Electromagnetic actuator and electrical switch unit including the same

Abstract

The electromagnetic actuator (2) comprises: a fixed body (4); a moving part (6) which forms a magnetic core of the actuator and can be translated relative to the fixed body (4) between a retracted position and an extended position; a magnetic member (10) which forms a permanent magnet, the permanent magnet being adjusted to generate a first magnetic force to keep the moving part in the retracted position; and a coil (12) which is adjusted to generate a second magnetic force opposite to the first magnetic force when the coil is supplied with an electrical excitation current. The moving part (6) comprises one or more notches formed in the body of the moving part (6).

Description

Technical Field

[0001] The invention relates to an electromagnetic actuator and an electrical switching device comprising the actuator. Background Art

[0002] Electrical switching devices used in devices for distributing electrical power, such as circuit breakers, generally include an electromagnetic actuator whose function is to switch the electrical device from an electrically closed state to an electrically open state in response to a control signal. For example, the moving part of the actuator is coupled to a switching mechanism of the electrical device. The actuator in particular allows interruption of the distribution of electrical power in the event of a detected electrical fault.

[0003] FR-2893445-B1 discloses a known electromagnetic actuator comprising a fixed body, a moving part and an electrically excited magnetic circuit which is adjusted to move the moving part. The magnetic circuit comprises a permanent magnet and an exciting coil powered by a control signal.

[0004] Such actuators must meet many requirements. They must be compact and of small size in order to be easily integrated within the switchgear. They must react quickly in response to control signals, especially in the event of electrical faults. They must be reliable and not trip unintentionally, as this would affect the functionality of the switchgear. In particular, they must not trip when exposed to parasitic magnetic fields generated during a short circuit downstream of the switchgear. They must also be able to function within switchgear where the control signals are provided by an embedded energy storage device. Summary of the invention

[0005] It is these drawbacks that the present invention more particularly intends to remedy by proposing an electromagnetic actuator with improved functionality.

[0006] To this end, the present invention relates to an electromagnetic actuator, comprising:

[0007] -Fix the main body;

[0008] - a mobile part which forms the magnetic core of the actuator and which is movable in translation relative to the fixed body between a retracted position and a deployed position;

[0009] - a magnetic piece forming a permanent magnet adjusted to generate a first magnetic force holding the mobile part in the retracted position;

[0010] - a coil which is regulated to generate a second magnetic force opposing the first magnetic force when the coil is supplied with an electrical excitation current.

[0011] The moving component includes one or more recesses formed in a body of the moving component.

[0012] Thanks to the invention, the notch arranged in the mobile part makes it possible to limit the eddy currents that appear in the mobile part during the excitation of the coil. In addition, the notch makes it possible to change the inductance of the magnetic circuit and thus reduce the energy required to control the tripping of the actuator.

[0013] According to an advantageous but not mandatory aspect of the invention, such an actuator may comprise one or more of the following features, alone or according to any technically permissible combination:

[0014] - Moving parts are made of iron-silicon alloy.

[0015] The mass concentration of silicon in the alloy is greater than or equal to 2% and less than or equal to 6.5%, preferably greater than or equal to 2.5% and less than or equal to 3.5%.

[0016] - The moving parts are manufactured according to the metal injection molding method.

[0017] - Each notch is arranged radially relative to the centre of the moving part.

[0018] The number of notches is between 1 and 10, preferably 4.

[0019] The angle between the opposite edges of the notch is greater than or equal to 5° and less than or equal to 50°.

[0020] The radius of the moving part is greater than or equal to 3 mm and less than or equal to 10 mm, the length of the radial notch being greater than or equal to 30% and less than or equal to 90% of the radius.

[0021] The notches are arranged on either side of a central geometrical plane of the magnetic element and are aligned perpendicular to this plane.

[0022] According to another aspect, the invention relates to an electrical switching device comprising a switching mechanism and an electromagnetic actuator coupled to the switching mechanism, the electromagnetic actuator being an actuator as described above. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The invention will be better understood and further advantages of the invention will appear more clearly from the description of an embodiment of the electromagnetic actuator, which description is given by way of example only and is made with reference to the accompanying drawings, in which:

[0024] - Figure 1 is a schematic diagram of a cross-sectional view of an electromagnetic actuator according to an embodiment of the present invention;

[0025] - Figure 2 yes Figure 1 A schematic diagram of a first embodiment of a moving part of a magnetic excitation circuit of an actuator along a viewing angle;

[0026] - Figure 3 According to the first embodiment Figure 2 A cross-sectional view of the moving parts of FIG. 1 in section III;

[0027] - Figure 4 yes Figure 2 and 3 A cross-sectional view of an alternative embodiment of an actuator;

[0028] - Figure 5 is a schematic diagram of an electrical device including an electromagnetic actuator according to an embodiment of the present invention. DETAILED DESCRIPTION

[0029] Figure 1 An electromagnetic actuator 2 is shown, comprising a stationary body 4 and a moving part 6 forming the magnetic core of the actuator 2 .

[0030] The mobile part 6 is movable in translation relative to the fixed body 4 between a deployed position and a retracted position along the longitudinal axis Z2 of the actuator 2. In the deployed position, also called the "tripped position", the mobile part 6 is at least partially deployed outside the fixed body 4. In the retracted position, also called the "standby position", the mobile part 6 is retracted inside the fixed body 4.

[0031] The body 4 here forms a housing of hollow cylindrical shape centered on the longitudinal axis Z2. The housing ensures translational guidance of the mobile part 6 when it moves between the retracted and deployed positions.

[0032] The actuator 2 also comprises a magnetic excitation circuit 8 which, in addition to the mobile part 6, comprises a magnetic piece 10 forming the core of the magnetic circuit and generating a first magnetic force for keeping the mobile part 6 in the retracted position when the actuator 2 is not excited.

[0033] The magnetic element 10 has the shape of a flat disk centered on the longitudinal axis Z2. When the magnetic element 10 is mounted inside the actuator 2, the main side faces of the magnetic element 10 are perpendicular to the axis Z2.

[0034] According to an example, the magnetic element 10 is made of a material having permanent magnetization, preferably a ferromagnetic material.

[0035] The magnetic circuit 8 also comprises a coil 12 capable of generating a second magnetic force opposite to the first magnetic force when the coil is powered by an electrical excitation current. The second magnetic force is opposite to the first magnetic force and allows the release of the mobile part 6 as described below.

[0036] In the example shown, the first force and the second force are directed along the axis Z2. The coil 12 comprises, for example, turns of an electrically conductive wire wound concentrically around the axis Z2.

[0037] According to an embodiment example, the magnetic circuit 8 also comprises an object 14 for concentrating the magnetic flux. In this example, the object 14 is in contact with its lower side on the upper side of the magnetic element 10. In the retracted position, the mobile part 6 is in contact with the upper part of the object 14.

[0038] The actuator also comprises an elastic return member 16 mechanically coupled to the mobile member 6 and exerting a restoring force tending to move the mobile member 6 towards its deployed position. For example, the return member 16 is a spring, in particular a compression helical spring mounted coaxially around the axis Z2.

[0039] When the actuator 2 is stationary, the first force exerted by the magnetic member 10 is greater than the restoring force exerted by the component 16, so that the mobile component 6 remains in its retracted position. When the coil 12 is energized by a power source, for example in response to a control signal sent to the actuator 2, it generates a magnetic field opposite to the magnetic field generated by the magnetic member 10, thereby reducing the magnetic force generated. The restoring force exerted by the component 16 then moves the mobile component 6 towards its deployed position.

[0040] According to the example, the moving part 6 comprises a substantially cylindrical body and a rectilinear narrow rod-like portion extending longitudinally from the upper end of the body.

[0041] According to the embodiment shown, the mobile member 6 comprises a mobile head 18 mounted to slide along the rod-shaped portion and coupled to an auxiliary return member 20, which is in turn mounted on the mobile member 6. The member 20 is, for example, a helical spring concentric with the axis Z2. The return member 16 is supported on the one hand on the body 4 and on the other hand on the opposite end, namely on the head 18.

[0042] According to an embodiment example, the fixed body 4 is formed by assembling at least two parts 22 and 24 arranged concentrically and connected together, for example, by a seal. Reference numeral 26 denotes a base plate closing the body 4 at its lower end. For example, the magnetic element 10 is mounted on the upper side of the base plate 26. The head 18 extends at the opposite end of the body 4.

[0043] For example, the actuator 2 is similar to the one described in patent FR 2 893 445 B1 and functions in a similar way.

[0044] like Figure 2As shown, the mobile part 6 comprises one or more notches 30, such as grooves or recesses, arranged in the body of the mobile part 6. The notches 30 preferably extend from a peripheral edge 32 of the body of the mobile part 6. According to an embodiment, the notches 30 are radial notches, that is to say notches arranged radially relative to the center of the mobile part 6, that is to say here relative to the longitudinal axis of the mobile part 6. When the mobile part 6 is mounted in the actuator 2, the longitudinal axis of the mobile part 6 merges with the axis Z2. Therefore, the notches 30 extend substantially perpendicularly to the peripheral edge 32 of the mobile part 6.

[0045] For example, each notch 30 extends from a peripheral edge 32 of the mobile part 6 towards the center of the mobile part 6 while defining a radial cross-sectional portion of the mobile part 6. "Radial cross-sectional portion" here means that the notch 30 does not form a complete radial portion of the mobile part 6, since the notch 30 does not extend completely to the center of the mobile part 6. Instead, each notch 30 ends towards the center by an inner end edge 34, which is located at a non-zero distance from the center.

[0046] exist Figure 3 , reference R6 denotes the radius of the mobile part 6 measured at the body of the mobile part 6 forming the recess 30. Reference w30 denotes the angle between opposite edges of the recess 30. For example, the angle w30 is measured at the edge 32. Reference l30 denotes the width of the recess 30.

[0047] According to an embodiment, the recesses 30 of the mobile part 6 are identical.

[0048] The notches 30 are preferably regularly spaced relative to one another, that is to say they are evenly distributed over the entire periphery of the mobile part 6. In this case, when the mobile part 6 is mounted in the actuator 2, it has a rotational symmetry about the axis Z2.

[0049] According to an embodiment, the number of radial notches 30 is greater than or equal to 1 and is preferably between 1 and 10 and further preferably between 3 and 10. In the example shown, the number of notches 30 is four.

[0050] According to an embodiment, the angle w30 of the notch is greater than or equal to 5° and less than or equal to 50°, or the angle w30 is greater than or equal to 20° and less than or equal to 40°. For example, the width l30 is greater than or equal to 5° and less than or equal to 20°. Other angle values ​​are also possible.

[0051] The recess 30 preferably extends in height along the body of the mobile part 6 parallel to the longitudinal axis of the mobile part 6. For example, the height of the recess 30 is greater than or equal to 20% of the length of the body of the mobile part 6.

[0052] According to a particular embodiment, the radius R6 of the mobile part 6 is preferably greater than or equal to 3 mm and less than or equal to 10 mm.

[0053] For example, the length L30 of the radial notch is greater than or equal to 30% and less than or equal to 90% of the radius R6, and preferably greater than or equal to 40% and less than or equal to 70% of the radius R6.

[0054] In practice, the precise values ​​of the number and dimensions of the slots 30 are optimized according to the application and in particular according to the expected performance of the actuator 2. According to the example, it is preferred to increase the circumference of the mobile part 6 while maintaining a sufficiently large cross section w30 so that the first magnetic force is sufficient to ensure satisfactory functioning of the actuator 2.

[0055] For example, according to an embodiment, the ratio of the circumference length of the mobile part 6 to the circumference of a disk of the same radius without the notch 30 is greater than or equal to 1.5, preferably greater than or equal to 2 and also preferably greater than or equal to 5.

[0056] According to a variant not shown, each notch 30 has an elliptical shape, the side edges of which are parallel to each other. Thus, each notch 30 has a quadrilateral shape, for example a rectangular shape. In this case, the width l30 is the same whether measured at the edge 34 of the mobile part 6 or at the edge 32 of the part.

[0057] When the coil 12 is excited to control the actuator 2, it generates a magnetic flux aligned along the axis Z2. This magnetic flux generates eddy currents in the mobile part 6, which causes energy losses. These eddy currents usually circulate along the peripheral edge 32 in a plane of the mobile part 6 perpendicular to the direction of the magnetic flux. The notch 30 is arranged tangentially to the magnetic flux generated by the coil 12, making it possible to increase the length of the equivalent path of the eddy current travel, which hinders their circulation and reduces energy losses.

[0058] Reducing the energy losses due to eddy currents makes it possible to reduce the energy required to power the coil 12. This is advantageous when the actuation of the actuator 2 in the electrical device is done by using a battery or energy reserve with limited storage capacity.

[0059] Furthermore, the choice of the number and size of the notches 30 makes it possible to vary the magnetic resistance of the mobile part 6 , which makes it possible to optimize the inductance value of the mobile part 6 and therefore reduce the energy required to trip the actuator 2 .

[0060] Finally, the notch 30 reduces the weight of the mobile part 6. The mobile part 6 is therefore easier to move. The response time of the actuator 2 is thus reduced.

[0061] According to an advantageous embodiment, the moving part 6 is made of an iron-silicon alloy.

[0062] The mass concentration of silicon in the iron-silicon alloy is preferably greater than or equal to 2% and less than or equal to 6.5%, preferably greater than or equal to 2.5% and less than or equal to 3.5%.

[0063] According to a particularly advantageous embodiment, the mobile part 6 is manufactured by a metal injection molding method.

[0064] The use of an iron-silicon alloy makes it possible to obtain magnetic performance values ​​close to those of pure iron, in particular in terms of saturation induction and permeability, while having a resistivity at least two or three times greater than that of pure iron, which makes it possible to limit energy losses due to eddy currents when a second magnetic force is exerted on the magnetic element 10.

[0065] The manufacture of the mobile part 6 according to the metal injection molding method makes it possible to manufacture the mobile part 6 from an iron-silicon alloy more easily than using known forming techniques, such as machining or turning, which do not give satisfactory results with iron-silicon alloys, in particular for the manufacture of small parts such as the mobile part 6.

[0066] Figure 4 A mobile part 6' is shown which corresponds to another embodiment of the mobile part 6. Elements of the mobile part 6' which are similar to those of the mobile part 6 have the same reference numerals with the addition of the symbol ' and are not described in detail, except that the above description is carried over. The mobile part 6' can in particular be integrated inside the actuator 2 in place of the mobile part 6.

[0067] The mobile part 6' differs in particular from the mobile part 6 in that the recesses 30' of the mobile part 6' are not oriented radially. Instead, the recesses 30' here are arranged on either side of the central geometrical plane of the mobile part 6' and are aligned perpendicularly to this plane along parallel directions. The central plane is perpendicular to the section plane, which shows Figure 4 The mobile part 6 ′ on the Z2 is therefore parallel to the axis Z2.

[0068] Thus, the first set of notches 30 ′ is disposed on one side of the central plane and the second set of notches 30 ′ is disposed on the other side of the central plane.

[0069] In each of the first and second groups, the number of notches 30' is preferably the same.For example, the central plane is the plane of symmetry of the mobile part 6'.

[0070] According to an embodiment, the number of notches 30' in each of the first and second groups is greater than or equal to 2 and less than or equal to 6. In practice, the number and size of the notches 30' depends on the method of manufacturing the mobile part 6', in particular on the demoulding constraints. In the example shown, each of the first and second groups comprises four notches 30'.

[0071] For example, the mobile part 6 ′ is manufactured in the same material as the mobile part 6 and follows a manufacturing method similar to that of the mobile part 6 .

[0072] The corresponding inner end edges 34 of the notches 30' on the same side of the center plane are preferably aligned and located at the same distance from the center plane. Due to the circular shape of the peripheral edge 32, the notches 30' whose inner end edges 34 are aligned along the same axis can in this case have different lengths L30'.

[0073] exist Figure 4 LA denotes the distance between the inner end edges 34 of the first and second groups of notches 30'. The distance LA here is greater than or equal to 5% and less than or equal to 30% of the diameter of the mobile part 6'.

[0074] In practice, the dimensions of the notch 30', such as the maximum value of the length L30' of the notch 30', the spacing W30' between two consecutive notches 30' and the width l30' of the notch 30', are chosen similar to the moving part 6, especially when the purpose is to increase the length of the equivalent path for the propagation of the eddy current and to optimize the inductance value of the moving part 6'. Figure 5 An electrical switching device 40 is shown, such as a circuit breaker or a contactor or a relay or any other equivalent device.

[0075] The device 40 includes a current input / output connection terminal 41 , a separable electrical contact 42 , a switching mechanism 44 , and an actuator 2 .

[0076] The separable contact 42 is connected between the terminals 41 and can be switched between an open state and a closed state to respectively prevent or allow the flow of current under the action of a switching mechanism 44 .

[0077] The actuator 2 is coupled to a switching mechanism 44 to trip the opening of the separable contacts 42 , for example in response to a control signal provided by a trip device or by a control unit external to the device 40 .

[0078] The embodiments and variations envisaged above can be combined together to create new embodiments.

Claims

1. An electromagnetic actuator (2), comprising: - fixing the body (4); - moving parts (6; 6 '), which forms the magnetic core of the actuator and is movable in translation along the longitudinal axis (Z2) relative to the fixed body (4) between a retracted position and a deployed position; - a magnetic element (10) forming a permanent magnet, the permanent magnet being adjusted to generate a first magnetic force holding the mobile part in the retracted position; - a coil (12) which is regulated to generate a second magnetic force opposite to said first magnetic force when the coil is supplied with an electrical excitation current; Characterized in that the mobile part (6; 6') comprises one or more recesses (30; 30') formed in the body of the mobile part (6; 6'); The magnetic member (10) has a flat disk shape centered on the longitudinal axis (Z2), and the main side surface of the magnetic member (10) is perpendicular to the longitudinal axis (Z2); And wherein the electromagnetic actuator (2) further comprises an object (14) for concentrating magnetic flux, the object (14) contacts the magnetic member (10) through one side thereof, and in the retracted position, the moving part (6) contacts the other side of the object (14).

2. The actuator according to claim 1, characterized in that The moving part (6; 6') is made of an iron-silicon alloy.

3. The actuator according to claim 2, characterized in that The mass concentration of silicon in the alloy is greater than or equal to 2% and less than or equal to 6.5%.

4. The actuator according to claim 3, characterized in that The mass concentration of silicon in the alloy is greater than or equal to 2.5% and less than or equal to 3.5%.

5. The actuator according to claim 2 or 3, characterized in that: The moving part (6; 6') is manufactured according to the metal injection molding method.

6. The actuator according to any one of claims 1 to 3, characterized in that: Each notch (30) is arranged radially relative to the center of the moving part (6).

7. The actuator according to claim 6, characterized in that The number of the notches (30) is between one and ten.

8. The actuator according to claim 7, characterized in that The number of the notches (30) is four.

9. The actuator according to claim 6, characterized in that The angle (w30) between the opposite edges of the notch (30) is greater than or equal to 5° and less than or equal to 50°.

10. The actuator according to claim 6, characterized in that The radius (R6) of the moving part (6) is greater than or equal to 3 mm and less than or equal to 10 mm, and the length (L30) of the radial notch (30) is greater than or equal to 30% and less than or equal to 90% of the radius.

11. The actuator according to any one of claims 1 to 3, characterized in that: The notches (30') are arranged on either side of a central geometric plane of the magnetic element (6') and are aligned perpendicular to the plane.

12. An electrical switching device (40) comprising a switching mechanism (44) and an electromagnetic actuator coupled to the switching mechanism, characterized in that: The electromagnetic actuator (2) is an actuator according to any one of the preceding claims.

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