EP4643355A1

EP4643355A1 - Solenoid actuator with (improved) armoured containment box

Info

Publication number: EP4643355A1
Application number: EP23822103.0A
Authority: EP
Inventors: Fabio FEDELI; Angelo LORUSSO
Original assignee: Acl Srl
Current assignee: Acl Srl
Priority date: 2022-12-29
Filing date: 2023-11-28
Publication date: 2025-11-05
Also published as: WO2024141824A1; CN120322835A; IT202200027075A1

Abstract

Electromechanical solenoid actuator comprising a coil housed in an armature made of ferromagnetic material with a perimeter development that facilitates a path for conveying the magnetic field generated by the coil generating a mechanical force by induction onto a movable element or movable core sliding within the coil. The actuator comprises an armature composed of two portions, which can be separated from each other and complimentary in shape so as to allow an axial insertion into the armature, thus making the steps of assembling the actuator components quick and easy.

Description

DESCRIPTION

SOLENOID ACTUATOR WITH (IMPROVED) ARMOURED CONTAINMENT BOX

The present invention relates to an electromechanical solenoid actuator comprising an armature made of ferromagnetic material with a perimeter development, with said armature being composed of two parts that can be separated and coupled together, and associated assembly method.

Electromechanical solenoid actuators are well known in the technical literature. Said actuators are electromechanical devices capable of converting electrical energy into mechanical energy on a movable body or movable core made of ferromagnetic material through electromagnetic interaction. They are used in a variety of applications where an element or component needs to be moved, pushed, pulled or pressed or activated with a mechanical impulse over a short distance with little power consumption. One of the best known examples is the use in electrovalves adapted to control the opening or closing of the flow passage of a working fluid.

The use of electromechanical actuators characterised in that they use so- called “armoured coils” is also well known in the technical literature. This type of coil consists in arranging the solenoid inside an armature (or armour), consisting of a plate of ferromagnetic material that is folded and arranged in a closed perimeter around the solenoid spool. Unlike systems without an armoured coil, the magnetic flow is channelled more precisely from the armature surfaces to the manoeuvring channel of the movable core. Consequently, the presence of the armour makes it possible to deliver a higher electromechanical force on said movable core using smaller actuators than in armour-free systems. This type of actuator is particularly useful in circumstances where it is required at the same time an actuator with small size and high electromechanical force performance. A prior art example describing the use of this type of actuators envisages the use of said actuators as a component of electromechanical valves applied in railway vehicle braking systems.

For example, a so-called "polar electromagnet device" with small power consumption is known from EP2141723, wherein a drive shaft is supported so as to move alternately in the central direction of the axis at a central hole of a coil wound with a coil, wherein a movable iron core is fixed to a lower end of the drive shaft on the same axis centre and wherein the drive shaft is made to move alternately with the movable iron core moving alternately according to the excitation and demagnetisation of the coil; a permanent magnet is integrally arranged at the movable iron core on the same axis centre.

It is also known from DE3442223 an armature magnet system of the plunger type wherein the magnet housing consists of a U-shaped yoke part and a flow-guide element which can be firmly connected to each other by means of its free branches, and wherein suitable circular notches are arranged in the flow-guide element and in the connecting rib of the yoke part which surround the armature with small air gaps; in such a device of the prior art, the excitation coil former is axially supported by means of bearings arranged on the end surfaces of the two flange parts, in bearing recesses in the flow-guide element and in the connecting rib, and in addition, there is in its core, a pass-through hole in the longitudinal direction which has constrictions at the outlet ends to support the movable armature without clearance.

It is further known from US 2022/0181060 a solenoid containing a yoke 2, a coil 3 having an electromagnetic coil 4 arranged within the yoke 2, and an iron core 5 arranged within the coil 3; in such a solenoid, a connector portion 6 incorporating a predefined number of metal end fittings 7 is provided on an end portion of the coil 3, and therefore, since a relatively large space is not required for the disposal of conductive wires as in the prior art, the solenoid is small, so that the solenoid can be produced cost- effectively.

Furthermore, it is known from FR2665017 an electromagnet comprising a coil former whose extensions interact with a yoke cross member and a flow closure part in such a way as to ensure, on the one hand, that a fixed core placed in the hole of the former is applied without gaps and, on the other hand, that this hole is strictly aligned with an opening of this part so as to allow a magnetically and mechanically adequate sliding of the movable core; this electromagnet is particularly suitable for coil feeding by direct current and is suitable for a technically cost-effective series production.

It is finally known from US4443775 a high performance solenoid actuator comprising a coil surrounded externally by a magnetic frame and having a stationary core arranged therein, with a movable core attracted to the stationary core after excitation of the coil arranged axially sliding, wherein the magnetic frame comprises a pair of magnets as well as frame parts each manufactured from a sheet material by folding the sheet so as to define a top plate and a bottom plate integrally joined together with a side plate to cover the top, bottom and side of the coil, and the pair of magnetic frame parts are assembled to each other with the top and bottom plates overlapping each other, thereby providing a simplified structure and an easy assembly.

The prior art, however, proves to be lacking in some aspects.

It is ascertained that the geometry of the prior art actuators forces to find a compromise between the minimum size the actuators can reach and the cost and time required during the process of assembling the parts. In the prior art, the armature generally consists of a piece of metal sheet made of ferromagnetic material, folded at four points along its length to obtain four walls constituting in section a quadrilateral with parallel opposite sides and adjacent sides that are perpendicular to each other, preferably a rectangle. The prior art requires that there is a total overlap of the two extreme edges to form the wall corresponding to the end side of the quadrilateral, where one of the two axial supports of the solenoid is applied.

This overlap is necessary because it is required that there be as large a surface area as possible between the two parts, as they are separated. Any differences in thickness or any jumps along the wall risk causing a non-continuity of the magnetic flow induced through the armature and compromising the actuator performance.

It should be further specified that the armature must have a minimum thickness throughout the perimeter in order to optimally channel the magnetic flow and reduce reluctance.

A disadvantage of the prior technique results from the fact that the current design of said actuators employs a non-linear manufacturing process. In particular, the operation of assembling the various components requires multiple operations from different sides by operators and auxiliary machinery. In particular, due to the armature closed development and the fact that it must initially be made by bending the sheet metal, the subsequent assembly of the solenoid requires a transverse insertion thereof in the armature, followed by the transverse insertion of the electrical connection elements and, finally, the locking of the solenoid in the armature by means of two axial components, at least one of which is applied in a hole present in the wall defined by the overlapping end flaps.

Especially in the cases where small-sized actuators have to be produced, it is difficult for operators and auxiliary machinery to carry out the assembly of the components, requiring the use of a process divided into several working steps. This has a negative impact in terms of working time and costs.

A second disadvantage of the prior art is given by the mandatory use of electrical wire used for winding of the type with a low-insulating power coating, as tinning and soldering of the pins for the electrical connection is required.

The object of the present invention is to overcome said disadvantages of the prior art. In particular, a solution is proposed for an electromechanical actuator made up in such a way as to both minimise the overall dimensions and ensure a time- and cost-efficient process for component assembly operations, guaranteeing use in space-restricted environments due to the actuator small footprint.

The outlined technical task and the specified object are substantially achieved by an electromechanical actuator comprising an “armoured” coil where the armature for conveying the magnetic flow is composed of two portions that are separate and assembled by form fitting, resulting in a four-walled, quadrilateral-shaped structure along the closed profile, such that it possesses parallel opposite sides and adjacent sides perpendicular to each other.

With the same minimum thickness of the armature, this arrangement makes it possible to avoid overlapping of material composing the armature while ensuring the required dimensional compactness with the same performance. This electromagnetic actuator is defined by the features of the attached claim 1 .

A method of assembling the actuator in accordance with the features set forth in the attached claim 10 is also an object of the invention.

In addition, said actuator configuration allows all components to be axially assembled in sequence, taking advantage of a single assembly step where the components are assembled on a single axial working dimension, saving time and effort during assembly operations.

Further features and advantages of the present invention will become clearer from the indicative, and therefore non-limiting, description of a preferred but non-exclusive embodiment of an electromechanical solenoid actuator in accordance with the invention and the associated assembly method.

This description will be set forth hereinafter with reference to the accompanying drawings, wherein:

- Figure 1 is a complete schematic representation of an electromechanical solenoid actuator provided with an armature and electrical connection elements, including connection pins, according to the invention;

- Figure 2 is a representation of the coil provided with the power supply elements, in particular the connection pins for the power supply;

- Figure 3a is a schematic representation of the first major portion of the armature and associated details;

- Figure 3b is a schematic representation of the second portion (or closing plate) and associated details;

- Figure 4 is a side section view of an electromechanical solenoid actuator provided with armature and electrical connection elements, including connection pins;

- Figure 5 is a complete schematic representation of an electromechanical solenoid actuator provided with electrical connection elements in the final operative form, i.e. enclosed in an encapsulating mould made of insulating material;

- Figure 6 is a representation of an exploded view of a complete electromechanical solenoid actuator with electrical connection elements and encapsulation mould.

With reference to the attached figures, an electromechanical solenoid actuator according to the invention has been globally indicated by 1 , referring to a preferred but not exclusive use as an electromechanical actuator for valves of railway vehicle braking systems. In particular, the actuator has features and configuration such that it is 15 mm wide.

The actuator comprises a coil 2 housed inside an armature 3 and having electrical terminals 4 for connection to a power supply source.

Referring to Figure 2, the coil 2 is cylindrical and comprises a solenoid 5, defined by a conductive wire that is wound to define a winding. The solenoid 5 is arranged around a spool 6 of insulating material comprising a cavity 7 passing through the entire support. The purpose of the cavity 7 is to house a fixed core (not shown) and a movable core configured to interact with the magnetic field generated by the solenoid 5 and couplable with, or forming part of, a translatable actuating member.

The armature 3 extends perimetrally along a closed profile that extends perimetrally around the coil so that the axial ends of the spool 6 face respective portions, opposite to each other, of the armature 3. Thus, the magnetic flow axially leaving one end of the coil 2 splits into two sides passing through opposite portions of the armature and join at the opposite end of the coil 3.

Having fixed a system of x-y-z coordinates indicating the length, width and height dimensions respectively, the perimeter development of the armature 3 around the coil 2 winds entirely the coil 2 along the x- and z- dimensions, having uncovered sides with the coil 2 in view along the y- dimension. The perimeter development of the armature 3 has a quadrilateral shape (square or rectangle) with parallel opposite sides and adjacent sides perpendicular to each other. The cross section of the armature remains substantially constant along the entire perimeter development

Advantageously, according to the invention, the armature 3 is defined by at least two separable parts that are complementary to each other and defining, in an assembled configuration, the aforementioned perimeter development. A first portion 8 defines a prevailing portion of the perimeter development and has an open profile with at least a “C” or “U” shape, while the second portion 9 defines a completion cover applicable to the first portion 8. In particular, the first portion 8 has an open or “glassshaped” profile made up of three walls, namely a bottom wall 8a and two side walls 8b and 8c. This first portion 8 is preferably obtained by folding a metal sheet in two points.

Advantageously, moreover, the second portion 9 is coupled or may be coupled to a first axial end of the coil 2, while the second axial end of the coil 2 is coupled to a bottom wall 8a of the first portion 8, which defines in particular a central area thereof.

In greater detail, the bottom wall 8a has a pass-through hole 10 in order to accommodate by interlocking a polar expansion 11 . The polar expansion 11 has a cylindrical or tubular part 11 a axially inserted into the pass- through hole 10. The length of said insertable part 11a is greater than the thickness of the armature section, such that once inserted into the hole 10, it projects inwardly engaging the end 6a of the spool 6, thereby securing the coil 2 in place. The polar expansion 11 also has a pass-through notch 11 b. The inner diameter of the pass-through notch 11 b is aligned with the diameter of the cavity 7 of the spool 6, forming a single channel where the movable part of the actuator can be moved.

In the present embodiment, the insertable part 11 a of the polar expansion 11 may optionally be accompanied by an insulating material ring 11 c.

In the present embodiment, at least one of the side walls of the first portion 8 of the armature 3, in particular the side wall 8b in the present illustration, has a plurality of holes 12 intended to fix the elements of the electrical connection system 4.

In greater detail, the electrical connection system 4 comprises at least two power supply connection pins 4a and 4b, preferably in the form of rigid connectors made of conductive material. These pins 4a, 4b are inserted inside the aforementioned holes 12, specifically one for each dedicated hole, in such a way that each pin connected to the coil 2 passes through the respective hole projecting externally to the armature 3.

Preferably, the holes dedicated to the pins 4a, 4b are defined by end recesses, 12a and 12b, made on at least one of the two side walls of the first portion 8, then indentations from the open side profile, and are closed by applying the second portion 9 as a cover. This arrangement of the recesses 12a and 12b defines an overall “E”-shape of the corresponding end and is intended to facilitate the operation of assembling the overall actuator as it allows the coil 2, previously provided with the supply pins 4a, 4b, to be fixed inside the first portion 8 of the armature 3, to then proceed to close, by form fitting, the first portion 8 and the second portion 9.

Preferably, the second portion 9 is made in the form of a flat wall or plate. This second portion 9 also has end shapes adapted to engage by form fitting with the corresponding free ends of the side walls 8b and 8c of the first portion 8. In the present embodiment, on one end, the second portion 9 has two protrusions 13a and 13b, which are adapted to couple with the corresponding recesses 12a and 12b of the first side wall 8b of the first portion 8. Similarly, the second portion 9 has a head notch 14 which in turn may be coupled with an end tooth 15 located on the second side wall 8c of the second portion 8.

The second portion 9 has such an extension that its removal creates an opening on the upper side of the first portion 8 (opposite the back wall 8a) sufficient to allow axially extracting the coil 2 from the first portion 8, preferably extending throughout the width of the armature 3.

The coupling set forth above makes it possible to obtain the closure of said perimeter development of the armature 3 having in the x-z plane the form of a perfect quadrilateral with a constant cross section of said armature. All shaped coupling ends are formed such as to obtain contact surfaces that are as smooth as possible to maximise contact between the parts and avoid impedance and disturbance in the magnetic flow within the armature.

The second portion 9 also has at the centre a pass-through hole 16 intended to fix a fixed core 17 to the coil 2. The fixed core 17 is engaged or may be engaged axially with the end 6b of the spool 6 by being inserted into the cavity 7 up to an intermediate position to also define an axial stop for the movable part of the actuator. The fixed core 17 may comprise parts made of ferromagnetic material with the function of channelling the magnetic flow into the sliding channel of the movable core.

Preferably, the fixed core 17 is coupled to the second portion 9 in a permanent and/or stable manner, for example by interference fit within the aforementioned pass-through hole 16.

In the present embodiment, the fixed core 17 may possibly be accompanied by an insulating material ring 17a.

Both on the second portion 9 and on the bottom wall 8a of the first portion 8 there are axially aligned perforations 18 in order to accommodate retaining elements in the form of a threaded member (not shown) extending axially throughout the development of the armature with the purpose of firmly fixing by coupling with the valve or with the most appropriate utility, depending on the contingent requirements. In particular, these retaining elements are available in angular positions on the two portions, so that they are arranged outside the cylindrical footprint of the coil 2.

Finally, the complete actuator, as described above, is placed in an encapsulation mould 19 and moulded with insulating material to secure any manipulation by operators once installed and in operation. The capsule has holes 20, aligned with and corresponding to the holes 18 of the two armature portions 8 and 9, adapted to accommodate the threaded member fasteners. In particular, these fasteners may be inserted from outside the capsule (not shown in the current figures).

DESCRIPTION OF THE ASSEMBLY METHOD

With reference to Figure 7, the proposed assembly method is set forth hereinafter, which is adapted to solve the technical problem underlying the invention and employing electromechanical solenoid actuators of the type described above.

The method involves first of all the step of arranging a coil 2, and a step of adding suitable power supply elements 4 (e.g. power supply pins 4a and 4b) to the coil 2 itself: arranging the coil 2 can be implemented by defining an electrical winding on a spool 6.

Next, the first portion 8 of the armature 3 is arranged and the polar expansion 11 is added thereto in the specific hole 10 on the bottom wall 8a.

At the same time, the second section 9 is arranged by inserting the fixed core 17 into the dedicated hole, interposing if necessary an insulating material ring 17a.

Next, the axial application of the coil 2 on the first portion 8 takes place.

The coil 3 is positioned in such a way that the part 11 a of the polar expansion 11 internally facing the first portion 8 is accommodated within the cavity 7 of the end 6a of the spool 6, opposite to the support containing the connections to the power supply pins 4a and 4b, possibly interposing an insulating material ring 11 c.

At the same time, care is taken to ensure that the power supply pins 4a and 4b are placed in the suitable dedicated housings given by recesses 12a and 12b on the second side wall 8b of the first portion 8. In this context, following the axial insertion of the coil 2 into the first portion 8 (i.e. along the magnetic axis of the coil), the pins 4a and 4b are automatically placed in their respective recesses 12a and 12b on the respective side walls 8b and/or 8c of the first portion 8.

The armature 3 is then closed, interlocking the second section 9 on the first one, fixing the coil 2 by axially inserting the fixed core 17 inside the hole 7 of the spool 6 at the second end 6b, entirely enclosing the coil 2 in the perimeter armature.

The two portions 8 and 9 of the armature 3 are then fixed.

In conclusion, the mould for incapsulating the armature in the capsule is defined.

Claims

1 ) Electromechanical solenoid actuator, comprising:

- An armature made of ferromagnetic material with a closed perimeter development defining therein a housing for a coil; and

- A hollow cylindrical coil inserted into said housing in such a way that said armature defines a path for conveying the magnetic field generated by the coil, wherein:

- said armature is defined by at least two separable parts that are complementary to each other and defining, in an assembled configuration, said perimeter development, wherein:

- a first one of said parts defines a prevailing portion of said perimeter development and having a "C" or "U"-shaped open profile; and

- said second one of said parts defines a completion cover applicable to said first portion; and wherein

- said second portion is coupled or couplable to a first axial end of said coil, said first portion and said second portion being couplable to each other by form fitting in particular such that the thickness of the armature is substantially uniform throughout the perimeter development of the armature, characterized in that the actuator has a width of 15 mm, in particular for use as an actuator for railway vehicle braking equipment.

2) Electromechanical solenoid actuator according to claim 1 , wherein said first portion has a bottom wall provided with a bottom opening and wherein the actuator further comprises a hollow polar expansion which may be inserted in the bottom opening and engaged with a second axial end of the coil, opposite to the first one, to simultaneously engage the coil to the bottom wall and allow the movable core to slide between the inside and the outside of the coil.

3) Electromechanical solenoid actuator according to claim 1 or 2, wherein the second portion lies on a plane and is preferably defined by a closing plate, in particular said plate having a thickness at least equal to, and preferably greater than, the thickness of the first portion.

4) Electromechanical solenoid actuator according to any one of the preceding claims, wherein the second portion has such an extension that its removal allows extracting the coil from the first portion, in particular the second portion extending throughout the width of the armature.

5) Electromechanical solenoid actuator according to any one of the preceding claims, wherein the second portion has a fixed core which may be stably inserted within the respective axial end of the coil, said fixed core being preferably stably inserted within a corresponding hole of the second portion.

6) Electromechanical solenoid actuator according to any one of the preceding claims, wherein the first portion has a plane bottom wall and side walls that are plane and parallel to each other and perpendicular to the bottom wall, wherein the second portion is applied to end portions of the side walls.

7) Electromechanical solenoid actuator according to any one of the preceding claims, comprising connecting means for stably connecting said first and second portions to each other.

8) Electromechanical solenoid actuator according to claim 9, said connecting means comprise threaded parts passing through specific holes and aligned on respective first and second sections and extending throughout the axial development of the armature, in particular arranged outside a cylindrical coil volume. 9) Electromechanical solenoid actuator according to any one of the preceding claims, wherein the first portion has one or more through- openings for introducing coil electrical connections, preferably on the first section around the matching area of the two coupled sections.

10) Method for assembling the electromechanical solenoid actuator according to any of the preceding claims, comprising the steps of:

- Arranging the first and second portions of the armature, separated from each other; - Arranging the coil;

- Arranging electrical connections to the coil;

- Applying the second portion to the first portion by interposing the coil; and

- Engaging the first and second portions together in such a way that the coil remains locked in a stable position between said first and second portions.

11 ) Method according to claim 10, wherein the coil is applied to the first portion by insertion in the axial direction.