(19)
(11)EP 3 322 964 B1

(12)EUROPEAN PATENT SPECIFICATION

(45)Mention of the grant of the patent:
09.10.2019 Bulletin 2019/41

(21)Application number: 16741266.7

(22)Date of filing:  08.07.2016
(51)Int. Cl.: 
G01G 23/00  (2006.01)
(86)International application number:
PCT/EP2016/066237
(87)International publication number:
WO 2017/009212 (19.01.2017 Gazette  2017/03)

(54)

LOAD CELL HAVING AN OVERLOAD PROTECTION

WÄGEZELLE MIT ÜBERLASTSCHUTZ

CAPTEUR DE FORCE DOTÉ D'UNE PROTECTION CONTRE LES SURCHARGES


(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

(30)Priority: 15.07.2015 CN 201510415673
15.07.2015 CN 201520512666 U

(43)Date of publication of application:
23.05.2018 Bulletin 2018/21

(73)Proprietor: Mettler-Toledo GmbH
8606 Greifensee (CH)

(72)Inventors:
  • YANG, Chun
    Shanghai 201699 (CN)
  • WU, Chao
    Shanghai 201620 (CN)
  • SUN, Weixiang
    Shanghai 200092 (CN)
  • BIAN, Naifeng
    Shanghai 200231 (CN)
  • BURKHARD, Hans-Rudolf
    8492 Wila (CH)

(74)Representative: Mettler-Toledo 
IP Department Im Langacher 44
8606 Greifensee
8606 Greifensee (CH)


(56)References cited: : 
EP-A1- 1 912 048
  
      
    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 invention relates to a load cell having an overload protection and an electronic balance with a load cell having an overload protection.

    Background Art



    [0002] In the prior art, during the use or the transport, if there is no overload protection or the overload protection is imperfect, the electronic balance can be easily damaged due to the effects of static or dynamic impact forces. US 4'574'898 discloses a load cell with an overload protection, the load cell comprises a load-receiver member, a main member and a load-transmitting member connecting the load-receiver member to the main member. Because the load-transmitting member comprises some separate parts, the assembling increases work and cost of the product.

    [0003] EP 1'912'048 A1 relates to an overload block for a load cell, comprising a force introduction element for force-effective connection with a load, and a force discharge element for force-effective connection with a load cell, wherein between the force application element and the force discharge element a free space is arranged and the force introduction element is movable relative to the force discharge element.

    [0004] Hence, it is desired to have a load cell solving the problem above.

    Summary of invention



    [0005] The object of this invention is to provide a load cell and an electronic balance that has simple structure, is easy to assemble and has an overload protection.

    [0006] In accordance with the present invention, a load cell comprises a load receiving member, a main member and a load transmitting member and a stop portion. The main member comprises a movable portion, a fixed portion and a parallel guiding member for connecting the fixed portion and the movable portion. The load transmitting member comprises a first mounting portion for mounting the load receiving member, a second mounting portion for mounting the movable portion and a parallel guiding member for connecting the first mounting portion to the second mounting portion. The first mounting portion is movable vertically relative to the second mounting portion when a load being applied on the first mounting portion and the load transmitting member is a single piece. The load cell further comprises a stop portion for preventing the first mounting portion from further moving downwardly for overload protection wherein the fixed portion comprises an end portion and an extending portion extending forwardly from the end portion and wherein the extending portion being the stop portion.

    [0007] Other objects, advantages and novel features of the present invention will become more apparent from the following detailed description of the present embodiment when taken in conjunction with the accompanying drawings.

    Brief description of drawings



    [0008] Details of the load cell according to the invention will be apparent from the description of the embodiments that are illustrated in the drawings, wherein
    Fig. 1
    is a perspective view of the load cell according to the present invention;
    Fig. 2
    is a front view of the load cell;
    Fig. 3
    is a sectional view of the load cell;
    Fig. 4
    is an exploded view of the load cell;
    Fig. 5
    is a perspective view of the load transmitting member;
    Fig. 6
    is another perspective view of the load-transmitting member;
    Fig. 7
    is an exploded view of the load cell according to the second embodiment of the invention;
    Fig. 8
    is a front view of the load cell of FIG. 7; and
    Fig. 9
    is a perspective view of the load transmitting member of FIG. 7.

    Description of embodiments



    [0009] Within this description, relative directions refer to a load cell when used in mode for operation, wherein the forward direction is defined as the direction from the fixed portion to the movable portion, the vertical direction is defined as the direction that is perpendicular to the forward direction and essentially parallel to applied load, wherein the upward direction in the vertical direction is defined as the direction from a plane that is closer to the ground where on which the load cell is mounted to a plane that is more distant from the latter plane.

    [0010] With reference to figures 1 to 6, the invention provides a load cell. The load cell comprises a load receiving member 1, a main member 3, a load transmitting member 2 and a stop portion.

    [0011] The load receiving member 1 comprises a base portion 11 and a cylindrical connecting portion 12 extending downwardly from the base portion 11.

    [0012] The main member 3, 3' comprises a movable portion 31, 31', a fixed portion 32, 32' and a first parallel guiding member 33 for connecting the fixed portion 32, 32' to the movable portion 31, 31'. The first parallel guiding member 33 comprises a first upper parallel guiding plate 331, 331' and a first lower parallel guiding plate 332. Slots extending in the transverse direction are formed in the first guiding member 3, 3'. The slots are arc-shaped or square-shaped. In this embodiment, the slots are disposed at the two ends of the first upper parallel guiding member 331 and the first low parallel guiding plate 332.

    [0013] The load transmitting member 2, 2' comprises a first mounting portion 21, 21' for mounting the load receiving member 1, 1', a second mounting portion 22, 22' for mounting the movable portion 31, 31' and a parallel guiding connection member 24, 24' for connecting the first mounting portion 21, 21' to the second mounting portion 22, 22'. The connection portion 12 is mounted to the first mounting portion 21, 21' for transmitting the force applied on the load receiving member 1, 1' to the load transmitting member 2, 2'. The load transmitting member 2, 2' is a single piece for having a simple structure and being easily assembled. The load transmitting member 2, 2' can be made by die-cast moulding, by machining or by both of them.

    [0014] With reference to figure 3, the load transmitting member 2 is set above the main member 31, 32, 33 and extends in the X direction so that the load cell has a compact structure.

    [0015] With reference to figure 4, the fixed portion 32 comprises an end portion 321, an extending portion 322 extending forwardly from the end portion 321 and the supporting portions (323, 324) extending forwardly from the extending portion 322. The supporting portions comprise a first supporting portion 323 and a second supporting portion 324. The extending portion 322 defines a first upper surface 3221 extending horizontally and an upper surface 3222 lower than the first upper surface 3221 extending horizontally. In other embodiment, the first upper surface 3221 and the upper surface 3222 can be in the same plane.

    [0016] In this embodiment, the extending portion 322 is a stop portion. When an overload is applied on the load receiving member 1, the bottom surface of the first mounting portion 21 abuts to the upper surface 322 for overload protection. At least a portion of the movable portion 31 is disposed in the space formed between the first supporting portion 323 and the second supporting portion 324.

    [0017] With reference to figure 5 and to figure 6, a second through hole 23 extending downwardly from the upper surface 26 of the load transmitting member 2 between the first mounting portion 21 and the second mounting portion 22, so that the load receiving member 2 has a smaller weight and the rigidity of the load-receiver member 2 is lower.

    [0018] The parallel guiding connection member 24 comprises an upper parallel guiding connection plate 241 and a lower parallel guiding connection plate 242. A first through hole 243 extending horizontally in the transverse direction is formed between the upper parallel guiding connection plate 241 and the lower parallel guiding connection plate 242. The first through hole 243 is "H" shaped. The upper parallel guiding connection plate 241 comprises a fist slot 2411 and a second slot 2412. The lower parallel guiding connection plate 242 comprises a third slot 2421 corresponding to the first slot 2411 and a forth slot 2422 corresponding to the second slot 2412. When a load is applied on the load receiving member 1, the bottom surface of the first mounting portion 21 moves downwardly. Because of the parallel guiding connection member 24, no matter of a center load or an eccentric load, the first mounting portion 21 can only move in the vertically downwarded direction, so that the force of the center load and eccentric load is closer to each other. This can prevent the load cell from introducing an eccentric load into the movable member.

    [0019] The load transmitting member 2 comprises a third through hole 27 extending in the X direction whereby the third through hole 27 has an opening facing downwardly.

    [0020] In the exemplary embodiment, the first mounting portion 21, 21' comprises protruding portions 25, 25' extending vertically and downwardly. When a load is applied on the load receiver member 1, 1', the first mounting portion 21, 21' moves downwardly. The first mounting portion 21, 21' can only produce a vertical downward displacement because of effect of the parallel guiding member 24, 24'. When the load exceeds the predefined maximum, the protruding portions 25 abut to the upper surface 3222 for overload protection.

    [0021] The movable portion 31 comprises a body portion 311 and an attaching portion 312 extending upwardly from the body portion 311. The load transmitting member 2 is mounted on the attaching portion 312 and at least a portion of the attaching portion 312 is disposed in the third through hole 27, so that the load cell can have a small volume.

    [0022] The figure 7 and figure 9 illustrate another embodiment of this invention. The load transmitting member 2' comprises a first mounting portion 21' for mounting the load receiving member 1', a second mounting portion 22' and a parallel guiding member 24' for connecting the first mounting portion 21' to the second mounting portion 22'.The parallel guiding connection member is divided by the first through hole 243'. The first through hole 243' is H shaped. The load transmitting member 2' comprises a protruding portion 23' and protruding portions 25' extending downwardly. The protruding portion 23' is below the second mounting portion 22' and the protruding portions 25' are disposed on the lower surface of the first mounting portion 21'. The protruding portions 25' are protruding on both sides of the first upper parallel guiding plate 331' to the stop portion. The protruding portions 23' is to fix the load transmitting member 2' onto the movable portion 31'. A distance is formed between the lower surface of the load transmitting member 2' and the upper surface of the main member 3' for vertical displacement of the load transmitting member 2'. In the exemplary embodiment, a pair of protruding posts 33' extends upwardly from the fixed portion 32'. The protruding posts 33' are arranged below the protruding portions 25'. When overload is applied on the load receiving member 1', the protruding portions 25' abut on the protruding posts 33' to protect the load cell. The protruding posts 33' are square shaped or other shaped.

    Reference signs list



    [0023] 
    1, 1'
    load receiving member
    2, 2'
    load transmitting member
    3, 3'
    main member
    11
    base portion
    12
    cylindrical connecting portion
    21, 21'
    first mounting portion
    22, 22'
    second mounting portion
    23, 23'
    second through hole
    24, 24'
    parallel guiding connection member
    25, 25'
    protruding portions
    26
    upper surface
    27
    third through hole
    31, 31'
    movable portion
    32, 32'
    fixed portion
    33
    first parallel guiding member
    33'
    protruding posts
    241
    upper parallel guiding connection plate
    242
    lower parallel guiding connection plate
    243, 243'
    first through hole
    311
    body portion
    312
    attaching portion
    321
    end portion
    322
    extending portion
    323
    first supporting portion
    324
    second supporting portion
    331, 331'
    first upper parallel guiding plate
    332
    first lower parallel guiding plate
    2411
    fist slot
    2412
    second slot
    2421
    third slot
    2422
    forth slot
    3221
    first upper surface
    3222
    upper surface



    Claims

    1. Load cell for an electronic balance, comprising

    a load receiving member (1, 1');

    a main member (3, 3'), the main member (3, 3') comprising

    a movable portion (31, 31'),

    a fixed portion (32, 32') and

    a parallel guiding member (33) for connecting the fixed portion (32, 32') and the movable portion (31, 31'),

    wherein the movable portion (31, 31') being movable vertically relative to the fixed portion (32, 32') when a load being applied on the movable portion (31, 31');

    a load transmitting member (2, 2'), the load transmitting member (2, 2') comprising

    a first mounting portion (21, 21') for mounting the load receiving member (1, 1'),

    a second mounting portion (22, 22') for mounting the load transmitting member (2, 2') to the movable portion (3, 3') and

    a parallel guiding connection member (24, 24') for connecting the first mounting portion (21, 21') to the second mounting portion (22, 22'),

    wherein the first mounting portion (21, 21') being movable vertically relative to the second mounting portion (22, 22') when a load being applied on the first mounting portion (21, 21'), and

    wherein the load transmitting member (2, 2') being formed of a single piece of solid material; and

    a stop portion for preventing the first mounting portion (21, 21') from further moving downwardly for overload protection;

    characterized in that the fixed portion (32, 32') comprises

    an end portion (321) and

    an extending portion (322) extending forwardly from the end portion (231), and in that the extending portion (322) being the stop portion.


     
    2. Load cell according to claim 1, wherein the load transmitting member (2, 2') is set above the main member (3, 3') when the load cell is in mode for operation.
     
    3. Load cell according to claim 1 or 2, wherein the parallel guiding connection member (24, 24') comprises

    an upper parallel guiding connection plate (241),

    a lower parallel guiding connection plate (242), and

    a first through hole (243, 243') extending horizontally in a transverse direction formed between the upper parallel guiding connection plate (241) and the lower parallel guiding connection plate (242) when the load cell is in mode for operation,
    wherein the through hole (243, 243') being "H" shaped.


     
    4. Load cell according to one of the claims 1 to 3, wherein a second through hole (23, 23') is disposed between the first mounting portion (21, 21') and the second mounting portion (22, 22') and is extending downwardly when the load cell is in mode for operation.
     
    5. Load cell according to one of the claims 1 to 4, wherein the load transmitting member comprises a third through hole (27) extending in a longitudinal direction and having a downward opening when the load cell is in mode for operation..
     
    6. Load cell according to claim 5, wherein the movable portion (3) comprises

    a body portion (311) and

    an attaching portion (312) extending upwardly from the body portion (322),

    wherein the load transmitting member (1) being mounted on the attaching portion (312) and wherein at least a portion of the attaching portion (312) being disposed in the third through hole (27).
     
    7. Load cell according to claim 5, wherein the parallel guiding connection member (24) comprises

    an upper parallel guiding connection plate (241) and

    a lower parallel guiding connection plate (242),

    wherein at least a portion of the lower parallel guiding connection plate (242) being disposed in the third through hole (27).
     
    8. Load cell according to one of the claims 1 to 7, wherein two protruding portions (25, 25') extending downwardly from the first mounting portion (21, 21') and are disposed on both sides of the latter.
     
    9. Electronic balance comprising a load cell according to one of the claims 1 to 8.
     


    Ansprüche

    1. Wägezelle für eine elektronische Waage, umfassend
    ein Lastempfangselement (1, 1');
    ein Hauptelement (3, 3'), wobei das Hauptelement (3, 3') Folgendes umfasst:

    einen bewegbaren Abschnitt (31, 31'),

    einen festen Abschnitt (32, 32'), und

    ein paralleles Führungselement (33) zum Verbinden des festen Abschnitts (32, 32') und des bewegbaren Abschnitts (31, 31'),

    wobei der bewegbare Abschnitt (31, 31') vertikal relativ zu dem festen Abschnitt (32, 32') bewegbar ist, wenn eine Last auf den bewegbaren Abschnitt (31, 31') aufgebracht wird;

    ein Lastübertragungselement (2, 2'), wobei das Lastübertragungselement (2, 2') Folgendes umfasst:

    einen ersten Montageabschnitt (21, 21') zum Montieren des Lastempfangselements (1, 1'),

    einen zweiten Montageabschnitt (22, 22') zum Montieren des Lastübertragungselements (2, 2') an dem bewegbaren Abschnitt (3, 3'), und

    ein paralleles Führungsverbindungselement (24, 24') zum Verbinden des ersten Montageabschnitts (21, 21') mit dem zweiten Montageabschnitt (22, 22'),

    wobei der erste Montageabschnitt (21, 21') vertikal relativ zu dem zweiten Montageabschnitt (22, 22') bewegbar ist, wenn eine Last auf den ersten Montageabschnitt (21, 21') aufgebracht wird, und

    wobei das Lastübertragungselement (2, 2') aus einem einzelnen Stück aus festem Material gebildet ist; und

    einen Anschlagsabschnitt zum Verhindern, dass sich der erste Montageabschnitt (21, 21') weiter nach unten bewegt, für den Überlastschutz;
    dadurch gekennzeichnet, dass
    der feste Abschnitt (32, 32') Folgendes umfasst:

    einen Endabschnitt (321), und

    einen Erstreckungsabschnitt (322), der sich von dem Endabschnitt (231) nach vorne erstreckt, und dass der Erstreckungsabschnitt (322) der Anschlagsabschnitt ist.


     
    2. Wägezelle nach Anspruch 1, wobei das Lastübertragungselement (2, 2') oberhalb des Hauptelements (3, 3') gesetzt ist, wenn sich die Wägezelle im Betriebsmodus befindet.
     
    3. Wägezelle nach Anspruch 1 oder 2, wobei das parallele Führungsverbindungselement (24, 24') Folgendes umfasst:

    eine obere parallele Führungsverbindungsplatte (241),

    eine untere parallele Führungsverbindungsplatte (242), und

    ein erstes Durchgangsloch (243, 243'), das sich horizontal in einer Querrichtung erstreckt, die zwischen der oberen parallelen Führungsverbindungsplatte (241) und der unteren parallelen Führungsverbindungsplatte (242) gebildet ist, wenn sich die Wägezelle im Betriebsmodus befindet,

    wobei das Durchgangsloch (243, 243') "H"-förmig ist.


     
    4. Wägezelle nach einem der Ansprüche 1 bis 3, wobei ein zweites Durchgangsloch (23, 23') zwischen dem ersten Montageabschnitt (21, 21') und dem zweiten Montageabschnitt (22, 22') angeordnet ist und sich nach unten erstreckt, wenn sich die Wägezelle im Betriebsmodus befindet.
     
    5. Wägezelle nach einem der Ansprüche 1 bis 4, wobei das Lastübertragungselement ein drittes Durchgangsloch (27) umfasst, das sich in einer Längsrichtung erstreckt und eine Abwärtsöffnung aufweist, wenn sich die Wägezelle im Betriebsmodus befindet.
     
    6. Wägezelle nach Anspruch 5, wobei der bewegbare Abschnitt (3) Folgendes umfasst:

    einen Körperabschnitt (311), und

    einen Anbringungsabschnitt (312), der sich von dem Körperabschnitt (322) nach oben erstreckt,

    wobei das Lastübertragungselement (1) an dem Anbringungsabschnitt (312) montiert ist und wobei zumindest ein Abschnitt des Anbringungsabschnitts (312) in dem dritten Durchgangsloch (27) angeordnet ist.
     
    7. Wägezelle nach Anspruch 5, wobei das parallele Führungsverbindungselement (24) Folgendes umfasst:

    eine obere parallele Führungsverbindungsplatte (241), und

    eine untere parallele Führungsverbindungsplatte (242),

    wobei zumindest ein Abschnitt der unteren parallelen Führungsverbindungsplatte (242) in dem dritten Durchgangsloch (27) angeordnet ist.


     
    8. Wägezelle nach einem der Ansprüche 1 bis 7, wobei sich zwei vorstehende Abschnitte (25, 25') von dem ersten Montageabschnitt (21, 21') nach unten erstrecken und auf beiden Seiten des letzteren angeordnet sind.
     
    9. Elektronische Waage, umfassend eine Wägezelle nach einem der Ansprüche 1 bis 8.
     


    Revendications

    1. Capteur de force pour une balance électronique, comprenant
    un élément de réception de force (1, 1') ;
    un élément principal (3, 3'), l'élément principal (3, 3') comprenant

    une partie mobile (31, 31'),

    une partie fixe (32, 32') et

    un élément de guidage parallèle (33) pour raccorder la partie fixe (32, 32') et la partie mobile (31, 31'),

    dans lequel la partie mobile (31, 31') peut être déplacée verticalement par rapport à la partie fixe (32, 32') lorsqu'une force est appliquée sur la partie mobile (31, 31') ;

    un élément de transmission de force (2, 2'), l'élément de transmission de force (2, 2') comprenant:

    une première partie de montage (21, 21') pour monter l'élément de réception de force (1, 1'),

    une seconde partie de montage (22, 22') pour monter l'élément de transmission de force (2, 2') sur la partie mobile (3, 3') et

    un élément de raccord de guidage parallèle (24, 24') pour raccorder la première partie de montage (21, 21') à la seconde partie de montage (22, 22'),

    dans lequel la première partie de montage (21, 21') peut être déplacée verticalement par rapport à la seconde partie de montage (22, 22') lorsqu'une force est appliquée sur la première partie de montage (21, 21'), et

    dans lequel l'élément de transmission de force (2, 2') est formé d'une seule pièce de matériau solide ; et

    une partie d'arrêt pour empêcher la première partie de montage (21, 21') de se déplacer davantage vers le bas pour une protection contre les surcharges ;
    caractérisé en ce que
    la partie fixe (32, 32') comprend

    une partie d'extrémité (321) et

    une partie d'extension (322) s'étendant vers l'avant depuis la partie d'extrémité (231), et en ce que la partie d'extension (322) est la partie d'arrêt.


     
    2. Capteur de force selon la revendication 1, dans lequel l'élément de transmission de force (2, 2') est placé au-dessus de l'élément principal (3, 3') lorsque le capteur de force est en mode de fonctionnement.
     
    3. Capteur de force selon la revendication 1 ou 2, dans lequel l'élément de raccord de guidage parallèle (24, 24') comprend
    une plaque de raccord de guidage parallèle supérieure (241),
    une plaque de raccord de guidage parallèle inférieure (242), et
    un premier trou traversant (243, 243') s'étendant horizontalement dans une direction transversale formée entre la plaque de raccord de guidage parallèle supérieure (241) et la plaque de raccord de guidage parallèle inférieure (242) lorsque le capteur de force est en mode de fonctionnement,
    dans lequel le trou traversant (243, 243') est en forme de « H ».
     
    4. Capteur de force selon l'une des revendications 1 à 3, dans lequel un deuxième trou traversant (23, 23') est disposé entre la première partie de montage (21, 21') et la seconde partie de montage (22, 22') et s'étend vers le bas lorsque le capteur de force est en mode de fonctionnement.
     
    5. Capteur de force selon l'une des revendications 1 à 4, dans lequel l'élément de transmission de force comprend un troisième trou traversant (27) s'étendant dans une direction longitudinale et doté d'une ouverture vers le bas lorsque le capteur de force est en mode de fonctionnement.
     
    6. Capteur de force selon la revendication 5, dans lequel la partie mobile (3) comprend
    une partie de corps (311) et
    une partie de fixation (312) s'étendant vers le haut depuis la partie de corps (322),
    dans lequel l'élément de transmission de force (1) est monté sur la partie de fixation (312) et dans lequel au moins une partie de la partie de fixation (312) est disposée dans le troisième trou traversant (27).
     
    7. Capteur de force selon la revendication 5, dans lequel l'élément de raccord de guidage parallèle (24) comprend
    une plaque de raccord de guidage parallèle supérieure (241) et
    une plaque de raccord de guidage parallèle inférieure (242),
    dans lequel au moins une partie de la plaque de raccord de guidage parallèle inférieure (242) est disposée dans le troisième trou traversant (27).
     
    8. Capteur de force selon l'une des revendications 1 à 7, dans lequel deux parties en saillie (25, 25') s'étendent vers le bas depuis la première partie de montage (21, 21') et sont disposées des deux côtés de celle-ci.
     
    9. Balance électronique comprenant un capteur de force selon l'une des revendications 1 à 8.
     




    Drawing