(19)
(11)EP 3 425 648 B1

(12)EUROPEAN PATENT SPECIFICATION

(45)Mention of the grant of the patent:
29.07.2020 Bulletin 2020/31

(21)Application number: 16892566.7

(22)Date of filing:  03.03.2016
(51)International Patent Classification (IPC): 
H01F 7/16(2006.01)
H01F 7/08(2006.01)
H01F 7/122(2006.01)
(86)International application number:
PCT/JP2016/056601
(87)International publication number:
WO 2017/149726 (08.09.2017 Gazette  2017/36)

(54)

SOLENOID

MAGNETSPULE

SOLÉNOÏDE


(84)Designated Contracting States:
AL AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HR HU IE IS IT LI LT LU LV MC MK MT NL NO PL PT RO RS SE SI SK SM TR

(43)Date of publication of application:
09.01.2019 Bulletin 2019/02

(73)Proprietor: Nachi-Fujikoshi Corp.
Tokyo (JP)

(72)Inventor:
  • MATSUI, Takeshi
    Toyama-shi Toyama 930-8511 (JP)

(74)Representative: Gevers Patents 
Intellectual Property House Holidaystraat 5
1831 Diegem
1831 Diegem (BE)


(56)References cited: : 
EP-A2- 1 225 609
JP-A- S 646 573
JP-A- 2002 289 430
US-A- 4 419 643
WO-A1-2008/075640
JP-A- S59 501 928
US-A- 4 127 835
US-A- 4 419 643
  
      
    Note: Within nine months from the publication of the mention of the grant of the European patent, any person may give notice to the European Patent Office of opposition to the European patent granted. Notice of opposition shall be filed in a written reasoned statement. It shall not be deemed to have been filed until the opposition fee has been paid. (Art. 99(1) European Patent Convention).


    Description

    TECHNICAL FIELD



    [0001] The present invention relates to a solenoid provided with both a permanent magnet and a coil.

    BACKGROUND ART



    [0002] Conventionally, in a solenoid provided with both a permanent magnet and a coil, when the coil is not energized, magnetic flux generated by the permanent magnet passes through a portion (attraction portion) where a movable iron core and another part are attracted to each other, so that attraction force is generated. When the coil is energized, magnetic flux generated by the coil flows so as to counteract the magnetic flux generated by the magnet. As a result, since the magnetic flux (generated by the magnet) passing through the attraction portion is reduced, the attraction force decreases and finally can be canceled.

    [0003] For example, PATENT LITERATURE 1 discloses a solenoid provided with both a permanent magnet and a coil. The solenoid according to the literature has a structure in which the permanent magnet is disposed in a space surrounded by a movable iron core and a fixed iron core. Therefore, a magnetic field (magnetic path) generated by energizing the coil does not have a direct effect on the permanent magnet. Further, the literature explains that the permanent magnet is not demagnetized even in a release operation of the solenoid, so that a long life of the solenoid can be ensured.

    CITATION LIST


    PATENT LITERATURE



    [0004] PATENT LITERATURE 1: JP 2002-289430 A

    SUMMARY OF INVENTION


    TECHNICAL PROBLEM



    [0005] However, in the solenoid disclosed in PATENT LITERATURE 1, when energization of the coil is started in the release operation, magnetic flux BC generated in the coil flows against magnetic flux BM generated by the magnet (see FIG. 5 in the literature). Then, the amount of magnetic flux generated by the permanent magnet that passes through an attraction portion (a portion where a disk-shaped steel plate 6 and a protrusion 4 are in contact with each other shown in FIG. 5 of the literature) is reduced, and attraction force of the movable iron core decreases.

    [0006] After that, if the coil generates such an amount of magnetic flux that exactly counteracts the magnetic flux generated by the permanent magnet, the magnetic flux passing through the attraction portion is eliminated, so that the attraction force of the movable iron core almost disappears finally. However, if the magnetic flux generated by energizing the coil is sufficiently greater than the magnetic flux generated by the permanent magnet, the magnetic flux passing through the attraction portion is switched from the magnetic flux generated by the permanent magnet to the magnetic flux generated by the energization of the coil, and therefore there has been a problem that the generation of the attraction force is started again. In other words, there has been a problem that the release operation of the solenoid becomes incomplete depending on the amount of magnetic flux generated by the energization of the coil.

    [0007] Therefore, the present invention has been made for solving the above problems, and an object thereof is to provide a solenoid which can reliably perform a release operation by suppressing increase in amount of magnetic flux passing through an attraction portion to decrease attraction force of a movable iron core even when magnetic flux generated by the energization of a coil is greater than magnetic flux generated by a magnet.

    SOLUTION TO PROBLEM



    [0008] In order to solve the problems described above, according to the present invention, there is provided a solenoid according to present claim 1. Preferably, the predetermined distance, specified in present claim 1, is selected as specified in present claim 2.

    ADVANTAGEOUS EFFECTS OF INVENTION



    [0009] According to the solenoid of the present invention, in the type of solenoid which is provided with both the permanent magnet and the coil, the coil is disposed in the case so that the whole coil is covered with the metallic coil cover, the second ring member and the case. With this configuration, a magnetic path through which magnetic flux generated by the permanent magnet passes, and a magnetic path through which magnetic flux generated by energizing the coil passes are separately and independently generated. Further, the solenoid is configured so that a portion (attraction portion) where a movable iron core and a ring member are in contact with each other does not exist in the middle of the magnetic paths. Accordingly, even when magnetic flux generated by the coil is greater than magnetic flux generated by the magnet, it is possible to achieve a quick release operation of the solenoid by suppressing increase in amount of magnetic flux passing through the attraction portion to reliably decrease attraction force of the movable iron core.

    BRIEF DESCRIPTION OF DRAWINGS



    [0010] 

    FIG. 1A is a longitudinal sectional view (during non-energization) of a solenoid 10 which is one example of an embodiment of the present invention.

    FIG. 1B is an enlarged view of an A part of FIG. 1A.

    FIG. 2 is an operation explaining view (during energization) of the solenoid 10 shown in FIG. 1A.

    FIG. 3 is an explanatory view of a flow of a magnetic path 25 during non-energization of the solenoid 10 shown in FIG. 1A.

    FIG. 4 is an explanatory view (when a ring member 14 and a movable iron core 19 are attracted to each other) of flows of magnetic paths 26 and 27 during energization of the solenoid 10 shown in FIG. 1A.

    FIG. 5 is an explanatory view (when the ring member 14 and the movable iron core 19 are separated from each other) of the flows of the magnetic paths 26 and 27 during energization of the solenoid 10 shown in FIG. 1A.

    FIG. 6 is an explanatory view of a different embodiment where the flow of the magnetic path is in an opposite direction to the flow of the magnetic path during energization of the solenoid 10 shown in FIG. 4.


    DESCRIPTION OF EMBODIMENTS



    [0011] Hereinafter, a specific embodiment is shown to describe a solenoid according to the present invention in detail with reference to the accompanying drawings. FIG. 1A is a longitudinal sectional view of a solenoid 10 according to the present invention. FIG. 1B is an enlarged view of an A part shown in FIG. 1A.

    [0012] The solenoid 10 according to the present invention is of a type in which a permanent magnet 13 and a coil 16 are disposed in a cylindrical case 11 as shown in FIG. 1A. A circular opening 12 is formed in an end face 11a (on an upper side in FIG. 1A) of the case 11. The permanent magnet 13 of a cylindrical shape having a hole 13a is provided inside the case 11 in such a manner as to closely contact a back side (inner side) of the end face 11a of the case 11. Moreover, the hole 13a of the permanent magnet 13 and the opening 12 of the case 11 are arranged in such a positional relation as to be concentric with each other as shown in FIG. 1A.

    [0013] It should be noted that a clearance may be provided between the permanent magnet 13 and an inner wall surface of the case 11 as shown in FIG. 1A, and the clearance may be filled with a nonmagnetic material such as resin. The configurations of the permanent magnet and the coil constituting the solenoid of the present invention will be described below in detail.

    [0014] A ring member 14 is disposed on the permanent magnet 13 built in the case 11 so as to be in close contact with a lower surface (on a lower side in FIG. 1A) of the permanent magnet 13. The inside diameter side of the ring member 14 is disposed so as to be concentric with the hole 13a of the permanent magnet 13 as shown in FIG. 1A.

    [0015] Furthermore, as shown in FIG. 1B, the outside diameter side of the ring member 14 is disposed inside the case 11 at a given distance d from the inner side (inner wall) of the case 11. The distance d is in the range of 0.1 mm to 0.3 mm due to the relation with a magnetic path described below.

    [0016] A movable iron core (plunger) 19 is inserted in the cylindrically shaped coil (electromagnetic coil) 16 built in the case 11, and the movable iron core 19 can be moved in an axial direction (up-down direction in FIG. 1A) by electromagnetic force generated by energization of the coil 16 (see FIGS. 1A and 2). A recess 20 is provided in the axial direction on the one end side (lower side of FIG. 1A) of the movable iron core 19, and a spring 21 is attached to the inside of the recess 20. The one end side (upper side in FIG. 1A) of the spring 21 is fitted in the recess 20, and the other end side (lower side in FIG. 1A) of the spring 21 is fitted and thus fixed to a protrusion formed in a cap member 24 of the solenoid 10.

    [0017] Moreover, a shaft 22 is provided on the other end side (upper side of FIG. 1A) of the movable iron core 19, namely, on the side opposite to the recess 20. When the movable iron core moves in the axial direction (up-down direction in FIG. 1A), the shaft 22 can move through the opening 12 of the case 11, the hole 13a of the permanent magnet 13, and the inside diameter side of the ring member 14 accordingly.

    [0018] In addition, a metallic coil cover 17 is disposed between the coil 16 and the movable iron core 19 so as to cover the whole coil 16. The coil cover 17 has a flange 17a on its one end side. The coil cover 17 is fixed to the case 11 in such a manner that the flange 17a is fitted in the inner wall surface of the case 11 while covering the one end side (upper side in FIG. 1A) of the coil 16. Further, a clearance 18 of a given distance is formed in the axial direction of the solenoid 10 between an upper surface (upper side of FIG. 1A) of the flange 17a and a lower surface (lower side of FIG. 1A) of the ring member 14. The other end side (lower side of FIG. 1A) of the coil 16 is fixed by caulking the cap member 24 and the case 11 via a ring member 23. It should be noted that the clearance 18 may be filled with a nonmagnetic material such as resin.

    [0019] The solenoid 10 according to the present embodiment is basically configured as above. Next, its operation and effects are described with reference to the drawings. When the coil 16 in the solenoid 10 shown in FIG. 1A is not energized, the respective parts of the solenoid 10 such as the movable iron core 19 and the shaft 22 are arranged as shown in FIG. 3.

    [0020] That is, the movable iron core 19 is attracted to the permanent magnet 13 side (upper side of FIG. 3) due to the elastic force of the spring 21 attached to the recess 20 and the magnetic force of the permanent magnet 13, and then comes into contact with the ring member 14. In this instance, if the north pole of the permanent magnet 13 is located on the ring member 14 side (lower side of FIG. 3) and the south pole thereof is located on the opening 12 side (upper side of FIG. 3) of the case 11, the flow of magnetic flux generated (by the permanent magnet 13) in the solenoid 10 is formed as a first magnetic path 25 shown in FIG. 3.

    [0021] When the coil 16 in the solenoid 10 shown in FIG. 1A is energized, a magnetic path generated in the solenoid 10 is formed as shown in FIG. 4. That is, if the coil 16 is energized as shown in FIG. 4 (namely, if the coil 16 is excited so as to have magnetic flux in an opposite direction to the magnetic flux of the permanent magnet 13), the magnetic flux of the coil 16 flows in a second magnetic path 26 which is present in the middle of the first magnetic path 25 shown in FIG. 3. Since the second magnetic path 26 is located in the middle of the first magnetic path 25, if the magnetic flux of the coil 16 circles in the second magnetic path 26 by the excitation of the coil 16, the first magnetic path 25 is magnetically saturated, and thus increases in magnetoresistance.

    [0022] As a result, the magnetic flux of the permanent magnet 13 starts to pass in a third magnetic path 27, rather than the first magnetic path 25 which is high in magnetoresistance, via the distance d between the outside diameter side of the ring member 14 and the inner side (inner wall) of the case 11. Accordingly, the magnetic flux passing through a place where the ring member 14 and the movable iron core 19 are attracted to each other is reduced. Consequently, the movable iron core 19 and the ring member 14 are separated from each other as shown in FIG. 5, and the movable iron core 19 can be moved to a lower position by slight external force (in the direction of an arrow in FIG. 5).

    [0023] It should be noted that the solenoid according to the present invention brings about the advantageous effects of the present invention in the case of a state where the direction of the magnetic flux generated by the permanent magnet is opposite to the direction of the magnetic flux generated by the energization of the coil as shown in FIGS. 4 and 5. Moreover, similar advantageous effects to those of the present invention are brought about even in the case where the direction of the magnetic flux generated by the permanent magnet and the direction of the magnetic flux generated by the energization of the coil are made opposite as shown in FIG. 6 to those shown in FIGS. 4 and 5.

    [0024] Contrary to this, it goes without saying that the advantageous effects of the present invention are not exerted if the permanent magnet is disposed in an opposite direction to that shown in FIGS. 4 to 6, or if the direction of applying current in the coil or the winding direction of a wire rod such as a copper wire wound around the coil is reversed so that only the direction of magnetic flux is opposite to that shown in FIGS. 4 to 6.

    REFERENCE SIGNS LIST



    [0025] 

    10: Solenoid

    11: Case

    12: Opening of case 11

    13: Permanent magnet

    14: Ring member

    16: Coil

    17: Coil cover

    19: Movable iron core

    d: Distance between inner wall of case 11 and outer side of ring member 14




    Claims

    1. A solenoid (10) comprising:

    a cylindrical case (11) having an opening (12);

    a permanent magnet (13) and a coil (16) both built into the cylindrical case, wherein the permanent magnet (13) and the coil (16) are arranged separated in a length axial direction in the case (11) so that the permanent magnet (13) is located nearer to the opening (12) than the coil (16) is;

    a first ring member (14) having a center hole and an outer periphery which is arranged in the case adjacently to the permanent magnet (13) on the far side of the permanent magnet from the opening (12);

    a movable iron core (19) which is inserted in the coil (16) so as to be arranged on a far side of the first ring member (14) from the opening (12);

    a metallic coil cover (17) having a flange (17a) on its end facing the first ring member (14) which cover is provided between the movable iron core (19) and the coil (16); and

    a second ring member (23) which is arranged on an opposite side of the coil (16) to the flange (17a) and which is fixed to the case (11), wherein the coil cover (17) and the second ring member (23) together with the case completely cover the coil, characterized in that the first ring member (14) is arranged to form a predetermined distance (d) in the radial direction of the first ring member between the outer periphery of the first ring member (14) and an inner wall of the case (11), in that a first magnetic path (25) is formed through the first ring member (14), the movable iron core (19), the coil cover (17), the second ring member (23), the case (11) and the flange (17a) by the permanent magnet (13) during non-energization of the coil (16), a second magnetic path (26) is formed through the coil cover (17), the second ring member (23), the case (11) and the flange (17a) by the coil (16) during energization of the coil (16), a third magnetic path (27) is formed through the first ring member (14), the space forming said distance and the case (11) by the permanent magnet (13) during energization of the coil (16), and in that a diameter of the iron core (19) is larger than a diameter of the center hole of the first ring member (14), the diameters being taken perpendicular to said length axial direction.


     
    2. The solenoid according to claim 1, characterized in that the predetermined distance (d) between the inner wall of the case (11) and the outer periphery of the first ring member (14) is in a range of 0.1 mm to 0.3 mm.
     


    Ansprüche

    1. Solenoid (10), umfassend:

    - ein zylindrisches Gehäuse (11), das eine Öffnung (12) aufweist;

    - einen Permanentmagneten (13) und eine Spule (16), die beide in das zylindrische Gehäuse eingebaut sind, wobei der Permanentmagnet (13) und die Spule (16) in einer axialen Längsrichtung in dem Gehäuse (11) getrennt angeordnet sind, sodass der Permanentmagnet (13) näher bei der Öffnung (12) liegt als die Spule (16);

    - ein erstes Ringelement (14), das ein Mittelloch und einen Außenumfang aufweist, das in dem Gehäuse angrenzend an den Permanentmagneten (13) an der hinteren Seite des Permanentmagneten von der Öffnung (12) aus angeordnet ist;

    - einen beweglichen Eisenkern (19), der in die Spule (16) eingesetzt ist, um an einer hinteren Seite des ersten Ringelements (14) von der Öffnung (12) aus angeordnet zu sein;

    - eine metallische Spulenabdeckung (17), die einen Flansch (17a) an ihrem Ende aufweist, das zu dem ersten Ringelement (14) zeigt, wobei die Abdeckung zwischen dem beweglichen Eisenkern (19) und der Spule (16) bereitgestellt ist; und

    - ein zweites Ringelement (23), das an einer gegenüberliegenden Seite der Spule (16) zu dem Flansch (17a) angeordnet ist und das an dem Gehäuse (11) fixiert ist, wobei die Spulenabdeckung (17) und das zweite Ringelement (23) gemeinsam mit dem Gehäuse die Spule vollständig abdecken,

    - dadurch gekennzeichnet, dass das erste Ringelement (14) angeordnet ist, einen vorgegebenen Abstand (d) in der radialen Richtung des ersten Ringelements zwischen dem Außenumfang des ersten Ringelements (14) und einer Innenwand des Gehäuses (11) zu bilden,

    - dadurch, dass ein erster magnetischer Pfad (25) durch das erste Ringelement (14), den beweglichen Eisenkern (19), die Spulenabdeckung (17), das zweite Ringelement (23), das Gehäuse (11) und den Flansch (17a) durch den Permanentmagneten (13) während Nicht-Energetisierung der Spule (16) gebildet ist, ein zweiter magnetischer Pfad (26) durch die Spulenabdeckung (17), das zweite Ringelement (23), das Gehäuse (11) und den Flansch (17a) durch die Spule (16) während Energetisierung der Spule (16) gebildet ist, ein dritter magnetischer Pfad (27) durch das erste Ringelement (14), den Raum, der den Abstand bildet, und das Gehäuse (11) durch den Permanentmagneten (13) während Energetisierung der Spule (16) gebildet ist und

    - dadurch, dass ein Durchmesser des Eisenkerns (19) größer als ein Durchmesser des Mittellochs des ersten Ringelements (14) ist, wobei die Durchmesser senkrecht zu der axialen Längsrichtung genommen sind.


     
    2. Solenoid nach Anspruch 1, dadurch gekennzeichnet, dass der vorgegebene Abstand (d) zwischen der Innenwand des Gehäuses (11) und dem Außenumfang des ersten Ringelements (14) in einer Spanne von 0,1 mm bis 0,3 mm ist.
     


    Revendications

    1. Solénoïde (10) comprenant :

    un boîtier cylindrique (11) présentant une ouverture (12) ;

    un aimant permanent (13) et une bobine (16) tous deux intégrés à l'intérieur du boîtier cylindrique, dans lequel l'aimant permanent (13) et la bobine (16) sont agencés séparés dans une direction axiale longitudinale dans le boîtier (11) de sorte que l'aimant permanent (13) est situé plus près de l'ouverture (12) que l'est la bobine (16) ;

    un premier élément annulaire (14) présentant un trou central et une périphérie extérieure qui est agencée dans le boîtier de manière adjacente à l'aimant permanent (13) sur le côté éloigné de l'aimant permanent depuis l'ouverture (12) ;

    un noyau de fer mobile (19) qui est inséré dans la bobine (16) de façon à être agencé sur un côté éloigné du premier élément annulaire (14) depuis l'ouverture (12) ;

    un couvercle de bobine métallique (17) présentant une bride (17a) sur son extrémité tournée vers le premier élément annulaire (14), lequel couvercle étant prévu entre le noyau de fer mobile (19) et la bobine (16) ; et

    un second élément annulaire (23) qui est agencé sur un côté opposé de la bobine (16) à la bride (17a) et qui est fixé au boîtier (11), dans lequel le couvercle de bobine (17) et le second élément annulaire (23) recouvrent complètement la bobine avec le boîtier,

    caractérisé en ce que le premier élément annulaire (14) est agencé pour former une distance prédéterminée (d) dans la direction radiale du premier élément annulaire entre la périphérie extérieure du premier élément annulaire (14) et une paroi intérieure du boîtier (11),

    en ce qu'un premier trajet magnétique (25) est formé à travers le premier élément annulaire (14), le noyau de fer mobile (19), le couvercle de bobine (17), le second élément annulaire (23), le boîtier (11) et la bride (17a) par l'aimant permanent (13) pendant la non-excitation de la bobine (16), un deuxième trajet magnétique (26) est formé à travers le couvercle de bobine (17), le second élément annulaire (23), le boîtier (11) et la bride (17a) par la bobine (16) pendant l'excitation de la bobine (16), un troisième trajet magnétique (27) est formé à travers le premier élément annulaire (14), l'espace formant ladite distance et le boîtier (11) par l'aimant permanent (13) pendant l'excitation de la bobine (16), et

    en ce qu'un diamètre du noyau de fer (19) est supérieur à un diamètre du trou central du premier élément annulaire (14), les diamètres étant pris perpendiculairement à ladite direction axiale longitudinale.


     
    2. Solénoïde selon la revendication 1, caractérisé en ce que la distance prédéterminée (d) entre la paroi intérieure du boîtier (11) et la périphérie extérieure du premier élément annulaire (14) se situe dans une plage de 0,1 mm à 0,3 mm.
     




    Drawing

















    Cited references

    REFERENCES CITED IN THE DESCRIPTION



    This list of references cited by the applicant is for the reader's convenience only. It does not form part of the European patent document. Even though great care has been taken in compiling the references, errors or omissions cannot be excluded and the EPO disclaims all liability in this regard.

    Patent documents cited in the description