Solenoid actuator with (improved) armored protection box

Abstract

An electromechanical solenoid actuator includes a coil housed in an armoured body made of ferromagnetic material, the armoured body having a circumferentially deployed structure that contributes to a path for transmitting a magnetic field generated by the coil that generates a mechanical force by inducing a movable element or a movable magnetic core sliding within the coil. The actuator comprises an armor body made up of two parts that can be separated from each other and shaped complementarily so as to allow axial insertion into the armor body, thereby enabling the step of assembling the actuator components to be rapid and easy.

Description

[0001] The present invention relates to an electromechanical solenoid actuator and an associated assembly method, the actuator comprising an armature made of ferromagnetic material having a perimeter development, wherein the armature consists of two parts that can be separated and joined together.

[0002] Electromechanical solenoid actuators are well known in the technical literature. The actuators are electromechanical devices capable of converting electrical energy into mechanical energy on a movable body or movable magnetic core made of ferromagnetic material through electromagnetic interaction. They are used in various applications where elements or components need to be moved, pushed, pulled, or pressed over a short distance with very low power consumption or activated with a mechanical impulse. One of the best-known examples is their use in electrovalves suitable for controlling the opening or closing of flow channels for working fluids.

[0003] The use of electromechanical actuators, characterized by the use of so-called "armoured coils", is also well known in the technical literature. This type of coil is contained within a solenoid arranged within an armature (or armour) made of ferromagnetic material plates that are bent and arranged in a closed perimeter around the solenoid axis. Different from systems without armoured coils, the magnetic flux is more precisely guided from the surface of the armature to the manipulation channel of the movable magnetic core. Therefore, the presence of the armour makes it possible to transfer higher mechanical power on the movable magnetic core using an actuator smaller than in non-armoured systems. This type of actuator is particularly useful in cases where actuators with both small size and high mechanical power performance are required. Prior art examples describing the use of this type of actuator envision using the actuator as a component of an electromechanical valve applied to a railway vehicle braking system.

[0004] For example, from EP2141723, a so-called "polar electromagnetic device" with low power consumption is known, in which a drive shaft is supported to alternately move in the central direction of the axis at the central hole of a coil wound with a coil, where a movable ferromagnetic core is fixed to the lower end of the drive shaft on the same axis, and where, as the movable ferromagnetic core alternately moves according to the excitation and demagnetization of the coil, the drive shaft alternately moves; a permanent magnet is integrally provided at the movable ferromagnetic core on the same axis.

[0005] A plunger-type armored body magnet system is also known from DE3442223, in which the magnet housing consists of a U-shaped yoke and a current-carrying element, which can be firmly connected to each other by their free branches, and in which suitable circular grooves are arranged in the connecting ribs of the current-carrying element and the yoke, which surround the armored body with a small air gap; in such a prior art device, the excitation coil former is supported axially by means of bearings arranged on the end faces of two flange parts, in bearing grooves in the current-carrying element and in the connecting ribs. In addition, there is a through hole in the longitudinal direction in its magnetic core, which has a constriction at the outlet end to support the movable armored body without clearance.

[0006] A solenoid is further known from US 2022 / 0181060, which comprises a yoke 2, a coil 3 having an electromagnetic coil 4 arranged therein, and a ferromagnetic core 5 arranged within the coil 3; in such a solenoid, a connector part 6 including a specified number of metal end fittings 7 is provided at the end of the coil 3. Therefore, since a relatively large space is not required to handle the wires as in the prior art, the solenoid is small and can thus be manufactured at low cost.

[0007] In addition, an electromagnet is known from FR2665017, which includes a coil former, the extension of which interacts with the yoke cross member and the flow closing part in such a way as to ensure, on the one hand, a clearance-free application of a fixed ferromagnetic core placed in the hole of the former and, on the other hand, that the hole is strictly aligned with the opening of this part in order to allow a movable ferromagnetic core to slide fully magnetically and mechanically; this electromagnet is particularly suitable for coil feeding by direct current and for technically cost-effective mass production.

[0008] Finally, a high-performance solenoid actuator is known from US4443775, which includes a coil externally surrounded by a magnetic frame and having a fixed magnetic core arranged therein, in which a movable magnetic core is attracted to the fixed magnetic core after axially slidably arranging the coil excitation, and in which the magnetic frame includes a pair of magnets and frame parts, each frame part being made from sheet material by folding the sheet in order to define a top plate and a bottom plate that are integrally joined to side plates to cover the top, bottom and sides of the coil, and the pair of magnetic frame parts being assembled with each other with the top plate and the bottom plate overlapping each other, thereby providing a simplified structure and easy assembly.

[0009] However, the prior art has proven to be lacking in certain aspects.

[0010] It is certain that the geometry of prior art actuators forces a compromise to be found between the minimum size achievable by the actuator and the costs and time required in the process of assembling the components. In the prior art, the armored body generally consists of a sheet of metal made of ferromagnetic material, which is bent at four points along the length of the sheet to obtain four walls that form a quadrilateral in cross-section, the quadrilateral having opposite parallel sides and adjacent sides perpendicular to each other, preferably rectangular. The prior art requires that the two extreme edges completely overlap to form the walls corresponding to the end sides of the quadrilateral, where one of the two axial supports of the solenoid is applied.

[0011] This overlap is necessary because when the two parts are separated, it is required that there be as large a surface area as possible between them. Any difference in thickness or any step along the walls risks causing discontinuity of the magnetic flux induced through the armored body and impairing the performance of the actuator.

[0012] It should be further stipulated that the armored body must have a minimum thickness throughout the circumferential direction in order to optimally guide the magnetic flux and reduce the magnetic resistance.

[0013] The disadvantages of the prior art stem from the fact that the current design of the said actuator employs a non-linear manufacturing process. Specifically, the operation of assembling the various components requires multiple operations by the operator and auxiliary machinery from different sides. Specifically, due to the unfolding of the closure of the armored body and the fact that the armored body must first be manufactured by bending a metal sheet, the subsequent assembly of the solenoid requires its lateral insertion into the armored body, followed by the lateral insertion of the electrical connection elements, and finally the locking of the solenoid in the armored body by two axial components, at least one of which is applied in a hole present in the wall defined by the overlapping end flaps.

[0014] Especially in the case where small actuators must be produced, it is difficult for the operator and auxiliary machinery to assemble the components, and a process divided into several working steps needs to be used. This has a negative impact on working time and costs.

[0015] The second disadvantage of the prior art is the forced use of wires with a low insulation strength coating type for winding because tin plating and soldering are required for the pins used for electrical connection.

[0016] The object of the present invention is to overcome the said disadvantages of the prior art. Specifically, a solution for an electromechanical actuator is proposed, which is configured such that the overall size is minimized to the greatest extent and a time- and cost-efficient process for the component assembly operation is ensured. Due to the small footprint of the actuator, its use in space-constrained environments is guaranteed.

[0017] The technical task outlined and the specified purpose are basically achieved by an electromechanical actuator including an "armored" coil, wherein the armored body for transmitting magnetic flux consists of two parts, which are separate and assembled by form fit, thereby generating a four-sided quadrilateral structure along a closed contour such that it has parallel opposite sides and adjacent sides perpendicular to each other.

[0018] In the case of the same minimum thickness of the armored body, this arrangement enables the avoidance of overlapping of the materials constituting the armored body while ensuring the required dimensional compactness and the same performance. The electromagnetic actuator is defined by the features of claim 1 appended hereto.

[0019] A method of assembling an actuator according to the features set forth in claim 10 appended hereto is also an object of the present invention.

[0020] Furthermore, the actuator configuration allows all components to be assembled axially in sequence, making full use of the one-way assembly steps of assembling components in a single axial working dimension, thereby saving time and effort during the assembly operation.

[0021] Other features and advantages of the present invention will become more apparent from an indicative and thus non-limiting description of a preferred but non-exclusive embodiment of the electromechanical solenoid actuator according to the present invention and the related assembly method.

[0022] The description will be elaborated below with reference to the accompanying drawings, wherein: Figure 1 is a complete schematic view of an electromechanical solenoid actuator according to the present invention, which is provided with an armored body and electrical connection elements (including connection pins); Figure 2 is an illustration of a coil provided with power supply elements (in particular connection pins for power supply); Figure 3a is a schematic view of the first main part of the armored body and related details; Figure 3b is a schematic view of the second part (or closing plate) and related details; Figure 4 is a side sectional view of an electromechanical solenoid actuator provided with an armored body and electrical connection elements (including connection pins); Figure 5 is a complete schematic view of an electromechanical solenoid actuator provided with electrical connection elements (i.e., enclosed in an encapsulation mold made of insulating material) in a final operating form; Figure 6 is an illustration of an exploded view of a complete electromechanical solenoid actuator with electrical connection elements and an encapsulation mold.

[0023] With reference to the accompanying drawings, the electro-mechanical solenoid actuator according to the present invention is generally indicated by 1 and represents a preferred but non-exclusive electro-mechanical actuator for use as a valve in a railway vehicle braking system. Specifically, the actuator has a feature and construction such that it is 15 mm wide.

[0024] The actuator includes a coil 2, which is housed within an armored body 3 and has electrical terminals 4 for connection to a power supply.

[0025] Referring Figure 2 , the coil 2 is cylindrical and includes a solenoid 5, which is defined by a wire wound to define a winding. The solenoid 5 is arranged around a bobbin 6 of insulating material, which includes a cavity 7 passing through the entire support. The purpose of the cavity 7 is to house a fixed magnetic core (not shown) and a movable magnetic core, which is configured to interact with the magnetic field generated by the solenoid 5 and can be coupled to or form part of a translatable actuating member.

[0026] The armored body 3 extends circumferentially along a closed contour extending circumferentially around the coil such that the axial end faces of the bobbin 6 face corresponding parts of the armored body 3 that are opposite each other. Thus, the magnetic flux leaving one end of the coil 2 axially divides into two paths passing through opposite parts of the armored body, and these two paths converge at the opposite ends of the coil 3.

[0027] After fixing the x-y-z coordinate system respectively indicating the length, width, and height dimensions, the circumferentially unfolded structure of the armored body 3 completely covers the coil 2 along the x dimension and the z dimension, while having an uncovered side along the y dimension such that the coil 2 is visible. The circumferentially unfolded structure of the armored body 3 has a quadrilateral shape (square or rectangle), which has parallel opposite sides and adjacent sides that are perpendicular to each other. The cross-section of the armored body remains substantially constant along the entire circumferentially unfolded structure.

[0028] Advantageously, according to the present invention, the armored body 3 is defined by at least two separable parts, which are complementary to each other and define the aforementioned circumferentially unfolded structure in the assembled configuration. The first part 8 defines the main part of the circumferentially unfolded structure and at least has an open profile in the shape of a "C" or a "U", while the second part 9 defines a completion cover applicable to the first part 8. Specifically, the first part 8 has an open or "glass-shaped" profile formed by three walls, namely a bottom wall 8a and two side walls 8b and 8c. Preferably, the first part 8 is obtained by bending a metal plate at two points.

[0029] In addition, the second part 9 is advantageously coupled or can be coupled to the first axial end of the coil 2, while the second axial end of the coil 2 is coupled to the bottom wall 8a of the first part 8, which specifically defines the central region of the coil 2.

[0030] More specifically, the bottom wall 8a has a through-hole 10 for receiving the polar extension portion 11 by interlocking therewith. The polar extension portion 11 has a cylindrical or tubular portion 11a that is axially inserted into the through-hole 10. The length of the insertable portion 11a is greater than the thickness of the armored body section, such that once inserted into the hole 10, it projects inwardly to engage the end 6a of the spool 6, thereby fixing the coil 2 in place. The polar extension portion 11 also has a through-notch 11b. The inner diameter of the through-notch 11b is aligned with the diameter of the cavity 7 of the spool 6, thereby forming a single channel through which the movable part of the actuator can move.

[0031] In this embodiment, the insertable portion 11a of the polar extension portion 11 may optionally be attached with a ring 11c of insulating material.

[0032] In this embodiment, at least one of the side walls of the first part 8 of the armored body 3 (specifically the side wall 8b in this illustration) has a plurality of holes 12 for fixing the components of the electrical connection system 4.

[0033] More specifically, the electrical connection system 4 includes at least two power connection pins 4a and 4b, preferably in the form of rigid connectors made of conductive material. These pins 4a, 4b are inserted inside the above-mentioned holes 12, specifically one pin for each dedicated hole, such that each pin connected to the coil 2 passes through the corresponding hole and projects outside the armored body 3.

[0034] Preferably, the holes dedicated to the pins 4a, 4b are defined by end grooves 12a and 12b, which are formed on at least one of the two side walls of the first part 8, then form a recess from the open side profile, and are closed by applying the second part 9 as an end cap. This arrangement of the grooves 12a and 12b defines an overall "E" shape at the corresponding ends and is intended to facilitate the assembly operation of the entire actuator, as it allows the coil 2 pre-set with the power pins 4a, 4b to be fixed inside the first part 8 of the armored body 3, and then the first part 8 and the second part 9 are closed by form fit.

[0035] Preferably, the second part 9 is made in the form of a flat wall or plate. The second part 9 also has an end shape adapted to engage by form fit with the corresponding free ends of the side walls 8b and 8c of the first part 8.

[0036] In this embodiment, at one end, the second part 9 has two protrusions 13a and 13b, which are adapted to be coupled with the corresponding grooves 12a and 12b of the first side wall 8b of the first part 8. Similarly, the second part 9 has a head groove 14, which in turn can be coupled with the end teeth 15 located on the second side wall 8c of the second part 8.

[0037] The second part 9 has such an extension that the removal of the extension creates an opening on the upper side of the first part 8 (opposite the bottom wall 8a) sufficient to allow the coil 2 to be axially withdrawn from the first part 8, preferably extending throughout the width of the entire armored body 3.

[0038] The above-mentioned connection makes it possible to obtain the closure of the circumferential expansion structure of the armored body 3, which has the form of a perfect quadrilateral in the x-z plane and the cross-section of the armored body remains constant. All formed connection ends are formed so as to obtain as smooth a contact surface as possible, thereby maximizing the contact between the parts and avoiding the impedance and interference of the magnetic flux within the armored body.

[0039] The second part 9 also has a through-hole 16 in the center for fastening the fixed magnetic core 17 to the coil 2. The fixed magnetic core 17 is axially engaged or can be axially engaged with the end 6b of the spool 6 by being inserted into the cavity 7 until the middle position, thereby also defining an axial stop for the movable part of the actuator. The fixed magnetic core 17 may include a part made of ferromagnetic material, which has the function of guiding the magnetic flux into the sliding channel of the movable magnetic core.

[0040] Preferably, the fixed magnetic core 17 is connected to the second part 9 in a permanent and / or stable manner (e.g., by an interference fit within the aforementioned through-hole 16).

[0041] In this embodiment, the fixed magnetic core 17 may also be attached with a ring 17a of insulating material.

[0042] Axially aligned perforations 18 are present both on the second part 9 and on the bottom wall 8a of the first part 8 to accommodate retaining elements in the form of threaded members (not shown), which axially extend through the entire expansion structure of the armored body, with the aim of being firmly fixed (depending on actual requirements) by connection to a valve or the most suitable utility. In particular, these retaining elements may be provided at angular positions on both parts such that they are arranged outside the cylindrical covering area of the coil 2.

[0043] Finally, the complete actuator as described above is placed in the encapsulation mold 19 and molded with insulating material to ensure the avoidance of any mismanipulation by the operator during installation and operation. The capsule has holes 20 that are aligned with and correspond to the holes 18 of the two armored body parts 8 and 9, and the holes 20 are adapted to accommodate the threaded member fasteners. Specifically, these fasteners can be inserted from the outside of the capsule (not shown in the current figure). Description of the assembly method

[0044] Referring to Figure 7, the proposed assembly method is described below, which is suitable for solving the technical problems addressed by the present invention and employing an electromechanical solenoid actuator of the above type.

[0045] The method first involves the step of arranging the coil 2 and the step of adding a suitable power supply element 4 (for example, power pins 4a and 4b) to the coil 2 itself: the arrangement of the coil 2 can be achieved by defining an electrical winding on the spool 6.

[0046] Then, the first part 8 of the armored body 3 is arranged, and the polar extension 11 is added to a specific hole 10 on the bottom wall 8a.

[0047] At the same time, the second part 9 is arranged by inserting the fixed magnetic core 17 into a dedicated hole (with an insulating material ring 17a added as required).

[0048] Next, the coil 2 is axially applied to the first part 8.

[0049] The coil 3 is positioned in such a way that the inward-facing part 11a of the polar extension 11 (which may be added with an insulating material ring 11c) is received in the cavity 7 at the end 6a of the spool 6 (opposite to the support including the connection to the power pins 4a and 4b).

[0050] At the same time, care is taken to ensure that the power pins 4a and 4b are placed in suitable dedicated receiving portions provided by the grooves 12a, 12b on the second side wall 8b of the first part 8. In this case, after the coil 2 is axially inserted into the first part 8 (i.e., along the magnetic axis of the coil), the pins 4a and 4b are automatically placed in the corresponding grooves 12a and 12b on the corresponding side walls 8b and / or 8c of the first part 8.

[0051] Then the armored body 3 is closed: the second part 9 is interlocked with the first part, and the coil 2 is fixed by axially inserting the fixed magnetic core 17 into the hole 7 at the second end 6b of the spool 6, thereby completely enclosing the coil 2 in the circumferential armored body.

[0052] Then the two parts 8 and 9 of the armored body 3 are fixed.

[0053] Finally, a mold for encapsulating the armored body in a sheath is defined.

Claims

1. An electromechanical solenoid actuator, comprising: - An armored body made of ferromagnetic material, the armored body having a closed circumferential expansion structure, within which an outer shell for a coil is defined; And - A hollow cylindrical coil, the coil being inserted into the outer shell such that the armored body defines a path for transmitting the magnetic field generated by the coil, wherein: -- The armored body is defined by at least two separable parts, the at least two separable parts being complementary to each other and defining the circumferential expansion structure in an assembled configuration, wherein: --- The first of the parts defines a main part of the circumferential expansion structure and has a "C" or "U" shaped open profile; and --- The second of the parts defines a completion end cap adapted for the first part; and wherein - The second part is connected or connectable to a first axial end of the coil, and the first part and the second part are connectable to each other by shape fitting, in particular such that the thickness of the armored body is substantially uniform throughout the circumferential expansion structure of the armored body, - Characterized in that the actuator has a width of 15 mm, in particular for use as an actuator for railway vehicle braking equipment.

2. The electromechanical solenoid actuator according to claim 1, wherein The first part has a bottom wall provided with a bottom opening, and wherein the actuator further includes a hollow polar extension that can be inserted into the bottom opening and engage a second axial end of the coil opposite the first axial end to simultaneously engage the coil to the bottom wall and allow a movable magnetic core to slide between the inside and outside of the coil.

3. The electromechanical solenoid actuator according to claim 1 or 2, wherein, The second part lies in a plane and is preferably defined by a closed plate, in particular, the thickness of the plate is at least equal to and preferably greater than the thickness of the first part.

4. The electromechanical solenoid actuator according to any one of the preceding claims, wherein, The second part has an extension such that removal of the extension allows the coil to be withdrawn from the first part, in particular the second part extends through the entire width of the armored body.

5. The electromechanical solenoid actuator according to any one of the preceding claims, wherein, The second part has a fixed magnetic core that can be stably inserted into the corresponding axial end of the coil, and the fixed magnetic core is preferably stably inserted into a corresponding hole in the second part.

6. The electromechanical solenoid actuator according to any one of the preceding claims, wherein, The first part has a flat bottom wall and side walls, the side walls being flat and parallel to each other and perpendicular to the bottom wall, wherein the second part is applied to the ends of the side walls.

7. The electromechanical solenoid actuator according to any one of the preceding claims, comprising connection means for stably connecting the first part and the second part to each other.

8. The electromechanical solenoid actuator according to claim 9, the connection means including threaded parts that pass through specific holes and are aligned on the corresponding first part and second part, and extend through the entire axial expansion of the armored body, in particular arranged outside the volume of the cylindrical coil.

9. The electromechanical solenoid actuator according to any one of the preceding claims, wherein, The first part has one or more through openings for introducing electrical connectors of the coil, the through openings preferably being around the mating region of two joined parts on the first part.

10. A method for assembling an electromechanical solenoid actuator according to any one of the preceding claims, comprising the steps of: Arranging a first part and a second part of the armored body, the first part and the second part being separated from each other; Arranging the coil; Arranging electrical connectors to the coil; Applying the second part to the first part by inserting the coil; and Joining the first part and the second part together such that the coil remains locked in a stable position between the first part and the second part.

11. The method according to claim 10, wherein, Applying the coil to the first part by axially inserting it.

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