JP3688556B2

JP3688556B2 - Resin gear, image forming apparatus, and resin rotation transmission means

Info

Publication number: JP3688556B2
Application number: JP2000160670A
Authority: JP
Inventors: 和幸酒巻
Original assignee: Enplas Corp
Current assignee: Enplas Corp
Priority date: 2000-05-30
Filing date: 2000-05-30
Publication date: 2005-08-31
Anticipated expiration: 2020-05-30
Also published as: JP2001336613A

Description

【０００１】
【発明の属する技術分野】
本発明は、複写機，プリンター，ファクシミリ，自動車用部品等の動力伝達機構に広く使用される樹脂製ギヤ及びこの樹脂製ギヤを介して感光体を駆動するように構成された複写機，プリンター，ファクシミリ等の画像形成装置に関する。
【０００２】
【従来の技術】
従来から複写機や自動車用部品等の動力伝達機構には、部品費用の低廉化，軽量化及び作動音の静粛化等を目的として樹脂製ギヤが使用されている。この樹脂製ギヤは、射出成形により所定の形状に形成されるが、使用目的に合致するような歯形精度と強度になるように、その形状が工夫されている。
【０００３】
（第１の従来例）
例えば、図１４〜図１５に示す樹脂製ギヤ５０は、歯５１が形成された円環状の歯部５２と軸５３に嵌合されるボス（軸支持部）５４とを薄板状のウェブ５５で接続するような形状に形成されており、歯部５２に接続されるウェブ５５が薄いため、射出成形後におけるウェブ５５と歯部５２の接続部及びその近傍の半径方向内方への収縮変形量が少なく、歯形精度を高精度に成形することができる。尚、歯部５２に接続されるウェブ５５の肉厚が厚い場合は、ウェブ５５の体積が大きくなり、射出成形後におけるウェブ５５の半径方向内方への収縮変形量が大きくなるため、ウェブ５５と歯部との接続部及びその近傍部分がウェブ５５の収縮方向へ引っ張られるように変形し、歯部５２の変形量が大きくなり、歯５１の成形精度の低下が大きくなる。
【０００４】
一方、これらの図１４〜図１５に示すような樹脂製ギヤ５０は、図１６のようなラジアル荷重ＷＲを受けた状態で動力伝達する場合、ラジアル荷重ＷＲを受けるウェブ５５の厚みが薄くて強度が低いため、図１６の点線で示すように楕円状に変形する量が大きくなり、回転伝達精度が低下する。又、図１５に示すような断面形状の樹脂製ギヤ５０がはすば歯車の場合、歯部５２及びウェブ５５にスラスト荷重ＷＳが作用することになるが、ウェブ５５の厚さが薄く、図１７の点線で示すようにスラスト荷重ＷＳの作用方向への撓み変形量が大きくなり、回転伝達精度が低下する。
【０００５】
（第２の従来例）
そこで、このような不具合を解消するため、図１８〜図２０に示すように、ウェブ５５の側面にボス５４と歯部５２を接続する半径方向リブ５６を形成し、ウェブ５５の剛性を高め、回転伝達精度を向上させるようにした樹脂製ギヤ５７が考えられた。しかし、このように、ボス５４と歯部５２を半径方向リブ５６で直接接続したような樹脂製ギヤ５７は、半径方向リブ５６と歯部５２との接続部及びその近傍の半径方向内方への収縮変形量（図１８及び図１９中の点線部分）が大きくなり、図２１に示すような歯５１の倒れ込みという現象を生じ、歯形精度が低下するという新たな不具合を招くことになった。
【０００６】
（第３の従来例）
このような従来例の不具合を解消できる樹脂製ギヤ６０として、図２２〜図２３に示すものが本願出願人により開発された。これらの図に示す樹脂製ギヤ６０は、ウェブ５５の側面にボス５４と同心状に第１の周方向リブ６１が形成され、この第１の周方向リブ６１と歯部５２との間のウェブ５５の側面に第２の周方向リブ６２が歯部５２と同心状に形成され、更にボス５４と第１の周方向リブ６１及びこの第１の周方向リブ６１と第２の周方向リブ６２がそれぞれ径方向リブ６３，６４で接続されており、径方向リブ６４を歯部５２に接続することなく、ウェブ５５の剛性を高めるようになっている。従って、このような樹脂製ギヤ６０は、歯形精度が高精度で且つ回転伝達精度が高精度であり、精密機器に広く利用されている（特開平１０−２７８１２４号公報参照）。
【０００７】
【発明が解決しようとする課題】
しかし、近年、カラープリンタやカラー複写機等の画像形成装置は、樹脂製ギヤ６０の僅かな回転伝達精度の誤差が色ずれとして現れる。そのため、色ずれを防止して、より一層鮮明な印刷を可能にするためには、樹脂製ギヤ６０の回転伝達精度（動的精度）を更に高精度化する必要がある。
【０００８】
又、近年のカラープリンターやカラー複写機等の画像形成装置は、デスクサイドに配置されて使用されることが多いため、作動時の振動や振動に起因する騒音を低減し、静粛な職場環境を維持し得るものであることが必要とされている。
【０００９】
そこで、本発明は、このような課題を解決できる樹脂製ギヤやこの樹脂製ギヤを使用する画像形成装置を提供することを目的とする。
【００１０】
【課題を解決するための手段】
即ち、請求項１の発明に係る樹脂製ギヤは、半径方向外方に形成された略円環状の歯部と、この歯部の回転中心を中心とするように半径方向内方に形成された軸支持部と、この軸支持部と前記歯部とを接続するウェブと、を備えている。そして、前記ウェブの両側面には、前記歯部と同心の周方向リブが形成されると共に、該周方向リブと前記軸支持部とを半径方向に接続する径方向リブが放射状に複数形成されている。また、前記ウェブの一方の側面側には、前記周方向リブと前記軸支持部とを径方向に接続する隣り合う一対の径方向リブのうちの一方と前記周方向リブとの接続部から前記一対の径方向リブのうちの他方と前記軸支持部との接続部に斜めに延びる一方の筋かいが形成されている。また、前記ウェブの他方の側面側には、前記周方向リブと前記軸支持部とを径方向に接続する隣り合う一対の径方向リブのうちの一方と前記軸支持部との接続部から前記一対の径方向リブのうちの他方と前記周方向リブとの接続部に斜めに延びる他方の筋かいが形成されている。そして、前記一方の筋かいと前記他方の筋かいとが逆方向に傾斜しており、動力伝達時に、前記一方の筋かいと前記他方の筋かいのいずれか一方が圧縮力を受け、前記一方の筋かいと前記他方の筋かいのいずれか他方が引っ張り力を受けるようになっており、前記筋かいは前記径方向リブから分岐するようになっている。
【００１１】
このような構成の本発明は、ウェブが周方向リブ及び径方向リブで補強されると共に周方向リブの内周面側に形成された筋かいによりウェブが補強される。その結果、本発明の樹脂製ギヤは、ウェブの肉厚を厚くしなくても剛性を大きくすることができる。従って、本発明によれば、ウェブの剛性を大きくすることによって歯形精度を損なうというようなことがない。即ち、本発明は、歯部の形状精度（静的精度）を維持しながら回転伝達精度（動的精度）を向上させることが可能になる。しかも、本発明によれば、ウェブの剛性を大きくすることにより、振動を低減し、振動に起因する騒音を低減することが可能になる。
また、請求項２の発明に係る樹脂製ギヤは、半径方向外方に形成された略円環状の歯部と、この歯部の回転中心を中心とするように半径方向内方に形成された軸支持部と、この軸支持部と前記歯部とを接続するウェブと、を備えている。そして、前記ウェブの両側面には、前記歯部と同心の周方向リブが前記歯部と前記軸支持部との間に複数形成され、前記軸支持部と前記周方向リブ及び径方向に隣り合う周方向リブ同士を半径方向に接続する径方向リブが放射状に複数形成されている。また、前記ウェブの一方の側面側には、少なくとも径方向に隣り合う前記周方向リブ同士を径方向に接続する隣り合う一対の径方向リブのうちの一方と前記周方向リブ同士の一方との接続部から前記一対の径方向リブのうちの他方と前記周方向リブ同士の他方との接続部に斜めに延びる一方の筋かいが形成されている。また、前記ウェブの他方の側面側には、少なくとも径方向に隣り合う前記周方向リブ同士を径方向に接続する隣り合う一対の径方向リブのうちの一方と前記周方向リブ同士の他方との接続部から前記一対の径方向リブのうちの他方と前記周方向リブ同士の一方との接続部に斜めに延びる他方の筋かいが形成されている。そして、前記一方の筋かいと前記他方の筋かいとが逆方向に傾斜しており、動力伝達時に、前記一方の筋かいと前記他方の筋かいのいずれか一方が圧縮力を受け、前記一方の筋かいと前記他方の筋かいのいずれか他方が引っ張り力を受けるようになっており、前記筋かいは前記径方向リブから分岐するようになっている。
請求項３の発明に係る樹脂製ギヤは、半径方向外方に形成された略円環状の歯部と、この歯部の回転中心を中心とするように半径方向内方に形成された軸支持部と、この軸支持部と前記歯部とを接続するウェブと、を備えている。この樹脂製ギヤにおいて、前記ウェブの両側面には、前記歯部と同心の周方向リブが形成されると共に、該周方向リブと前記軸支持部とを半径方向に接続する径方向リブが放射状に複数形成され、前記周方向リブと前記軸支持部とを径方向に接続する隣り合う一対の径方向リブのうちの一方と前記周方向リブとの接続部から前記一対の径方向リブのうちの他方と前記軸支持部との接続部に斜めに延びる筋かいがそれぞれ形成されている。そして、前記ウェブの両側面のそれぞれに形成された筋かいが同一方向に傾斜しており、動力伝達時に、前記ウェブの両側面の各筋かいが共に圧縮力又は引っ張り力を受けるようになっており、前記筋かいは前記径方向リブから分岐するようになっている。
請求項４の発明に係る樹脂製ギヤは、半径方向外方に形成された略円環状の歯部と、この歯部の回転中心を中心とするように半径方向内方に形成された軸支持部と、この軸支持部と前記歯部とを接続するウェブと、を備えている。この樹脂製ギヤにおいて、前記ウェブの両側面には、前記歯部と同心の周方向リブが前記歯部と前記軸支持部との間に複数形成されると共に、前記軸支持部と前記周方向リブ及び径方向に隣り合う周方向リブ同士を半径方向に接続する径方向リブが放射状に複数形成され、少なくとも径方向に隣り合う前記周方向リブ同士を径方向に接続する隣り合う一対の径方向リブのうちの一方と前記周方向リブ同士の一方との接続部から前記一対の径方向リブのうちの他方と前記周方向リブ同士の他方との接続部に斜めに延びる筋かいがそれぞれ形成されている。そして、前記ウェブの両側面のそれぞれに形成された筋かいが同一方向に傾斜しており、動力伝達時に、前記ウェブの両側面の各筋かいが共に圧縮力又は引っ張り力を受けるようになっており、前記筋かいは前記径方向リブから分岐するようになっている。
請求項５の発明に係る樹脂製ギヤは、半径方向外方に形成された略円環状の歯部と、この歯部の回転中心を中心とするように半径方向内方に形成された軸支持部と、この軸支持部と前記歯部とを接続するウェブと、を備えている。そして、前記ウェブには、前記歯部と同心の周方向リブが形成されると共に、該周方向リブと前記軸支持部とを半径方向に接続する径方向リブが放射状に複数形成されている。また、前記ウェブの少なくとも一方の側面には、前記周方向リブと前記軸支持部とを径方向に接続する隣り合う一対の径方向リブのうちの一方と前記周方向リブとの接続部から前記一対の径方向リブのうちの他方と前記軸支持部との接続部に斜めに延びる一方の筋かいが形成されると共に、前記一対の径方向リブのうちの一方と前記軸支持部との接続部から前記一対の径方向リブのうちの他方と前記周方向リブとの接続部に斜めに延びる他方の筋かいが形成されている。そして、動力伝達時に、前記一方の筋かいと前記他方の筋かいのいずれか一方が圧縮力を受け、前記一方の筋かいと前記他方の筋かいのいずれか他方が引っ張り力を受けるようになっており、前記筋かいは前記径方向リブから分岐するようになっている。
請求項６の発明に係る樹脂製ギヤは、半径方向外方に形成された略円環状の歯部と、この歯部の回転中心を中心とするように半径方向内方に形成された軸支持部と、この軸支持部と前記歯部とを接続するウェブと、を備えている。そして、前記ウェブには、前記歯部と同心の周方向リブが前記歯部と前記軸支持部との間に複数形成されると共に、前記軸支持部と前記周方向リブ及び径方向に隣り合う周方向リブ同士を半径方向に接続する径方向リブが放射状に複数形成されている。また、前記ウェブの少なくとも一方の側面には、少なくとも径方向に隣り合う前記周方向リブ同士を径方向に接続する隣り合う一対の径方向リブのうちの一方と前記周方向リブ同士の一方との接続部から前記一対の径方向リブのうちの他方と前記周方向リブ同士の他方との接続部に斜めに延びる一方の筋かいが形成されると共に、前記一対の径方向リブのうちの一方と前記周方向リブ同士の他方との接続部から前記一対の径方向リブのうちの他方と前記周方向リブ同士の一方との接続部に斜めに延びる他方の筋かいが形成されている。そして、動力伝達時に、前記一方の筋かいと前記他方の筋かいのいずれか一方が圧縮力を受け、前記一方の筋かいと前記他方の筋かいのいずれか他方が引っ張り力を受けるようになっており、前記筋かいは前記径方向リブから分岐するようになっている。
請求項７の発明に係る樹脂製ギヤは、半径方向外方に形成された略円環状の歯部と、この歯部の回転中心を中心とするように半径方向内方に形成された軸支持部と、この軸支持部と前記歯部とを接続するウェブと、を備えている。そして、前記ウェブには、前記歯部と同心の周方向リブが形成されると共に、該周方向リブと前記軸支持部とを半径方向に接続する径方向リブが放射状に複数形成されている。また、前記ウェブの一方の側面には、前記周方向リブと前記軸支持部とを径方向に接続する隣り合う一対の径方向リブのうちの一方と前記周方向リブとの接続部から前記一対の径方向リブのうちの他方と前記軸支持部との接続部に斜めに延びる筋かいが形成されている。そして、動力伝達時に、前記筋かいが回転方向によって圧縮力又は引っ張り力のいずれかを受けるようになっており、前記筋かいは前記径方向リブから分岐するようになっている。
請求項８の発明に係る樹脂製ギヤは、半径方向外方に形成された略円環状の歯部と、この歯部の回転中心を中心とするように半径方向内方に形成された軸支持部と、この軸支持部と前記歯部とを接続するウェブと、を備えている。そして、前記ウェブには、前記歯部と同心の周方向リブが前記歯部と前記軸支持部との間に複数形成されると共に、前記軸支持部と前記周方向リブ及び径方向に隣り合う周方向リブ同士を半径方向に接続する径方向リブが放射状に複数形成されている。また、前記ウェブの一方の側面には、少なくとも径方向に隣り合う前記周方向リブ同士を径方向に接続する隣り合う一対の径方向リブのうちの一方と前記周方向リブ同士の一方との接続部から前記一対の径方向リブのうちの他方と前記周方向リブ同士の他方との接続部に斜めに延びる筋かいが形成されている。そして、動力伝達時に、前記筋かいが回転方向によって圧縮力又は引っ張り力のいずれかを受けるようになっており、前記筋かいは前記径方向リブから分岐するようになっている。
【００１２】
請求項９の発明に係る画像形成装置は、前記請求項１〜８のいずれかの発明に係る樹脂製ギヤと、この樹脂製ギヤを介して感光体を回転駆動する駆動手段とを備えたことを特徴としている。
【００１３】
このような構成の画像形成装置は、駆動手段の回転が請求項１〜８のいずれかの発明の樹脂製ギヤを介して伝達され、感光体が高精度で回転駆動されるため、高精度の画像形成が行われると共に、静粛な画像形成が行われる。
【００１４】
請求項１０の発明に係る樹脂製回転伝達手段は、半径方向外方に形成された略円環状の歯部と、この歯部の回転中心を中心とするように半径方向内方に形成された軸支持部と、この軸支持部と前記歯部とを接続するウェブと、を備えている。そして、前記ウェブには、前記歯部と同心の周方向リブが形成されると共に、該周方向リブと前記軸支持部とを半径方向に接続する径方向リブが放射状に複数形成されている。また、前記ウェブの一方の側面には、前記周方向リブと前記軸支持部とを径方向に接続する隣り合う一対の径方向リブのうちの一方と前記周方向リブとの接続部から前記一対の径方向リブのうちの他方と前記軸支持部との接続部に斜めに延びる筋かいが形成されている。そして、動力伝達時に、前記筋かいが回転方向によって圧縮力又は引っ張り力のいずれかを受けるようになっており、前記筋かいは前記径方向リブから分岐するようになっている。
請求項１１の発明に係る樹脂製回転伝達手段は、半径方向外方に形成された略円環状の歯部と、この歯部の回転中心を中心とするように半径方向内方に形成された軸支持部と、この軸支持部と前記歯部とを接続するウェブと、を備えている。そして、前記ウェブには、前記歯部と同心の周方向リブが前記歯部と前記軸支持部との間に複数形成されると共に、前記軸支持部と前記周方向リブ及び径方向に隣り合う周方向リブ同士を半径方向に接続する径方向リブが放射状に複数形成されている。また、前記ウェブの一方の側面には、少なくとも径方向に隣り合う前記周方向リブ同士を径方向に接続する隣り合う一対の径方向リブのうちの一方と前記周方向リブ同士の一方との接続部から前記一対の径方向リブのうちの他方と前記周方向リブ同士の他方との接続部に斜めに延びる筋かいが形成されている。そして、動力伝達時に、前記筋かいが回転方向によって圧縮力又は引っ張り力のいずれかを受けるようになっており、前記筋かいは前記径方向リブから分岐するようになっている。
【００１５】
このような構成の樹脂製回転伝達手段は、ウェブが周方向リブ及び径方向リブで補強されると共に周方向リブの内周面側に形成された筋かいにより補強される。その結果、本発明の樹脂製回転伝達手段は、ウェブの肉厚を厚くしなくても剛性を大きくすることができる。従って、本発明によれば、ウェブの剛性を大きくすることによって歯形精度を損なうというようなことがない。即ち、本発明は、歯部の形状精度（静的精度）を維持しながら回転伝達精度（動的精度）を向上させることが可能になる。しかも、本発明によれば、ウェブの剛性を大きくすることにより、振動を低減し、振動に起因する騒音を低減することが可能になる。
【発明の実施の形態】
以下、本発明の実施の形態を図面に基づき詳述する。
【００１６】
（樹脂製ギヤ）
［第１の実施の形態］
図１〜図３は、本発明の実施の形態に係る樹脂製ギヤ１を示すものである。これらの図に示すように、樹脂製ギヤ１は、例えばポリアセタール、ポリアミド、ポリフェニレンスルフィド、ポリブチレンテレフタレート等の樹脂材料を使用して射出成形したものであり、軸２に係合される軸穴３が形成された軸支持部４と、この軸支持部４の外表面から半径方向外方へ向けて形成されたウェブ５と、このウェブ５で前記軸支持部４に接続される略円環状の歯部６とを備えている。そして、歯部６の外周側には使用目的に合致した歯形形状の歯７が形成されている。尚、本実施の形態の樹脂製ギヤ１は、その軸支持部４の軸穴３が軸２に対してキーやスプライン等の周知の回り止め手段により回り止めされた状態で嵌合されており、軸２と一体回動できるようになっている。
【００１７】
軸支持部４の外周側のウェブ５の両側には、略円環状の第１の周方向リブ８が歯部６と同心に形成されている。そして、この第１の周方向リブ８と歯部６との間のウェブ５の両側には、第１の周方向リブ８と同心に略円環状の第２の周方向リブ１０が形成されている。
【００１８】
又、軸支持部４と第１の周方向リブ８との間のウェブ５ａの両側面には、軸支持部４の外表面と第１の周方向リブ８の内周面とを接続する第１の径方向リブ１１が放射状に複数形成されている。そして、第２の周方向リブ１０と第１の周方向リブ８との間のウェブ５ｂの両側面には、第２の周方向リブ１０の内周面と第１の周方向リブ８の外周面とを接続する第２の径方向リブ１２が放射状に複数形成されている。
【００１９】
軸支持部４，第１の周方向リブ８及び隣り合う第１の径方向リブ１１，１１に囲まれるウェブ５ａの各側面にそれぞれ１本の筋かい１３，１３が形成されている。ここで、図１中表面側の筋かい１３は、同一方向に傾斜するように形成されている。一方、図１中裏面側の筋かい１３は、表面側と逆の方向へ傾斜するように形成されている。尚、図１中裏面側の筋かい１３の形成位置を破線で示す。
【００２０】
このように構成された樹脂製ギヤ１は、他の図示しない樹脂製ギヤに噛み合わされて、その図示しない樹脂製ギヤから軸２に回転を伝達する際に、歯部６（第１の周方向リブ８）に回転方向の力が作用する一方、軸支持部４には回転方向と逆方向の抵抗力が作用する。その結果、軸支持部４は、第１の周方向リブ８に対して回転方向と逆方向へ変位しようとする（図３参照）。しかし、この際、ウェブ５の表裏にそれぞれ形成された筋かい１３は、軸支持部４，第１の周方向リブ８及び隣り合う第１の径方向リブ１１，１１で形成された形状を保持するように機能し、軸支持部４が第１の周方向リブ８に対して回転方向と逆方向に変位するのを抑える。従って、本実施の形態の樹脂製ギヤ１は、動力伝達時にトルク変動があったとしても、軸支持部４と歯部６の回動方向に対するずれを少なくすることができ、回転伝達精度（動的精度）を従来例よりも良くすることができる。尚、この樹脂製ギヤ１は、動力伝達時において、ウェブ５の表裏にそれぞれ形成された筋かい１３，１３のいずれか一方に圧縮力が作用し、ウェブ５の表裏にそれぞれ形成された筋かい１３，１３のいずれか他方に引っ張り力が作用するようになっている。
【００２１】
又、本実施の形態の樹脂製ギヤ１は、動力伝達時に、歯部６にスラスト力やラジアル力が作用することになるが、ウェブ５が第１及び第２の周方向リブ８，１０、第１〜第２の径方向リブ１１，１２及び筋かい１３により補強されているため、外力に対するウェブ５の変形量を小さくすることができ、回転伝達精度を従来例よりも良くすることができる。
【００２２】
又、本実施の形態の樹脂製ギヤ１は、ウェブ５が第１及び第２の周方向リブ８，１０、第１〜第２の径方向リブ１１，１２及び筋かい１３により補強されているため、ウェブ５の肉厚を厚くすることなくウェブ５の剛性アップを図ることができる。従って、本実施の形態の樹脂製ギヤ１は、射出成形後におけるウェブ５（５ｃ）と歯部６との接続部及びその近傍の収縮変形に伴う歯形精度（静的精度）の悪化という不具合を招来することがない。
【００２３】
又、本実施の形態の樹脂製ギヤ１は、上記のように、ウェブ５が第１及び第２の周方向リブ８，１０、第１〜第２の径方向リブ１１，１２及び筋かい１３により補強されている分だけ、歯部６と第２の周方向リブ１０とを接続するウェブ５（５ｃ）の肉厚を薄くし、歯形精度のさらなる向上を図ることが可能になる。
【００２４】
更に、本実施の形態の樹脂製ギヤ１は、第１の周方向リブ８，第２の周方向リブ１０，第１の径方向リブ１１及び第２の径方向リブ１２でウェブ５の剛性を大きくすると共に、筋かい１３を形成することによりウェブ５の剛性を大きくするようになっているため、回転伝達力に起因するねじり振動やスラスト力（回転軸線方向に作用する力であって、回転方向に直交する方向の力）に起因する曲げ振動を低減でき、これら振動に起因する騒音を低減することができる。
【００２５】
尚、本実施の形態の樹脂製ギヤ１は、平歯車，はすば歯車，ウォームホイール，傘歯車及び内歯歯車等に広く適用することができる。
【００２６】
又、本実施の形態の樹脂製ギヤ１は、第１〜第２の周方向リブ８，１０及び第１〜第２の径方向リブ１１，１２でウェブ５を補強するように構成されているが、これに限られず、図４に示すように、少なくとも歯部６と軸支持部４との間に補強用の周方向リブ１４が形成され、この周方向リブ１４と軸支持部４との間のウェブ５の側面に径方向リブ１５，１５が放射状に形成されると共に筋かい１３が形成されたものであればよい。
【００２７】
又、本実施の形態の樹脂製ギヤ１は、噛み合う他の樹脂製ギヤから伝達された回転を軸２に伝達する態様を例示したが、軸２の回転を噛み合う他の樹脂製ギヤに伝達する場合にも適用できる。
【００２８】
又、本実施の形態の樹脂製ギヤ１は、軸支持部４の軸穴３に軸２が嵌合される態様が例示されているが、軸支持部４に軸２を一体形成するようにしてもよい。
【００２９】
［第２の実施の形態］
図５は、本発明の第２の実施の形態を示す樹脂製ギヤ１の正面図である。尚、本実施の形態において、前記第１の実施の形態に係る樹脂製ギヤ１と同一の構成には同一符号を付し、重複する説明を省略して詳述する。
【００３０】
本実施の形態に係る樹脂製ギヤ１は、軸支持部４の軸穴３に軸２が相対回動できるように嵌合され、アイドルギヤとして使用されるものであり、歯部６側のウェブ５の剛性を大きくするようになっている。即ち、第１の周方向リブ８，第２の周方向リブ１０及び隣り合う第２の径方向リブ１２，１２に囲まれるウェブ５ｂの各側面にそれぞれ１本の筋かい１３を形成することにより、歯部６側のウェブ５の剛性を大きくするようになっている。ここで、図１中表面側の筋かい１３は、同一方向に傾斜するように形成されている。一方、図１中裏面側の筋かい１３は、表面側と逆の方向へ傾斜するように形成されている。
【００３１】
このように構成された樹脂製ギヤ１は、図６に示すように、他の駆動側樹脂製ギヤ１６に噛み合わされると共に、他の被動側樹脂製ギヤ１７に噛み合わされ、他の駆動側樹脂製ギヤ１６から伝達された回転を他の被動側樹脂製ギヤ１７に伝達するようになっている。この際、アイドルギヤとして使用される本実施の形態に係る樹脂製ギヤ１の歯部６には、図６に示すように、回転力Ｆ１と抵抗力Ｆ２が作用することになる。その結果、範囲Ｂの歯部６及び歯部６近傍のウェブ５が圧縮され、範囲Ｃの歯部６及び歯部６近傍のウェブ５が引っ張られるため、範囲Ｂ内の歯７の円ピッチが押し縮められ、範囲Ｃ内の歯７の円ピッチが押し拡げられることになるが、上記のように筋かい１３を形成することにより（図５参照）、歯部６及び歯部６近傍のウェブ５の変形を抑えることができる。即ち、ウェブ５の表裏にそれぞれ形成された筋かい１３，１３は、第１の周方向リブ８，第２の周方向リブ１０及び隣り合う第２の径方向リブ１２，１２で形成された形状を保持するように機能する。従って、本実施の形態の樹脂製ギヤ１は、動力伝達時にトルク変動があったとしても、円ピッチの寸法変化を抑えることができ、回転伝達精度（動的精度）を従来例よりも良くすることができる。
【００３２】
尚、上記の各実施の形態の樹脂製ギヤ１は、ウェブ５の両側面にそれぞれ第１〜第２の周方向リブ８，１０及び第１〜第２の径方向リブ１１，１２を形成する態様を例示したが、これに限られず、ウェブ５のいずれか一方の側面にのみ第１〜第２の周方向リブ８，１０及び第１〜第２の径方向リブ１１，１２を形成し、そのウェブ５のいずれか一方の側面にのみ筋かい１３を形成するようにしてもよい。
【００３３】
又、筋かい１３は、図７に示すように、軸支持部４と第１の周方向リブ８との間のウェブ５（５ａ）の側面と、第１の周方向リブ８と第２の周方向リブ１０との間のウェブ５（５ｂ）の側面にそれぞれ形成するようにしてもよい。
【００３４】
又、上記の各実施の形態において、筋かい１３は、軸支持部４，第１の周方向リブ８及び第１の径方向リブ１１，１１で囲まれる部分の全て（図１参照）、又は、第１の周方向リブ８，第２の周方向リブ１０及び第２の径方向リブ１２，１２で囲まれる部分の全てに形成されるようになっているが（図５参照）、これに限られず、例えば図８に示すように、周方向に適当な間隔をあけて形成するようにしてもよい。
【００３５】
又、上記の各実施の形態において、筋かい１３は、ウェブ５の表裏で傾斜方向が逆向きになるように形成されているが、これに限られず、ウェブ５の表裏で傾斜方向が同一方向になるように形成するようにしてもよい。
【００３６】
又、上記の各実施の形態において、筋かい１３は、１本だけ形成するようになっているが、これに限られず、図９に示すように、２本を交叉させるように形成してもよい。
【００３７】
又、筋かい１３は、例えば第２の実施の形態において、図１０に示すように、隣り合う第２の径方向リブ１２，１２の一方の下端と他方の上端を接続するように形成するのが好ましい。即ち、筋かい１３は、その上端を第２の周方向リブ１０に直接接続したり、その下端を第１の周方向リブ８に直接接続するのではなく、第２の径方向リブ１２，１２から分岐するように形成するのが好ましい。
【００３８】
（画像形成装置）
図１１は、上記各実施の形態の樹脂製ギヤ１が使用されるカラー複写機（画像形成装置）２０を示すものである。
【００３９】
この図１１に示す画像形成装置２０は、給紙部２１から送り出されたシート材２２をシート搬送部２３によって感光体２４と転写ローラ２５の間に送り込み、感光体２４上に形成したカラー画像をシート材２２に転写した後、そのシート材２２を定着部２６の定着ローラ２７ａ，２７ｂ間に送り込み、シート材２２表面に形成されたカラー画像を定着させ、この定着作業終了後のシート材２２を排紙ローラ対２８で排紙トレイ３０上に排出するようになっている。
【００４０】
感光体２４は、図１１中右回り方向（矢印方向）に回動させられるようになっており、周囲にクリーニングユニット３１，除電ランプ３２，帯電器３３，露光ユニット３４及びカラー現像ユニット３５が配置されている。この感光体２４は、例えば、図１２に示すように、感光体ドラム３６の回転中心部に固定された感光体駆動用の軸２が前記実施の形態に係る樹脂製ギヤ１の軸支持部４に一体回動できるように係合されており、その樹脂製ギヤ１に連繋された駆動手段としてのモータ３７により回動させられ、その表面上にカラー現像ユニット３５のイエロー（Ｙ），マゼンタ（Ｍ），シアン（Ｃ），ブラック（ＢＫ）の４色のカラー像が重ねて形成されるようになっている。
【００４１】
このような構成の画像形成装置２０は、モータ３７の回転が上記実施の形態の樹脂製ギヤ１を介して円滑に且つ高精度に感光体２４に伝達されるため、感光体２４の回転角速度の変動が抑えられ、感光体２４上に作成される各色のカラー画像のずれが抑えられ、鮮明なカラー画像の印刷が可能になる。しかも、回転伝達に使用される上記実施の形態に係る樹脂製ギヤ１は、剛性が大きく、振動を低減できるため、振動に起因する騒音の発生を抑え、静粛な画像形成が可能になる。
【００４２】
尚、上記実施の形態において、感光体２４として感光体ドラム３６を例示したが、これに限られず、感光体２４として感光体ベルトを使用するようにしてもよい。即ち、図１３に示すように、感光体ベルト３８の駆動用ローラ４０に前記実施の形態に係る樹脂製ギヤ１を一体回動できるように接続し、この樹脂製ギヤ１にモータ３７のギヤ（樹脂製ギヤ）４１を噛み合わせ、モータ３７の回転をギヤ４１，樹脂製ギヤ１を介して駆動用ローラ４０に伝達し、感光体ベルト３８を円滑且つ高精度に回動させるようにしてもよい。このような構成によっても上記実施の形態と同様の効果を得ることができる。
【００４３】
又、上記実施の形態は、感光体２４の駆動用に本発明に係る樹脂製ギヤ１を使用する態様を例示したが、これに限られず、給紙部２１の給紙ローラ２１ａ，シート搬送部２３のレジストローラ２３ａ，カラー現像ユニット３５の現像ローラ３５ａ〜３５ｄ，定着ローラ２７ａ，２７ｂ等の駆動用ギヤ又は回転伝達用のアイドルギヤ等として本発明に係る樹脂製ギヤ１を適宜使用することができる。更に、上記実施の形態に限られず、中間転写体を使用する構成の画像形成装置（図示せず）の場合には、中間転写体の駆動用に本発明に係る樹脂製ギヤ１を使用することができる。
【００４４】
又、前記実施の形態に係る樹脂製ギヤ１は、上記のように、複写機，プリンター，ファクシミリ等の画像形成装置２０に使用する態様を例示したが、これに限られず、インクジェットプリンターや自動車部品及びその他の精密機械等に広く適用することができ、円滑且つ高精度の回転伝達が可能になる。
【００４５】
又、本発明は、ギヤに限られず、タイミングベルトに噛み合う歯を備えた樹脂製回転伝達手段としての樹脂製プーリに適用することができる。
【００４６】
【発明の効果】
以上のように、本発明の樹脂製ギヤは、ウェブが周方向リブ及び径方向リブで補強されると共に筋かいによって補強されるようになっており、ウェブの肉厚を厚くすることなくウェブの剛性を高めることができるため、歯部を高精度に成形することができると共に、外力に対する変形（例えば、円ピッチ寸法の変化）を小さくすることができ、回転伝達精度を向上させることができる。
【００４７】
又、本発明の樹脂製ギヤは、ウェブが周方向リブ及び径方向リブで補強されると共に筋かいによって補強されるようになっており、外力に対するウェブの剛性が大きいため、回転伝達力に起因するねじり振動やスラスト力（回転軸線方向に作用する力であって、回転方向に直交する方向の力）に起因する曲げ振動を低減でき、これら振動に起因する騒音を低減することができる。
【００４８】
又、本発明の画像形成装置は、上記のような本発明の樹脂製ギヤを介して感光体に回転を伝達するようになっているため、感光体を円滑に且つ高精度で回動することができ、色ずれ等の不具合を招来することなく、高精度の画像形成が可能になると共に、静粛な画像形成が可能になる。
【図面の簡単な説明】
【図１】本発明の第１の実施の形態に係る樹脂製ギヤの正面図である。
【図２】図１に示す樹脂製ギヤのＡ−Ａ線に沿って切断して示す断面図である。
【図３】図１の樹脂製ギヤに対応する従来例の変形例を示す図である。
【図４】第１の実施の形態に係る樹脂製ギヤの応用例を示す正面図である。
【図５】本発明の第２の実施の形態に係る樹脂製ギヤの正面図である。
【図６】同樹脂製ギヤの使用例を示す図である。
【図７】第１及び第２の実施の形態に係る樹脂製ギヤの第１の変形例を示す正面図である。
【図８】第２の実施の形態に係る樹脂製ギヤの第２の変形例を示す正面図である。
【図９】第２の実施の形態に係る樹脂製ギヤの第３の変形例を示す正面図である。
【図１０】筋かいの形成例を示す樹脂製ギヤの一部拡大図である。
【図１１】本発明の樹脂製ギヤを使用した画像形成装置の概略構成図である。
【図１２】感光体ドラムの駆動機構を示す図である。
【図１３】感光体ベルトの駆動機構を示す図である。
【図１４】第１の従来例を示す樹脂製ギヤの正面図である。
【図１５】図９のＤ−Ｄ線に沿って切断して示す樹脂製ギヤの断面図である。
【図１６】第１の従来例に係る樹脂製ギヤのラジアル荷重による変形例を示す正面図である。
【図１７】第１の従来例に係る樹脂製ギヤのスラスト荷重による変形例を示す断面図である。
【図１８】第２の従来例に係る樹脂製ギヤの正面図である。
【図１９】図１３の一部を拡大して示す図である。
【図２０】図１３のＥ−Ｅ線に沿って切断して示す樹脂製ギヤの断面図である。
【図２１】第２の従来例に係る樹脂製ギヤの歯の変形状態を拡大して示す図である。
【図２２】第３の従来例に係る樹脂製ギヤの正面図である。
【図２３】図１７のＦ−Ｆ線に沿って切断して示す樹脂製ギヤの断面図である。
【符号の説明】
１……樹脂製ギヤ、４……軸支持部、５……ウェブ、６……歯部、８……第１の周方向リブ、１０……第２の周方向リブ、１１……第１の径方向リブ、１２……第２の径方向リブ、１３……筋かい、１４……周方向リブ、１５……径方向リブ、２０……カラー複写機（画像形成装置）、２４……感光体、３７……モータ（駆動手段）[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a resin gear widely used in a power transmission mechanism such as a copying machine, a printer, a facsimile machine, an automobile part, and the like, and a copying machine, a printer configured to drive a photoconductor through the resin gear, The present invention relates to an image forming apparatus such as a facsimile.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, resin gears have been used in power transmission mechanisms such as copying machines and automobile parts for the purpose of reducing the cost of parts, reducing the weight, and reducing the operating noise. This resin gear is formed into a predetermined shape by injection molding, but the shape is devised so that the tooth profile accuracy and strength match the intended purpose.
[0003]
(First conventional example)
For example, the resin gear 50 shown in FIGS. 14 to 15 includes an annular tooth portion 52 formed with teeth 51 and a boss (shaft support portion) 54 fitted to the shaft 53 by a thin plate-like web 55. Since the web 55 connected to the tooth portion 52 is thin so as to be connected, the amount of shrinkage deformation inward in the radial direction in the vicinity of the connection portion between the web 55 and the tooth portion 52 after injection molding. Therefore, the tooth profile can be formed with high accuracy. When the web 55 connected to the tooth portion 52 is thick, the volume of the web 55 increases, and the amount of shrinkage deformation inward in the radial direction of the web 55 after injection molding increases. The connecting portion between the tooth portion and the vicinity thereof is deformed so as to be pulled in the shrinking direction of the web 55, the deformation amount of the tooth portion 52 is increased, and the reduction in the molding accuracy of the tooth 51 is increased.
[0004]
On the other hand, when the resin gear 50 as shown in FIGS. 14 to 15 transmits power while receiving the radial load WR as shown in FIG. 16, the thickness of the web 55 receiving the radial load WR is thin and strong. Therefore, as shown by the dotted line in FIG. 16, the amount of deformation into an ellipse increases, and the rotation transmission accuracy decreases. Further, when the resin gear 50 having a cross-sectional shape as shown in FIG. 15 is a helical gear, the thrust load WS acts on the tooth portion 52 and the web 55, but the thickness of the web 55 is small. As indicated by the dotted line 17, the amount of bending deformation in the acting direction of the thrust load WS increases, and the rotation transmission accuracy decreases.
[0005]
(Second conventional example)
Therefore, in order to eliminate such problems, as shown in FIGS. 18 to 20, radial ribs 56 that connect the bosses 54 and the tooth portions 52 are formed on the side surfaces of the web 55 to increase the rigidity of the web 55, A resin gear 57 designed to improve rotation transmission accuracy has been considered. However, in this way, the resin gear 57 in which the boss 54 and the tooth portion 52 are directly connected by the radial rib 56 is inwardly connected to the radial rib 56 and the tooth portion 52 and radially inward in the vicinity thereof. The amount of contraction deformation (dotted line portion in FIGS. 18 and 19) increases, causing a phenomenon of falling of the tooth 51 as shown in FIG. 21 and a new problem that the tooth profile accuracy is lowered.
[0006]
(Third conventional example)
As the resin gear 60 capable of solving such problems of the conventional example, those shown in FIGS. 22 to 23 have been developed by the applicant of the present application. In the resin gear 60 shown in these drawings, a first circumferential rib 61 is formed concentrically with the boss 54 on the side surface of the web 55, and the web between the first circumferential rib 61 and the tooth portion 52 is formed. A second circumferential rib 62 is formed concentrically with the tooth portion 52 on the side surface of 55, and further, the boss 54, the first circumferential rib 61, and the first circumferential rib 61 and the second circumferential rib 62. Are connected by radial ribs 63 and 64, respectively, and the rigidity of the web 55 is increased without connecting the radial rib 64 to the tooth portion 52. Therefore, such a resin gear 60 has a high tooth profile accuracy and a high rotation transmission accuracy, and is widely used in precision instruments (see Japanese Patent Application Laid-Open No. 10-278124).
[0007]
[Problems to be solved by the invention]
However, in recent years, in an image forming apparatus such as a color printer or a color copying machine, a slight error in rotational transmission accuracy of the resin gear 60 appears as a color shift. Therefore, in order to prevent color misregistration and enable clearer printing, it is necessary to further improve the rotation transmission accuracy (dynamic accuracy) of the resin gear 60.
[0008]
Also, recent image forming apparatuses such as color printers and color copiers are often used by being placed on the desk side. Therefore, vibration during operation and noise caused by vibration are reduced, and a quiet work environment is achieved. There is a need to be able to maintain.
[0009]
Accordingly, an object of the present invention is to provide a resin gear that can solve such a problem and an image forming apparatus that uses the resin gear.
[0010]
[Means for Solving the Problems]
In other words, the resin gear according to the first aspect of the present invention is formed in a radially inward direction centering on a substantially annular tooth portion formed radially outward and the rotation center of the tooth portion. A shaft support portion, and a web connecting the shaft support portion and the tooth portion are provided. Further, circumferential ribs concentric with the tooth portions are formed on both side surfaces of the web, and a plurality of radial ribs that radially connect the circumferential ribs and the shaft support portions are formed radially. ing. Further, on one side of the web, the connection portion between the circumferential rib and one of a pair of adjacent radial ribs that connect the circumferential rib and the shaft support portion in the radial direction. One brace extending obliquely is formed at a connection portion between the other of the pair of radial ribs and the shaft support portion. Further, on the other side surface side of the web, the connection portion between the shaft support portion and one of a pair of adjacent radial ribs that connect the circumferential rib and the shaft support portion in the radial direction. The other brace extending obliquely is formed at the connecting portion between the other of the pair of radial ribs and the circumferential rib. The one brace and the other brace are inclined in opposite directions, and at the time of power transmission, either the one brace or the other brace receives a compressive force, One of the other brace and the other brace receives the pulling force The brace branches off from the radial rib It is like that.
[0011]
In the present invention having such a configuration, the web is reinforced by the circumferential ribs and the radial ribs, and the web is reinforced by the brace formed on the inner peripheral surface side of the circumferential rib. As a result, the resin gear of the present invention can increase the rigidity without increasing the thickness of the web. Therefore, according to the present invention, the tooth profile accuracy is not impaired by increasing the rigidity of the web. That is, the present invention can improve the rotation transmission accuracy (dynamic accuracy) while maintaining the shape accuracy (static accuracy) of the tooth portion. Moreover, according to the present invention, by increasing the rigidity of the web, it is possible to reduce vibration and to reduce noise caused by vibration.
The resin gear according to the invention of claim 2 is formed radially inward so as to be centered on a substantially annular tooth portion formed radially outward and the rotation center of the tooth portion. A shaft support portion, and a web connecting the shaft support portion and the tooth portion are provided. A plurality of circumferential ribs concentric with the tooth portion are formed between the tooth portion and the shaft support portion on both side surfaces of the web, and are adjacent to the shaft support portion, the circumferential rib and the radial direction. A plurality of radial ribs that connect the circumferential ribs in the radial direction are radially formed. Also, on one side of the web, at least one of a pair of adjacent radial ribs that connect the circumferential ribs adjacent to each other in the radial direction and one of the circumferential ribs. One brace extending diagonally from the connecting portion to the connecting portion between the other of the pair of radial ribs and the other of the circumferential ribs is formed. Also, on the other side of the web, at least one of a pair of adjacent radial ribs connecting the circumferential ribs adjacent to each other in the radial direction and the other of the circumferential ribs. The other brace extending diagonally from the connecting portion to the connecting portion between the other of the pair of radial ribs and one of the circumferential ribs is formed. The one brace and the other brace are inclined in opposite directions, and at the time of power transmission, either the one brace or the other brace receives a compressive force, One of the other brace and the other brace receives the pulling force The brace branches off from the radial rib It is like that.
According to a third aspect of the present invention, there is provided a resin gear according to the present invention, comprising: a substantially annular tooth portion formed radially outward; and a shaft support formed radially inward so as to be centered on a rotation center of the tooth portion. And a web connecting the shaft support portion and the tooth portion. In this resin gear, circumferential ribs concentric with the tooth portions are formed on both side surfaces of the web, and radial ribs that radially connect the circumferential ribs and the shaft support portions are radially formed. And a plurality of adjacent radial ribs that connect the circumferential rib and the shaft support portion in the radial direction from a connection portion between the circumferential rib and one of the adjacent radial ribs. A brace extending obliquely is formed at the connecting portion between the other of the two and the shaft support portion. The braces formed on both side surfaces of the web are inclined in the same direction, and at the time of power transmission, the braces on both side surfaces of the web both receive a compressive force or a tensile force. The brace branches off from the radial rib It is like that.
According to a fourth aspect of the present invention, a resin gear includes a substantially annular tooth portion formed radially outward and a shaft support formed radially inward so as to be centered on the rotation center of the tooth portion. And a web connecting the shaft support portion and the tooth portion. In this resin gear, on both side surfaces of the web, a plurality of circumferential ribs concentric with the tooth portion are formed between the tooth portion and the shaft support portion, and the shaft support portion and the circumferential direction are formed. A plurality of radial ribs that radially connect the ribs and the circumferential ribs that are adjacent in the radial direction are radially formed, and at least a pair of adjacent radial directions that connect the circumferential ribs that are adjacent in the radial direction in the radial direction A brace extending obliquely is formed from a connection portion between one of the ribs and one of the circumferential ribs to a connection portion between the other of the pair of radial ribs and the other of the circumferential ribs. ing. The braces formed on both side surfaces of the web are inclined in the same direction, and at the time of power transmission, the braces on both side surfaces of the web both receive a compressive force or a tensile force. The brace branches off from the radial rib It is like that.
The resin gear according to the invention of claim 5 is a substantially annular tooth portion formed radially outward and a shaft support formed radially inward so as to be centered on the rotation center of the tooth portion. And a web connecting the shaft support portion and the tooth portion. The web is formed with circumferential ribs concentric with the tooth portions, and a plurality of radial ribs that radially connect the circumferential ribs and the shaft support portions. Further, on at least one side surface of the web, the connection portion between the circumferential rib and one of a pair of adjacent radial ribs that connect the circumferential rib and the shaft support portion in the radial direction. One brace extending obliquely is formed at the connection portion between the other of the pair of radial ribs and the shaft support portion, and the connection between one of the pair of radial ribs and the shaft support portion is formed. The other brace extending diagonally from the portion to the connecting portion between the other of the pair of radial ribs and the circumferential rib is formed. During power transmission, either one of the one brace or the other brace receives a compressive force, and either one of the one brace or the other brace receives a tensile force. The The brace branches off from the radial rib It is like that.
The resin gear according to the invention of claim 6 is a substantially annular tooth portion formed radially outward and a shaft support formed radially inward so as to be centered on the rotation center of the tooth portion. And a web connecting the shaft support portion and the tooth portion. The web is formed with a plurality of circumferential ribs concentric with the tooth portion between the tooth portion and the shaft support portion, and is adjacent to the shaft support portion, the circumferential rib and the radial direction. A plurality of radial ribs that connect the circumferential ribs in the radial direction are radially formed. Further, at least one side surface of the web includes at least one of a pair of adjacent radial ribs connecting the circumferential ribs adjacent to each other in the radial direction and one of the circumferential ribs. One brace extending obliquely from the connecting portion to the connecting portion between the other of the pair of radial ribs and the other of the circumferential ribs, and one of the pair of radial ribs The other brace extending diagonally from the connecting portion between the other circumferential ribs to the connecting portion between the other of the pair of radial ribs and one of the circumferential ribs is formed. During power transmission, either one of the one brace or the other brace receives a compressive force, and either one of the one brace or the other brace receives a tensile force. The The brace branches off from the radial rib It is like that.
According to a seventh aspect of the present invention, a resin gear includes a substantially annular tooth portion formed radially outward and a shaft support formed radially inward so as to be centered on the rotation center of the tooth portion. And a web connecting the shaft support portion and the tooth portion. The web is formed with circumferential ribs concentric with the tooth portions, and a plurality of radial ribs that radially connect the circumferential ribs and the shaft support portions. Further, on one side surface of the web, the pair of the circumferential rib and the shaft support portion is connected to the pair of the radial ribs from a connecting portion between one of a pair of adjacent radial ribs and the circumferential rib. A brace extending obliquely is formed at the connecting portion between the other of the radial ribs and the shaft support portion. And during power transmission, the brace receives either compressive force or tensile force depending on the direction of rotation. The brace branches off from the radial rib It is like that.
The resin gear according to the invention of claim 8 is a substantially annular tooth portion formed radially outward and a shaft support formed radially inward so as to be centered on the rotation center of the tooth portion. And a web connecting the shaft support portion and the tooth portion. The web is formed with a plurality of circumferential ribs concentric with the tooth portion between the tooth portion and the shaft support portion, and is adjacent to the shaft support portion, the circumferential rib and the radial direction. A plurality of radial ribs that connect the circumferential ribs in the radial direction are radially formed. Further, on one side surface of the web, at least one of a pair of adjacent radial ribs that connect the circumferential ribs adjacent in the radial direction in the radial direction and one of the circumferential ribs is connected. A brace extending obliquely is formed at the connecting portion between the other of the pair of radial ribs and the other of the circumferential ribs. And during power transmission, the brace receives either compressive force or tensile force depending on the direction of rotation. The brace branches off from the radial rib It is like that.
[0012]
Claim 9 The image forming apparatus according to the invention is characterized in that 8 A resin gear according to any one of the inventions, and a driving means for rotationally driving the photosensitive member via the resin gear.
[0013]
In the image forming apparatus having such a configuration, the rotation of the driving unit is defined in claims 1 to 3. 8 Since the photoconductor is transmitted through the resin gear of any one of the inventions and is driven to rotate with high accuracy, high-precision image formation is performed and quiet image formation is performed.
[0014]
Claim 10 The resin-made rotation transmission means according to the invention includes a substantially annular tooth portion formed radially outward and a shaft support portion formed radially inward so as to be centered on the rotation center of the tooth portion. And a web connecting the shaft support portion and the tooth portion. The web is formed with circumferential ribs concentric with the tooth portions, and a plurality of radial ribs that radially connect the circumferential ribs and the shaft support portions. Further, on one side surface of the web, the pair of the circumferential rib and the shaft support portion is connected to the pair of the radial ribs from a connecting portion between one of a pair of adjacent radial ribs and the circumferential rib. A brace extending obliquely is formed at the connecting portion between the other of the radial ribs and the shaft support portion. And during power transmission, the brace receives either compressive force or tensile force depending on the direction of rotation. The brace branches off from the radial rib It is like that.
Claim 11 The resin-made rotation transmission means according to the invention includes a substantially annular tooth portion formed radially outward and a shaft support portion formed radially inward so as to be centered on the rotation center of the tooth portion. And a web connecting the shaft support portion and the tooth portion. The web is formed with a plurality of circumferential ribs concentric with the tooth portion between the tooth portion and the shaft support portion, and is adjacent to the shaft support portion, the circumferential rib and the radial direction. A plurality of radial ribs that connect the circumferential ribs in the radial direction are radially formed. Further, on one side surface of the web, at least one of a pair of adjacent radial ribs that connect the circumferential ribs adjacent in the radial direction in the radial direction and one of the circumferential ribs is connected. A brace extending obliquely is formed at the connecting portion between the other of the pair of radial ribs and the other of the circumferential ribs. And during power transmission, the brace receives either compressive force or tensile force depending on the direction of rotation. The brace branches off from the radial rib It is like that.
[0015]
In the resin rotation transmitting means having such a configuration, the web is reinforced by the circumferential ribs and the radial ribs, and is reinforced by the brace formed on the inner peripheral surface side of the circumferential ribs. As a result, the resin rotation transmission means of the present invention can increase the rigidity without increasing the thickness of the web. Therefore, according to the present invention, the tooth profile accuracy is not impaired by increasing the rigidity of the web. That is, the present invention can improve the rotation transmission accuracy (dynamic accuracy) while maintaining the shape accuracy (static accuracy) of the tooth portion. Moreover, according to the present invention, by increasing the rigidity of the web, it is possible to reduce vibration and to reduce noise caused by vibration.
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[0016]
(Resin gear)
[First Embodiment]
1 to 3 show a resin gear 1 according to an embodiment of the present invention. As shown in these drawings, the resin gear 1 is formed by injection molding using a resin material such as polyacetal, polyamide, polyphenylene sulfide, polybutylene terephthalate, and the like, and a shaft hole 3 engaged with the shaft 2 is used. A shaft support portion 4 formed with a web 5, a web 5 formed radially outward from the outer surface of the shaft support portion 4, and a substantially annular shape connected to the shaft support portion 4 by the web 5 And a tooth portion 6. Then, tooth-shaped teeth 7 matching the purpose of use are formed on the outer peripheral side of the tooth portion 6. The resin gear 1 of the present embodiment is fitted in a state in which the shaft hole 3 of the shaft support portion 4 is prevented from rotating with respect to the shaft 2 by a known detent means such as a key or a spline. The shaft 2 can be rotated together.
[0017]
A substantially annular first circumferential rib 8 is formed concentrically with the tooth portion 6 on both sides of the web 5 on the outer peripheral side of the shaft support portion 4. Then, on both sides of the web 5 between the first circumferential rib 8 and the tooth portion 6, a substantially annular second circumferential rib 10 is formed concentrically with the first circumferential rib 8. Yes.
[0018]
Further, on both side surfaces of the web 5 a between the shaft support portion 4 and the first circumferential rib 8, the outer surface of the shaft support portion 4 and the inner circumferential surface of the first circumferential rib 8 are connected. A plurality of radial ribs 11 are radially formed. Then, on both side surfaces of the web 5b between the second circumferential rib 10 and the first circumferential rib 8, the inner circumferential surface of the second circumferential rib 10 and the outer circumference of the first circumferential rib 8 are provided. A plurality of second radial ribs 12 connecting the surfaces are radially formed.
[0019]
A brace 13, 13 is formed on each side of the web 5 a surrounded by the shaft support 4, the first circumferential rib 8 and the adjacent first radial ribs 11, 11. Here, the brace 13 on the surface side in FIG. 1 is formed so as to be inclined in the same direction. On the other hand, the brace 13 on the back side in FIG. 1 is formed so as to be inclined in the direction opposite to the front side. In addition, the formation position of the brace 13 on the back side in FIG.
[0020]
The resin gear 1 configured in this manner is engaged with another resin gear (not shown) and transmits the rotation from the resin gear (not shown) to the shaft 2 (first circumferential direction). A force in the rotational direction acts on the rib 8), while a resistance force in the direction opposite to the rotational direction acts on the shaft support portion 4. As a result, the shaft support portion 4 tends to be displaced in the direction opposite to the rotation direction with respect to the first circumferential rib 8 (see FIG. 3). However, at this time, the braces 13 respectively formed on the front and back of the web 5 maintain the shape formed by the shaft support portion 4, the first circumferential rib 8 and the adjacent first radial ribs 11, 11. The shaft support portion 4 is restrained from being displaced in the direction opposite to the rotation direction with respect to the first circumferential rib 8. Therefore, the resin gear 1 of the present embodiment can reduce the displacement of the shaft support portion 4 and the tooth portion 6 in the rotational direction even if there is a torque fluctuation during power transmission, and the rotation transmission accuracy (dynamic Accuracy) can be improved compared to the conventional example. In the resin gear 1, when power is transmitted, the compression force acts on one of the struts 13 and 13 formed on the front and back sides of the web 5, and the struts formed on the front and back sides of the web 5. A pulling force acts on one of the other of 13,13.
[0021]
In the resin gear 1 of the present embodiment, a thrust force and a radial force act on the tooth portion 6 during power transmission, but the web 5 has the first and second circumferential ribs 8, 10, Since it is reinforced by the first to second radial ribs 11 and 12 and the brace 13, the deformation amount of the web 5 with respect to external force can be reduced, and the rotation transmission accuracy can be improved as compared with the conventional example. .
[0022]
Further, in the resin gear 1 of the present embodiment, the web 5 is reinforced by the first and second circumferential ribs 8 and 10, the first and second radial ribs 11 and 12, and the brace 13. Therefore, the rigidity of the web 5 can be increased without increasing the thickness of the web 5. Therefore, the resin gear 1 of the present embodiment has a problem that the tooth profile accuracy (static accuracy) deteriorates due to the contraction deformation of the connection portion between the web 5 (5c) and the tooth portion 6 and the vicinity thereof after the injection molding. There is no invitation.
[0023]
Further, in the resin gear 1 of the present embodiment, the web 5 has the first and second circumferential ribs 8 and 10, the first and second radial ribs 11 and 12, and the brace 13 as described above. Accordingly, the thickness of the web 5 (5c) connecting the tooth portion 6 and the second circumferential rib 10 can be reduced by the amount reinforced by the above, and the tooth profile accuracy can be further improved.
[0024]
Furthermore, the resin gear 1 of the present embodiment has the rigidity of the web 5 by the first circumferential rib 8, the second circumferential rib 10, the first radial rib 11, and the second radial rib 12. The rigidity of the web 5 is increased by forming the brace 13 as well as torsional vibrations and thrust forces (forces acting in the direction of the rotation axis due to the rotational transmission force, Bending vibration due to the force in a direction perpendicular to the direction), and noise due to these vibrations can be reduced.
[0025]
The resin gear 1 of the present embodiment can be widely applied to spur gears, helical gears, worm wheels, bevel gears, internal gears, and the like.
[0026]
The resin gear 1 of the present embodiment is configured to reinforce the web 5 with the first to second circumferential ribs 8 and 10 and the first to second radial ribs 11 and 12. However, the present invention is not limited to this, and as shown in FIG. 4, a circumferential rib 14 for reinforcement is formed at least between the tooth portion 6 and the shaft support portion 4, and the circumferential rib 14 and the shaft support portion 4 The radial ribs 15 and 15 may be formed radially on the side surface of the web 5 between them, and the brace 13 may be formed.
[0027]
Moreover, although the resin gear 1 of this Embodiment illustrated the aspect which transmits the rotation transmitted from the other resin gear which meshes | engages to the axis | shaft 2, it transmits the rotation of the axis | shaft 2 to the other resin gear which meshes | engages. It can also be applied to cases.
[0028]
Further, in the resin gear 1 of the present embodiment, the mode in which the shaft 2 is fitted into the shaft hole 3 of the shaft support portion 4 is illustrated, but the shaft 2 is integrally formed with the shaft support portion 4. May be.
[0029]
[Second Embodiment]
FIG. 5 is a front view of the resin gear 1 showing the second embodiment of the present invention. In the present embodiment, the same components as those of the resin gear 1 according to the first embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted.
[0030]
The resin gear 1 according to the present embodiment is fitted to the shaft hole 3 of the shaft support portion 4 so that the shaft 2 can be relatively rotated, and is used as an idle gear, and the web on the tooth portion 6 side. The rigidity of 5 is increased. That is, by forming one brace 13 on each side surface of the web 5b surrounded by the first circumferential rib 8, the second circumferential rib 10, and the adjacent second radial ribs 12, 12. The rigidity of the web 5 on the tooth portion 6 side is increased. Here, the brace 13 on the surface side in FIG. 1 is formed so as to be inclined in the same direction. On the other hand, the brace 13 on the back side in FIG. 1 is formed so as to be inclined in the direction opposite to the front side.
[0031]
As shown in FIG. 6, the resin gear 1 configured in this manner is engaged with another drive-side resin gear 16 and is also engaged with another driven-side resin gear 17, so that another drive-side resin is engaged. The rotation transmitted from the gear 16 is transmitted to another driven resin gear 17. At this time, as shown in FIG. 6, the rotational force F1 and the resistance force F2 act on the tooth portion 6 of the resin gear 1 according to the present embodiment used as an idle gear. As a result, the tooth portion 6 in the range B and the web 5 in the vicinity of the tooth portion 6 are compressed and the tooth portion 6 in the range C and the web 5 in the vicinity of the tooth portion 6 are pulled, so that the circular pitch of the teeth 7 in the range B is increased. Although it is compressed and the circular pitch of the teeth 7 in the range C is expanded, by forming the brace 13 as described above (see FIG. 5), the tooth portion 6 and the web in the vicinity of the tooth portion 6 are formed. 5 deformation can be suppressed. That is, the braces 13 and 13 formed on the front and back of the web 5 are formed by the first circumferential rib 8, the second circumferential rib 10, and the adjacent second radial ribs 12 and 12. Function to hold. Therefore, the resin gear 1 of the present embodiment can suppress the dimensional change of the circular pitch even if there is a torque fluctuation during power transmission, and the rotation transmission accuracy (dynamic accuracy) is improved compared to the conventional example. be able to.
[0032]
The resin gear 1 of each of the above embodiments forms first to second circumferential ribs 8 and 10 and first to second radial ribs 11 and 12 on both side surfaces of the web 5, respectively. Although an aspect was illustrated, it is not restricted to this, The 1st-2nd circumferential ribs 8 and 10 and the 1st-2nd radial ribs 11 and 12 are formed only in any one side of web 5, The brace 13 may be formed only on either side of the web 5.
[0033]
Further, as shown in FIG. 7, the brace 13 includes the side surface of the web 5 (5 a) between the shaft support portion 4 and the first circumferential rib 8, the first circumferential rib 8, and the second circumferential rib 8. You may make it form in the side surface of the web 5 (5b) between the circumferential direction ribs 10, respectively.
[0034]
Further, in each of the above-described embodiments, the brace 13 is the portion surrounded by the shaft support portion 4, the first circumferential rib 8 and the first radial ribs 11, 11 (see FIG. 1), or The first circumferential rib 8, the second circumferential rib 10, and the second radial ribs 12, 12 are formed on all of the portions (see FIG. 5). For example, as shown in FIG. 8, it may be formed at an appropriate interval in the circumferential direction.
[0035]
Further, in each of the above-described embodiments, the brace 13 is formed so that the inclination direction is opposite to the front and back of the web 5, but is not limited to this, and the inclination direction is the same direction on the front and back of the web 5. You may make it form so that it may become.
[0036]
Further, in each of the above embodiments, only one brace 13 is formed. However, the present invention is not limited to this, and as shown in FIG. Good.
[0037]
Further, for example, in the second embodiment, the brace 13 is formed so as to connect one lower end and the other upper end of the adjacent second radial ribs 12 and 12 as shown in FIG. Is preferred. That is, the brace 13 is not connected directly to the second circumferential rib 10 at its upper end or directly connected to the first circumferential rib 8 at its lower end, but rather to the second radial ribs 12, 12. It is preferable to form so as to branch from
[0038]
(Image forming device)
FIG. 11 shows a color copying machine (image forming apparatus) 20 in which the resin gear 1 of each of the above embodiments is used.
[0039]
In the image forming apparatus 20 shown in FIG. 11, a sheet material 22 sent out from a paper feeding unit 21 is sent between a photosensitive member 24 and a transfer roller 25 by a sheet conveying unit 23 to form a color image formed on the photosensitive member 24. After the transfer to the sheet material 22, the sheet material 22 is sent between the fixing rollers 27 a and 27 b of the fixing unit 26 to fix the color image formed on the surface of the sheet material 22. A paper discharge roller pair 28 discharges the paper onto the paper discharge tray 30.
[0040]
The photosensitive member 24 is rotated clockwise (in the direction of the arrow) in FIG. Has been. For example, as shown in FIG. 12, the photosensitive member 24 includes a shaft supporting portion 4 of the resin gear 1 according to the above-described embodiment. And is rotated by a motor 37 as a driving means connected to the resin gear 1, and on the surface thereof, yellow (Y), magenta ( Four color images of M), cyan (C), and black (BK) are formed in an overlapping manner.
[0041]
In the image forming apparatus 20 having such a configuration, the rotation of the motor 37 is smoothly and accurately transmitted to the photoconductor 24 via the resin gear 1 of the above-described embodiment. The variation is suppressed, the shift of the color image of each color created on the photoconductor 24 is suppressed, and a clear color image can be printed. In addition, since the resin gear 1 according to the above-described embodiment used for rotation transmission has high rigidity and can reduce vibration, generation of noise due to vibration is suppressed, and quiet image formation becomes possible.
[0042]
In the above embodiment, the photosensitive drum 36 is exemplified as the photosensitive member 24. However, the present invention is not limited to this, and a photosensitive belt may be used as the photosensitive member 24. That is, as shown in FIG. 13, the resin gear 1 according to the above-described embodiment is connected to the driving roller 40 of the photosensitive belt 38 so as to be integrally rotatable, and the gear 37 of the motor 37 is connected to the resin gear 1. (Resin gear) 41 is engaged, and the rotation of the motor 37 is transmitted to the driving roller 40 via the gear 41 and the resin gear 1 so that the photosensitive belt 38 can be smoothly and accurately rotated. . Even with such a configuration, it is possible to obtain the same effects as those of the above embodiment.
[0043]
Moreover, although the said embodiment illustrated the aspect which uses the resin-made gear 1 which concerns on this invention for the drive of the photoreceptor 24, it is not restricted to this, The paper feed roller 21a of the paper feed part 21, the sheet conveyance part The resin gear 1 according to the present invention is appropriately used as a driving gear or a rotation transmission idle gear for the registration rollers 23a, the developing rollers 35a to 35d of the color developing unit 35, the fixing rollers 27a and 27b, and the like. it can. Furthermore, the present invention is not limited to the above embodiment, and in the case of an image forming apparatus (not shown) configured to use an intermediate transfer member, the resin gear 1 according to the present invention is used for driving the intermediate transfer member. Can do.
[0044]
Further, as described above, the resin gear 1 according to the above-described embodiment has been illustrated as being used in the image forming apparatus 20 such as a copying machine, a printer, and a facsimile. And can be widely applied to other precision machines and the like, and smooth and highly accurate rotation transmission becomes possible.
[0045]
The present invention is not limited to gears, and can be applied to resin pulleys as resin rotation transmission means having teeth that mesh with timing belts.
[0046]
【The invention's effect】
As described above, in the resin gear of the present invention, the web is reinforced by the circumferential ribs and the radial ribs and is also reinforced by the brace, and the web gear is not increased without increasing the thickness of the web. Since the rigidity can be increased, the tooth portion can be formed with high accuracy, and deformation with respect to an external force (for example, change in the circular pitch dimension) can be reduced, so that rotation transmission accuracy can be improved.
[0047]
In the resin gear of the present invention, the web is reinforced by the circumferential ribs and the radial ribs and is also reinforced by the brace, and the rigidity of the web with respect to the external force is large. Bending vibration caused by torsional vibration or thrust force (force acting in the direction of the rotation axis and in a direction perpendicular to the rotation direction) can be reduced, and noise caused by these vibrations can be reduced.
[0048]
Further, since the image forming apparatus of the present invention transmits rotation to the photoconductor through the resin gear of the present invention as described above, the photoconductor can be rotated smoothly and with high accuracy. Therefore, it is possible to form a highly accurate image without causing problems such as color misregistration and to form a quiet image.
[Brief description of the drawings]
FIG. 1 is a front view of a resin gear according to a first embodiment of the present invention.
2 is a cross-sectional view taken along line AA of the resin gear shown in FIG. 1. FIG.
FIG. 3 is a view showing a modification of the conventional example corresponding to the resin gear shown in FIG. 1;
FIG. 4 is a front view showing an application example of the resin gear according to the first embodiment.
FIG. 5 is a front view of a resin gear according to a second embodiment of the present invention.
FIG. 6 is a view showing a usage example of the resin gear.
FIG. 7 is a front view showing a first modification of the resin gear according to the first and second embodiments.
FIG. 8 is a front view showing a second modification of the resin gear according to the second embodiment.
FIG. 9 is a front view showing a third modification of the resin gear according to the second embodiment.
FIG. 10 is a partially enlarged view of a resin gear showing an example of forming a brace.
FIG. 11 is a schematic configuration diagram of an image forming apparatus using the resin gear of the present invention.
FIG. 12 is a diagram illustrating a driving mechanism of a photosensitive drum.
FIG. 13 is a diagram illustrating a driving mechanism of a photosensitive belt.
FIG. 14 is a front view of a resin gear showing a first conventional example.
15 is a cross-sectional view of a resin gear cut along the line DD in FIG. 9. FIG.
FIG. 16 is a front view showing a modification of the resin gear according to the first conventional example due to a radial load.
FIG. 17 is a cross-sectional view showing a modification of a resin gear according to a first conventional example due to a thrust load.
FIG. 18 is a front view of a resin gear according to a second conventional example.
19 is an enlarged view of a part of FIG.
20 is a cross-sectional view of a resin gear cut along the line EE in FIG.
FIG. 21 is an enlarged view showing a deformed state of teeth of a resin gear according to a second conventional example.
FIG. 22 is a front view of a resin gear according to a third conventional example.
23 is a cross-sectional view of a resin gear cut along the line FF in FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Resin gear, 4 ... Shaft support part, 5 ... Web, 6 ... Tooth part, 8 ... 1st circumferential rib, 10 ... 2nd circumferential rib, 11 ... 1st , 12... Second radial rib, 13... Brace, 14... Circumferential rib, 15... Radial rib, 20 .. color copier (image forming apparatus), 24. Photoconductor, 37... Motor (drive means)

Claims

A substantially annular tooth portion formed radially outward, a shaft support portion formed radially inward so as to be centered on the rotation center of the tooth portion, the shaft support portion and the tooth portion; In a resin gear provided with a web for connecting
On both side surfaces of the web, circumferential ribs concentric with the tooth portions are formed, and a plurality of radial ribs that radially connect the circumferential ribs and the shaft support portions are formed radially,
On one side of the web, the pair of adjacent ribs that connect the circumferential rib and the shaft support portion in the radial direction from the connection portion between the circumferential rib and the pair of the circumferential ribs. One brace extending obliquely is formed at the connecting portion between the other of the radial ribs and the shaft support portion,
On the other side surface side of the web, the pair of adjacent radial ribs that connect the circumferential rib and the shaft support portion in the radial direction from the connection portion between the shaft support portion and the pair of the pair of radial ribs. The other brace extending obliquely is formed at the connecting portion between the other of the radial ribs and the circumferential rib,
The one brace and the other brace are inclined in opposite directions,
During power transmission, either one of the other brace and the one brace is subjected to compressive forces is adapted to receive the other one is pulling force of the other brace and the one bracing ,
The resin gear, wherein the brace branches off from the radial rib .

A substantially annular tooth portion formed radially outward, a shaft support portion formed radially inward so as to be centered on the rotation center of the tooth portion, the shaft support portion and the tooth portion; In a resin gear provided with a web for connecting
A plurality of circumferential ribs concentric with the tooth portion are formed between the tooth portion and the shaft support portion on both side surfaces of the web, and the shaft support portion, the circumferential rib and a circumferentially adjacent circumference are formed. A plurality of radial ribs connecting the directional ribs in the radial direction are formed radially,
One side of the web has a connecting portion between at least one of a pair of adjacent radial ribs connecting at least the circumferential ribs adjacent in the radial direction and one of the circumferential ribs. One brace extending obliquely is formed at the connection portion between the other of the pair of radial ribs and the other of the circumferential ribs,
On the other side surface of the web, at least a connection portion between one of a pair of adjacent radial ribs connecting the circumferential ribs in the radial direction and the other of the circumferential ribs. From the other of the pair of radial ribs and the other brace extending obliquely at the connection portion between the circumferential ribs is formed,
The one brace and the other brace are inclined in opposite directions,
During power transmission, either one of the other brace and the one brace is subjected to compressive forces is adapted to receive the other one is pulling force of the other brace and the one bracing ,
The resin gear, wherein the brace branches off from the radial rib .

A substantially annular tooth portion formed radially outward, a shaft support portion formed radially inward so as to be centered on the rotation center of the tooth portion, the shaft support portion and the tooth portion; In a resin gear provided with a web for connecting
On both side surfaces of the web, circumferential ribs concentric with the tooth portions are formed, and a plurality of radial ribs that radially connect the circumferential ribs and the shaft support portions are formed radially, One of a pair of adjacent radial ribs that connect the circumferential rib and the shaft support portion in the radial direction and a connection portion between the circumferential rib and the other of the pair of radial ribs and the shaft support A brace extending obliquely is formed at the connecting part with the part,
The brace formed on each side of the web is inclined in the same direction,
At the time of power transmission, the braces on both sides of the web are both subjected to compressive force or tensile force ,
The resin gear, wherein the brace branches off from the radial rib .

A substantially annular tooth portion formed radially outward, a shaft support portion formed radially inward so as to be centered on the rotation center of the tooth portion, the shaft support portion and the tooth portion; In a resin gear provided with a web for connecting
A plurality of circumferential ribs concentric with the tooth portion are formed between the tooth portion and the shaft support portion on both side surfaces of the web, and adjacent to the shaft support portion, the circumferential rib and the radial direction. A plurality of radial ribs that connect the circumferential ribs in the radial direction are radially formed, and at least one of a pair of adjacent radial ribs that connect the circumferential ribs adjacent in the radial direction in the radial direction; A brace extending obliquely from the connecting portion with one of the circumferential ribs to the connecting portion with the other of the pair of radial ribs and the other of the circumferential ribs is formed, respectively.
The brace formed on each side of the web is inclined in the same direction,
At the time of power transmission, the braces on both sides of the web are both subjected to compressive force or tensile force ,
The resin gear, wherein the brace branches off from the radial rib .

A substantially annular tooth portion formed radially outward, a shaft support portion formed radially inward so as to be centered on the rotation center of the tooth portion, the shaft support portion and the tooth portion; In a resin gear provided with a web for connecting
The web is formed with a circumferential rib concentric with the tooth portion, and a plurality of radial ribs that radially connect the circumferential rib and the shaft support portion are formed radially,
On at least one side surface of the web, the pair of adjacent ribs that connect the circumferential rib and the shaft support portion in the radial direction from the connecting portion between the circumferential rib and the pair of the circumferential ribs. One brace extending obliquely is formed at a connection portion between the other of the radial ribs and the shaft support portion, and from a connection portion between one of the pair of radial ribs and the shaft support portion. The other brace extending obliquely is formed at the connection portion between the other of the pair of radial ribs and the circumferential rib,
During power transmission, either one of the other brace and the one brace is subjected to compressive forces is adapted to receive the other one is pulling force of the other brace and the one bracing ,
The resin gear, wherein the brace branches off from the radial rib .

A substantially annular tooth portion formed radially outward, a shaft support portion formed radially inward so as to be centered on the rotation center of the tooth portion, the shaft support portion and the tooth portion; In a resin gear provided with a web for connecting
The web is formed with a plurality of circumferential ribs concentric with the tooth portion between the tooth portion and the shaft support portion, and the circumferential direction adjacent to the shaft support portion, the circumferential rib and the radial direction. A plurality of radial ribs that connect the ribs in the radial direction are formed radially,
At least one side surface of the web has a connecting portion between at least one of a pair of adjacent radial ribs that connect the circumferential ribs adjacent to each other in the radial direction and one of the circumferential ribs. One brace extending obliquely is formed at a connecting portion between the other of the pair of radial ribs and the other of the circumferential ribs, and one of the pair of radial ribs and the circumference The other brace that extends obliquely from the connecting portion between the other of the directional ribs to the connecting portion between the other of the pair of radial ribs and one of the circumferential ribs is formed,
During power transmission, either one of the other brace and the one brace is subjected to compressive forces is adapted to receive the other one is pulling force of the other brace and the one bracing ,
The resin gear, wherein the brace branches off from the radial rib .

A substantially annular tooth portion formed radially outward, a shaft support portion formed radially inward so as to be centered on the rotation center of the tooth portion, the shaft support portion and the tooth portion; In a resin gear provided with a web for connecting
The web is formed with a circumferential rib concentric with the tooth portion, and a plurality of radial ribs that radially connect the circumferential rib and the shaft support portion are formed radially,
On one side surface of the web, the pair of diameters from a connection portion between one of a pair of adjacent radial ribs that connect the circumferential rib and the shaft support portion in the radial direction and the circumferential rib. A brace extending obliquely is formed at the connecting portion between the other of the directional ribs and the shaft support portion,
During power transmission, the brace receives either compressive force or tensile force depending on the direction of rotation ,
The resin gear, wherein the brace branches off from the radial rib .

A substantially annular tooth portion formed radially outward, a shaft support portion formed radially inward so as to be centered on the rotation center of the tooth portion, the shaft support portion and the tooth portion; In a resin gear provided with a web for connecting
The web is formed with a plurality of circumferential ribs concentric with the tooth portion between the tooth portion and the shaft support portion, and the circumferential direction adjacent to the shaft support portion, the circumferential rib and the radial direction. A plurality of radial ribs that connect the ribs in the radial direction are formed radially,
On one side surface of the web, a connection portion between at least one of a pair of adjacent radial ribs that connect the circumferential ribs adjacent in the radial direction in the radial direction and one of the circumferential ribs. A brace extending obliquely is formed at the connecting portion between the other of the pair of radial ribs and the other of the circumferential ribs,
During power transmission, the brace are adapted to receive either a compressive force or tensile force by the direction of rotation,
The resin gear, wherein the brace branches off from the radial rib .

9. An image forming apparatus comprising: the resin gear according to claim 1; and a driving unit that rotationally drives the photosensitive member via the resin gear.

A substantially annular tooth portion formed radially outward, a shaft support portion formed radially inward so as to be centered on the rotation center of the tooth portion, the shaft support portion and the tooth portion; A rotation transmission means made of resin comprising a web for connecting
The web is formed with a circumferential rib concentric with the tooth portion, and a plurality of radial ribs that radially connect the circumferential rib and the shaft support portion are formed radially,
On one side surface of the web, the pair of diameters from a connection portion between one of a pair of adjacent radial ribs that connect the circumferential rib and the shaft support portion in the radial direction and the circumferential rib. A brace extending obliquely is formed at the connecting portion between the other of the directional ribs and the shaft support portion,
During power transmission, the brace receives either compressive force or tensile force depending on the direction of rotation ,
Resin rotation transmission means characterized in that the brace branches off from the radial rib .

A substantially annular tooth portion formed radially outward, a shaft support portion formed radially inward so as to be centered on the rotation center of the tooth portion, the shaft support portion and the tooth portion; A rotation transmission means made of resin comprising a web for connecting
The web is formed with a plurality of circumferential ribs concentric with the tooth portion between the tooth portion and the shaft support portion, and the circumferential direction adjacent to the shaft support portion, the circumferential rib and the radial direction. A plurality of radial ribs that connect the ribs in the radial direction are formed radially,
On one side surface of the web, a connection portion between at least one of a pair of adjacent radial ribs that connect the circumferential ribs adjacent in the radial direction in the radial direction and one of the circumferential ribs. A brace extending obliquely is formed at the connecting portion between the other of the pair of radial ribs and the other of the circumferential ribs,
During power transmission, the brace receives either compressive force or tensile force depending on the direction of rotation ,
Resin rotation transmission means characterized in that the brace branches off from the radial rib .