Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
  • H01H50/00—Details of electromagnetic relays
  • H01H50/16—Magnetic circuit arrangements
  • H01H50/36—Stationary parts of magnetic circuit, e.g. yoke
• • 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

Definitions

• the present invention relates to an electromechanical actuator for a switchgear, in particular of the contactor, relay or contactor-circuit breaker type, the magnetic circuit of which passes through the excitation coil of the actuator one or more times.
• This type of actuator is particularly adapted to be realized in MEMS technology.
• the invention also relates to a switch device provided with such an actuator.
• a switchgear has fixed contacts that cooperate with movable contacts for the purpose of switching power to an electrical load connected downstream of the apparatus.
• the movement of the moving contacts is generally effected by means of an electromechanical actuator, or electromagnet.
• This actuator usually comprises a magnetic circuit of ferromagnetic material, such as iron, which is composed of a fixed part and a movable part, which are separated by an air gap.
• the mobile part also called mobile pallet, is coupled to the moving contacts of the switch device and moves between an open position and a closed position under the action of an electric control current flowing in a control coil, also called excitation coil.
• the open position corresponds to a maximum air gap between the fixed part and the moving part of the magnetic circuit and the closed position corresponds to a minimum air gap.
• the magnetic circuit passes through the space inside the winding of the excitation coil.
• the attractive force of the moving part towards the fixed part of the magnetic circuit is substantially proportional to the square of the amperes-turns (that is to say electric current of control of the coil multiplied by the number of turns of the coil) creating the magnetic flux. It is also practically inversely proportional to the square of the air gap of the magnetic circuit. In the open position, the attractive force must be sufficiently large at the start of the call phase to attract the mobile part of the magnetic circuit and overcome the mechanical stress resistant, despite a maximum gap. This therefore requires a lot of ampere-turns which are obtained by a large number of turns of the coil and / or by a large control electric current.
• the invention describes an electromechanical actuator for a switch electrical apparatus, comprising an excitation coil consisting of a coil wound around an interior space, a magnetic circuit made of ferromagnetic material comprising a fixed part and a pallet which is movable. between an open position and a closed position under the action of an electric current flowing in the coil and causing the circulation of a magnetic flux in the magnetic circuit.
• said magnetic flux crosses several times the internal space of the coil in the open position and passes once inside the space of the coil in the closed position.
• FIG. 1 represents an exemplary embodiment of an actuator according to the invention, in plan view along an axis YY, - Figures 2 and 3 show the example of Figure 1 respectively in the open position and in the closed position, in side view along an axis XX, - the FIGS. 4a, 4b schematize the path of the magnetic flux flowing in the magnetic circuit of the actuator of FIG. 1 respectively in the open and closed position;
• FIG. 5 gives, for the actuator of FIG. 1, a simplified view of the curve representing the force as a function of the stroke of the movable pallet of the actuator
• - Figure 6 shows another embodiment of an actuator according to the invention.
• an electromechanical actuator of a switch device comprises a conventional excitation coil 10 formed by a
• the actuator also comprises a magnetic circuit made of ferromagnetic material comprising a fixed part 20 and a movable pallet 30 which can move between an open position and a closed position.
• the open position corresponds to a gap e1 maximum between the fixed portion 20 and the movable pallet 30 and the closed position corresponds to a gap e2 minimum between the fixed portion 20 and the movable pallet 30.
• This minimum gap e2 is retained either by means mechanical devices that prevent the movable portion 30 from being pressed completely against the fixed portion 20, or by a non-ferromagnetic material of thickness e2 which covers one of the surfaces placed facing each other in the magnetic circuit.
• the moving pallet 30 is nevertheless represented in dashed lines in FIG. 1.
• an electric control current flows in the coil 10
• a magnetic flux is created in the magnetic circuit causing a force tending to decrease the gap, that is to say to bring the movable blade 30 of the fixed portion 20 of the magnetic circuit.
• the reverse movement can be obtained by various return means such as a return spring.
• the fixed part 20 of the magnetic circuit comprises a first end 21, a median section 23 which is connected to the first end 21 by a first part of the magnetic circuit 41, 42, 43 passing through the internal space 15 of the coil 10, and comprises a second end 22 which is connected to the median section 23 by a second portion of the magnetic circuit 45,46,47, disjoint from the first part, also passing through the internal space 15 of the coil 10.
• the median section 23 is therefore between the two ends 21,22 and the two ends 21,22 are positioned on either side of the coil 10.
• the fixed part 20 comprises a first, a second and a third element, each element being substantially U-shaped with a central base surrounded by two lateral branches.
• the cross section of these elements can be either rectangular as shown in Figures 2 and 3, or circular.
• the first branch 41 of the first element carries the first end 21 of the fixed part 20 of the magnetic circuit.
• the central base 42 of the first element passes through the interior space 15 of the coil 10.
• the first branch 43 of the second element is common to the second branch of the first element.
• the central base 44 of the second element is external to the coil 10 and carries the middle portion 23 of the fixed portion 20 of the magnetic circuit.
• the first branch 45 of the third element is common to the second branch of the second element.
• the central base 46 of the third element passes through the inner space 15 of the coil 10 and the second leg 47 of the third element carries the second end 22 of the fixed part 20 of the magnetic circuit.
• the movable pallet is rotatable between the open and closed positions.
• the first end 21, the second end 22 and the median section 23 of the magnetic circuit are oriented towards the face 31 of the mobile pallet 30 and are arranged so that, when the movable vane 30 is in the closed position, they are all substantially equidistant from the inner face 31 of the movable vane 30, corresponding to the minimum gap e2 as shown in Figure 3.
• the dimensions of the pallet 30 are sufficient to substantially cover the ends 21,22 and the median section 23, as in FIG. 1.
• the ends 21,22 and the median section 23 of the magnetic circuit are raised relative to the remainder of the part fixed 20 of the magnetic circuit, so that, in the closed position, the magnetic flux coming from the moving vane 30 passes exclusively through the first end 21, the second end x 22 and the middle section 23 of the magnetic circuit.
• the distance e1 between the movable pallet 30 and each end 21,22 of the fixed portion 20 of the magnetic circuit is less than the distance e3 between the movable pallet 30 and the section median 23. In the case of the example described, this is due to the fact that the pallet 30 is rotatable about an axis which is closer to the ends 21,22 that the median section 23.
• the dotted line corresponds to the passage of the magnetic flux B in the moving part 30. It can thus easily be seen in FIG. 4a that the path of the magnetic flux is as follows: 30, e1, 21, 41, 42, 43, 44, 45, 46, 47, 22, e1, 30.
• the magnetic flux B must therefore cross twice the internal space of the coil 10, via the bases 42,46, to bounce off the moving pallet 30. As and when the approximation of the pallet 30 during the call phase, the distance between the distances e1 and e3 will gradually decrease to arrive at the single value e2, corresponding to the gap of the closed position of FIG. 3.
• the flow B passes as much between the movable portion 30 and the two ends 21,22 as between the movable portion 30 and the middle portion 23, which is represented by the dashed lines of Figure 4b.
• the two ends 21,22 and the middle section 23 are in magnetic "short-circuit" so that the path of the magnetic flux B is as follows: 30, e2, 21/23, 41 / 45, 42/46, 43/47, 22/23, e2, 30.
• the magnetic flux B thus crosses the inner space of the coil 10 through the bases 42, 46 which must be considered as being parallel and therefore comparable to a single element passing through the coil 10.
• FIG. 5 schematizes a diagram of the forces applied to the mobile pallet 30 as a function of its stroke, during the closing phase.
• the symbols F and O respectively correspond to the closed and open positions of the pallet 30.
• the vertical line 54 corresponds to the position where the movable contacts connected to the movable pallet 30 come into contact with the fixed contacts of the switch device ; the contact crushing stroke is located to the left of this line 54.
• a first curve 50 shows the motor force curve obtained with an actuator whose flow continuously crosses the coil twice.
• a second curve 51 shows a stress curve with an equivalent actuator whose flow continuously crosses the coil once. It is evident that the curve 50 is always above the curve 51 because the effort generated is logically always greater with an actuator permanently crossing the coil twice.
• a third curve 52 corresponds to the actual curve of the actuator according to the invention described in the example of FIGS. 1 to 3.
• the curve 52 is comparable to the race 50 and then moves away from it progressively. align on the curve 51 in the closed position. This spacing is progressive since, as indicated above, as the approximation of the pallet 30 during the call phase, the distance between the distances e1 and e3 will gradually decrease to arrive at the single value e2.
• FIG. 5 also shows in dotted line the resisting force 53 of the actuator. It can be seen that in order to overcome the resistive force 53 in the open position with a conventional solution, it would have been necessary to take an actuator conforming to the curve 50, since the motor force 51 is less than the resistive force 53 in this open position.
• this curve 50 gives a very important effort not necessary in the closed position, which can cause including significant mechanical shocks at the end of the call phase and unnecessarily high consumption in the maintenance phase of the closed position.
• the invention therefore provides the advantage of reducing mechanical shocks during closure, as well as better control of the dropout voltage.
• the curve 52 makes it possible to optimize the motor force necessary to overcome the resisting force 53 whatever the position of the mobile pallet, without requiring additional electrical or electronic means, but playing only on the arrangement of the magnetic circuit.
• the actuator described in the invention can be made in conventional technology, but the MEMS (Micro Electro-Mechanical System) technology is also particularly suitable for producing such an actuator. Indeed, the realization by Deposition of successive layers in an iterative process lends itself well to the manufacture of a magnetic circuit and a coil having the form described. With this MEMS technology, the return means creating the resistant force could be obtained by elastic deformation of one of the parts. Furthermore, an electrical device could then include one or more actuators, so as to achieve the desired breaking capacity.
• MEMS Micro Electro-Mechanical System
• the variant shown in Figure 6 shows another example of arrangement of the fixed portion 20 'of the magnetic circuit, to create three separate passages in the inner space of the coil 10', instead of two.
• the fixed part then comprises two median sections 23 ', 24' which, in the closed position, are arranged to be situated at the same distance from the movable pallet 30 'as the two ends 21', 22 'of the part fixed.
• the magnetic flux then only crosses the inside space of the coil once, via three "parallel" passages.
• the median sections 23 ', 24 "are farther from the moving pallet 30' than the two ends 21 ', 22', so that the magnetic flux passes only between the movable pallet and the two ends of the pallet.
• fixed part which forces the magnetic flux to cross three times the inner space of the coil, as can be seen clearly in Figure 6.
• the multiplier effect is obviously greater.

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• Physics & Mathematics (AREA)
• Electromagnetism (AREA)
• Reciprocating, Oscillating Or Vibrating Motors (AREA)
• Electromagnets (AREA)
• Valve-Gear Or Valve Arrangements (AREA)
• Valve Device For Special Equipments (AREA)

Priority Applications (3)

Applications Claiming Priority (2)

Publications (1)

Family

ID=34630332

Family Applications (1)

Country Status (7)

Citations (2)

• 2003
  • 2003-12-19 FR FR0314978A patent/FR2864329B1/fr not_active Expired - Fee Related
• 2004
  • 2004-12-16 PL PL04804898T patent/PL1697955T3/pl unknown
  • 2004-12-16 WO PCT/EP2004/053552 patent/WO2005066989A1/fr active IP Right Grant
  • 2004-12-16 AT AT04804898T patent/ATE356419T1/de not_active IP Right Cessation
  • 2004-12-16 ES ES04804898T patent/ES2281847T3/es active Active
  • 2004-12-16 EP EP04804898A patent/EP1697955B1/de not_active Not-in-force
  • 2004-12-16 DE DE602004005243T patent/DE602004005243T2/de active Active

Patent Citations (2)

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