WO2007016985A1 - Actionneur électromagnétique - Google Patents

Actionneur électromagnétique Download PDF

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Publication number
WO2007016985A1
WO2007016985A1 PCT/EP2006/005006 EP2006005006W WO2007016985A1 WO 2007016985 A1 WO2007016985 A1 WO 2007016985A1 EP 2006005006 W EP2006005006 W EP 2006005006W WO 2007016985 A1 WO2007016985 A1 WO 2007016985A1
Authority
WO
WIPO (PCT)
Prior art keywords
ferromagnetic
coil
members
electromagnetic actuator
circuit
Prior art date
Application number
PCT/EP2006/005006
Other languages
English (en)
Inventor
Patrick Ward
Original Assignee
Tripco Limited
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Tripco Limited filed Critical Tripco Limited
Publication of WO2007016985A1 publication Critical patent/WO2007016985A1/fr

Links

Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H51/00—Electromagnetic relays
    • H01H51/01—Relays in which the armature is maintained in one position by a permanent magnet and freed by energisation of a coil producing an opposing magnetic field
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H50/00—Details of electromagnetic relays
    • H01H50/16—Magnetic circuit arrangements
    • H01H50/18—Movable parts of magnetic circuits, e.g. armature
    • H01H50/32—Latching movable parts mechanically
    • H01H50/326—Latching movable parts mechanically with manual intervention, e.g. for testing, resetting or mode selection
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H71/00—Details of the protective switches or relays covered by groups H01H73/00 - H01H83/00
    • H01H71/10—Operating or release mechanisms
    • H01H71/12—Automatic release mechanisms with or without manual release
    • H01H71/24—Electromagnetic mechanisms
    • H01H71/32—Electromagnetic mechanisms having permanently magnetised part
    • H01H71/321—Electromagnetic mechanisms having permanently magnetised part characterised by the magnetic circuit or active magnetic elements
    • H01H71/322—Electromagnetic mechanisms having permanently magnetised part characterised by the magnetic circuit or active magnetic elements with plunger type armature

Definitions

  • This invention relates to an electromagnetic actuator.
  • Figures IA and IB show an example of an electromagnetic actuator configured for use as a circuit breaker.
  • the actuator comprises a solenoid 10 comprising a bobbin 12 having a coil 13 wound on it.
  • the bobbin 12 is fixed to a printed circuit board (PCB) 15 on which are also fitted two fixed contacts 16.
  • An axially slidable ferromagnetic plunger 14 is fitted within the bore of the bobbin 12.
  • the plunger 14 has a reset button 18 and is biased downwardly against the PCB 15 by a compression spring 20 acting between the PCB and reset button.
  • the actuator further comprises an inverted generally U-shaped contact closure member 22 which cooperates with two movable electrical contacts 24 carried at the ends of respective spring arms 26 made, for example, of beryllium copper.
  • the spring arms 26 resiliently bias the contact closure member 30 away from the PCB 15 to a first position against stops 28 fixed relative to the PCB 15, so as to maintain the moving contacts 24 normally out of contact with the fixed contacts 16.
  • the movable contacts 24 may be mounted directly on the lower ends of the opposite arms 22 A of the member 22, the latter being biased against the stops 28 by separate spring(s), not shown.
  • the contact closure member 22 includes a compartment containing a permanent magnet 30.
  • the reset button 18 When the reset button 18 is pressed upwards against the bias of the spring 20, the plunger 14 slides upwardly in the solenoid 10 until the air gap between the top of the plunger 14 and the permanent magnet 30 is closed to such an extent that the plunger magnetically entrains the permanent magnet.
  • the biasing force of the spring 22 acting downwardly on the plunger 14 is greater than that of the springs 26 acting upwardly on the member 22, and providing also that the permanent magnet 30 is sufficiently strong to remain magnetically entrained with plunger, when the reset button 18 is released the contact closure member 22 is drawn from its first position to a second position in which the moving contacts 24 come to reset on the fixed contacts 16, thereby closing an electrical circuit.
  • Figure 1 can be used as a circuit breaker wherein the contacts are closed by manual means and automatically opened by electrical means.
  • Figure 1 is referred to as a mechanically latching mechanism because the actuator can be latched in the absence of current flow in the solenoid coil.
  • the arrangement of Figure 1 can be modified very easily to provide for an electrically latching version, in which the actuator can only be latched when a current of sufficient magnitude flows in the solenoid coil, operating in similar manner to a conventional relay.
  • the permanent magnet 30 is replaced with a ferromagnetic material, for example a mild steel plate, and a current is caused to flow continuously through the solenoid coil 13 so as to produce a magnetic field in the plunger 14.
  • the reset button 18 is pressed upwards as before so as to present the plunger to the plate, and provided the current is above a predetermined threshold the magnetic attraction between the plate and plunger will be of sufficient strength to cause the plunger to entrain the plate when the reset button is released and cause the circuit breaker contacts 16, 24 to be closed as before. They will remain closed provided the current remains above the threshold, but reduction of the current below the threshold will so reduce the magnetic field as to cause automatic opening of the contacts.
  • the electrically latching version offers the benefit of automatic opening of the contacts by intentional or unintentional interruption of the current flow through the solenoid coil.
  • FIG. 1 A problem in the design of Figure 1 is that it is an inefficient electromagnet in that it requires a relatively large current for its effective operation as a circuit breaker. Efficiency can be improved by adding a ferromagnetic frame to the arrangement so as to use more of the available magnetic flux.
  • An example is shown in Figure 2.
  • Figure 2 A shows an arrangement of an electromagnetic actuator with a ferromagnetic frame 32 surrounding the solenoid 10.
  • the operation of the actuator is essentially the same as for the electrically latching version of Figure 1, having a mild steel plate 34 in place of the permanent magnet 30.
  • the frame 32 as shown is referred to as a box frame because it is shaped like a four-sided box.
  • the frame 32 and solenoid 10 are fixed relative to the PCB 15, and the frame 32 has a hole at the top and bottom to provide clearance for the travel of the plunger 14.
  • Figure 2B shows the reset button 18 in the depressed state such that the top of the plunger 14 engages the plate 34.
  • the reset button is released, the contact closure member 22 is drawn downwards as before so that the moving contacts 24 engage the fixed contacts 16.
  • the arrangement of Figure 2 provides a significant improvement in efficiency over that of Figure 1 because much of the external magnetic field is harnessed by the frame.
  • a weakness in the arrangement of Figure 2 is that even with the frame fitted, there are large air gaps in the magnetic circuit. These air gaps exist between the frame and the plunger at the top and bottom of the frame, and are unavoidable because the plunger has to be able to move freely within the frame. It is well known that the most critical factor in the performance of an electromagnetic actuator is the sum of the air gaps, the larger the air gaps the weaker the available electromagnetic force.
  • the invention provides an electromagnetic actuator comprising a plurality of ferromagnetic members including at least first and second ferromagnetic members, a coil surrounding at least one of the plurality of ferromagnetic members, and resilient biasing means biasing the first and second ferromagnetic members apart, the second ferromagnetic member being movable towards and into engagement with the first ferromagnetic member such that the plurality of ferromagnetic members form a closed ferromagnetic circuit substantially without air gaps, the ferromagnetic circuit remaining in the closed state upon release of the second ferromagnetic member, by magnetic attraction between its components, provided a predetermined current condition exists in the coil, a sufficient change in the current flowing in the coil reducing the magnetic attraction between the components of the ferromagnetic circuit to allow the first and second ferromagnetic members to separate under the action of the resilient biasing means.
  • one of the first and second ferromagnetic members is associated with at least one movable contact such that upon closure of the ferromagnetic circuit and release of the second ferromagnetic member the movable contact is maintained in engagement with at least one fixed contact as long as the predetermined current condition exists.
  • Figure IA is a schematic diagram of a known electromagnetic actuator configured for use as a circuit breaker.
  • Figure IB is a side view of the contact closure member of Figure IA with the contacts open.
  • Figures 2A and 2B previously described, are schematic diagrams of a modified electromagnetic actuator with a ferromagnetic frame surrounding the solenoid.
  • Figures 3 A to 3 C are schematic diagrams of an electromagnetic actuator according to a first embodiment of the invention.
  • FIGS 4 to 9 are schematic diagrams of further embodiments of the invention respectively.
  • orientation and relative position such as “top”, “bottom”, “above” and “below” refer to the orientation of the various actuators as seen in the drawings and do not limit their orientation in use.
  • Figure 3 A is a schematic diagram of a first embodiment of the invention in its open state, and is a modification of the electrical latching actuator of Figure 2.
  • the frame comprises two mild steel ferromagnetic members: a lower generally U-shaped member 36 whose opposite arms extend upwardly along opposite sides of the solenoid 10, and an upper member in the form of a plate 38 fixed to the contact closure member 22 and extending transversely across the free upper ends of the arms of the U-shaped member 36.
  • Coaxially aligned ferromagnetic plungers 14A and 14B are rigidly fixed to the lower and upper frame members 36 and 38 respectively, the plungers extending towards one another into opposite ends of the solenoid coil 13 wound on the bobbin 12.
  • the plunger 14A or 14B is a press fit into the U-shaped member 36 or plate 38 respectively so as to minimise the air gaps within each plunger/frame section.
  • the plungers 14 A, 14B are independently slidable within the bore of the bobbin 12, which is fixed relative to the PCB 15, and in the open state of the actuator the member 22 is biased by the springs 26 against the stops 28 and the plunger 14A is biased against the PCB 15 by the spring 20.
  • the open state of the actuator there is an air gap G between the adjacent ends of the plungers 14 A, 14B within the solenoid, and a respective air gap G between each free upper end of the U-shaped frame member 36 and the transverse frame member 38, all three air gaps G being substantially the same width.
  • a current above a predetermined threshold flows continuously through the solenoid coil 13.
  • the frame member 36 and affixed plunger 14A move upwardly until the free end of the plunger 14A engages the free end of the plunger 14B and the transverse frame member 38 engages the free upper ends of the U-shaped frame member 36, Figure 3B.
  • the frame members 36 and 38 and the plungers 14A and 14B form a closed ferromagnetic circuit substantially without air gaps.
  • Figure 4 shows a further embodiment of the invention which' juses a permanent magnet 30, the actuator being shown in its open state.
  • one or more of the plungers 14 A, 14B and frame members 36, 38 could be made as a permanent magnet.
  • each part 14A/36 and 14B/38 of the ferromagnetic circuit has three surfaces which mate with corresponding surfaces of the other part.
  • each plunger is forcibly fitted into its respective frame member and the various mating surfaces of the plungers and the frame members are ground to a high degree of flatness.
  • the permanent magnet 30 provides the magnetic holding force to keep the ferromagnetic circuit closed.
  • the springs 26 act on the member 22 to bias it to the open position against the stops 28. Because the reset spring 20 is stronger than the springs 26, the reset spring will cause the closed ferromagnetic circuit to come to rest with the contacts 16, 24 in the closed position when the reset button is released. Under this condition there will be a net downward force on the contacts and the top section of the mechanism. It will require a current of a predetermined magnitude and polarity to sufficiently reduce the magnetic holding force so as to cause automatic opening of the contacts.
  • the plunger 14B is omitted and the plunger 14A made long enough to directly engage the transverse frame member 38 when the latter engages the upper ends of the U- shaped frame member 36.
  • the plunger 14A is omitted and the plunger 14B made long enough to directly engage the base of the U-shaped frame member 36 when the transverse frame member 38 engages the upper ends of the U-shaped frame member.
  • a closed ferromagnetic circuit substantially without air gaps is formed when the reset button 18 is pressed, and apart from the replacement of two plungers by a single plunger the actuators operate the same as that of Figures 3 A to 3 C.
  • Each can also be adapted to incorporate a permanent magnet, either as a separate entity 30 or as part of the ferromagnetic circuit itself, and in that case would operate as described for Figure 4.
  • the spring 42 is omitted and the member 22 and contacts 24 are fixed relative to the PCB 15.
  • the contacts 16 are the movable contacts, and they are fitted to arms extending laterally from the frame member 36 rather than to the PCB.
  • the spring 40 normally holds the contacts open but when the button 18 is pressed the U-shaped frame member 36 and plunger 14A move upwardly to close the ferromagnetic circuit. This also closes the contacts 16 onto the contacts 24. This is the closed condition of the actuator and is maintained in this condition, against the fort of the spring 40 tending to open it, by a sufficient current flowing in the solenoid coil 13.
  • a U-shaped ferromagnetic frame member 36 with a transverse member 38 provides a double box frame providing two closed magnetic paths having a common centre part constituted by the plunger(s) 14 or 14A/14B and respective outer parts extending along opposite sides of the solenoid 13.
  • the actuator would also work quite effectively with a frame using just a single closed magnetic path.
  • the advantage of a single path arrangement is that there are only two air gaps to close, which can be done more easily than trying to close three air gaps simultaneously.
  • Figure 8 shows an embodiment to illustrate this arrangement, and is a modification of Figure 5.
  • the lower frame member 36 is L-shaped. It has a full length plunger 14A forcible fitted into it.
  • the top frame member 38 is selected in length so as to straddle the top of the plunger 14A and the top of the L-shaped member 36. This provides for a single magnetic path when the ferromagnetic circuit is closed.
  • the operation of this embodiment is the same as for the double box framed version of Figure 5.
  • the single magnetic path modification shown in Figure 8 can be applied to any of the preceding embodiments using a double box frame.
  • the plunger or plungers are force fitted into their respective frame members to minimise air gaps.
  • the air gaps will not be completely eliminated due to plating and slight imperfections between the mating surfaces.
  • the ferromagnetic circuit will remain in its closed state and move, as a whole, downwardly relative to the fixed solenoid coil 13 under the action of the spring 20 (whose restoring force is greater than the force of the springs 26) until the movable contacts 24 engage the fixed contacts 16.
  • the actuator will remain in this state until the current in the coil 13 falls below the predetermined threshold whereupon the electromagnetic attraction between the two parts 36A and 38 of the ferromagnetic circuit is no longer strong enough to maintain the circuit closed against the force of the springs 20, 26 tending to bias them apart. The actuator thus reverts to the open state shown in Figure 9.
  • the actuator of Figure 9 can be modified to incorporate a permanent magnet, either as a separate entity 30 ( Figure 4) or as part of the ferromagnetic circuit itself.
  • a permanent magnet either as a separate entity 30 ( Figure 4) or as part of the ferromagnetic circuit itself.
  • the solenoid coil 13 consists of only a single winding.
  • the solenoid coil can comprise one or more windings, and these may overlap on the same ferromagnetic member or be disposed on different ferromagnetic members.
  • the actuator will latch only when the vector sum of the currents in the various windings is above a predetermined threshold, and will revert to the open state when the vector sum of the currents drops below the threshold.
  • the actuator will latch only when the vector sum of the currents flowing in the various windings and acting in opposition to the permanent magnetic field is below a predetermined threshold, and will revert to the open state when the vector sum of the currents rises above the threshold.
  • the bobbin 12 and coil 13 are fixed in position relative to the PCB 15, so that the housing 36 and the plungers 14A and/or 14B, or the arm 14C, slide relative to the fixed coil 16 as the actuator closes and opens.
  • the coil 13 it is possible to mount the coil 13 so that it moves relative to the PCB 15 with the reset button 18, for example by fixing it to the plunger 14A or arm 14C.

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  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Electromagnets (AREA)

Abstract

L’invention concerne un actionneur électromagnétique comprenant un premier élément de châssis ferromagnétique et un second élément de châssis ferromagnétique (36, 38) de même qu’une bobine solénoïde (13) entourant au moins un autre élément ferromagnétique (14 A, 14B) s’étendant depuis le premier élément de châssis ou bien le second élément de châssis vers l’autre élément de châssis. Un moyen de polarisation résilient (20, 26) polarise le premier élément de châssis et le second élément de châssis pour les écarter. Le second élément de châssis (38) est mobile en direction du (et peut s’engager dans le) premier élément de châssis (36) de sorte que le premier élément de châssis et le second élément de châssis et ledit au moins un autre élément ferromagnétique forment un circuit ferromagnétique fermé sensiblement sans entrefer. Le circuit ferromagnétique reste en condition fermée jusqu’au relâchement du second élément de châssis, par attraction magnétique entre ses composants, sous réserve de la présence d’une condition de courant prédéterminée dans la bobine solénoïde. La suppression de la condition de courant prédéterminée réduit l’attraction magnétique entre les composantes du circuit ferromagnétique pour permettre au premier élément de châssis et au second élément de châssis de se séparer sous l’action du moyen de polarisation résilient.
PCT/EP2006/005006 2005-07-28 2006-05-24 Actionneur électromagnétique WO2007016985A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
IES2005/0511 2005-07-28
IES20050511 IES20050511A2 (en) 2005-07-28 2005-07-28 An electromagnetic actuator

Publications (1)

Publication Number Publication Date
WO2007016985A1 true WO2007016985A1 (fr) 2007-02-15

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PCT/EP2006/005006 WO2007016985A1 (fr) 2005-07-28 2006-05-24 Actionneur électromagnétique

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IE (1) IES20050511A2 (fr)
WO (1) WO2007016985A1 (fr)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2013139521A1 (fr) * 2012-03-23 2013-09-26 Tripco Limited Commutateur électromagnétique s'utilisant avec un équipement électrique
US9404198B2 (en) * 2012-07-30 2016-08-02 Rayton Solar Inc. Processes and apparatuses for manufacturing wafers
US9800043B2 (en) 2014-12-18 2017-10-24 Shakira Limited Residual current devices
DE102018216292B4 (de) 2018-09-25 2021-10-07 Siemens Aktiengesellschaft Elektromagnetischer Auslöser für elektromagnetische Schaltgeräte mit einem gewinkelten Aufbau

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3895330A (en) * 1974-03-15 1975-07-15 Ledex Inc Bi-level solenoid holding device
US5010312A (en) * 1990-04-10 1991-04-23 Rostra Engineered Components Solenoid actuators
US5485133A (en) * 1993-12-15 1996-01-16 Tripco Limited Circuit breaker
WO2003081623A1 (fr) * 2002-03-21 2003-10-02 Tripco Limited Dispositif de commutation a reenclenchement

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3895330A (en) * 1974-03-15 1975-07-15 Ledex Inc Bi-level solenoid holding device
US5010312A (en) * 1990-04-10 1991-04-23 Rostra Engineered Components Solenoid actuators
US5485133A (en) * 1993-12-15 1996-01-16 Tripco Limited Circuit breaker
WO2003081623A1 (fr) * 2002-03-21 2003-10-02 Tripco Limited Dispositif de commutation a reenclenchement

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2013139521A1 (fr) * 2012-03-23 2013-09-26 Tripco Limited Commutateur électromagnétique s'utilisant avec un équipement électrique
US9404198B2 (en) * 2012-07-30 2016-08-02 Rayton Solar Inc. Processes and apparatuses for manufacturing wafers
US9800043B2 (en) 2014-12-18 2017-10-24 Shakira Limited Residual current devices
US10581234B2 (en) 2014-12-18 2020-03-03 Shakira Limited Residual current devices
DE102018216292B4 (de) 2018-09-25 2021-10-07 Siemens Aktiengesellschaft Elektromagnetischer Auslöser für elektromagnetische Schaltgeräte mit einem gewinkelten Aufbau

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Publication number Publication date
IES20050511A2 (en) 2006-08-09

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