Contactor device for making or breaking a connection between a load and a power supply

Abstract

There is provided a contactor device for making or breaking a connection between a load and a power supply, comprising: a coil (12) having an interior space extending between a first coil opening and a second coil opening; a frame (14) at least partly surrounding the coil and having a first side (24) with a first frame aperture (26) at the first coil opening and a second side (28) with a second frame aperture (30) at the second coil opening; a plunger (16) extending through the interior space of the coil and through the first and second frame aperture and being provided with a first plate (18) at its first end and with a second plate (20) at its second end, wherein the first and second plate are located outside the frame and wherein the plunger is axially moveable from a first position to a second position by energizing the coil, and wherein the load is connected to the power supply in one of the first and second position and is disconnected from the power supply in the other one of the first and second position; a permanent magnet arrangement (22) located within the frame and outside the coil between the coil and the second side of the frame, with the plunger extending through the permanent magnet arrangement; a spring arrangement (36) for axially moving the plunger from the s0econd position to the first position when the coil is deenergized. The frame is made of a ferromagnetic material, and the plunger comprises a ferromagnetic portion (16A) substantially extending within the interior space of the coil towards the first frame aperture and a non-ferromagnetic portion (16B) located axially adjacent to the ferromagnetic portion and substantially extending within the permanent magnet arrangement.

Description

[0001] Contactor device for making or breaking a connection between a load and a power supply

[0002] The invention relates to contactor device for making or breaking a connection between a load and a power supply, comprising a coil and a plunger axially moveable within the coil by energizing the coil.

[0003] CN113921336A relates to a contactor device with a spring-biased non-magnetic shaft carrying an iron core coated with a non-magnetic silver layer and covered by a non-magnetic plunger cap, wherein the iron core is axially movable within a coil surrounded by an iron yoke. The shaft may extend partly through a fixed iron core extending into the coil.

[0004] KR20110028871 A relates to a contactor device with a magnetic spring-biased substantially cylindrical plunger that moves axially within a coil. A hollow-cylindrical permanent magnet is provided axially adjacent to the lower end of the plunger mostly within the coil, with a guide pin of the plunger, which is surrounded by the spring, extending into the permanent magnet. The coil is located within a metal cover.

[0005] CN112614746A relates to a contactor device with an armature piece that moves axially within a coil surrounded by a magnetic yoke. Two permanent magnet bars are provided between the bottom part of the yoke and the coil.

[0006] It is an object of the invention to provide a contactor device which allows for a high opening I closing velocity, a constant contact resistance with low contact bouncing time and relatively low manufacturing costs.

[0007] According to the invention, this object is achieved by a device as defined in claim 1.

[0008] The contactor device comprises a ferromagnetic frame at least partly surrounding the coil and a permanent magnet arrangement located within the frame and outside the coil between the coil and the first side of the frame, with the plunger extending through the permanent magnet arrangement, wherein the plunger comprises a ferromagnetic portion substantially extending within the interior space of the coil and a non-ferromagnetic portion located axially adjacent to the ferromagnetic portion and substantially extending within the permanent magnet arrangement. The invention is beneficial in that a high opening and closing velocity and a constant contact resistance with low contact bouncing time can be achieved; further, relatively low manufacturing costs can be achieved, e.g., since no armature piece is needed.

[0009] Preferred embodiments are defined in the dependent claims. According to one example, the frame is made of steel. For example, the frame may have a cuboidal shape with two opposite open sides.

[0010] According to one example, the permanent magnet arrangement comprises two parallel bars, with the plunger extending between the two bars. In particular, the plunger may be perpendicular to the two bars. For example, the distance between the two bars may be equal to or greater than the respective dimension of the second opening of the coil. Alternatively, the permanent magnet arrangement may comprise, for example, one or more circular magnets.

[0011] According to one example, the magnetization direction of the permanent magnet arrangement may be the same as that of the magnetic field generated by the coil.

[0012] According to one example, the ferromagnetic portion of the plunger is made of steel.

[0013] According to one example, the non-ferromagnetic portion of the plunger is made of brass.

[0014] According to one example, the plunger may have a substantially cylindrical shape between the plates. For example, the plunger may have the shape of a full cylinder between the plates and / or or at least a part of the non-ferromagnetic portion of the plunger may have the shape of a full cylinder.

[0015] According to one example, a volume of the non-ferromagnetic portion is from 20% to 50% of the volume of the plunger.

[0016] According to one example, when the coil is energized, the plunger is actuated such that the non-ferromagnetic portion moves axially away from the coil. In particular, when the coil is deenergized, the spring arrangement actuates the plunger such that the non-ferromagnetic portion moves axially towards the coil.

[0017] According to one example, the non-ferromagnetic portion of the plunger extends over the entire axial length of an interior space of the permanent magnet arrangement when the plunger is in the first position.

[0018] According to one example, the load is connected to the power supply in the second position.

[0019] According to one example, the spring arrangement comprises a single conical spring. According to one example, the spring arrangement acts on an end portion of the plunger comprising the non-ferromagnetic portion. Hereinafter, an example of the invention will be illustrated by reference to the attached drawings, wherein:

[0020] Fig. 1 is an exploded view of an example of the drive assembly of a contactor device;

[0021] Fig. 2 is a cross sectional view of the drive assembly of Fig. 1 in an open condition;

[0022] Fig. 3 is perspective view of the plunger of the drive assembly of Fig. 2;

[0023] Fig. 4 is a cross sectional view of an example of a contactor device utilizing the drive assembly of Fig. 1 , with a open condition being shown; and

[0024] Fig. 5 is a view like Fig. 4, with a closed condition being shown.

[0025] Figs. 1 and 2 are an exploded view and a cross-sectional view, respectively, of an example of the drive assembly 10 of a contactor device for making or breaking a connection between a load and a power supply (not shown), which comprises a coil 12 with an interior space extending between a first coil opening and a second coil opening, a frame 14 at least partly surrounding the coil 12, a plunger 16 provided with a top plate 18 at one end and a bottom plate 20 at the other end and a permanent magnet assembly 22. The magnetization direction of the permanent magnet arrangement 22 may be the same as that of the magnetic field generated by the coil 12 so that the magnetic flux of the permanent magnet arrangement 22 adds to the magnetic flux generated by the coil 12 when energized.

[0026] The frame 14 has a first side (top side) 24 with a first frame aperture 26 at the first coil opening and a second side (bottom side) 28 with a second frame aperture 30 at the second coil opening. In the example of Figs. 1 and 2 the frame 14 has a cuboidal shape with two opposite open sides (indicated at 32 and 34 in Fig. 1). The frame 14 is made of a ferromagnetic material, such as steel.

[0027] The plunger 16 extends through the interior space of the coil 12 and the first frame aperture 26 and the second frame aperture 30, with top plate 18 being located above the top side 24 and the bottom plate 20 being located below the bottom side 28, so that the plates 18, 20 are located outside the frame 14. The plunger 16 is axially moveable from a first position to a second position by energizing the coil, wherein the load is connected to the power supply in one of the first and second position and is disconnected from the power supply in the other one of the first and second position. In the example of Figs. 1 and 2, in the first position (where the coil 12 is not energized) the bottom plate 20 of the plunger 16 abuts the bottom side 28 of the frame 14 (the first position is shown in Figs. 2 and 4), and in the second position (where the coil 12 is energized) the top plate 18 of the plunger 16 abuts the top side 24 of the frame 14 (the second position is shown in Fig. 5).

[0028] A spring arrangement is provided for axially moving the plunger 16 from the second position to the first position when the coil 12 is de-energized, i.e. , for biasing the plunger 16 towards the first position. For example, the spring arrangement may comprise a single conical spring 36 located below the bottom plate 20 (see Fig. 4), which acts on the lower end of the plunger 16 via the bottom plate 20, with the top of the spring 36 abutting the lower surface of the bottom plate 20 so that the spring 23 can push the bottom plate 20 upward.

[0029] The permanent magnet arrangement 22 is located within the frame 14 and outside the coil 12 between the coil 12 and the second side (bottom side) 28 of the frame 14, with the plunger 16 extending through the permanent magnet arrangement 22. In the example of Figs. 1 and 2, the permanent magnet arrangement 22 comprises two parallel bars 22A, 22B, with the plunger 16 extending between the two bars 22A, 22B, wherein the plunger 16 is oriented perpendicular to the two bars 22A, 22B. The distance between the two bars 22A, 22B may be equal to or greater than the respective dimension of the second coil opening.

[0030] As shown in Figs. 2 to 5, the plunger 16 comprises a ferromagnetic portion 16A substantially extending within the interior space of the coil 12 towards the first frame aperture 26 and a non-ferromagnetic portion 16B located axially adjacent to the ferromagnetic portion 16A and substantially extending within the permanent magnet arrangement 22. Also the top plate 18 and the bottom plate 20 may be made of a ferromagnetic material.

[0031] For example, the ferromagnetic portion 16A of the plunger 16 and the top plate 18 and the bottom plate 20 may be made of steel, and the non-ferromagnetic portion 16B of the plunger 16 may be made of brass , copper or plastic.

[0032] The plunger 16 may have a substantially cylindrical shape between the plates 18, 20. In particular, the plunger 16 may have a substantially circular-cylindrical shape between the plates 18, 20, with the ferromagnetic portion 16A and the non-ferromagnetic portion 16B having the same diameter. For example, the plunger 16 may be a solid cylinder between the plates 18, 20. In particular, also at least a part of the non-ferromagnetic portion 16B of the plunger then may be a solid cylinder. It is noted that the top plate 18 and the bottom plate 20, while being shown as having a circular shape in the example illustrated in Figs. 1 to 3, may have other shapes, like rectangular or elliptical.

[0033] According to one example, the volume of the non-ferromagnetic portion 16B is less than 50% of the volume of the plunger 16 but more than 20%.

[0034] As can be seen in Figs. 4 and 5, where the lower part of an example of the plunger is shown in a cross-sectional view, the ferromagnetic portion 16A and the non-ferromagnetic portion 16B may be connected by threaded engagement, wherein, for example, a projection 16C of the ferromagnetic portion 16A having an outer thread is screwed into a cavity of the non- ferromagnetic portion 16B having an inner thread.

[0035] In the examples of Figs. 1 to 5, when the coil 12 is energized, the plunger 16 is actuated, by magnetic forces exerted by the coil 12 drawing the ferromagnetic portion 16A of the plunger 16 into the coil, 12 such that the non-ferromagnetic portion 16B moves - against the biasing force applied by the spring 36 - axially away from the coil 12 until the top plate 18 abuts the top side 24 of the frame 14. In turn, when the coil 12 is de-energized, the spring 36 actuates the plunger 16 such that the non-ferromagnetic portion 16B moves axially towards the coil 12 until the bottom plate 20 abuts the bottom side 28 of the frame 14. According to one example, the non-ferromagnetic portion 16B of the plunger 16 extends over the entire axial length of an interior space of the permanent magnet arrangement 22, i.e. , the space between the two bars 22A, 22B, when the plunger 16 is in the first position.

[0036] When the plunger 16 is in the first position (i.e., when the coil 12 is not energized and the plunger 16 has been moved by the spring 36 from the second position into the first position), the permanent magnet arrangement 22 assists the spring 36 by providing for an additional biasing force towards the first position by attracting the bottom plate 20. In the second position the permanent magnet arrangement 22 attracts the ferromagnetic portion 16A of the plunger (because of the smaller air gap toward portion 16A, which directs the magnetic field to close through the plunger 16).

[0037] When the plunger 16 is in the second position and the coil 12 has just been de-energized, so that the spring 36 can start to move the plunger 16 from the second position into the first position, the permanent magnet arrangement 22 provides for some initial magnetic attractive force on the top plate 18 which is overcome by the spring and becomes weaker when the plunger moves on towards the first position, whereas the attractive force exerted by the permanent magnetic arrangement 22 on the bottom plate 20 becomes stronger when the plunger 16 moves on towards the first position. It is believed that the ‘centre of magnetic flux’ shifts from above the permanent magnet arrangement 22 in the second position to below the permanent magnet arrangement 22 in the first position, after the coil 12 is deenergized, since the force on the plunger 16 is attractive always due to ferromagnetism. In other words, the direction of the net magnetic force changes from downward-oriented to upward-oriented, with reference to the embodiment illustrated in Figs. 4, 5. In turn, when the coil 12 is energized when the plunger 16 is in the first position, the initial biasing force of the permanent magnet arrangement 22 (and the biasing force of the spring 36) is overcome by the magnetic force exerted by the coil 12 on the ferromagnetic portion 16A of the plunger 16, with the permanent magnet arrangement 22 subsequently attracting the ferromagnetic portion 16A of the plunger 16 when the plunger 16 approaches the second position, thereby assisting the closing action of the coil 12.

[0038] The shortest magnetic flux path through the plunger 16, the frame 14 and the permanent magnet arrangement 22 is indicated at 38 in Fig. 2 for the condition when the coil 12 is energized, while still being in the first position (i.e. , before having started to move to the second position as a consequence of being energized).

[0039] It is noted that the frame 14 may be provided with a cut on the top side 24 and on the bottom side 28, respectively, extending over the entire length of the respective side 24, 28 across the frame apertures 26, 30, so as to create an air gap for magnetic flux and to accordingly increase the magnetic flux through the plunger 16, thereby increasing the closing force from the first (open) position to the second (closed) position (by providing such air gap in the frame 14 magnetic flux lines should pass through the plunger 16 and follow the shortest path to increase the closing force). Such optional cuts are indicated in Fig. 1 by dashed lines.

[0040] Figs. 4 and 5 are cross sectional views of an example of a contactor device 40 utilizing a drive assembly 10 of the type shown in Figs. 1 to 3. The drive assembly 10 is operatively connected to a contact assembly 50 comprising a contact bridge 52 connected to and operated by the plunger 16, namely by the top plate 18 of the plunger 16. The contact bridge 52 comprises an axially moving contact 54 which is driven by the plunger 16 and which - in the closed position shown in Fig. 5 - is in contact with fixed contacts 56A, 56B electrically connected to terminals 60A, 60B for the load and the power supply, respectively. In the closed position shown in Fig. 5 the load is electrically connected to the power supply, and in the open position shown in Fig. 4 the load is disconnected from the power supply. It is noted that two shock pads 70A, 70B are provided below the bottom side 28 of the frame 14 in the region of the bottom plate 20 so as to reduce contact bouncing during closing of the contacts 54 and 56A, 56B.

[0041] This closed position of the contacts 54 and 56A, 56B corresponds to the second position of the plunger 16, i.e., when the coil 12 is energized. The open position of the contacts 54 and 56A, 56B corresponds to the first position of the plunger 16, i.e., when the coil 12 is not energized and the plunger 16 is biased towards the first position by the spring 36. Thus, in the example of Figs. 4 and 5, the contactor device 40 has a “normally off” configuration, wherein the load is connected to the power supply only when the coil 12 is energized i.e., when the plunger 16 is in the second position.

Claims

Claims1. A contactor device for making or breaking a connection between a load and a power supply, comprising: a coil (12) having an interior space extending between a first coil opening and a second coil opening; a frame (14) at least partly surrounding the coil and having a first side (24) with a first frame aperture (26) at the first coil opening and a second side (28) with a second frame aperture (30) at the second coil opening; a plunger (16) extending through the interior space of the coil and through the first and second frame aperture and being provided with a first plate (18) at its first end and with a second plate (20) at its second end, wherein the first and second plate are located outside the frame and wherein the plunger is axially moveable from a first position to a second position by energizing the coil, and wherein the load is connected to the power supply in one of the first and second position and is disconnected from the power supply in the other one of the first and second position; a permanent magnet arrangement (22) located within the frame and outside the coil between the coil and the second side of the frame, with the plunger extending through the permanent magnet arrangement; a spring arrangement (36) for axially moving the plunger from the sOecond position to the first position when the coil is de-energized; wherein the frame is made of a ferromagnetic material, and wherein the plunger comprises a ferromagnetic portion (16A) substantially extending within the interior space of the coil towards the first frame aperture and a nonferromagnetic portion (16B) located axially adjacent to the ferromagnetic portion and substantially extending within the permanent magnet arrangement.

2. The contactor device of claim 1 , wherein the frame (14) is made of steel.

3. The contactor device of one of claims 1 and 2, wherein the frame (14) has a cuboidal shape with two opposite open sides (32, 34).

4. The contactor device of one of the preceding claims, wherein the permanent magnet arrangement (22) comprises two parallel bars (22A, 22B), with the plunger (16) extending between the two bars.

5. The contactor device of claim 4, wherein the plunger (16) is perpendicular to the two bars (22A, 22B).

6. The contactor device of one of claims 4 and 5, wherein the distance between the two bars (22A, 22B) is equal to or greater than the respective dimension of the second opening of the coil (12).

7. The contactor device of one of the preceding claims, wherein the ferromagnetic portion (16A) of the plunger (16) is made of steel.

8. The contactor device of one of the preceding claims, wherein the non-ferromagnetic portion (16B) of the plunger (16) is made of brass, copper or a plastics material.

9. The contactor device of one of the preceding claims, wherein the plunger (16) has a substantially cylindrical shape between the plates (18, 20).

10. The contactor device of claim 9, wherein the plunger (16) is a solid cylinder between the plates (18, 20).

11. The contactor device of one of claims 9 and 10, wherein at least a part of the nonferromagnetic portion (16B) of the plunger (16) is a solid cylinder.

12. The contactor device of one of the preceding claims, wherein a volume of the nonferromagnetic portion (16B) is from 20% to 50% of the volume of the plunger (16).

13. The contactor device of one of the preceding claims, wherein, when the coil (12) is energized, the plunger (16) is actuated such that the non-ferromagnetic portion moves (16B) axially away from the coil.

14. The contactor device of claim 13, wherein when the coil (12) is de-energized, the spring arrangement (36) actuates the plunger (16) such that the non-ferromagnetic portion (16B) moves axially towards the coil.

15. The contactor device of one of the preceding claims, wherein the non-ferromagnetic portion (16B) of the plunger (16) extends over the entire axial length of an interiorspace of the permanent magnet arrangement (22) when the plunger is in the first position.

16. The contactor device of one of the preceding claims, wherein the load is connected to the power supply in the second position.

17. The contactor device of one of the preceding claims, wherein the spring arrangement comprises a single conical spring (36).

18. The contactor device of one of the preceding claims, wherein the spring arrangement (36) acts on an end portion (16B, 20) of the plunger (16) comprising the nonferromagnetic portion (16B).

Images