JP3701854B2

JP3701854B2 - electronic balance

Info

Publication number: JP3701854B2
Application number: JP2000299606A
Authority: JP
Inventors: 広明綿引; 勲一村田; 昭夫坂井
Original assignee: アンリツ産機システム株式会社
Priority date: 2000-09-29
Filing date: 2000-09-29
Publication date: 2005-10-05
Anticipated expiration: 2020-09-29
Also published as: JP2002107218A

Description

【０００１】
【発明の属する技術分野】
本発明は、被計量物の質量を測定する電子天秤に係り、特に計量機構を収納する筐体の開口に設けたじゃばら部材に、筐体の製造誤差や筐体と本体の組み立て誤差等に起因する無理な力が加わらないようにした電子天秤に関する。
【０００２】
【従来の技術】
図２３は、従来の電子天秤（特公平６−２９７６１号に開示）を示す正面断面図、図２４は同斜視図である。他に特開平１１−５１７５６号公報に開示されたものがある。これらの電子天秤１８０は、載置皿１９０が設けられた可動部１８１ｂが固定部１８１ａに対し可動するロバーバル機構１８１と、可動部１８１ｂの移動に連動するレバー１８３と、レバー１８３が平衡状態となるよう移動制御する電磁コイル１８５と、レバー１８３の平衡状態を検出する位置検出センサ（不図示）と、電磁コイル１８５を通電制御して被計量物の質量を演算出力する制御部（不図示）とによって大略構成されている。
【０００３】
図示のようにロバーバル機構１８１は、直方体形状のアルミニウム等を側部からくり抜き形成し上下一対の平行なロバーバル部１８６を有する。ロバーバル部１８６には計４点の薄肉なバネ部１８７が形成され、可動部１８１ｂの載置皿１９０上に被計量物が載置されると、この荷重を受けてバネ部１８７部分が変形し、可動部１８１ｂが水平状態を維持した状態のまま下方向に移動する。
【０００４】
連動してレバー１８３の自由端１８３ｂは平衡位置から上方向に変位する。制御部は、位置検出センサの出力に基づき、レバー１８３が平衡する状態となるよう電磁コイル１８５を通電制御し、レバー１８３平衡時における電磁コイル１８５への電流値等に基づき被計量物の質量を演算出力する。
【０００５】
なお、図示の構成におけるレバー１８３は、ロバーバル機構１８１と一体形成されたものであるのに対して、上記他の電子天秤（特開平１１−５１７５６号公報）のものは、別体で形成されている点が異なるが、いずれもロバーバル機構１８１は、上記一体塊をくり抜きして形成されている。
【０００６】
【発明が解決しようとする課題】
上述した電子天秤のように、ロバーバル機構等の計量機構を収納して保護する筐体がないと、使用環境によっては電子天秤の測定に誤差が生じたり、計量機構が故障しやすいことが考えられる。例えば、食品などのような湿気のある被搬送物、粉体又は搬送時に粉体が発生しやすい被搬送物などを搬送する場合には、計量機構をカバーしておかなければかかる不都合が生じやすい。しかし、上述したような電子天秤において計量機構をカバーで覆う構造とする場合には、計量機構の荷重受け部分を筐体の外側に導出する開口部を設けなければならない。この開口部には防水性乃至防塵性を有する密封部材が必要であるとともに、この密封部材には荷重を受けて移動する荷重受け部に追随して変形しうる程度の可撓性も必要であると考えられる。しかし、筐体の製造誤差や筐体と本体の組み立て誤差等のために密封部材が無理な力を加えられた状態で取り付けられれば、この無理な力が測定に悪影響を及ぼすこともありうると考えられる。
【０００７】
本発明は、上記課題に鑑みなされたものであり、筐体の計量機構を覆う筐体の開口部に防水・防塵用の密封部材を設けるについて、筐体自体や筐体と本体の組み立てに誤差等があっても、密封部材が無理な力が加えられた状態で取り付けられることがないようにすることを目的としている。
【０００８】
【課題を解決するための手段】
請求項１に記載された電子天秤は、ベース板（１０）と、前記ベース板の上に固定されて荷重の受け部（４１，４２）を上面に備えた計量機構（２）と、その上面には前記計量機構の受け部を外部に表出させるための開口（６１，６２）が形成され、前記計量機構を収納して前記ベース板に固定される筐体（６０）と、前記筐体の開口の周囲に下端が固定されるじゃばら部材（９０）と、前記じゃばら部材の上端が係合されるとともに、前記じゃばら部材の内部において前記計量機構の受け部に固定されるじゃばら受け（８０）と、を有し、前記受け部（４１，４２）には荷重を伝達する支持軸（４３）が固定されており、前記じゃばら受け（８０）には前記支持軸よりも大径で前記支持軸を挿通させるための通孔（８２）と、前記受け部に締結される締結手段を挿通するための締結通孔（８３）とが形成されており、前記通孔に前記支持軸を挿通した状態で、前記じゃばら部材（９０）が変形しないような前記受け部に対する前記じゃばら受けの位置を定め、前記締結通孔を介して締結手段を前記受け部に締結することによって前記じゃばら受けを前記受け部に固定することを特徴としている。
【０００９】
請求項２に記載された電子天秤は、請求項１記載の電子天秤において、前記じゃばら受け（８０）の上には、前記筐体（６０）の開口（６１，６２）付近と前記じゃばら部材（９０）を覆うように、下面が解放された皿型のカバー（１００）が被せられ、カバーから上方に突出した前記支持軸（４３）に止めナット（１０１）を螺締したことを特徴としている。
【００１０】
請求項３に記載された電子天秤は、請求項１記載の電子天秤において、前記計量機構が、ロバーバル機構２と、荷重受け部材４０と、レバー４を有している。前記ロバーバル機構２は、固定部１２と、被計量物の荷重を受けて移動する可動部１４と、固定部１２と前記可動部１４との間に所定長を有し一対で設けられて可動部１４を水平状態のまま移動させるロバーバル部１８と、前記固定部１２及び前記可動部１４と前記ロバーバル部１８との間にそれぞれ形成される複数のバネ部２０とを有している。前記荷重受け部材４０は、前記可動部１４に固定される取り付け部４４と、前記取り付け部４４と一体に形成されて前記可動部１４に近接した位置に設けられた第１の受け部４１と、前記取り付け部４４及び前記第１の受け部４１と一体に形成されて前記固定部１２又は前記ロバーバル部１８に近接した位置に設けられた第２の受け部４２とを有している。前記レバー４は、前記荷重受け部材４４に加えられた荷重による前記可動部１４の移動に連動して自由端が平衡状態から変位する。そして、前記計量機構は、さらに自由端が変位した前記レバーを平衡状態に移動させる平衡駆動手段６と、前記平衡駆動手段６の作動状態から前記荷重を演算する制御手段とを有している。
【００１１】
【発明の実施の形態】
以下、本発明の電子天秤の実施形態を説明する。図１は、電子天秤の概要構成を示す斜視図である。
この電子天秤１は、概ね次のように構成されている。即ち、ベース板１０の上にロバーバル機構２が固定され、ロバーバル機構２の内部にはレバー４が組み付けられている。ロバーバル機構２にはレバー４を平衡状態に制御する電磁コイルからなる平衡駆動手段６と、位置検出手段（不図示）がある。ロバーバル機構２の可動部１４には、鞍状の荷重受け部材が固定され、この荷重受け部材上にコンベアが載置した動秤を構成できる。これらの機構は全体として筐体６０内に収納される。荷重受け部材の第１及び第２の受け部４１，４２に設けられた複数本（本例では４本）の支持軸４３は、筐体６０の開口６１，６２、じゃばら受け８０、及びじゃばら９０を介して筐体６０外の上方に突出している。そして、支持軸４３に取り付けられた図示しないコンベアで被計量物を搬送させながら、図示しない制御部によって被計量物の質量を測定するようになっている。なお、支持軸４３に載置皿を設け、被計量物を載置皿上に載せて質量を測定する静秤として使用することも可能である。
【００１２】
、図２はロバーバル機構２を示す正面図、図３は同平面図、図４は同側面図である。
ロバーバル機構２は、固定部１２と、固定部１２に対し上下方向に可動する可動部１４を有する。可動部１４の上面は、固定部１２に対しやや高く形成されている。このロバーバル機構２は、長さＬ、幅Ｗ１の直方体形状のアルミニウム塊等を正面側からくり抜き内部に中空部１６を貫通形成してなる。また、このロバーバル機構は押出成形等により中空部１６を形成してもよい。この際、上下に所定厚を有する一対の平行なロバーバル部１８が設けられる。これら一対のロバーバル部１８は長さ方向Ｌに対して同じ長さを有し、両端にはそれぞれ薄肉なバネ部２０が形成されている。バネ部２０は、上下面に２カ所づつ計４カ所設けられ、各々上下面から側面で見て円弧状であり、幅Ｗ１方向に連続する直線状に形成されている。
【００１３】
上部のロバーバル部１８の直下位置には、このロバーバル部１８と平行にレバー４を固定するためのレバー固定部２２が形成されている。このレバー固定部２２は、ロバーバル部１８の固定部１２と可動部１４に対応して長さＬ方向の中途部に切断部２２ｓを有し、固定部１２に対する可動部１４の移動を妨げない隙間を有している。この切断によって、レバー固定部２２は、固定側２２ａと可動側２２ｂを有する。
【００１４】
このロバーバル機構２の長さ方向Ｌの一端側２ａには、上部に所定長さの突出片２４が突出形成されており、下面には平衡駆動手段６が取り付けられる。また、この一端側２ａに位置するロバーバル機構２の一側面の中央部からロバーバル機構２の内部に向けて、くり抜きによりほぼ直方体形状のレバー収容部２ｂが開口形成される。このレバー収容部２ｂは、レバー固定部２２の下面に形成されるものであり、図２の正面側から見て可動部１４側の位置まで（上記ロバーバル部１８のバネ部２０を越えた位置に達するまで）くり抜き形成されている。
【００１５】
図５はレバー４の正面図、図６は同平面図、図７は同側面図である。
レバー４は、ロバーバル機構２の幅Ｗ１に対して小さな幅Ｗ２を有し小型軽量化が図られている。基端部４ａ側には、ロバーバル部１８の固定部１２、可動部１４にそれぞれ固定される固定部３０、可動部３２ａが形成されている。また他端側は自由端４ｂとされ、この自由端４ｂはレバー固定後の状態でロバーバル機構２の外部位置まで延出され突出片２４の直下に位置する。
【００１６】
このレバー４は、ロバーバル機構２の可動部１４の移動に可動部３２ａが連動し、自由端４ｂ側が上下に移動する。このレバー４は、２箇所の支点Ａ，Ｂを有しており、可動部１４に加わる被計量物の質量（荷重負荷）をこの２箇所の支点Ａ，Ｂにより所定量減衰させる機能、及びレバー４の長さＬ２の短縮化が図られている。
【００１７】
このレバー４についても、アルミニウム塊等をくり抜き形成される。特に正面から見て略Ｕ字形状に切削部２８（２８ａ、２８ｂ、２８ｃ）が貫通形成される。
この切削部２８によって略中央部に固定部３０、固定部３０の両側及び下面にそれぞれ可動部３２（３２ａ，３２ｂ，３２ｃ）が形成される。
レバー４の固定部３０と可動部３２は、支点Ａ，Ｂに位置する２箇所の薄肉のバネ部３４によって互いに接続されている。バネ部３４は、ロバーバル機構２のバネ部２０とほぼ同様の形状で形成されるものであり、説明は省略する。
【００１８】
なお、可動部３２側には、基端部４ａに負荷される荷重をバネ部３４での支点Ａ，Ｂを介して効率よく自由端４ｂ側に伝達し、併せてバネ部３４の強度を維持するために所要箇所（計３カ所）に複数のバネ部３６がバネ部３４同様に形成されている。
【００１９】
図１２は、電子天秤の測定機構の組み立て状態を示す一部裁断正面図である。この図を用いて、前述したロバーバル機構２とレバー４の組み立て構造を説明する。なお、この図は、便宜上、レバー４は裁断せずロバーバル機構２のみ裁断した状態とした。
電子天秤１は、ロバーバル機構２内部にレバー４を挿入、固定して構成される。ロバーバル機構２は、固定部１２がベース板１０上にネジ１１で固定される。レバー収容部２ｂには、レバー４が挿入され基端側４ａがレバー固定部２２にネジ２５で固定される。レバー収容部２ｂを形成するレバー固定部２２下面には、長さ方向Ｌに沿ってレバー４の一側面を案内する段差部２２ｄが形成されている。これにより、レバー４挿入時の位置決めを行いやすく組み立てを容易に行える。
【００２０】
そして、レバー４の固定部３０はレバー固定部２２の固定側２２ａに固定され、レバー４の可動部３２ａはレバー固定部２２の可動側２２ｂに固定される。
この固定状態で、レバー４の自由端４ｂはロバーバル機構２の一端側２ａに突出し、突出片２４の直下に位置する。
このように、ロバーバル機構２の内部にレバー４を設けることにより、全体の小型化が図れる。
【００２１】
レバー４の自由端４ｂ側には、錘取付片３８が下方に向けて突出形成され、略水平なネジ穴３８ｂ部分に平衡用錘４０が水平方向にスライド可能に取り付けられる。これにより、ロバーバル機構２の可動部１４上に対する荷重受け部材等の重量負荷時に、この平衡用錘４０の調整でレバー４を平衡させることができる。なお、レバー４の平衡状態は、この自由端４ｂに設けられるスリットと、突出片２４側に固定の位置検出センサ（不図示）により検出され、併せてレバー４の移動方向も検出されるようになっている。
【００２２】
平衡駆動手段６を構成する電磁コイルは、円環状の磁石体６ａが突出片２４下面に固定され、レバー４の自由端４ｂ上面には磁石体６ａの円環内部に巻回状のコイル６ｂが固定されている。このように、電磁コイルはロバーバル機構２の外部に設けることができるため、製造時の組み立て及び保守を簡単に行えるようになる。
この平衡駆動手段６は、被計量物の測定時に制御手段の電流制御を受け、コイル６ｂに供給する電流によって磁石体６ａとの間の磁力を変化させ、レバー４を平衡状態に復帰させる。
そして、制御手段が、コイル６ｂに与える電流値から前記荷重を演算する。
【００２３】
図８は荷重受け部材４０の正面図、図９は同平面図、図１０は同側面図、図１１は同底面図である。荷重受け部材４０は、上壁４６と側壁４７からなり、前後及び下方に開口した断面略コ字形の部材であり、鞍状の外形を呈している。この荷重受け部材４０は前記ロバーバル機構２に被せられ、ロバーバル機構２の上面と前記長さ方向に沿う両側面とを覆うように配置される。荷重受け部材４０は、図８の左側略半部がロバーバル機構２の可動部１４に対する取り付け部４４である。取り付け部４４は上壁４６及び側壁４７ともに他の部分に比べて肉厚が大きくなっている。従って、図１２及び図１３に示すように、当該取り付け部４４を可動部１４に複数本のボルト４５で固定すると、荷重受け部材４０の上壁４６及び側壁４７の内、取り付け部４４以外の部分は、ロバーバル機構２の外面と所定間隔をおいて対面し、ロバーバル機構２には接触しない。
【００２４】
荷重受け部材４０の一方の端部には、第１の受け部４１が一体に形成されている。第１の受け部４１は、可動部１４に固定された取り付け部に近く、ロバーバル機構２から外れた位置にある。また、荷重受け部材４０の他方の端部には、第２の受け部４２が一体に形成されている。第２の受け部４２は、ロバーバル機構２の固定部１２又はロバーバル部１８の近傍に配置される。
【００２５】
また、図８に示すように、荷重受け部材４０の側壁４７は、取り付け部４４において最も長く可動部１４の全体を覆っているが、第２の受け部４２に近づくにつれて下辺が傾斜して切れ上がって行き、第２の受け部４２において最も短くなっている。かかる形状から、荷重受け部材４０の重心は、その長手方向についていえば、二つの受け部４１，４２の間において第２の受け部４２よりも第１の受け部４１に近い位置にある。第１の受け部４１と第２の受け部４２に加わる荷重及び自重は、バランスよくロバーバル機構２の可動部１４に加わることとなっている。
【００２６】
このように、本例によれば、荷重受け部材４０の取り付け部４４は、上壁４６と両側壁４７の合計３面でロバーバル機構２の可動部１４に接し、これらの面において強固なねじ止め構造で一体化してある。また、荷重受け部材４０には２ヶ所に荷重が加わるが、可動部１４に最適な状態で荷重が加わるように、形状を工夫してバランスを考慮している。よって、荷重受け部材４０とロバーバル機構２を主要部とする本装置の計量機構は剛性が高く、測定精度が高く、耐久性にも優れている。
【００２７】
図１４は筐体６０の正面図、図１５は同平面図、図１６は同側面図である。筐体は、下面が開放された直方体形である。筐体６０の上面には前記受け部を外部に表出させるための開口６１が形成されている。開口６１は、円形の一部が弓型に閉止された形状である。開口の近傍には、ねじ孔７０が形成された締結部７１とされている。筐体の側面には内部点検用の開口６３があり、着脱可能な蓋体６４で閉止されている。
【００２８】
図１及び図２０に示すように、前述した計量機構のベース板には、筐体６０を取り付けるための２つの取り付け部材６５，６６が固定されている。取り付け部材６５，６６は、前記計量機構の上面よりも上方の位置に、水平な固定部６５ａ，６６ａをそれぞれ有している。各固定部６５ａ，６６ａにはねじ孔が形成されている。
【００２９】
前述した計量機構のベース板１０の下に底板６７を配置し、計量機構の上から筐体６０を被せ、底板６７と筐体６０の間にはパッキン６８を設ける。この時、筐体６０の各締結部７１，７１は、筐体６０内にある取り付け部材６５，６６の各固定部６５ａ，６６ａに対応している。ここで、図２０に示すように締結手段としてのねじ７３，７３をねじ孔７０，７０から固定部６５ａ，６６ａのねじ孔にねじ込めば、筐体６０と計量機構側を一体化できる。筐体６０と計量機構の本体側とのねじ７３による結合は、筐体６０の上面側で行なえるので作業がしやすい。
【００３０】
図１７（ａ）はじゃばら部材９０の一部を断面とした正面図、同図（ｂ）は平面図であり、図１８は図１７（ａ）の拡大図である。じゃばら部材９０は周壁がじゃばら構造とされた略円筒形の部材であり、ゴムなどの可撓性部材乃至弾性部材で構成されている。じゃばら部材９０の下端にはねじ孔９１が形成されており、開口６１の周囲にはねじ孔６９が設けられている。図１又は図２０に示すように、ねじ孔６９とねじ孔９１を介してねじ９２を締結することにより、じゃばら部材９０は筐体６０に固定される。じゃばら部材９０の上端には、下向きで断面角型の突起９３が周状に形成されている。
【００３１】
このような構造であると、筐体６０と計量機構の本体側とを結合するねじ７３は、じゃばら部材９０の内部に隠れるので外部に組み立て用のねじ類が露出せず見栄えがよく、装置の外面を清掃する際も作業し易い。
【００３２】
図１９（ａ）はじゃばら受け８０の平面図であり、同図（ｂ）はじゃばら受け８０の正面図である。じゃばら受け８０の上面には周状に凹溝８１がある。じゃばら部材９０の周状の突起９３が、この凹溝８１に押し込まれて固定され、じゃばら部材９０とじゃばら受け８０は一体になる。じゃばら受け８０には、前記計量機構の荷重受け部材４０の受け部４１に設けられた支持軸４３が挿通するために、通孔８２が２個形成されている。通孔８２の内径は支持軸４３の外径よりも大きく、２つの通孔８２の中心間隔は２本の支持軸４３，４３の中心間隔と同じである。また、じゃばら受け８０には、じゃばら受け８０自体を受け部４１に締結するための締結手段（ねじ）を挿通させる締結通孔８３が一ヶ所形成されている。また、じゃばら受け８０には、前述した筐体６０と計量機構側の取り付け部材６５，６６とを結合するためのねじ７３を操作するための操作孔８４が形成されている。また、図２０に示すように、一方のじゃばら受け８０には、筐体６０の内部にある計量機構からの配線を導出するための導出孔８５が形成されている。じゃばら受け８０は、支持軸４３を通孔８２に挿通させた状態で荷重受け部材４０の受け部４１，４２にねじで固定する。
【００３３】
受け部４１，４２に固定されたじゃばら受け８０の上にはカバー１００が被せられる。カバー１００は下面が開放された円盤型（皿型）の部材であり、支持軸を挿通する孔が形成されている。支持軸４３を孔に通してカバー１００をじゃばら受け８０に被せると、筐体６０の開口６１，６２付近とじゃばら部材９０はカバー１００の下に覆い隠される。カバー１００から上方に突出した支持軸４３に止めナット１０１を螺入してカバー１００を固定し、支持棒４３にはコンベア等の非計量物が載置される装置類１０２が取り付けられる。
【００３４】
ここで、前記じゃばら部材９０とじゃばら受け８０を筐体６０乃至計量機構側に取り付ける作業について説明する。
じゃばら受け８０は、支持軸４３を通孔８２に挿通させた状態で荷重受け部材４０の受け部４１，４２にねじで固定する。ここで、じゃばら受け８０の２個の通孔８２に２本の支持軸４３をそれぞれ挿入した時、じゃばら受け８０は支持軸４３によって一義的に位置決めがなされるわけではない。即ち、大径の通孔８２と小径の支持軸４３の間には隙間があるので、じゃばら受け８０は受け部４１，４２の上である程度の余裕を以って移動可能な状態にあることとなる。本例では１本のねじでじゃばら受け８０を受け部４１，４２に固定するので、じゃばら受け８０の受け部４１，４２に対する取り付け位置にはある程度の自由度があることとなる。一方、じゃばら受け８０に一体化されたじゃばら部材９０の下端は、筐体６０側にねじで固定される。
【００３５】
しかし、各部品の製作誤差や組み立て誤差のために、計量機構の支持軸４３の位置と、筐体６０の開口６１，６２の位置とは、必ずしも設計通りに正規の状態にならない。よって、じゃばら部材９０の下端を筐体６０側に取り付け、じゃばら部材９０と一体であるじゃばら受け８０を計量機構側（受け部）に固定すると、筐体６０側と計量機構側との位置関係が正規の状態になっていない場合には、じゃばら部材９０に外力が加わって変形した状態で取り付けられてしまう。じゃばら部材９０は、このように外力が加わって変形した状態で取り付けられて使用されると、測定結果に誤差を生じさせてしまう。例えば、じゃばら部材が変形状態にあると、被測定物を載置する位置によって測定結果に違いが生じることがあった。
【００３６】
しかしながら、本例の構成によれば、じゃばら受け８０を荷重受け部材４０と別部材とするとともに、支持軸４３を通す通孔８２の内径を大きくして、じゃばら受け８０を荷重受け部材４０に対して水平方向に適宜に位置決めして取り付けられるようにしている。即ち、通孔８２に支持軸４３を挿通した状態で、じゃばら部材９０が変形しないように受け部４１，４２に対するじゃばら受け８０の位置を定め、締結通孔８３を介して締結手段を受け部４１，４２に締結すれば、じゃばら受け８０を受け部４１，４２に固定することができる。即ち、筐体６０など各部品の製作誤差や各部の組み立て誤差に関わらず、可撓性のじゃばら部材８０が正規の状態となるように取り付けることができる。
【００３７】
次に、上記構成の電子天秤１による被計量物の質量測定動作を説明する。
平衡用錘５０の調整により、荷重受け部（図示しないコンベア重量を含む）の重量負荷状態におけるレバー４の平衡が取られる。このレバーの平衡状態は位置検出センサにより検出される。
【００３８】
次に、被計量物がコンベア上に載置されこのコンベア上を搬送移動する。図２において、ロバーバル機構２は、被計量物の荷重を受けて可動部１４が図中Ｚ１方向に下降する。この際、ロバーバル部１８は計４カ所のバネ部２０の変形により、可動部１４を水平状態を維持したままの状態で下降させる。
【００３９】
可動部１４の下降に連動して、レバー４の可動部３２ａが同様に下降する。可動部３２ａが下降すると、バネ部３４（支点Ａ）を中心として可動部３２ｂがＺ２方向に上昇し、レバー４の自由端４ｂ（可動部３２ｃ）はバネ部３４（支点Ｂ）を中心としてＺ３方向に上昇する。
【００４０】
レバー４の自由端４ｂは、平衡状態に対し所定量変位（上昇）し、この変位量が位置検出センサで検出される。制御部は、レバー４が再度平衡状態に復帰するよう平衡手段６の電磁コイルを通電制御する。
この際、電磁コイルのコイル６ｂに対する電流方向、及び供給する電流量を制御し、位置検出センサによりレバー４が再度平衡状態となったことを検出した際における電磁コイル６ｂへの電流値を得て、この電流値に基づき被計量物の質量を演算出力する。
【００４１】
上記のようにレバー４に支点を２箇所Ａ，Ｂ設けることにより、可動部３２側に加わる被計量物の質量（荷重負荷）を、自由端４ｂ側へ減衰して伝達でき、同時に可動部３２側の移動量に対して自由端４ｂ側の変位量を増大させて得ることができる。これにより、計量精度の向上が図れる。また、レバー４の長さＬ２を短くしつつ所定の減衰量を有する構成にでき小型軽量化が図れる。
レバー４を小型、軽量化したことにより、荷重に対する移動の反応をより敏感にでき、計量精度の向上が図れる。
なお、レバー４自由端４ｂ側から力を加えれば、増大させて可動部３２側（ロバーバル機構２の可動部１４）側に伝達できる為、自由端４ｂ側での小さな力でレバー４を制動できるようになる。
【００４２】
そして、上記の電子天秤１は、特に、ロバーバル機構２と荷重受け部材４０が高い剛性を以って一体とされているので、荷重受け部材４０上にコンベア等の重量物が設けられる動秤としての使用に耐えることができる。この剛性は、ロバーバル機構２が比較的広い幅Ｗ１（図３参照）を有していることにより得られる。この剛性の向上により、コンベア上に被計量物が載置される際の衝撃等に耐え得る電子天秤１を構成できる。
以上説明した実施の形態では、筐体の内部に収納された計量機構はロバーバル機構を用いた電子天秤であったが、本発明は他の計量機構、例えばロードセル等にも適用することができる。
【００４３】
【発明の効果】
本発明の電子天秤によれば、ロバーバル機構等の計量機構を筐体に収納して保護するとともに、筐体の開口部に防水・防塵用の密封部材を設けているが、その密封部材の構成に次のような特徴がある。即ち、計量機構の支持軸をより大径の通孔に対して水平位置調整可能なように挿通し、じゃばら部材が変形しないようにじゃばら受けの位置を定めて受け部に固定している。従って、筐体自体や筐体と本体の組み立てに誤差等があっても、じゃばら部材が無理な力が加えられた状態で取り付けられることがなく、測定に誤差が生じるおそれがなく、水分や塵埃の多い使用環境であっても安定して高い信頼性をもって使用することができる。従って、例えば、食品などのような湿気のある被搬送物、粉体又は搬送時に粉体が発生しやすい被搬送物などの搬送にも支障なく使用することができる。
【図面の簡単な説明】
【図１】本発明の電子天秤の実施の形態を示す分解拡散斜視図。
【図２】ロバーバル機構を示す正面図。
【図３】ロバーバル機構の平面図。
【図４】ロバーバル機構の側面図。
【図５】レバーを示す正面図。
【図６】レバーの平面図。
【図７】レバーの側面図。
【図８】荷重受け部材の正面図。
【図９】荷重受け部材の平面図。
【図１０】荷重受け部材の側面図。
【図１１】荷重受け部材の底面図。
【図１２】ロバーバル機構とレバーと荷重受け部材を組み立てた状態を示す裁断正面図。
【図１３】図１２の（イ）−（イ）切断線における断面図。
【図１４】筐体の正面図。
【図１５】筐体の平面図。
【図１６】筐体の側面図。
【図１７】（ａ）はじゃばら部材の一部を断面とした正面図、（ｂ）は同平面図。
【図１８】じゃばら部材の拡大断面図。
【図１９】（ａ）はじゃばら受けの平面図、（ｂ）は同正面図。
【図２０】本例の電子天秤の正面からみた断面図。
【図２１】底板を外した本例の電子天秤の底面図。
【図２２】本例の電子天秤の側面からみた断面図。
【図２３】従来の電子天秤を示す正面断面図。
【図２４】同従来の電子天秤の斜視図。
【符号の説明】
１…電子天秤、２…ロバーバル機構、２ｂ…レバー収容部、４…レバー、４ａ…基端部、４ｂ…自由端、６…平衡駆動手段（電磁コイル）、１２…固定部、１４…可動部、１８…ロバーバル部、２０…バネ部、２２…レバー固定部、２２ｓ…切断部、３０…固定部、３２（３２ａ、３２ｂ、３２ｃ）…可動部、３４…バネ部（支点Ａ，Ｂ）、４０…荷重受け部材、４１，４２…受け部、４３…支持軸、４４…取り付け部、６０…筐体、６１，６２…開口、６５，６６…取り付け部材、６９，７０…ねじ孔、７１…締結部、８０…じゃばら受け、８２…通孔、８３…通孔、９０…じゃばら部材、９１…ねじ孔、９２…ねじ。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an electronic balance that measures the mass of an object to be weighed, and in particular due to a manufacturing error of the casing, an assembly error of the casing and the main body, etc. on a loose member provided in an opening of the casing that houses the weighing mechanism. The present invention relates to an electronic balance that prevents excessive force from being applied.
[0002]
[Prior art]
FIG. 23 is a front sectional view showing a conventional electronic balance (disclosed in Japanese Patent Publication No. 6-29761), and FIG. 24 is a perspective view thereof. Another is disclosed in Japanese Patent Application Laid-Open No. 11-51756. In these electronic balances 180, the movable portion 181b provided with the mounting tray 190 is moved in a relative manner with respect to the fixed portion 181a, the lever 183 that is interlocked with the movement of the movable portion 181b, and the lever 183 is in an equilibrium state. An electromagnetic coil 185 for movement control, a position detection sensor (not shown) for detecting the equilibrium state of the lever 183, and a control unit (not shown) for calculating and outputting the mass of an object to be measured by energizing the electromagnetic coil 185. It is roughly constituted by.
[0003]
As illustrated, the Roverval mechanism 181 includes a pair of upper and lower parallel Roverval portions 186 formed by cutting a rectangular parallelepiped aluminum or the like from a side portion. A total of four thin spring portions 187 are formed on the rubber portion 186, and when an object to be weighed is placed on the placing plate 190 of the movable portion 181b, the spring portion 187 portion is deformed by receiving this load. The movable portion 181b moves downward while maintaining the horizontal state.
[0004]
In conjunction with this, the free end 183b of the lever 183 is displaced upward from the equilibrium position. Based on the output of the position detection sensor, the control unit controls energization of the electromagnetic coil 185 so that the lever 183 is in a balanced state, and calculates the mass of the object to be measured based on the current value to the electromagnetic coil 185 when the lever 183 is in equilibrium. Calculated output.
[0005]
The lever 183 in the illustrated configuration is integrally formed with the Roverval mechanism 181, whereas the other electronic balance (Japanese Patent Laid-Open No. 11-51756) is formed separately. In all cases, the Roverval mechanism 181 is formed by hollowing out the integral lump.
[0006]
[Problems to be solved by the invention]
If there is no housing that houses and protects the weighing mechanism such as the Roverval mechanism as in the above-described electronic balance, it may be possible that an error occurs in the measurement of the electronic balance or the measuring mechanism is likely to break down depending on the use environment. . For example, when transporting a wet transported object such as food or the like, a powder or a transported object that tends to generate powder during transport, such inconvenience is likely to occur unless the weighing mechanism is covered. . However, when the electronic balance as described above has a structure in which the weighing mechanism is covered with a cover, an opening for leading the load receiving portion of the weighing mechanism to the outside of the housing must be provided. The opening portion needs a waterproof or dustproof sealing member, and the sealing member needs to be flexible enough to follow the load receiving portion that moves under load. it is conceivable that. However, if the sealing member is attached with an excessive force due to a manufacturing error of the casing or an assembly error of the casing and the main body, this excessive force may adversely affect the measurement. Conceivable.
[0007]
The present invention has been made in view of the above-described problems, and there is an error in assembling the casing itself or the casing and the main body with respect to providing a waterproof / dustproof sealing member at the opening of the casing covering the weighing mechanism of the casing. The purpose of the sealing member is to prevent the sealing member from being attached with an excessive force applied.
[0008]
[Means for Solving the Problems]
The electronic balance according to claim 1 includes a base plate (10), a weighing mechanism (2) fixed on the base plate and having load receiving portions (41, 42) on the upper surface, and an upper surface thereof. Has an opening (61, 62) for exposing the receiving portion of the weighing mechanism to the outside, and a housing (60) that houses the weighing mechanism and is fixed to the base plate, and the housing The loose member (90) whose lower end is fixed around the opening of the open member and the loose member (80) fixed to the receiving portion of the measuring mechanism inside the loose member while being engaged with the upper end of the loose member. A support shaft (43) for transmitting a load is fixed to the receiving portions (41, 42), and the support shaft (80) has a larger diameter than the support shaft and the support shaft. The through hole (82) for inserting the A fastening through-hole (83) for inserting a fastening means to be joined, and the receiving member such that the loose member (90) is not deformed in a state where the support shaft is inserted through the through-hole. The position of the bellows receiver relative to is fixed, and the bellows receiver is fixed to the receiving portion by fastening fastening means to the receiving portion via the fastening through hole.
[0009]
An electronic balance according to claim 2 is the electronic balance according to claim 1, wherein the vicinity of the opening (61, 62) of the housing (60) and the loose member ( 90) is covered with a dish-shaped cover (100) whose lower surface is released, and a retaining nut (101) is screwed onto the support shaft (43) protruding upward from the cover. .
[0010]
An electronic balance according to a third aspect is the electronic balance according to the first aspect, wherein the weighing mechanism includes a Roverval mechanism 2, a load receiving member 40, and a lever 4. The Roverval mechanism 2 includes a fixed portion 12, a movable portion 14 that moves under the load of an object to be weighed, and a pair of movable portions having a predetermined length between the fixed portion 12 and the movable portion 14. And a plurality of spring parts 20 formed between the fixed part 12 and the movable part 14 and the rubber part 18, respectively. The load receiving member 40 includes a mounting portion 44 fixed to the movable portion 14, a first receiving portion 41 formed integrally with the mounting portion 44 and provided at a position close to the movable portion 14, The mounting portion 44 and the first receiving portion 41 are formed integrally with the fixing portion 12 or the second receiving portion 42 provided at a position close to the roberval portion 18. The free end of the lever 4 is displaced from the equilibrium state in conjunction with the movement of the movable portion 14 due to the load applied to the load receiving member 44. The measuring mechanism further includes equilibrium driving means 6 for moving the lever whose free end is displaced to an equilibrium state, and control means for calculating the load from the operating state of the equilibrium driving means 6.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the electronic balance of the present invention will be described. FIG. 1 is a perspective view showing a schematic configuration of an electronic balance.
The electronic balance 1 is generally configured as follows. That is, the Roverval mechanism 2 is fixed on the base plate 10, and the lever 4 is assembled inside the Roverval mechanism 2. The Roverval mechanism 2 includes balanced driving means 6 composed of an electromagnetic coil for controlling the lever 4 in a balanced state, and position detecting means (not shown). A hook-shaped load receiving member is fixed to the movable portion 14 of the Roverval mechanism 2, and a dynamic balance having a conveyor placed on the load receiving member can be configured. These mechanisms are housed in the housing 60 as a whole. A plurality (four in this example) of support shafts 43 provided in the first and second receiving portions 41 and 42 of the load receiving member are the openings 61 and 62 of the housing 60, the bellows receiver 80, and the bellows 90. It protrudes upward outside the housing 60 via Then, while the object to be weighed is conveyed by a conveyor (not shown) attached to the support shaft 43, the mass of the object to be weighed is measured by a control unit (not shown). In addition, it is also possible to provide a mounting tray on the support shaft 43 and use it as a static balance for measuring the mass by placing an object to be weighed on the mounting tray.
[0012]
2 is a front view showing the Roverval mechanism 2, FIG. 3 is a plan view thereof, and FIG. 4 is a side view thereof.
The Roverval mechanism 2 includes a fixed portion 12 and a movable portion 14 that is movable in the vertical direction with respect to the fixed portion 12. The upper surface of the movable portion 14 is formed slightly higher than the fixed portion 12. This Roverval mechanism 2 is formed by punching a rectangular parallelepiped aluminum lump having a length L and a width W1 from the front side to form a hollow portion 16 therethrough. Further, this Rovalval mechanism may form the hollow portion 16 by extrusion molding or the like. At this time, a pair of parallel robust parts 18 having a predetermined thickness are provided above and below. The pair of Roverval portions 18 have the same length in the length direction L, and thin spring portions 20 are formed at both ends. The spring portion 20 is provided in a total of four locations, two on the top and bottom surfaces, each having a circular arc shape when viewed from the top and bottom surfaces, and is formed in a straight line continuous in the width W1 direction.
[0013]
A lever fixing portion 22 for fixing the lever 4 is formed at a position directly below the upper rubber portion 18 in parallel with the rubber portion 18. The lever fixing portion 22 has a cutting portion 22 s in the middle of the length L direction corresponding to the fixing portion 12 and the movable portion 14 of the rubber valve 18, and a gap that does not hinder the movement of the movable portion 14 relative to the fixed portion 12. have. By this cutting, the lever fixing portion 22 has a fixed side 22a and a movable side 22b.
[0014]
On one end side 2a in the length direction L of the Roverval mechanism 2, a protruding piece 24 having a predetermined length is formed on the upper portion, and the equilibrium driving means 6 is attached to the lower surface. In addition, an approximately rectangular parallelepiped-shaped lever accommodating portion 2b is formed by opening from the central portion of one side surface of the Roverval mechanism 2 located on the one end side 2a toward the inside of the Roverval mechanism 2. The lever accommodating portion 2b is formed on the lower surface of the lever fixing portion 22, and reaches the position on the movable portion 14 side as viewed from the front side in FIG. 2 (at a position beyond the spring portion 20 of the above-mentioned Roverval portion 18). (Until reached)
[0015]
5 is a front view of the lever 4, FIG. 6 is a plan view thereof, and FIG. 7 is a side view thereof.
The lever 4 has a small width W2 with respect to the width W1 of the Roverval mechanism 2, and is reduced in size and weight. On the base end portion 4a side, a fixed portion 12 of the Roverval portion 18, a fixed portion 30 fixed to the movable portion 14, and a movable portion 32a are formed. The other end is a free end 4b, and the free end 4b extends to a position outside the Roverval mechanism 2 in a state after the lever is fixed, and is located immediately below the protruding piece 24.
[0016]
In the lever 4, the movable portion 32a is interlocked with the movement of the movable portion 14 of the Roverval mechanism 2, and the free end 4b side moves up and down. The lever 4 has two fulcrums A and B, a function of attenuating the mass (load load) of an object to be measured applied to the movable portion 14 by a predetermined amount by the two fulcrums A and B, and the lever. The length L2 of 4 is shortened.
[0017]
The lever 4 is also formed by cutting out an aluminum lump or the like. In particular, the cutting portions 28 (28a, 28b, 28c) are formed in a substantially U shape when viewed from the front.
By this cutting portion 28, a fixed portion 30 is formed at a substantially central portion, and movable portions 32 (32a, 32b, 32c) are formed on both sides and the lower surface of the fixed portion 30, respectively.
The fixed portion 30 and the movable portion 32 of the lever 4 are connected to each other by two thin spring portions 34 located at the fulcrums A and B. The spring part 34 is formed in a shape substantially the same as the spring part 20 of the Roverval mechanism 2, and description thereof is omitted.
[0018]
On the movable part 32 side, the load applied to the base end part 4a is efficiently transmitted to the free end 4b side via the fulcrums A and B of the spring part 34, and the strength of the spring part 34 is also maintained. In order to achieve this, a plurality of spring portions 36 are formed in the same manner as the spring portions 34 at required locations (a total of three locations).
[0019]
FIG. 12 is a partially cut front view showing an assembled state of the measuring mechanism of the electronic balance. The assembly structure of the above-described Robarval mechanism 2 and lever 4 will be described with reference to FIG. In this figure, for convenience, the lever 4 is not cut and only the Roverval mechanism 2 is cut.
The electronic balance 1 is configured by inserting and fixing a lever 4 inside a robust mechanism 2. In the Roverval mechanism 2, the fixing portion 12 is fixed on the base plate 10 with screws 11. The lever 4 is inserted into the lever accommodating portion 2b, and the base end side 4a is fixed to the lever fixing portion 22 with screws 25. On the lower surface of the lever fixing portion 22 forming the lever accommodating portion 2b, a step portion 22d for guiding one side surface of the lever 4 along the length direction L is formed. This facilitates positioning when inserting the lever 4 and facilitates assembly.
[0020]
The fixed portion 30 of the lever 4 is fixed to the fixed side 22a of the lever fixed portion 22, and the movable portion 32a of the lever 4 is fixed to the movable side 22b of the lever fixed portion 22.
In this fixed state, the free end 4 b of the lever 4 protrudes to the one end side 2 a of the Roverval mechanism 2 and is located directly below the protruding piece 24.
In this way, by providing the lever 4 inside the Roverval mechanism 2, the overall size can be reduced.
[0021]
On the free end 4b side of the lever 4, a weight mounting piece 38 is formed so as to protrude downward, and a balancing weight 40 is slidably mounted in a substantially horizontal screw hole 38b portion. As a result, the lever 4 can be balanced by adjusting the balancing weight 40 when the load receiving member or the like is loaded on the movable portion 14 of the Roverval mechanism 2. The equilibrium state of the lever 4 is detected by a slit provided at the free end 4b and a position detection sensor (not shown) fixed on the protruding piece 24 side, and the moving direction of the lever 4 is also detected. It has become.
[0022]
The electromagnetic coil constituting the balanced driving means 6 has an annular magnet body 6a fixed to the lower surface of the projecting piece 24, and a coil 6b wound around the ring of the magnet body 6a on the upper surface of the free end 4b of the lever 4. It is fixed. As described above, since the electromagnetic coil can be provided outside the Roverval mechanism 2, assembly and maintenance during manufacture can be easily performed.
The balance driving means 6 receives the current control of the control means when measuring the object to be measured, changes the magnetic force between the magnet body 6a by the current supplied to the coil 6b, and returns the lever 4 to the balanced state.
And a control means calculates the said load from the electric current value given to the coil 6b.
[0023]
8 is a front view of the load receiving member 40, FIG. 9 is a plan view thereof, FIG. 10 is a side view thereof, and FIG. 11 is a bottom view thereof. The load receiving member 40 is composed of an upper wall 46 and a side wall 47, is a member having a substantially U-shaped cross section that opens in the front-rear direction and the lower direction, and has a bowl-shaped outer shape. The load receiving member 40 is placed on the Roverval mechanism 2 and is disposed so as to cover the upper surface of the Roverval mechanism 2 and both side surfaces along the length direction. In the load receiving member 40, the substantially half on the left side in FIG. 8 is an attachment portion 44 for the movable portion 14 of the Roverval mechanism 2. The attachment portion 44 is thicker on the upper wall 46 and the side wall 47 than on other portions. Therefore, as shown in FIGS. 12 and 13, when the mounting portion 44 is fixed to the movable portion 14 with a plurality of bolts 45, the portion other than the mounting portion 44 in the upper wall 46 and the side wall 47 of the load receiving member 40. Faces the outer surface of the Roverval mechanism 2 at a predetermined interval and does not contact the Roverval mechanism 2.
[0024]
A first receiving portion 41 is integrally formed at one end of the load receiving member 40. The first receiving portion 41 is close to the attachment portion fixed to the movable portion 14 and is at a position away from the Roverval mechanism 2. A second receiving portion 42 is formed integrally with the other end of the load receiving member 40. The second receiving part 42 is disposed in the vicinity of the fixed part 12 or the rubber part 18 of the rubber valve mechanism 2.
[0025]
As shown in FIG. 8, the side wall 47 of the load receiving member 40 covers the entire movable portion 14 for the longest time in the mounting portion 44, but the lower side is inclined and cut as it approaches the second receiving portion 42. It goes up and is the shortest in the second receiving part 42. From this shape, the center of gravity of the load receiving member 40 is located closer to the first receiving portion 41 than the second receiving portion 42 between the two receiving portions 41 and 42 in the longitudinal direction. The load and its own weight applied to the first receiving portion 41 and the second receiving portion 42 are applied to the movable portion 14 of the Roverval mechanism 2 with a good balance.
[0026]
As described above, according to this example, the attachment portion 44 of the load receiving member 40 is in contact with the movable portion 14 of the Roverval mechanism 2 on the total three surfaces of the upper wall 46 and the both side walls 47, and is firmly screwed on these surfaces. It is integrated with the structure. Further, although load is applied to the load receiving member 40 at two locations, the shape is devised so that the load is applied to the movable portion 14 in an optimum state, and balance is taken into consideration. Therefore, the measuring mechanism of the present apparatus mainly including the load receiving member 40 and the Roverval mechanism 2 has high rigidity, high measurement accuracy, and excellent durability.
[0027]
14 is a front view of the housing 60, FIG. 15 is a plan view thereof, and FIG. 16 is a side view thereof. The housing has a rectangular parallelepiped shape with an open bottom surface. An opening 61 is formed on the upper surface of the housing 60 to expose the receiving portion to the outside. The opening 61 has a shape in which a circular part is closed in a bow shape. In the vicinity of the opening, a fastening portion 71 having a screw hole 70 is formed. An opening 63 for internal inspection is provided on the side surface of the housing and is closed by a detachable lid 64.
[0028]
As shown in FIGS. 1 and 20, two attachment members 65 and 66 for attaching the housing 60 are fixed to the base plate of the measurement mechanism described above. The attachment members 65 and 66 have horizontal fixing portions 65a and 66a, respectively, at positions above the upper surface of the measuring mechanism. Screw holes are formed in the respective fixing portions 65a and 66a.
[0029]
The bottom plate 67 is disposed under the base plate 10 of the weighing mechanism described above, the casing 60 is covered from above the weighing mechanism, and a packing 68 is provided between the bottom plate 67 and the casing 60. At this time, the fastening portions 71 and 71 of the housing 60 correspond to the fixing portions 65 a and 66 a of the attachment members 65 and 66 in the housing 60. Here, as shown in FIG. 20, if the screws 73, 73 as fastening means are screwed into the screw holes of the fixing portions 65a, 66a from the screw holes 70, 70, the housing 60 and the measuring mechanism side can be integrated. Since the connection between the housing 60 and the main body side of the measuring mechanism by the screw 73 can be performed on the upper surface side of the housing 60, the operation is easy.
[0030]
FIG. 17A is a front view with a cross section of a part of the loose member 90, FIG. 17B is a plan view, and FIG. 18 is an enlarged view of FIG. The loose member 90 is a substantially cylindrical member whose peripheral wall has a loose structure, and is made of a flexible member or an elastic member such as rubber. A screw hole 91 is formed at the lower end of the loose member 90, and a screw hole 69 is provided around the opening 61. As shown in FIG. 1 or FIG. 20, the loose member 90 is fixed to the housing 60 by fastening the screw 92 through the screw hole 69 and the screw hole 91. On the upper end of the loose member 90, a protrusion 93 having a downward and square cross section is formed in a circumferential shape.
[0031]
With such a structure, the screw 73 that couples the housing 60 and the main body side of the measuring mechanism is hidden inside the loose member 90, so that the assembly screws are not exposed to the outside and the appearance is good. It is easy to work when cleaning the outer surface.
[0032]
FIG. 19A is a plan view of the bellows receiver 80, and FIG. 19B is a front view of the bellows receiver 80. The upper surface of the bellows receiver 80 has a concave groove 81 in a circumferential shape. The circumferential protrusion 93 of the loose member 90 is pushed into the concave groove 81 and fixed, and the loose member 90 and the loose receiver 80 are integrated. In the bellows receiver 80, two through holes 82 are formed so that the support shaft 43 provided in the receiving portion 41 of the load receiving member 40 of the measuring mechanism is inserted. The inner diameter of the through hole 82 is larger than the outer diameter of the support shaft 43, and the center distance between the two through holes 82 is the same as the center distance between the two support shafts 43, 43. Further, the loose receptacle 80 is formed with one fastening through hole 83 through which a fastening means (screw) for fastening the loose receptacle 80 itself to the receiving portion 41 is inserted. Further, the bellows receiver 80 is formed with an operation hole 84 for operating a screw 73 for coupling the housing 60 and the attachment members 65 and 66 on the weighing mechanism side. As shown in FIG. 20, one of the loose receptacles 80 is formed with a lead-out hole 85 for leading out the wiring from the measuring mechanism inside the housing 60. The loose receiver 80 is fixed to the receiving portions 41 and 42 of the load receiving member 40 with screws in a state where the support shaft 43 is inserted into the through hole 82.
[0033]
A cover 100 is placed on the loose receiver 80 fixed to the receiving portions 41 and 42. The cover 100 is a disk-shaped (dish-shaped) member having an open bottom surface, and has a hole through which the support shaft is inserted. When the support shaft 43 is passed through the hole and the cover 100 is put on the loose receiver 80, the vicinity of the openings 61 and 62 of the housing 60 and the loose member 90 are covered under the cover 100. A lock nut 101 is screwed into a support shaft 43 protruding upward from the cover 100 to fix the cover 100, and a device 102 on which a non-weighing object such as a conveyor is placed is attached to the support bar 43.
[0034]
Here, an operation of attaching the loose member 90 and the loose receiver 80 to the casing 60 or the weighing mechanism side will be described.
The loose receiver 80 is fixed to the receiving portions 41 and 42 of the load receiving member 40 with screws in a state where the support shaft 43 is inserted into the through hole 82. Here, when the two support shafts 43 are respectively inserted into the two through holes 82 of the bellows receiver 80, the bellows receiver 80 is not uniquely positioned by the support shaft 43. That is, since there is a gap between the large-diameter through hole 82 and the small-diameter support shaft 43, the loose receiver 80 is movable on the receiving portions 41 and 42 with a certain margin. Become. In this example, since the loose receiver 80 is fixed to the receiving portions 41 and 42 with one screw, the attachment position of the loose receiver 80 with respect to the receiving portions 41 and 42 has a certain degree of freedom. On the other hand, the lower end of the loose member 90 integrated with the loose receptacle 80 is fixed to the housing 60 side with a screw.
[0035]
However, the position of the support shaft 43 of the measuring mechanism and the positions of the openings 61 and 62 of the housing 60 are not necessarily in a normal state as designed due to manufacturing errors and assembly errors of each part. Therefore, when the lower end of the loose member 90 is attached to the housing 60 side and the loose receiver 80 integral with the loose member 90 is fixed to the weighing mechanism side (receiving portion), the positional relationship between the housing 60 side and the weighing mechanism side is If it is not in the normal state, the loose member 90 is attached in a deformed state due to an external force applied thereto. If the loose member 90 is attached and used in such a state that it is deformed by applying an external force in this way, an error is caused in the measurement result. For example, when the loose member is in a deformed state, the measurement result may differ depending on the position where the object to be measured is placed.
[0036]
However, according to the configuration of this example, the bellows receiver 80 is a separate member from the load receiving member 40 and the inner diameter of the through hole 82 through which the support shaft 43 is passed is increased so that the bellows receiver 80 is separated from the load receiving member 40. Thus, it can be positioned and mounted appropriately in the horizontal direction. That is, in a state where the support shaft 43 is inserted into the through hole 82, the position of the loose receiver 80 with respect to the receiving portions 41 and 42 is determined so that the loose member 90 is not deformed, and the fastening means receiving portion 41 is connected via the fastening through hole 83. , 42 can be fixed to the receiving portions 41, 42. In other words, the flexible loose member 80 can be attached in a normal state regardless of the manufacturing error of each part such as the housing 60 or the assembly error of each part.
[0037]
Next, the mass measurement operation of the object to be weighed by the electronic balance 1 having the above configuration will be described.
By adjusting the balancing weight 50, the lever 4 is balanced in a weight load state of a load receiving portion (including a conveyor weight not shown). The equilibrium state of the lever is detected by a position detection sensor.
[0038]
Next, an object to be weighed is placed on the conveyor and transported and moved on the conveyor. In FIG. 2, the Roverval mechanism 2 receives the load of the object to be measured, and the movable portion 14 descends in the Z1 direction in the figure. At this time, the rubber part 18 lowers the movable part 14 while maintaining the horizontal state by the deformation of the spring parts 20 in four places in total.
[0039]
In conjunction with the lowering of the movable part 14, the movable part 32a of the lever 4 is similarly lowered. When the movable part 32a is lowered, the movable part 32b rises in the Z2 direction around the spring part 34 (fulcrum A), and the free end 4b (movable part 32c) of the lever 4 is Z3 around the spring part 34 (fulcrum B). Ascend in the direction.
[0040]
The free end 4b of the lever 4 is displaced (increased) by a predetermined amount with respect to the equilibrium state, and this displacement amount is detected by the position detection sensor. The control unit controls energization of the electromagnetic coil of the balancing means 6 so that the lever 4 returns to the balanced state again.
At this time, the current direction to the coil 6b of the electromagnetic coil and the amount of current to be supplied are controlled, and the current value to the electromagnetic coil 6b when the lever 4 is detected to be in an equilibrium state again by the position detection sensor is obtained. Based on this current value, the mass of the object to be weighed is calculated and output.
[0041]
By providing two fulcrums A and B on the lever 4 as described above, the mass (load load) of the object to be weighed applied to the movable part 32 side can be attenuated and transmitted to the free end 4b side, and at the same time, the movable part 32 is provided. This can be obtained by increasing the amount of displacement on the free end 4b side relative to the amount of movement on the side. Thereby, the measurement accuracy can be improved. Further, the length L2 of the lever 4 can be shortened while a predetermined amount of attenuation can be provided, and the size and weight can be reduced.
By making the lever 4 smaller and lighter, the movement response to the load can be made more sensitive, and the measurement accuracy can be improved.
If a force is applied from the lever 4 free end 4b side, it can be increased and transmitted to the movable part 32 side (movable part 14 of the Roverval mechanism 2) side, so that the lever 4 can be braked with a small force on the free end 4b side. It becomes like this.
[0042]
The electronic balance 1 is particularly a dynamic balance in which a heavy load such as a conveyor is provided on the load receiving member 40 because the robust mechanism 2 and the load receiving member 40 are integrated with high rigidity. Can withstand the use of This rigidity is obtained by the Roverval mechanism 2 having a relatively wide width W1 (see FIG. 3). By improving the rigidity, it is possible to configure the electronic balance 1 that can withstand an impact or the like when an object to be weighed is placed on the conveyor.
In the embodiment described above, the weighing mechanism housed in the casing is an electronic balance using a Robert mechanism, but the present invention can also be applied to other weighing mechanisms such as a load cell.
[0043]
【The invention's effect】
According to the electronic balance of the present invention, a measuring mechanism such as a Roverval mechanism is housed and protected in the housing, and a waterproof / dustproof sealing member is provided at the opening of the housing. Has the following characteristics. In other words, the support shaft of the measuring mechanism is inserted so that the horizontal position can be adjusted with respect to the larger-diameter through hole, and the position of the loose receiver is determined and fixed to the receiving portion so that the loose member is not deformed. Therefore, even if there is an error in the housing itself or the assembly of the housing and the main body, the loose member is not attached with excessive force applied, there is no risk of errors in measurement, and moisture and dust It can be used stably and with high reliability even in an environment where there are many. Therefore, for example, it can be used without difficulty for transporting a transported object such as a food product with moisture, a powder or a transported object in which powder is easily generated during transport.
[Brief description of the drawings]
FIG. 1 is an exploded diffusion perspective view showing an embodiment of an electronic balance of the present invention.
FIG. 2 is a front view showing a robust mechanism.
FIG. 3 is a plan view of a Roberval mechanism.
FIG. 4 is a side view of a roberval mechanism.
FIG. 5 is a front view showing a lever.
FIG. 6 is a plan view of a lever.
FIG. 7 is a side view of the lever.
FIG. 8 is a front view of a load receiving member.
FIG. 9 is a plan view of a load receiving member.
FIG. 10 is a side view of a load receiving member.
FIG. 11 is a bottom view of the load receiving member.
FIG. 12 is a cut front view showing a state in which the Roverval mechanism, the lever, and the load receiving member are assembled.
13 is a cross-sectional view taken along line (A)-(A) in FIG.
FIG. 14 is a front view of the housing.
FIG. 15 is a plan view of a housing.
FIG. 16 is a side view of the housing.
17A is a front view with a cross section of a part of a loose member, and FIG. 17B is a plan view of the same.
FIG. 18 is an enlarged sectional view of a loose member.
FIG. 19A is a plan view of a loose receptacle, and FIG. 19B is a front view thereof.
FIG. 20 is a cross-sectional view of the electronic balance of this example as seen from the front.
FIG. 21 is a bottom view of the electronic balance of the present example with the bottom plate removed.
FIG. 22 is a cross-sectional view of the electronic balance of this example as seen from the side.
FIG. 23 is a front sectional view showing a conventional electronic balance.
FIG. 24 is a perspective view of the conventional electronic balance.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Electronic balance, 2 ... Roberval mechanism, 2b ... Lever accommodating part, 4 ... Lever, 4a ... Base end part, 4b ... Free end, 6 ... Balance drive means (electromagnetic coil), 12 ... Fixed part, 14 ... Movable part 18 ... Roberval part, 20 ... Spring part, 22 ... Lever fixing part, 22s ... Cut part, 30 ... Fixing part, 32 (32a, 32b, 32c) ... Moving part, 34 ... Spring part (fulcrum A, B), 40 ... load receiving member, 41, 42 ... receiving portion, 43 ... support shaft, 44 ... mounting portion, 60 ... housing, 61, 62 ... opening, 65, 66 ... mounting member, 69, 70 ... screw hole, 71 ... Fastening portion, 80 ... loose receiving, 82 ... through hole, 83 ... through hole, 90 ... loose member, 91 ... screw hole, 92 ... screw.

Claims

A base plate (10);
A weighing mechanism (2) fixed on the base plate and provided with a load receiving portion (41, 42) on the upper surface;
Openings (61, 62) for exposing the receiving portion of the weighing mechanism to the outside are formed on the upper surface, and a housing (60) that houses the weighing mechanism and is fixed to the base plate,
A loose member (90) having a lower end fixed around the opening of the housing;
A loose receiver (80) that is engaged with an upper end of the loose member and is fixed to a receiving portion of the measuring mechanism inside the loose member;
Have,
A support shaft (43) for transmitting a load is fixed to the receiving portions (41, 42), and the loose receiver (80) has a diameter larger than that of the support shaft and is inserted through the support shaft. A hole (82) and a fastening through hole (83) for inserting a fastening means fastened to the receiving portion are formed,
In the state where the support shaft is inserted into the through hole, the position of the loose receiving relative to the receiving portion is determined so that the loose member (90) is not deformed, and the fastening means is connected to the receiving portion via the fastening through hole. An electronic balance characterized in that the loose receiver is fixed to the receiving portion by fastening .

A dish-shaped cover (100) having a lower surface opened so as to cover the vicinity of the openings (61, 62) of the casing (60) and the bellows member (90) is provided on the bellows receiver (80). The electronic balance according to claim 1 , wherein a retaining nut (101) is screwed onto the support shaft (43) that is covered and protrudes upward from the cover .

A fixed part (12), a movable part (14) that moves under the load of the object to be weighed, and a pair having a predetermined length between the fixed part and the movable part, the movable part being in a horizontal state A Roverval mechanism (2) having a Roverval portion (18) to be moved and a plurality of spring portions (20) formed between the fixed portion, the movable portion and the Roverval portion;
A mounting portion (44) fixed to the movable portion; a first receiving portion (41) formed integrally with the mounting portion and provided at a position close to the movable portion; the mounting portion and the first A load receiving member (40) having a second receiving portion (42) formed integrally with one receiving portion and provided at a position close to the fixed portion or the roberval portion;
A lever (4) in which a free end is displaced from an equilibrium state in conjunction with movement of the movable part due to a load applied to the load receiving member;
Equilibrium drive means (6) for moving the lever, whose free end is displaced, to an equilibrium state;
And control means for calculating the load from the operating state of the equilibrium drive means,
The electronic balance according to claim 1 or 2, wherein the weighing mechanism is configured.