EP3336352A1 - Coil for electromagnetic pump - Google Patents

Abstract

Coil (1) for electromagnetic pump, comprising a winding (2) constituted by a conductive wire wound around a hollow cylindrical support (21); a frame (3) of ferromagnetic material comprising firstly a core (30) provided with a cylindrical opening and passing through said winding, and secondly a loop (31) around the winding (2) to close the magnetic circuit between the two ends of this nucleus; an overmoulding (4) of synthetic material around the winding, and whose outer surface forms radial cooling fins (40).

Description

Technical area

The present invention relates to the field of electromagnetic pumps and coils for electromagnetic pumps.

State of the art

An example of an electromagnetic pump 5 is illustrated on the figure 10 . Conventionally, the illustrated pump comprises a fluid supply duct 6 upstream of the pump, a fluid outlet duct 7 downstream of the pump, and a movable piston 8 between the two ducts. An electromagnetic coil 2 creates a magnetic field that moves the piston 8 in a cylinder 302, against the action of a spring 9, to produce a pumping movement. Examples of such pumps are described for example in patent applications WO2013152975 and WO2014177442 in the name of the plaintiff.

A first type of coil 1 of the prior art for an electromagnetic pump is illustrated on the Figures 1 to 3 . The illustrated coil comprises a winding 2 formed by a conductive wire wound around a hollow cylindrical support and whose outer surface is protected by a varnish or an insulator. A ferromagnetic frame (or yoke) creates a magnetic path around this coil; it comprises a core 30 formed of a sleeve 30 illustrated on the figure 3 , and a loop 31. The loop is used to close the magnetic circuit at both ends of the core 30. The core 30 is inserted into an axial hole 312 through two sides of the loop and through the coil. It comprises an axial opening 302 serving as a cylinder and in which a piston can slide to move the pumped fluid.

In this type of coil, the frame is formed of a sheet folded and closed on itself, as illustrated on the figure 2 . The magnetic field in this frame creates eddy currents which produce a rapid heating of this frame, and a deterioration of its performances. For this reason, the type of coils shown on the Figures 1 to 3 is intended to be used for intermittently used pumps, with pumping times that typically do not exceed one minute; they must then stop to cool, or continue to operate with less efficiency.

An example of a coil 1 of the prior art for an electromagnetic pump and suitable for longer durations of use is illustrated in FIGS. Figures 4 to 5 . In this embodiment, the frame 31 is made by laminating sheets parallel to the axis of the coil, which greatly reduces the eddy currents and the heating. This coil is therefore also suitable for pumps used continuously or for long periods.

The laminated frame 31 figures 4 and 5 is typically made by assembling two E elements, which are commercially available. The shorter intermediate branch of the two elements forms a core 30 providing an air gap in the central branch, in order to increase the reluctance of the coil and to delay the saturation. The size and position of this air gap must be precisely controlled according to the desired application. However, they depend on a precise positioning of the two half-frames against each other, which is difficult to guarantee in a reproducible manner. Furthermore, the drilling of the axial hole 302 for the passage of the piston through the central branch of the frame (core) is difficult, especially when the edges of this hole must be coated to ensure the tightness of the cylinder or to avoid the risk of contamination of the pumped liquid. For all these reasons, the manufacture of electromagnetic pumps with a laminated frame is more expensive than manufacturing from a folded sheet frame.

The reel illustrated on these Figures 4 to 5 comprises a winding protected by a cover or a molding having a substantially square section in the transverse plane. This square shape facilitates the mounting of the pump which can be placed or fixed in a housing of corresponding shape, without the risk of accidental pivoting.

The core 30 illustrated in the embodiment of figures 4 and 5 also has a rectangular section. It is indeed difficult to achieve a laminated core with a circular section. This square section core fills only a portion of the cylindrical opening in the coil. This results in a reduced section core, which heats up unnecessarily, and parasitic magnetic flux in the gap between the core 30 and the opening through the coil.

The coils of these two examples are therefore suitable for different applications, for example rather inexpensive electromagnetic pumps, operating intermittently or with a low efficiency, in the example of Figures 1 to 3 , and more expensive electromagnetic pumps, able to operate for longer periods with less heating, in the case of Figures 4 to 5 . The need for a pump manufacturer to provide two different types of coils, which are distinguished from each other by the frame, adds cost and complicates logistics.

Each of these types of pumps must also be produced according to different specifications depending on the intended application. For example, electromagnetic pumps are frequently used for oil-burning applications, condensate removal in air-conditioning coolers, coffee dispensers such as coffee machines, pressurized water cleaning equipment, etc. . These devices require different trade-offs between size, ease of assembly, and price. Moreover, among other factors, the necessary pumping power, the duration of use, the stroke of the piston which must be performed with each pumping movement, the type of liquid to be pumped, vary by application. A large number of different coils must therefore be made in order to propose electromagnetic pumps adapted to these varied needs. The manufacture and distribution of such a large number of models is expensive and complex.

Brief summary of the invention

It would therefore be desirable to provide an electromagnetic pump coil construction that is more versatile or easier to adapt to these different needs.

Another object of the present invention is to provide an electromagnetic pump coil for low cost and low heating.

Another object of the invention is to provide a coil manufacturing method for electromagnetic pump at low cost and low temperature.

According to the invention, these objects are achieved in particular by means of an electromagnetic pump coil, comprising
a winding constituted by a conductive wire wound around a hollow cylindrical support;
a frame of ferromagnetic material comprising on the one hand a core provided with a cylindrical opening and passing through said winding, and on the other hand a loop around the winding to close the magnetic circuit between the two ends of this core;
the section of the core in a plane perpendicular to its axis being circular,
the loop having four branches forming a rectangle, the section of the branches being rectangular,
the core being removable.

The section of the core in a transverse plane (perpendicular to its axis) is circular, which allows it to completely fill the cylindrical volume inside the hollow cylindrical support. This reduces the parasitic magnetic flux between the core and the turns, as well as the heating problems due to a larger volume of the core.

The section of the branches of the rectangular loop facilitates the manufacture, and facilitate assembly and integration into an existing assembly, for example by screwing accessories.

The loop advantageously comprises four branches forming a hollow rectangle. It is thus possible to make it easily in one piece, without assembly needs from half-loops.

The frame thus has an unusual shape with a central core of circular section and passing through a rectangular loop and rectangular section.

The removable core can be made independently of the loop. It is thus possible to use other materials and other manufacturing processes, to achieve a precise air gap without increasing the entire frame.

It is thus possible to provide a single loop and equip it with different cores, chosen according to the application.

The loop of the frame can be laminated, for applications where the production of heat should be reduced as much as possible.

The loop of the frame may be formed of a folded sheet closed on itself. Sufficient heat removal for many applications can nevertheless be achieved by the cooling fins.

A same winding can be equipped with the choice of a laminated loop or a loop formed of a folded sheet. It is thus possible to make a set of identical windings and to choose at the last moment during the manufacturing process which loop should be used, depending on the application.

At least one of the branches of the loop is provided with a through hole along the axis of the coil. The core may be a hollow cylindrical socket inserted in this hole.

The core may comprise two hollow cylindrical ferromagnetic material housings arranged coaxially and separated from each other by a coaxial sleeve of non-ferromagnetic material forming an air gap.

The winding may comprise an overmoulding of synthetic material around the winding, and the outer surface of which forms radial cooling fins.

This construction is advantageous because the overmoulding provided with cooling fins makes it possible to effectively remove the heat released by the coil and the eddy currents in the core and the loop of the frame. It is therefore possible to use a simpler loop, for example a folded sheet metal loop, and less bulky, while avoiding or reducing the problems of heat release that these loops had in the prior art. This makes it possible to reduce the number of types of coils required, since coils with a single loop can, at least for certain applications, be implemented where in the prior art laminated loops were imperatively necessary to reduce the release of heat. .

In an advantageous embodiment, the section of overmolding in a plane perpendicular to the axis of the core substantially corresponds to a square with rounded corners. It exploits advantageously the volumes in at least some corners of the winding, which are used to have cooling fins longer than in the edges of this winding.

The overmolding and the hollow cylindrical support can form an integral assembly, that is to say a single closed plastic part which completely covers the coils of the coil, also protecting it from moisture.

In one embodiment, the overmolding may comprise a housing for a hot melt or a thermoswitch protective winding.

In one embodiment, the overmolding may comprise a housing for a removable connector for the electrical connection of the coil.

These housings can be provided in a corner of the overmolding.

The invention also relates to an electromagnetic pump comprising such a coil and a piston movable through said core.

• bobinage d'un fil conducteur autour d'un support cylindrique;
• placement du bobinage surmoulé dans une boucle ferromagnétique, la boucle comportant quatre branches formant un rectangle (par exemple un carré), la section des branches étant rectangulaires
• insertion d'un noyau du cadre à travers la boucle et le bobinage, la section du noyau dans un plan perpendiculaire à son axe étant circulaire.

The invention also relates to a coil manufacturing method comprising the following steps:

• winding a conductive wire around a cylindrical support;
• placement of the overmolded winding in a ferromagnetic loop, the loop having four branches forming a rectangle (for example a square), the section of the branches being rectangular
• inserting a core of the frame through the loop and the coil, the section of the core in a plane perpendicular to its axis being circular.

Thanks to the insertion of the core at the last moment, it is possible to choose a different core and adapted to each application, for example cores with dimensions and / or gap positions and / or different materials.

The method may include a step of overmoulding a synthetic material around the coil, the outer surface forming radial cooling fins. Thanks to this overmoulding, the coil can be used in a large number of different applications, including applications involving long-term operation.

The method may also include inserting a thermofusible or a winding protection thermoswitch into a housing of the overmolding.

The method may also include the insertion of a removable connector for the electrical connection of the coil in a housing overmoulding.

In one embodiment, at least two types of frame loops are provided, including a laminated loop and a non-laminated loop. It is thus possible to choose the type of loop among these types, and to make different coils and electromagnetic pumps from the same winding. The modular construction with interchangeable loops and cores around a universal winding makes it possible to satisfy very different applications starting from a single overmolded winding.

• un piston;
• un bobinage constitué par un fil conducteur enroulé autour d'un support cylindrique creux;
• un ensemble de plusieurs noyaux à choix, chaque noyau formant un cylindre dans lequel le piston est amené à coulisser, différents noyaux de l'ensemble se distinguant les uns des autres par la dimension et/ou la position d'un entrefer,
• un ensemble de plusieurs boucles ferromagnétiques à choix et destinées à être montée autour du bobinage pour refermer le circuit magnétique entre les deux extrémités de ce noyau, l'ensemble comportant au moins une boucle feuilletée et au moins une boucle non feuilletée.

The present invention also relates to an electromagnetic pump mounting kit, comprising:

• A piston;
• a winding constituted by a conductive wire wound around a hollow cylindrical support;
• a set of several cores to choose from, each core forming a cylinder in which the piston is slidable, different cores of the assembly being distinguished from each other by the size and / or the position of an air gap,
• a set of several ferromagnetic loops of choice and intended to be mounted around the winding to close the magnetic circuit between the two ends of this core, the assembly comprising at least one laminated loop and at least one non-laminated loop.

The kit may also include overmoulding of synthetic material around the winding, and the outer surface of which forms radial cooling fins.

Brief description of the figures

• La figure 1 illustre un exemple de bobine pour pompe électromagnétique avec un cadre partiellement en tôle pliée et un bobinage conventionnel.
• La figure 2 illustre une boucle de cadre en tôle pliée.
• La figure 3 illustre un noyau de cadre ferromagnétique cylindrique creux, pouvant servir de cylindre pour une pompe électromagnétique.
• La figure 4 illustre un exemple de bobine pour pompe électromagnétique avec un cadre en tôles feuilletées et un bobinage conventionnel.
• La figure 5 illustre un cadre feuilleté selon l'art antérieure, y compris un noyau feuilleté à section carrée.
• La figure 6 illustre un fil conducteur enroulé sur un support cylindrique creux.
• La figure 7 illustre un bobinage surmoulé avec des ailettes de refroidissement.
• La figure 8 illustre un exemple de bobine pour pompe électromagnétique avec une boucle de cadre en tôle pliée et un noyau pas encore inséré dans cette boucle.
• La figure 9 illustre un exemple de bobine pour pompe électromagnétique avec une boucle de cadre feuilletée et un noyau pas encore inséré dans cette boucle.
• La figure 10 illustre une pompe électromagnétique pouvant être équipée d'une des bobines ci-dessus.

Examples of implementation of are indicated in the description illustrated by the appended figures in which:

• The figure 1 illustrates an example of an electromagnetic pump coil with a frame partially folded sheet and a conventional winding.
• The figure 2 illustrates a folded sheet metal frame loop.
• The figure 3 illustrates a hollow cylindrical ferromagnetic frame core, which can serve as a cylinder for an electromagnetic pump.
• The figure 4 illustrates an example of an electromagnetic pump coil with a laminated sheet frame and a conventional winding.
• The figure 5 illustrates a laminated frame according to the prior art, including a square section laminated core.
• The figure 6 illustrates a conductive wire wound on a hollow cylindrical support.
• The figure 7 illustrates an overmolded winding with cooling fins.
• The figure 8 illustrates an example of an electromagnetic pump coil with a folded sheet frame loop and a core not yet inserted in this loop.
• The figure 9 illustrates an example of an electromagnetic pump coil with a laminated frame loop and a core not yet inserted in this loop.
• The figure 10 illustrates an electromagnetic pump that can be equipped with one of the above coils.

Example (s) of embodiment of the invention

The figure 6 illustrates a conductive wire 20 wound around a hollow cylindrical support 21 of insulating synthetic material. This element is intended to be overmoulded to serve as winding in the coil described below.

The figure 7 illustrates the same element as that of the figure 6 , but covered with an overmoulding 4 which completely surrounds the conductor wire protecting it and avoiding the risk of electrocution. The section of overmolding 4 in the plane transverse to the longitudinal axis a of the coil corresponds substantially to a square with rounded corners, although the section of the portion of overmolded wire is substantially circular. The overmolded edges are provided with radial cooling fins 40. The length of these fins is longer in at least two angles 41 than in the middle edges 42, so as to exploit the volume available between the corners of the square and the conductor volume.

A first housing 43 is provided for a hot melt or a removable thermoswitch that protects the driver in case of excessive current. A second housing 44 is provided for electrical connectors for powering the winding. The conductive wire 20 in the overmoulding is connected in series to the terminals of the hot-melt or thermoswitch in the housing 43 and the connection lugs in the housing 44. The housing 44 is preferably waterproof and prevents infiltration of water or moisture inside the overmoulding. An axial hole passes through the overmolded winding to insert the ferromagnetic core, as will be seen.

The figure 8 illustrates an overmolded winding 4 surrounded by the folded sheet metal loop of a ferromagnetic frame 31, which is closed on itself. A hole 310 in this loop is aligned coaxially with the hole of the overmolded coil, and allows to insert a ferromagnetic core 30 in the center of the coil. The loop of this example has a rectangular section. It may have holes for securing the coil to other components, or for attaching the fluid inlet and outlet conduits.

The ferromagnetic core 30 has a cylindrical section and is traversed by an opening forming a cylinder for the displacement of the piston of an electromagnetic pump. The core 30 has two sockets 300 of ferromagnetic material and separated by a sleeve 301 of non-ferromagnetic material used as air gap. The inner face of the core may be provided with a coating adapted to the liquid to be pumped, for example a coating of food material in the case of pumping a liquid food. It is possible to choose the core 30 among a set of cores available,

The figure 9 illustrates an overmolded winding 4 surrounded by the ferromagnetic loop 31 of a laminated frame. A hole 312 in this loop is aligned coaxially with the hole of the overmolded coil, and allows to insert a ferromagnetic core in the center of the coil. The loop of this example is formed of a stack of sheets parallel to the axis a of the coil; its section is rectangular. It may have holes for securing the coil to other components, or for attaching the fluid inlet and outlet conduits. The core 30 that can be inserted into this coil can be chosen by the same collection as in the embodiment of the figure 8 .

The figure 10 already described illustrates an example of conventional electromagnetic pump but which can be equipped with the coil of one of the described and claimed embodiments.

Reference numbers used in the figures

1

Coil

2

Winding

20

Conductive thread

21

Cylindrical support

3

Frame

30

Core

300

Sleeve forming a portion of the core

301

Sleeve made of non-ferromagnetic material forming an air gap

302

Cylinder

31

Loop

310

Hole of passage

311

Branches of the loop

312

Through axial hole

4

overmolding

40

fins

41

Rounded corners of overmolding

42

Overmolding edges

43

Housing for hot melt or thermoswitch

44

Connector slot

5

Electromagnetic pump

6

Fluid supply duct

7

Fluid outlet duct

70

valves

8

Piston

9

Spring

at

Core axis

Claims (21)

Coil (1) for electromagnetic pump, comprising
a winding (2) constituted by a conductive wire (0) wound around a hollow cylindrical support (21);
a frame (3) of ferromagnetic material comprising firstly a core (30) provided with a cylindrical opening and passing through said winding, and secondly a loop (31) surrounding the winding (2) to close the magnetic circuit between the two ends of this nucleus;
characterized in that the section of the core (30) in a plane perpendicular to its axis (a) is circular,
in that the loop (31) comprises four branches (311) forming a rectangle, the section of the branches being rectangular,
and in that the core is removable. Coil according to claim 1, the loop (31) being laminated. Coil according to claim 1, the loop (31) being formed of a sheet folded and closed on itself. Coil according to one of claims 1 to 3, at least one of the branches (311) of the loop (31) being provided with a through hole along the axis of the coil (312), the core (30) having a hollow cylindrical socket inserted in this hole. Coil according to one of claims 1 to 4, the core (30) having two hollow cylindrical sleeves (300) of ferromagnetic material arranged coaxially and separated from each other by a sleeve (301) coaxial non-ferromagnetic material forming a gap. Coil according to one of claims 1 to 5, comprising a overmoulding (4) of synthetic material around the coil, and whose outer surface forms radial cooling fins (40). Coil according to claim 6, the overmoulding section in a plane perpendicular to the axis of the core substantially corresponding to a square with rounded corners (41), the height of the cooling fins (40) in at least two of said rounded corners ( 41) being longer than the middle of the edges (42). Coil according to claim 7, the overmolding (4) and the hollow cylindrical support (21) forming an integral assembly. Coil according to one of claims 1 to 8, the overmolding comprising a housing (43) for a hot melt or a protective thermoswitch winding. Coil according to one of claims 1 to 9, the overmolding comprising a housing (44) for a removable connector for the electrical connection of the coil. Coil according to one of claims 9 or 10, the housing or said housing (43,44) being provided in a corner of the overmolding. Electromagnetic pump comprising a coil according to one of claims 1 to 11 and a piston movable through said core. A coil manufacturing method comprising the steps of: - winding a conductive wire (20) around a cylindrical support (21); placing the overmolded winding (4) in a ferromagnetic loop (31), the loop comprising four branches (311) forming a rectangle, the section of the branches being rectangular - Inserting a core (30) of the frame through the loop (31) and the coil, the section of the core (30) in a plane perpendicular to its axis (a) being circular. The method of claim 13, further comprising a step of overmolding a synthetic material (4) around the coil, the outer surface forming radial cooling fins (40). Method according to claim 14, comprising inserting a thermofusible or a winding protection thermoswitch into a housing (43) of the overmolding. Method according to one of claims 14 or 15, comprising the insertion of a removable connector for the electrical connection of the coil in a housing (44) overmolding. Method according to one of claims 13 to 16, comprising the prior provision of at least two types of loops, including a laminated loop and a non-laminated loop, and the choice of said loop among these types of loop. Method according to one of claims 13 to 17, comprising the prior provision of at least two types of cores with different dimensions and / or gap positions, and the choice of said core among these types of core. Method according to one of claims 13 to 18, comprising the prior provision of at least two types of cores with different materials, and the choice of said core among these types of core. Electromagnetic pump mounting kit, comprising: A piston; a winding (2) constituted by a conductive wire wound around a hollow cylindrical support (21); an assembly of a plurality of cores (30) of choice, each core forming a cylinder in which the piston is slidable, different cores of the assembly being distinguished from one another by the size and / or the position of a gap, a set of several ferromagnetic loops (31) of choice and intended to be mounted around the winding (2) to close the magnetic circuit between the two ends of this core, the assembly comprising at least one laminated loop and at least one non-loop flaky. Kit according to claim 20, the coil comprising a overmolding (4) of synthetic material whose outer surface forms radial cooling fins (40).

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