Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
  • H01H7/00—Devices for introducing a predetermined time delay between the initiation of the switching operation and the opening or closing of the contacts
  • H01H7/16—Devices for ensuring operation of the switch at a predetermined point in the ac cycle
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
  • H01H1/00—Contacts
  • H01H1/50—Means for increasing contact pressure, preventing vibration of contacts, holding contacts together after engagement, or biasing contacts to the open position
  • H01H1/54—Means for increasing contact pressure, preventing vibration of contacts, holding contacts together after engagement, or biasing contacts to the open position by magnetic force
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
  • H01H50/00—Details of electromagnetic relays
  • H01H50/005—Details of electromagnetic relays using micromechanics
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
  • H01H50/00—Details of electromagnetic relays
  • H01H50/005—Details of electromagnetic relays using micromechanics
  • H01H2050/007—Relays of the polarised type, e.g. the MEMS relay beam having a preferential magnetisation direction

Definitions

• the present invention relates to a microsystem integrating a reluctant magnetic circuit.
• This reluctant magnetic circuit makes it possible in particular, by creating an additional contact force, to be able to make an opening of an electric circuit without generating an electric arc.
• No. 4,427,957 discloses a switching device comprising a magnetic circuit consisting of a movable part consisting of a pivoting blade and a fixed part.
• a coil is wound around the fixed part of the magnetic circuit.
• An electrical circuit for supplying a load comprises in particular an electrical contact piece integral with the pivoting blade and initially spaced apart from a second electrical contact piece.
• the first electrical contact piece also acts as a mechanical spring for the pivoting blade.
• the magnetic circuit Upon passage of a current in the coil, the magnetic circuit is magnetized and generates a first attraction force to attract the pivoting blade.
• the blade pivots to the connection between the two electrical contact parts, causing the closure of the electrical circuit but also that of the magnetic circuit.
• the first attraction force is canceled. Only the additional force of attraction keeps the blade in the closed position of the circuit. Since the intensity of this force follows the oscillations of the current through the electric circuit, it takes a value of zero to one given moment. When the current reaches a value below a threshold value, the additional magnetic force becomes less than the mechanical force of return exerted by the spring on the pivoting blade. Under the action of this mechanical force, the pivoting blade deviates from the closed position which opens the electrical circuit.
• the current threshold value is for example close to zero, which makes it possible to cut the circuit when the current is low and thus to avoid the generation of an electric arc.
• the mechanical restoring force must be large enough to take off the contacts, generate a magnetic force of the same order of magnitude with a current flowing in a turn does not seem suitable for threshold currents of a few milliamperes.
• the object of the invention is to propose a microsystem making it possible to respond to the different requirements defined above, in which the breaking of the circuit with a current having a value lower than a threshold value is reliable and perfectly stable over time.
• a movable contact piece comprising a layer of ferromagnetic material mounted on a substrate for switching an electrical circuit between an open position and a closed position
• closing means capable of applying a main contact force to the movable contact piece in the closed position
• opening means which, following an opening command, apply to the movable contact piece an opening force of the electrical circuit, of which the intensity is equal to the sum of the intensity of the main contact force and the intensity of the additional contact force when it corresponds to a value of the alternating current lower than a threshold value, characterized in that ,
• the closing means are of the magnetic or electromagnetic type and generate a first magnetic field creating a magnetic component in the ferromagnetic material layer of the movable contact piece to keep it in the closed position
• the opening means comprise an electromagnet provided with an excitation coil able to be supplied with a temporary current to produce a second magnetic field and to create a reverse magnetic component in the ferromagnetic material layer of the movable contact piece, of sufficient intensity to control the passage of the movable contact piece from the closed position to the open position.
• the additional contact force generated is proportional to the square of the intensity of the current flowing through the microactuator. This force therefore follows successive positive oscillations.
• the device according to the invention is a question of directly opposing magnetic forces between them, that is to say the magnetic torque generated by the field of the excitation coil against the main contact force generated by the first magnetic field and the contact force additional generated during the passage of the current in the electrical circuit. It is therefore easier to adjust the level of the threshold current because the level of forces involved is similar.
• the magnetic forces generated are independent of the wear phenomena of the microsystem and variations in its assembly process.
• the movable contact piece is bistable.
• the first magnetic field is permanent and maintains the membrane in each of its positions.
• the second magnetic field created by the excitation coil is only transient and is only activated for the tilting of the membrane from one of its positions to the other of its positions.
• the first magnetic field is uniform and oriented perpendicularly to the substrate.
• the excitation coil is of the solenoid type and it surrounds the substrate and the movable contact piece.
• the threshold value corresponds to the value of intensity of appearance of an electric arc.
• the ferromagnetic layer forms with a ferromagnetic reinforcement circuit the magnetic circuit reluctant during the passage of the alternating current in the electric circuit.
• the magnetic reinforcement circuit is integrated in the substrate.
• the ferromagnetic reinforcement circuit consists of two symmetrical wings joined by a perpendicular central core, defining a U-shaped cross section.
• the ferromagnetic reinforcement circuit is oriented so as, in its longitudinal direction, to be parallel to the direction followed by the current when the electric circuit is closed.
• the wings of the ferromagnetic reinforcement circuit comprise two surfaces each defining an air gap with a parallel surface of the ferromagnetic layer of the movable contact piece located vis-a-vis.
• the movable contact piece consists of a ferromagnetic membrane pivotally mounted on the substrate and carrying a movable contact adapted in the closed position to electrically connect two fixed conductive tracks arranged on the substrate for closing the electrical circuit.
• Figure 1 illustrates, schematically and in longitudinal section, a first embodiment of the invention.
• FIG 2 illustrates, schematically, in cross section along A-A in Figure 1, the first embodiment of the invention.
• FIG. 3 schematically illustrates, taken in a cross section identical to that of Figure 2, a second embodiment of the invention.
• FIG. 4 represents, in perspective, a microactuator that can be used in the microsystem according to the invention.
• FIG. 5 illustrates the microactuator according to the invention positioned in the space defined inside a solenoid type excitation coil.
• FIGS. 6A to 6C illustrate, in side view, the various steps implemented for pivoting the membrane of the microactuator according to the invention.
• FIGS. 7A and 7B show a microsystem according to the invention placed between two gap pieces of a magnetic circuit.
• FIG. 8 represents the curve of variation of the contact force generated using the principle of the invention.
• the principle of the invention consists in integrating in a switch electrical apparatus of an electrical circuit a reluctant magnetic circuit to provide the aforementioned advantages.
• a reluctant magnetic circuit created by the passage of an alternating current in the closed electrical circuit allows applying to the movable contact piece an additional contact or crushing force F '.
• the intensity of the additional contact force F "varies as a function of the intensity of the alternating current flowing in the electric circuit and follows successive positive oscillations (FIGS. 5A and 5B), more precisely, the intensity of this force.
• additional contact F is proportional to the square of the current I flowing through the switch when the reluctant magnetic circuit is not saturated.
• the invention consists in using the variations of this additional contact force F "to allow the opening of the electric circuit when the current is at an intensity lower than a threshold value.
• This threshold value may correspond to the intensity of appearance of the The additional contact force F "can prevent the switch from being opened as long as the current flowing in it is greater than the threshold current.
• This threshold value is, for example, 0.2 Ampere.
• the movable contact piece In the closed position, the movable contact piece is subjected to a main contact force F created by closing means.
• the reluctant magnetic circuit generated by the passage of the alternating current flowing in the switch following closure of the circuit makes it possible to apply to the movable contact piece an additional contact force F "that varies according to the oscillations of the
• the opening of the electric circuit can thus be carried out according to the following process:
• the main contact force F is always applied to the moving contact piece.
• an opening force F O uv of opposite direction and intensity equal to the sum of the intensity of the main contact force F and of the additional contact force F "when this corresponds to a value of the alternating current which is lower than the threshold value of the electric arc flash current. is sure to obtain the opening of the electric circuit below the threshold current and thus to avoid the appearance of an electric arc.
• the main contact force F is generated by magnetic or electromagnetic closure means.
• the opening force is generated by electromagnetic opening means.
• a microsystem may be a device comprising at least one microactuator that can be manufactured using MEMS type technologies or conventional PCB or kapton PCB technologies.
• a microactuator such as that described below is a microswitch or microswitch current used in a micro-contactor, a micro-relay or a micro-reed.
• a microactuator such as that described below is a microswitch or microswitch current used in a micro-contactor, a micro-relay or a micro-reed.
• microactuator we will use the general term "microactuator" to refer to these different applications.
• a microsystem may comprise a microactuator 2 mounted on a flat surface 30 of a substrate 3 made of materials such as silicon, glass, ceramics or in the form of printed circuits.
• the substrate 3 carries on its surface 30, for example, at least two identical flat conductive tracks 31, 32 spaced apart and intended to be electrically connected in order to obtain the closing of the electric circuit.
• the magnetic microactuator 2 carries at least one movable contact 21 capable of effecting the electrical junction between the two tracks 31, 32 when the microactuator 2 is activated.
• the electrical circuit is closed, the current I follows a direction located in the plane of the conductive tracks 31, 32.
• Such a microactuator 2 is provided with a movable contact piece carrying the movable contact 21 and consisting of a membrane 20 having a longitudinal axis (A) connected by one of its ends to an anchor stud 23 secured to the substrate 3 by means of two link arms 22a, 22b.
• the movable contact 21 is for example formed on the membrane 20 near the free end of the membrane 20 and faces the surface 30 of the substrate 3.
• the membrane 20 consists for example of a layer 200 (FIGS. 2) of ferromagnetic material having on its surface facing the substrate 3 a recess in which the contact 21 is arranged.
• the microactuator 2 described in the invention can be realized by a planar duplication technology of MEMS (Micro Electro-Mechanical System) type. Indeed, the realization by deposition of successive layers in an iterative process lends itself well to the manufacture of such objects.
• the membrane 20 as well as the arms 22a, 22b are for example derived from the same layer of ferromagnetic material.
• the connecting arms 22a, 22b and a lower layer of the membrane 20 may be derived from a metal layer. A layer of a ferromagnetic material is deposited on this metal layer to generate the part 20.
• Such a configuration can make it possible to optimize the mechanical properties of the linking arms 22a, 22b by using, to enable the pivoting of the membrane 20, a material which is mechanically more suitable than the ferromagnetic material.
• the metal layer can act as a contact for closing an electrical circuit.
• the ferromagnetic material is for example of the soft magnetic type and can be for example an alloy of iron and nickel ("permalloy" Ni 80 Fe 20 ).
• the membrane 20 is pivotable relative to the substrate 3 along an axis (P) parallel to the axis described by the contact points of the membrane 20 with the conductive tracks and perpendicular to the longitudinal axis (A) of the membrane 20.
• the connecting arms 22a, 22b form an elastic connection between the membrane 20 and the anchor stud 23. In such a configuration, the pivoting of the membrane 20 is thus obtained by bending the connecting arms 22a, 22b.
• An electromagnet is able to drive by magnetic effect the pivoting movement of the membrane 20 between at least two positions, a closed position of the electrical circuit and an open position of the electric circuit.
• Another magnetic field generated for example by a permanent magnet or an electromagnet can be used to apply a main contact force F to the membrane 20 in its closed position.
• the membrane 20 is therefore possible to pivot the membrane 20 about its pivot axis (P) by subjecting the membrane 20 to a magnetic field produced by an external excitation coil 6 solenoid type or planar.
• the membrane 20 is therefore able to take two distinct extreme positions.
• a first extreme position (FIG. 6C)
• the end of the membrane 20 carrying the contact 21 is raised and does not bear against the conductive tracks 31, 32.
• the electrical circuit is so open.
• the second extreme position FIGS. 6A and 6B
• the end of the membrane 20 carrying the contact 21 bears against the conductive tracks 31, 32. In this second position, the electrical circuit is closed.
• a first magnetic field B 0 preferably as uniform as possible, is applied to the microactuator 2.
• This first magnetic field B 0 has field lines perpendicular to the surface 30 of the substrate 3. As shown in FIGS. 6C, the field lines of this first magnetic field B 0 are directed towards the surface 30 of the substrate 3.
• This first magnetic field B 0 can be generated by a permanent magnet or an electromagnet.
• a magnetic circuit having as its magnetic source a permanent magnet or an electromagnetic coil 5 ' may be used to create this first magnetic field B 0 .
• this magnetic circuit consists of a permanent magnet (FIG. 7A) or an electromagnetic coil 1 (FIG. 7B) and two parallel air gap pieces 50, 51. and other of the permanent magnet or the coil 5 'and between which the first magnetic field B 0 is generated.
• FIGS. 7A and 7B this magnetic circuit consists of a permanent magnet (FIG. 7A) or an electromagnetic coil 1 (FIG. 7B) and two parallel air gap pieces 50, 51. and other of the
• An electromagnet comprising an external solenoid excitation coil 6 as shown in FIG. 5, connected to a current source, surrounds the substrate 3 as well as the microactuator 2 supported by the substrate 3.
• the microactuator 2 is thus placed in the center of the excitation coil 6, in the central channel of the coil 6.
• the passage of a current in the excitation coil 6 generates a magnetic field direction parallel to the substrate 3 and perpendicular to the pivot axis (P) membrane to control the pivoting of the membrane 20 from one of its positions to the other of its positions.
• the direction of the current flowing through the excitation coil 6 decides the pivoting of the membrane 20 towards one or other of its extreme positions.
• the solenoid-type excitation coil 6 may be manufactured by printed circuit techniques or by winding a copper wire.
• the microsystem can comprise several microactuators organized in a matrix and subjected to the influence of the first magnetic field B 0 and that of the second temporary magnetic field created by the coil 6 to control the switching of the microactuators.
• the matrix is placed in the center of the excitation coil 6.
• the substrate 3 supporting the microactuator 2 and surrounded by the solenoid excitation coil 6 is placed under the effect of the first magnetic field B 0 , for example in the gap of the magnetic circuit described above in connection with FIGS. 7A and 7B.
• the first magnetic field B 0 initially generates a magnetic component BP 0 in the membrane 20 along its longitudinal axis (A).
• the magnetic torque resulting from the first magnetic field B 0 and the component BP 0 generated in the membrane 20 holds the membrane 20 in one of its extreme positions, for example in the second extreme position (FIG. 6A).
• the contact 21 carried by the membrane 20 electrically connects the two tracks 31, 32 and the conductive circuit is closed.
• the second magnetic field BS 1 created by the excitation coil 6 generates a magnetic component BP 1 in the magnetic layer of the membrane 20. If the current is delivered in a suitable direction, this new magnetic component BP 1 opposes the BP 0 component generated in the magnetic layer of the membrane 20 by the first magnetic field B 0 .
• the second magnetic field BS 1 created by the excitation coil 6 is only transient and is only useful for pivoting the membrane 20 from one position to the other.
• the membrane 20 is then held in its first position under the effect of the only first magnetic field B 0 creating a new magnetic component BP 2 in the membrane 20.
• the new magnetic pair created between the first magnetic field B 0 and the BP component 2 generated in the membrane 20 requires the membrane 20 to remain in its first position ( Figure 6C).
• the contact 21 carried by the membrane 20 is spaced from the two conductive tracks 31, 32 present on the substrate 3.
• the electrical circuit is then open.
• the membrane 20 must again be rotated to its second position.
• a current is delivered in the excitation coil 6 in a direction opposite to that defined above.
• the magnetic field created by the excitation coil 6 is therefore oriented in a direction opposite to the previous magnetic field BS 1 .
• This magnetic field generates a magnetic component in the membrane 20 opposite the BP 2 component. If this new magnetic component is of greater intensity than the component BP 2 , the magnetic torque resulting from the first magnetic field B 0 and this new magnetic component causes the tilting of the membrane 20 to its second position.
• the intensity of the current to be delivered in the excitation coil 4 for pivoting the membrane 20 depends on the number of turns constituting the excitation coil 6 as well as the density of the magnetic field along the excitation coil 6.
• the excitation coil is of planar type (not shown).
• the magnetic field created is therefore radial.
• the substrate is then arranged relative to the coil so that the radial magnetic field created by the coil is parallel to the surface 30 of the substrate 3 and perpendicular to the axis (P) of pivoting of the membrane 20.
• the excitation coil is external to the substrate and the microactuator, that is to say, it is independent of them.
• the substrate carrying the microactuator is for example glued to said coil.
• the invention consists in creating a reluctant magnetic circuit by using the ferromagnetic layer 200 of the membrane 20 and by integrating into the substrate 3 a reinforcement circuit 4 also made of ferromagnetic material.
• the ferromagnetic material used for this reinforcing circuit 4 and for the layer 200 of the membrane 20 is, for example, of the soft magnetic type and may be a FeNi type alloy ("permalloy").
• the reinforcing circuit 4 is disposed under the two conductive tracks 31, 32 and extends at the space between the two tracks 31, 32 to act on the membrane 20 above, in the vertical. Seen from the side, this reinforcement circuit 4 has the shape of a U (FIG. 2), and therefore has two symmetrical parallel wings 41, 42 joined by a central core 40 perpendicular to the two wings 41, 42.
• the central core 40 is disposed under the tracks 31, 32 conductors and the two wings 41, 42 extend perpendicularly on either side of the two tracks 31, 32 conductors.
• the reinforcing circuit 4 is oriented so as, in its longitudinal direction, to be parallel to the direction followed by the current I in the conductive tracks 31, 32 when the electric circuit is closed.
• the wings 41, 42 of the reinforcement circuit 4 each terminate in a surface 43 situated in a plane parallel to the plane of the conductive tracks 31, 32 so as to define each an air gap E 1 , E 2 with a parallel surface of the ferromagnetic layer. 200 of the membrane 20 located vis-à-vis.
• the two conductive tracks 31, 32 are slightly raised relative to the surfaces 43 of the wings 41, 42 so as to always leave a gap E 1 , E 2 residual between the reinforcing circuit and the ferromagnetic layer 200 of the membrane 20 even when the contact 21 of the membrane 20 is pressed against the tracks 31, 32 conductors.
• the actuation of the membrane 20 closes the electrical circuit.
• the reluctant magnetic circuit is then created so that the current I, crossing the conductive tracks 31, 32 and the mobile contact 21 effecting the junction, generates a magnetic field B whose field lines encircle the conductive tracks 31, 32 and the movable contact 21.
• These field lines are formed transversely to the direction of the current I through the tracks 31, 32 and follow the U-shape of the reinforcement circuit 4, pass through a first gap E 1 , follow the ferromagnetic layer 200 of the membrane 20 and pass by the second air gap E 2 before joining the reinforcement circuit 4 (FIGS. 1 and 2).
• the meaning of these lines of field is determined by the known rule of the corkscrew or the amp-man.
• the magnetic field B generates an additional contact force F 'of the movable contact 21 of the membrane 20 against the conductive tracks 31, 32 whose intensity varies as a function of the intensity of the current I passing through the microactuator 2.
• a given current for example less than a threshold current.
• This threshold current is for example the current of appearance of an electric arc.
• the additional contact force F may make it possible to prevent the opening of the microactuator as long as the current flowing in it is greater than the threshold current, this threshold value is, for example, 0.2 Ampere.
• the membrane 20 is pressed against the conductive tracks 31, 32 by a permanent main contact force F (FIG. 8) generated for example by the action of a permanent magnetic field such as the first magnetic field B 0 .
• F permanent main contact force
• the passage of the current I through the microactuator 2 creates an additional positive contact force F ', variable according to the oscillations of the current I.
• Such an opening force F O uv can be generated by energizing an electromagnet such as that comprising the excitation coil 6.
• the excitation coil 6 generates the second magnetic field BSi of sufficient intensity to create the opening force F O.
• the additional force that can be obtained with such a reluctant magnetic circuit, for a current of 0.2 A through the microactuator 2 is of the order of one hundred ⁇ N. If the main contact force F is 500 ⁇ N and the additional force F 1 of 100 ⁇ N for a current of 0.2A, it will suffice to generate an opening force F O uv greater than 500 ⁇ N and less than 600 ⁇ N, for example 520 ⁇ N to be sure to cause the opening of the microactuator 2 without generating an electric arc ( Figure 8).
• the conductive tracks 31, 32 and the movable contact piece 20 "comprising the ferromagnetic layer 200" and the movable contact 21 ' are placed in the U formed by the reinforcing circuit 4 in ferromagnetic material.
• the air gaps E 3 , E 4 of the reluctant magnetic circuit B 1 created by the passage of the current I in the closed electrical circuit, are made directly between the inner lateral faces 44 of each of the wings 41, 42 of the reinforcement circuit 4 and the surfaces parallel opposites of the ferromagnetic layer 200 '.
• the reluctant magnetic circuit B 1 thus passes through the reinforcement circuit 4 and the ferromagnetic layer 200 "to, as previously, to generate an additional contact force F".
• the movable contact piece 20 ' can be actuated by various means and in particular by closing means, for example magnetic or electromagnetic type generating the first magnetic field B 0 described above and by means of opening for example of the electromagnetic type such as the excitation coil 6 described above.
• closing means for example magnetic or electromagnetic type generating the first magnetic field B 0 described above
• opening for example of the electromagnetic type such as the excitation coil 6 described above.

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• Engineering & Computer Science (AREA)
• Power Engineering (AREA)
• Physics & Mathematics (AREA)
• Electromagnetism (AREA)
• Micromachines (AREA)
• Semiconductor Integrated Circuits (AREA)
• Magnetic Treatment Devices (AREA)

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Citations (6)

• 2006
  • 2006-01-06 DE DE602006012619T patent/DE602006012619D1/de active Active
  • 2006-01-06 EP EP06707675A patent/EP1836713B1/de not_active Not-in-force
  • 2006-01-06 AT AT06707675T patent/ATE459970T1/de not_active IP Right Cessation
  • 2006-01-06 WO PCT/EP2006/050075 patent/WO2006072628A1/fr active Application Filing

Patent Citations (6)

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