EP2092538A1

EP2092538A1 - Multiconnection coil structure

Info

Publication number: EP2092538A1
Application number: EP07825566A
Authority: EP
Inventors: Michele Cardone; Giovanni Cosmai; Roberto Faranda; Antonino Giglio
Original assignee: Politecnico di Milano; Tecnomagnete SpA
Current assignee: Politecnico di Milano; Tecnomagnete SpA
Priority date: 2006-11-16
Filing date: 2007-10-29
Publication date: 2009-08-26
Also published as: WO2008059332A1; ITMI20062202A1; CN101563736A

Abstract

The present invention relates to a multiconnection coil structure (1) comprising a support (2) of predetermined profile (2A) and at least one electric conductor (3) wound on said support (2) to form a winding (4). The multiconnection coil structure (1) has for each winding (4) at least two (5, 6) electric conductor means, each extending between a first (7) and a second (8) points of said profile (2A). Further, each conductor means (5, 6) are electrically connected to one of the terminal ends of the conductor (3), and include at least two distinct electric connection elements (5A, 5B, 6A, 6B), so that when one connection element (5A, 5B) of each conductor means (5, 6) is connected to a power source (V), said power source (V) is also applied to at least another connection element (6A, 6B) of each conductor means (5, 6).

Description

Multiconnection coil structure

The present invention relates to a multiconnection coil structure, and particularly but without limitation to a rnulticonnection coil structure for use in a permanent magnet clamping apparatus for ferrous workpieces, as defined in the preamble of claim 1.

It shall be noted that the term "permanent magnet clamping apparatus" as used herein is intended as any apparatus that uses permanently magnetized or magnetizable magnetic cores, which can be activated and/or deactivated by either reversing the magnetization of some of the magnetic cores or magnetizing and/or demagnetizing the cores. Clamping apparatus of the above mentioned type are known in the art and used for holding ferromagnetic workpieces to machine tools, such as millers, lifting systems and similar devices.

These apparatus are usually composed of: a ferromagnetic frame adapted to contain a plurality of pole units, each having:

- a ferromagnetic pole element defining a part of the clamping surface,-

- a main magnetic core formed of a magnetically reversible permanent magnet; - possibly, an array of secondary magnetic cores formed of πon reversible permanent magnets;

- a coil, having a bobbin on which an electric conductor is wound to form a winding, said coil being placed around each main magnetic core to activate and/or deactivate each pole unit of the clamping surface.

Particularly, in such apparatus, the pole units and the coils form an electromagnetic circuit which can activate or deactivate the magnetic clamping surface. For such purpose, the electromagnetic circuit is designed to have at least two electric connections for supplying power to each coil.

In prior art, the electric connections between the coil and a power source, the latter being able to deliver the power required to change the magnetic field generated by the magnetic cores in the apparatus, are obtained by manually soldering and/or crimping the terminal ends of the conductor wound around the bobbin of the coil. It shall be noted that the electric connections between the coils are also obtained by similar manual processes.

These electric connections require a plurality of electric cables to be laid in the frame of the apparatus. While this solution is effective per se, it is still affected by drawbacks and shortcomings, such as: - the electric connections of the coils with the power source and of the coils with each other may not be insulated from the ferromagnetic frame, thereby causing short-circuits and hence down times of the apparatus, which involve consequent repair costs; - establishing electric connections requires long times, for instance about five hours are required on average to establish electric connections in an apparatus comprising forty pole units;

- reliability and quality are strictly dependent on the ability of the operator to establish the various electric connections; establishing the various electric connections involves high costs, considering that such cost is proportional both to the time required for implementing connections and to the number of coils used in the apparatus; and finally a large volume is occupied by the electric connections in the ferromagnetic frame, since volume requirements vary both with the number of coils that need to be electrically connected together and/or with the power source, and with the section of the cables, which have to be suitably sized to allow transfer of the required power.

In view of the prior art as described above, the object of the present invention is to provide a coil structure that can obviate the prior art drawbacks.

According to the present invention, this object is fulfilled by a multiconnection coil structure as defined in the independent claim 1. This object is also fulfilled by a permanent magnet clamping apparatus as defined in the independent claim 14.

The present invention provides a coil structure that has such a quality and reliability as to ensure perfect insulation of the various windings from the frame, no manual soldering and/or crimping operation being needed for electric connection between the various multiconnection coil structures and between the multiconnection coil structure and the power source. An additional advantage achieved by the present invention is that it involves a well-determined time for fabricating the permanent magnet clamping apparatus, because different blocks of coil structures can be provided, prior to installation thereof in the frame of the permanent magnet apparatus, depending on specific employment requirements.

Furthermore, a smaller storage space is required, because there is no longer the need to keep several different reels of wire in stock to form the various coils and establish electric connections of the coils with the power source and of the coils with each other.

Finally, the present invention provides a multiσonnection coil structure that can considerably reduce the fabrication costs for the permanent magnet apparatus .

The characteristics and the advantages of the invention will appear from the following detailed description of several practical embodiments, which are shown without limitation in the annexed drawings, in whichi

- Figure 1 is an exploded perspective view of a first embodiment of the coil structure of the present invention;

- Figure 2 is a plan view of the first embodiment of the coil structure as shown in Figure 1;

Figure 3 is a sectional view of the first embodiment of the coil structure of Figure 2, as taken along line X-X;

- Figure 4 is a plan view of a circuit diagram that employs a plurality of coils as shown in Figure 2;

- Figure 5 is an exploded perspective view of a first embodiment of the coil structure of the present invention;

- Figure 6 is a plan view of the coil structure as shown in Figure 5; Figure 7 is a sectional view of the second embodiment of Figure 6, as taken along line Y-Y;

- Figure S is an exploded perspective view of a first embodiment of the coil structure of the present invention.

Referring to the annexed Figures 1 to 4, which show a first embodiment of the present invention, numeral 1 generally designates a multiconneσtion coil structure.

For simplicity and brevity, the term "multiconnection coil structure 1" shall be simply indicated herein as "coil 1" .

The coil 1 comprises a support 2 (also known as bobbin) of predetermined profile 2A and an electric conductor element 3 wound on said support 2 to form a winding 4.

In the preferred embodiment, the electric conductor element 3 is embodied by a thin metal conductor, e.g. made of copper, having two terminal ends (not shown in the Figures) . The support 2 is embodied by a non conductive polymer material, such as a plastic material.

Particularly, the profile 2Δ of the support 2 may have any one of triangular, quadrangular, polygonal, egg- shaped, elliptical and circular sections. The coil 1 further includes first electric conductor means 5 which are electrically connected to a terminal end of said electric conductor 3 and second electric conductor means 6 which are electrically connected to the other terminal end of said electric conductor 3. The first conductor means 5 in turn include two distinct electric connection elements 5A, 5B, and the second electric conductor means 6 in turn include two distinct electric connection elements 6A, 6B.

Advantageously_/ the first electric conductor means 5 and the second electric conductor means 6 extend each between a first point 7 and a second point 8 of the predetermined profile 2A of the support 2.

Thanks to this particular arrangement, each of the first electric conductor means 5 and the second electric conductor means 6 has such a shape as to enclose said predetermined profile 2A of said support 2 between the first point 7 and the second point 8 thereby creating two substantially equipotential surfaces.

Thus, if the electric connection element 5A of said first electric conductor means 5 and the electric connection element 6A of said second electric conductor means 6 are connected, for example, to a power source v, the latter is also applied to the other electric connection element 5B of said first electric conductor means 5 and to the other electric connection element 6B of said second electric conductor means 6.

In other words, the power supplied by the power source V to the winding 4 of the coil 1 through the electric connection element 5A of said first electric conductor means 5 and through the electric connection element 6A of said second electric conductor means 6, is also available to the electric connection element 5B and to the electric connection element 6B of said first electric conductor means 5 and said second electric conductor means 6 respectively.

Therefore, the coil 1 is eventually equipped with electric multiconnections, i.e. a plurality of electric terminals, e.g. 5A, 5B and 6A, βB, said multiconnections being equipotential thanks to the first and second electric conductor means 5 and 6.

If the power source V has the direction as shown in Figure 2, the first electric conductor means 5 represent the positive terminal and the second electric conductor means S represent the negative terminal. It shall be understood that the electric connection elements 5A and 5B of said first electric conductor means 5, as well as the electric connection elements 6A and SB of said second electric connection means 6 are electrically separated from each other. Also, the electric connection elements 5A and 5B of said first electric conductor means 5, as well as the electric connection elements 6A and 6B of said second electric connection means S can be located at the respective ends of said first electric conductor means 5 and said second electric conductor means 6.

It should be noted that the number of electric connections in the first and second electric conductor means 5 and 6 can be varied in response to specific requirements. According to a preferred embodiment of the present invention, the electric connection elements 5A, 5B and 6A, SB are embodied by electric terminals. Advantageously, the electric terminals 5A, 5B and 6A, 6B may be quick connect terminals such as those available under the name of "Faston terminals".

Particularly, one of two quick connect terminals 5A (or 5B) is a male Faston terminal and the other is a female Faston terminal. The same applies for terminals 6A and 6B. Therefore, the coil 1 is eventually equipped with electric multiconnections that are equipotential thanks to the provision of the first and the second electric conductor means 5 and 6, and also ensure electric and mechanical connection with any other coil. Thanks to this arrangement, in case of connection of multiple coils of the type as described hereinabove, there is no longer the need of supplying power to each coil by laying respective connection cables to connect the power supply with the coils and the coils with each other, but the coils need simply be connected together by fitting the male terminal of one coil in the female terminal of another.

For instance, Figure 4 shows a possible circuit arrangement of a plurality of coils 10 of the type as described hereinabove.

In this circuit configuration the plurality of coils 10 can be disposed in a matrix arrangement having three rows r1, r2, r3 and three columns c1, c2, c3.

The coils of each row rl, r2, r3 are electrically and mechanically connected together by means of the electric terminals and can be supplied with power from the power source V.

Indeed, assuming that the power supply voltage from the power supply V has the direction as shown in such Figure 4, power is applied from the power source V to the terminals 19A and 19B of the coil 19 and is transferred through the first and second conductor means 19C, 19D to the output terminals 19E and 19F, which are mechanically and electrically connected to the terminals of the next coil. Then, the power from the power supply V is transferred through the first and second conductor means

20C, 20D of the latter coil 20 to the terminals 20E, 20F of the same coil 20 and so on to the other coils in the circuit arrangement as shown in figure 4 ,

Furthermore, still with reference to Figure 4, a connection bridge 21 is shown which ensures that the power from the power source V is present at the terminals of each coil of said plurality of coils 10 in the circuit arrangement. Thus, with reference for example to the row 1-1 of the circuit matrix, the connection bridge 21 is embodied by an electric terminal 2IA having two electric connection elements, each being designed to be connected with a corresponding electric terminal 19A, 19B of the coil 19. Such connection bridge 21 further includes two electric conductors 21B, 21C of suitable section, which can transfer the positive pole and the negative pole to the other rows r2 and r3 of the circuit matrix.

According to an advantageous aspect of the present invention, the first electric conductor means 5 and the second electric conductor means 6 are associated to the support 2.

To this end, the support 2 comprises a first flange 2B and a second flange 2C in axially spaced relationship. Particularly, a receptacle or groove 2D may be formed within the thickness of the first flange 2B,

Otherwise, the receptacle 2D may be also formed in the thickness of second flange 2C.

This receptacle 2D also extends between said first point 7 and said second point 8 of said predetermined profile 2A.

Advantageously, the receptacle 2D has such a shape as to provide a form fit with said first electric conductor means 5 and with said second electric conductor means 6.

In other words, the first electric conductor means 5 and the second electric conductor means 6 are accommodated in said receptacle 2D .

The first electric conductor means 5 and the second electric conductor means 6 are connected to the support 2 through further connection means 9 to ensure firm fixation of said first and second electric conductor means 5 and 6 to the support 2 of the coil l.

These connection means 9 preferably consist of connectors of non conductive polymeric material, each of said connectors having a receptacle 9A and a slot 9B,

Particularly, the receptacle 9 has such a shape as to accommodate the terminal ends of said first and second electric conductor means 5 and 6. Furthermore, said first and second electric conductor means 5 and 6 have projecting elements 5C, 6C at their respective terminals 5A, 6A, 5B, SB, which can provide a form fit with said slot 9B of said receptacle 9A.

Advantageously, besides ensuring firm fixation of said first and second electric conductor elements 5 and 6 to the support 2 of the coil 1, such form fit also facilitates removal of the electric conductor elements 5, 6 in case of electric and/or mechanical problems to such, electric conductor elements 5, 6. Otherwise, said first electric means 5 and said second electric means 6 may be incorporated in said support 2, by providing a single cast that includes the support and the electric means S and 6.

In a preferred embodiment of the present invention, the first electric conductor means 5 and the second electric conductor means 6 may be embodied by metal sheets of electric conductive material having a predetermined thickness and such a shape as to conform to the profile 2A of the support 2. Particularly, the thickness of said first electric conductor means 5 and said second electric conductor means 6 shall allow transfer of the power required for proper operation, for example, of a permanent magnet apparatus, as well as proper coupling with said receptacle 2D. To this end, the metal sheets of said first and second electric conductor means 5 and 6 can have stiffening ribs 5D and 6D respectively.

Referring now to Figure 1, the first embodiment preferably has the following features:

- the profile 2 of the support 2A is a circular profile having a predetermined radius "r" ,

- the receptacle 2D is formed in the flange 2B and extends with an annular shape all along the circumference of said flange 2B, and that

- the first electric conductor means 5 and the second electric conductor means 6 are accommodated in said receptacle 2D and extend between said first point 7 and said second point S of said profile 2A, said first point 7 and said second point 8 being offset from each other at an angle in a range from 0° to 360°. preferably, said first point 7 and said second point S are in diametrically opposite positions, i.e. offset by 180°. Xn other words, the metal sheets of said first and second electric conductor means 5 and 6 are embodied by metal sheets having the shape of an arc of a circle and substantially provide an arrangement in which the electric terminals 5A, 5B and 6A, 6B of each metal sheet 5, 6 are offset by about 180°. Therefore; such arc of a circle is as long as about half the circumference of the flange 2B, i.e. a circumference of about π*r, where r stands for the radius of the support 2. Advantageously, if the power source V is applied, for instance, to the terminals 5A and 6A, the same power source V is made available to a position diametrically opposite to the one of the electric connection elements 5A, 6A. Referring now to Figures 5 to 7, in which the elements described above are designated by identical reference numerals, there are shown a perspective view, a plan view and a sectional view of a second embodiment of the coil 1 of the present invention. Particularly, in the specific embodiment of these figures, the coil 1 comprises the support 2 of predetermined profile 2A and the electric conductor element 3 wound on said support 2 to form a winding 4.

In the illustrated embodiment, the profile 2A of the support 2 has a circular section. The coil 1 further comprises:

- the first electric conductor means S, which are electrically connected to a terminal end of said electric conductor 3 and include four distinct electric connection elements 23A, .., 23D,- - the second electric conductor means 6, which are electrically connected to the other terminal end of said electric conductor 3 and include four distinct electric connection elements 24A, ..., 24D. Each of the first electric conductor means 5 and the second electric conductor means 6 extends between the first 7 and the second 3 point of the predetermined profile 2A of the support 2, and in the specific embodiment of Figure 5, each of the first electric conductor means 5 and the second electric conductor means 6 extends beyond half the circumference of the support 2. Otherwise, each of the first electric conductor means 5 and the second electric conductor means 6 can extend all along the circumference of the support 2. Advantageously, the electric terminals 23A, ..., 23D and 24A, ... 24D may be quick connect terminals such as those available under the name of "Faston terminals" .

Particularly, two of the four quick connect terminals 23A, ..,, 23D are male Fasten terminals and the others are female Faston terminals. The same applies for terminals 24A, ,.., 24D.

Therefore, the coil I is eventually equipped with electric multiconnections, i.e. four pairs of electric terminals, i.e. 23A, ..., 23D and 24A, ..., 24D respectively, said multiconnections being equipotential thanks to the first and. second electric conductor means 5 and 6.

Advantageously, in such configuration, by supplying power from the power source V to a pair of terminals of a first coil, three additional coils, electrically and mechanically connected to the first coil, may be also supplied with power through their respective electric terminals, and so on.

Once again, in the embodiment of Figures 5 and ^β, the first electric conductor means 5 and the second electric conductor means 6 are associated to the support 2, using well-known techniques.

In Figure 7, the support 2 comprises the flange 2B and the flange 2C. Still referring to Figure 7, it can be appreciated that two distinct receptacles or grooves 2D and 2E may be formed in the thickness of the flange 2B.

It shall be noted that the receptacle 2D, or the receptacle 2E or both receptacles 2D and 2E can be also formed in the thickness of the second flange 2C.

These receptacles 2D and 2E also extend between said first point 7 and said second point S of said predetermined profile 2A.

Particularly, the receptacle 2D is designed to accommodate the first electric conductor means 5 and the receptacle 2E is designed to accommodate the second electric conductor means 6. Referring now to Figure S, in which the elements described above are designated by identical reference numerals, there is shown a sectional view of a third embodiment of the present invention. In such Figure S, it will be noted that in addition to the conductor element 3, another conductor element 25 is also wound on the support 2A of the coil 1.

Each of these conductor elements 3, 25 can form a respective winding 4, 26, It shall be further noted that, in the specific embodiment of Figure S, in addition to the first electric conductor means 5 and the second electric conductor means

6, the coil 1 also has third electric conductor means 27.

Once again, in this third embodiment, each of the first electric conductor means 5, the second electric conductor means 6 and the third electric conductor means 27 extends between the first point 7 and the second point 8 of the predetermined profile 2A of the support 2.

While not shown in such Figure 7, it shall be understood that each of the first 5, the second 6 and the third 27 electric conductor means may include two distinct electric connection elements, having the same characteristics and the same position as shown above with reference to Figure 1. Otherwise, each of the first 5, the second S and the third 27 electric conductor means may include at least two distinct electric connection elements, having the same characteristics and the same position as shown above with reference to Figure 5. Advantageously, once again the electric connection terminals may be quick connect terminals such as those available under the name of "Faston terminals" .

It shall be noted that in a possible embodiment of the electric connections between the windings 4 and 2β and the first 5, second 6 and third 27 electric conductor means of the coil Ii

- the first electric conductor means 5 are connected to a terminal end of the conductor element 3; the second electric conductor means 6 are connected to a terminal end of the conductor element 25; the third electric conductor means 27 are connected to the other terminal ends of the conductor elements 3 and 25, respectively.

Still referring to Figure S, is can be noted that the first electric conductor means 5, the second electric conductor means 6 and the third electric conductor means

27 are associated to the support 2, using well-known techniques .

To this end, once again in this embodiment the support 2 comprises the flanges 2B and 2C. For example, three distinct receptacles 2D, 2E, 2P may be formed in the thickness of the flange 213.

Otherwise, any one of the receptacles 2D, 2E and 2P or all of the receptacles 2D, 2E and 2F can be formed within the thickness of the second flange 2C.

These receptacles 2D, 2E, 2F also extend between said first point 7 and said second point S of said predetermined profile 2A.

Particularly, the receptacle 2D is designed to accommodate the first electric conductor means 5, the receptacle 2E is designed to accommodate the second electric conductor means 6 and the receptacle 2F is designed to accommodate the third electric conductor means 27. The coil structure as shown in such Figure S may be advantageously used, for example, to create two different magnetization levels when the electric terminals of the electric conductor means are supplied with power from the power source V. The embodiments of the coils 1 as described herein can be advantageously employed in a permanent magnet clamping apparatus for ferrous wσrkpieces as described hereinbefore .

As clearly shown in the above description, the coil structure of the present invention fulfills the above mentioned needs and also obviates prior art drawbacks as set out in the introduction of this disclosure.

Those skilled in the art will obviously appreciate that a number of changes and variants tnay be made to the arrangements as described hereinbefore to meet specific needs, without departure from the scope of the invention, as defined in the following claims .

Claims

1. A multiconnection coil structure (1) comprising: - a support (2) of predetermined profile (2A) and

- at least one electric conductor element (3, 25) wound on said support (2) to form a respective winding (4, 26); characterized in that it comprises at least first (5) and second (S) electric conductor means for each of said windings (4, 26), said at least first (5) and second

(6) electric conductor means extending each between a first (7) and a second (8) points of said predetermined profile (2A) , wherein: - said first electric conductor means (5) are electrically connected to a terminal end of said at leaat one electric conductor (3, 25) and include at least two distinct electric connection means (5A, 5B, 23A, ... , 23D), - said second electric conductor means (6) are electrically connected to the other terminal end of said at least one electric conductor (3, 25) and include at least two distinct electric connection means (6A, 6B, 24A, ..., 24D) , so that when an electric connection element (5A, 5B, 23A, ..., 23D) of said first electric conductor means (5) and an electric connection element (6A, 6B, 24A, ..., 24D) of said second electric conductor means (6) are connected to a power source (V) , said power source (V) is also applied to at least another electric connection element (5A, 5B, 23A, ,.., 23D) of said first electric conductor means (5) and at least another electric connection element (6A, 6B, 24A, ..., 24D) of said second electric conductor means (6) .

2. A structure as claimed in claim 1, characterized in that it comprises third electric conductor means (27) which extends between said first (7) and said second (8) points of said predetermined profile (2A) .

3. A structure as claimed in claim 1 or 2, characterized in that said electric conductor means (5,

6, 27) have such a shape as to extend along the perimeter of said predetermined profile (2A) of said support (2) .

4. A structure as claimed in claims l to 3 , characterized in that said support (2) comprises at least one receptacle (2D, 2E, 2F) , said receptacle (2D, 2E, 2P) , extending between said first (7) and said second points (S) of said predetermined profile (2A) , said at least one receptacle (2D, 2E, 2F) having such a shape as to provide a form fit with said electric conductor means (5, 6, 27).

5. A structure as claimed in any one of the preceding claims l to 4, characterized in that said at least two distinct electric connection elements (5A, 5B, 23A, ..., 23D, 6A, SB, 24A, ..., 24D) of said electric conductor means (5, S, 27) are electrically separated from each other.

6. A structure as claimed in claims 1 to 5, characterized in that said at least two distinct electric connection elements (5A, 5B, 23A, ..., 23D, 6A, 6B, 24A, ..., 24D) of said electric conductor means {5, 6, 27) are quick connect electric terminals.

7. A structure as claimed in any one of the preceding claims, characterized in that said predetermined profile (2A) of said support (2) is selected from the group of triangular, quadrangular, polygonal, egg-shaped, elliptical or circular profiles.

8. A structure as claimed in claim 7, characterized in that, if said profile is circular, then said first electric conductor means (5) and said second electric conductor means (6) have such a conformation as to extend between said first point (7) and said second point (8), said first point (7) and said second point (8) being points offset from each other at an angle in a range from 0° to 3S0°.

9. A structure as claimed in claim 7, characterized in that_/ if said profile (2A) is circular, then said first electric conductor means (5) and said second electric conductor means (6) have such a conformation as to extend between said first point (7) and said second point (8) , said first point (7) and said second point (S) being diametrically opposite points of said circular profile, i.e. said first point (7) and said second point (8) are offset by about 180°.

10. A structure as claimed in claim 7, characterized in that, if said, profile (2A) is circular, then said first electric conductor means (5) and said second electric conductor means (6) have such a conformation as to extend between said first point (7) and said second point (8) , said first point (7) and said second point (8) being points offset by about 90°.

11. A structure as claimed in any one of the preceding claims, characterized in that said first electric conductor means (5) include four distinct electric connection elements (23A, ..., 23D) and said second electric conductor means (6) include four distinct electric connection elements (24A, ..., 24D) , said four distinct electric connection elements (23A, ..., 23D, 24A; „., 24D) being offset by about 90°C.

12. A structure as claimed in any one of the preceding claims, characterized in that said electric conductor means (5, 6, 27) are metal sheets of electric conductive material.

13. A structure as claimed in any one of the preceding claims, characterized in that said support (2) is formed of a non conductive polymer material.

14. A permanent magnet clamping apparatus for ferrous workpieσes, comprising a ferromagnetic frame a ferromagnetic frame adapted to contain a plurality of pole units, each of said pole units having a ferromagnetic pole unit defining a part of the clamping surface, a main magnetic core formed of a magnetically reversible permanent magnet and a coil located around each main magnetic core to activate and/or deactivate each pole unit, characterized in that said coil (1) is as claimed in any one of the preceding claims 1 to 13 ,