. figures 1 to 3 , the first end 1a of the fixed frame 1 comprises a fixing surface 1d. This fixing surface 1d is shaped to cooperate with the second end 22 of the magnetic core 2 along the lateral surface of the magnetic core 2, that is to say the peripheral surface which surrounds the longitudinal axis II of the magnetic core 2. The fixing of the magnetic core 2 is ensured by a laser weld 23 at the interface between the magnetic core 2 and the fixing surface 1d of the fixed armature 1. The laser weld 23 is an internal weld which is carried out so as to ensure a continuous metallurgical connection between the entire fixing surface 1d of the fixed frame 1 and the lateral surface of the second end section 22 of the magnetic core 2. In addition, in the embodiment illustrated in the figures, the fixing surface 1d of the fixed reinforcement 1 occupies the entire cross section of fixed reinforcement 1.

In reality, before making the laser weld 23, during the assembly of the electromechanical relay, the fixing surface 1d is shaped to allow free axial sliding of the magnetic core 2. In practice, provision is made between the fixing surface 1d and the lateral surface of the magnetic core 2, an initial clearance of between 0.1 mm and 0.2 mm, advantageously around 0.15 mm. After the step of adjusting the longitudinal position of the magnetic core 2 relative to the fixing surface 1d according to the desired overtravel, the laser weld 23 fills this clearance according to the fixing surface 1d.

In embodiments in which the attachment surface 1d does not occupy the entire cross section of the fixed frame 1, the initial clearance remains apparent between the magnetic core 2 and the excess area of fixed frame cross section. 1.

In the embodiment illustrated in the figures, the fixing surface 1d is an end surface of the fixed armature 1, so that the path of the magnetic flux is the shortest between the magnetic core 2 and the fixed armature 1.

As an alternative, it is possible to design a fixing surface which surrounds all or part of the second end section 22 of the magnetic core 2, then requiring a more extensive and longer peripheral weld to be carried out.

In the state of rest shown on the figure 1 , the control coil 5 is not supplied, and does not produce any magnetic field in the magnetic core 2. Thus, the movable armature 3 is not attracted by the magnetic core 2, and, by the stressing of the means of elastic return 9, stays away from the magnetic core 2 and comes to bear against the rest stop 11.

In the working condition shown on the figure 2 , the control coil 5 is supplied at a nominal control voltage, and produces in the magnetic core 2 a sufficient magnetic field to attract the movable armature 3, against the return stress exerted by the elastic return means 9, until the movable armature 3 comes into contact with the first end 21 of the magnetic core 2 via its active face 33. In this position, the contact pad 71 of the free contact end 7 is supported. against the fixed shoe 41 of the fixed working contact 4, so that the free contact end 7 is biased away from the fixing face 34, causing a bending or bending of the section of leaf spring 61 located between the intermediate fixing zone and the free contact end 7.

In this way, in the working state, the contact pad 71 of the free contact end 7 bears against the fixed pad 41 of the fixed work contact 4 according to a working force determined essentially by the stiffness characteristics. of the leaf spring 61, and by the length L and the amount of bending of the leaf spring section 61 located between the intermediate fixing zone and the free contact end 7.

The amount of bending of the section of leaf spring 61 depends on the rotational overtravel of the movable armature 3 until it comes to bear against the first end 21 of the magnetic core 2. To assess this, we now consider the figure 3 , which illustrates an intermediate state of the electromechanical relay between the idle state and the working state. In this intermediate state, the contact pad 71 of the free contact end 7 is just in contact with the fixed pad 41 of the fixed working contact 4, without any support force, so that the spring blade section 61 located between the fixing zone and the free contact end 7 is not flexed. The active face 33 of the movable armature 3 is then slightly away from the first end 21 of the magnetic core 2, from which it is separated by an air gap or overtravel S. From this position, to reach the working state illustrated on the figure 2 , the mobile armature 3 must perform an additional rotation according to an additional travel or overtravel S which cancels the air gap between the active face 33 of the mobile armature 3 and the magnetic core 2. This additional travel S produces the bending of the blade spring 61 in its section between the intermediate fixing zone and the free contact end 7, and produces the working force.

It will be understood that the additional stroke S, which produces the bending of the leaf spring 61 and the working force, strongly depends on the axial position of the magnetic core 2 with respect to the fixed armature 1. According to the present invention, it is thus possible appreciably reduce the disparity in the working forces and in the switching voltages of a series of electromechanical relays by ensuring a precise fixing of the magnetic core 2 without inducing any appreciable deformation of the parts, and thanks to its fixing by laser welding 23 on the fixing surface 1d of the fixed frame 1.

During the manufacture of such an electromechanical relay, it is possible to take advantage of the particular arrangements of the fixing means of the magnetic core 2 on the fixed armature 1, not only to ensure precise fixing of the magnetic core 2, but also to allow precise adjustment of the axial position of the magnetic core 2 before it is fixed. The absence of appreciable deformation of the parts during this adjustment makes it possible to greatly reduce the disparities in the value of the switching voltages of the relays.

Thus, the manufacture of an electromechanical relay according to the present invention can comprise the steps illustrated on the figures 4 to 6 .

On the figure 4 , there is an electromechanical relay blank, comprising all of the constituent parts of the electromechanical relay with the exception of the laser welding 23. In this state, the magnetic core 2 can slide freely along its longitudinal axis II, both in the control coil 5 and on the fixing surface 1d of the fixed armature 1. The control coil 5 is not supplied, and the elastic return means 9 keep the movable armature 3 in its position rest. The magnetic core 2 is positioned so that its first end 21 bears against the active face 33 of the movable armature 3.

From this position shown on the figure 4 , a bias illustrated by the arrow 36 is applied to the movable armature 3, for example with a pusher, to push it back in the direction of the control coil 5, until the intermediate position illustrated on the figure is reached. figure 5 . In this intermediate position, the contact pad 71 of the free contact end 7 is just in contact with the fixed pad 41 of the fixed working contact 4, without any support force. In its rotational movement between the position shown on the figure 4 and the position shown on the figure 5 , the movable armature 3 has axially repelled the magnetic core 2.

From this position shown on the figure 5 , the stress 36 applied to the movable armature 3 is continued according to an additional displacement of predetermined length, which is called overtravel S. This simultaneously produces an axial displacement of the magnetic core 2 according to this same value of overtravel S. At the end of the additional displacement, the magnetic core 2 is in the position shown in the figure 6 . In practice, an overtravel S is chosen, the predetermined length of which is between 0.1 mm and 0.25 mm. Good results have been obtained with an overtravel S, the predetermined length of which is approximately 0.15 mm.

In this position shown on the figure 6 , the movable armature 3 and the magnetic core 2 are kept in position relative to the fixed armature 1, and the magnetic core 2 is fixed by performing laser welding 23.

The execution of the laser weld 23 can be facilitated by providing an entry cone into which the laser beam can penetrate around the end of the magnetic core 2. The entry cone can be made by a chamfer on the magnetic core. 2, or by a chamfer both on the magnetic core 2 and at the entrance to the hole of the fixed armature 1, or by a chamfer on the only fixed armature 1. The depth of the cone can advantageously be about 20 % of the length of the section of the magnetic core which enters the fixed armature 1. The cone angle may be around 20 °.

The particular means of fixing the magnetic core 2 on the movable armature 3 are also applicable, while producing the same advantages, to an electromechanical relay structure of higher power, capable of driving voltages of the order of a few tens of volts. to a few hundred volts. In this case, the magnetic circuit and the electrical circuit are generally dissociated, by connecting the contact section to the magnetic section by an electrically insulating spacer to move the contact section away from the magnetic circuit.

The present invention is not limited to the embodiments which have been explicitly described, but it includes the various variations and generalizations contained within the scope of the following claims.

Claims (11)

Electromechanical relay comprising: - a fixed frame (1), made of a material capable of conducting a magnetic field between a first end (1a) and a second end (1c), the first end (1a) having a fixing surface (1d), - a control coil (5), capable of being supplied by a nominal control voltage, and comprising a cylindrical axial passage (52) extending along a longitudinal axis (II), - a magnetic core (2), slidably engaged in the cylindrical axial passage (52) of the control coil (5), able to conduct a magnetic field generated by the control coil (5) when the latter is supplied, and having a second end section (22) fixed to the fixed frame (1) by fixing means comprising at least one laser weld, - a movable frame (3), having an active face (33) oriented opposite a first end (21) of the magnetic core (2), and having a first end (31) articulated on the first end (1c) d 'fixed armature by hinge means ensuring conduction of the magnetic flux between the fixed armature (1) and the movable armature (3) and allowing the rotation of the movable armature (3) between a working state and a state of rest towards which it is recalled by return means (9), - a magnetic section (32) of movable armature, structured so as to be attracted by the magnetic core (2) when the latter conducts the magnetic field generated by the powered control coil (5), - a contact section (6) of the movable armature, which is integral with the magnetic section (32) of the movable armature, which extends to a free contact end (7), and which flexes elastically when the mobile armature (3) is in the working state, - a fixed work contact (4), facing the free contact end (7), - the fixing surface (1d) of the fixed frame (1) being shaped to be in contact with the second end of the magnetic core (2) according to the lateral surface of the second end section (22) of the magnetic core (2) , characterized in that : - the fixing surface (1d) of the fixed frame (1) is shaped so that the magnetic core (2) can slide axially on the fixing surface (1d) in the absence of said fixing means, - said at least one laser weld (23) is an internal weld which provides metallurgical connection between the fixing surface (1d) of the fixed frame (1) and the lateral surface of the second end section (22) of the magnetic core (2). Electromechanical relay according to Claim 1, characterized in that the said at least one laser weld (23) provides a continuous metallurgical connection along the entire fixing surface (1d) of the fixed armature (1). Electromechanical relay according to Claim 2, characterized in that the fixing surface (1d) of the fixed armature (1) occupies the entire cross section of the fixed armature (1). Electromechanical relay according to any one of Claims 1 to 3, characterized in that the fixing surface (1d) of the fixed armature is shaped, before carrying out the laser welding (23), so as to leave, with respect to the corresponding lateral surface of the magnetic core (2), a play of between 0.1 mm and 0.2 mm, advantageously about 0.15 mm. Method for making an electromechanical relay, comprising the following steps: (a) produce an electromechanical relay blank comprising: - a control coil (5), capable of being supplied by a nominal control voltage, and comprising a cylindrical axial passage (52) developing along a longitudinal axis (II), - a fixed frame (1), made of a material capable of conducting a magnetic field between a first end (1a) and a second end (1c), the first end (1a) having a fixing surface (1d), - a magnetic core (2), able to conduct a magnetic field generated by the control coil (5) when the latter is supplied, the magnetic core (2) being slidably engaged in the cylindrical axial passage (52) of the control coil (5), - a movable frame (3), having an active face (33) oriented facing a first end (21) of the magnetic core (2), and having a first end (31) articulated on the second end (1c) of the fixed armature (1) by hinge means ensuring the conduction of the magnetic flux between the fixed armature (1) and the mobile armature (3) and allowing the rotation of the mobile armature (3) between a state of work and a state of rest towards which it is recalled by return means (9), - a magnetic section (32) of movable armature, structured so as to be attracted by the magnetic core (2) when the latter conducts the magnetic field generated by the powered control coil (5), - a contact section (6) of mobile armature, which is integral with the magnetic section (32) of mobile armature, which extends to a free contact end (7), and which is able to flex elastically when the mobile armature (3) is in the working state, - a fixed work contact (4), facing the free contact end (7), - the fixing surface (1d) of the fixed frame (1) being shaped to face the side surface of the second end section (22) of the magnetic core (2), - the fixing surface (1d) of the fixed frame (1) being shaped so that the magnetic core (2) can slide axially on the fixing surface (1d), (b) position the magnetic core (2) so that the side surface of its second end section (22) is facing the fixing surface (1d) of the fixed frame (1), (f) fix the magnetic core (2) on the fixing surface (1d) of the fixed frame (1), making at least one laser weld (23) at the interface between the magnetic core (2) and the fixing surface (1d) of the fixed frame (1). Method according to Claim 5, characterized in that the fixing surface (1d) of the fixed frame is shaped so as to leave, before step f), with respect to the corresponding lateral surface of the magnetic core (2), a clearance between 0.1 mm and 0.2 mm, advantageously around 0.15 mm. Method according to one of claims 5 or 6, characterized in that the laser weld (23) is an internal weld which provides a continuous metallurgical connection along the entire fixing surface (1d) of the fixed reinforcement (1). Method according to Claim 7, characterized in that the fixing surface (1d) of the fixed frame (1) occupies the entire cross section of the fixed frame (1). Method according to any one of Claims 5 to 8, characterized in that , in order to position the magnetic core (2), the following steps are carried out: (c) in the absence of a power supply to the control coil (5), the movable armature (3) being in its rest state, position the magnetic core (2) so that its first end (21) either close to or in contact with the active face (33) of the mobile armature (3), (d) applying to the movable frame (3), along said longitudinal axis (II), a force adjustment by pivoting it in the direction of its working state by pushing back the movable core (2), until the free contact end (7) comes to rest on the fixed work contact (4), and (e) continuing to apply the adjustment force to rotate the movable armature (3) to thereby push back the magnetic core (2) by an overtravel (S) the length of which is predetermined. Method according to Claim 9, characterized in that the overtravel (S) has a predetermined length of between 0.1 mm and 0.25 mm. Method according to Claim 9, characterized in that the overtravel (S) has a predetermined length of approximately 0.15 mm.

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