JP3963833B2

JP3963833B2 - Driving transmission structure of work vehicle

Info

Publication number: JP3963833B2
Application number: JP2002381059A
Authority: JP
Inventors: 天奥山; 文男長野; 國祐中村
Original assignee: Kubota Corp
Current assignee: Kubota Corp
Priority date: 2002-12-27
Filing date: 2002-12-27
Publication date: 2007-08-22
Anticipated expiration: 2022-12-27
Also published as: JP2004210070A

Description

【０００１】
【発明の属する技術分野】
本発明は、右及び左の走行装置を備えた作業車の走行伝動構造に関する。
【０００２】
【従来の技術】
右及び左の走行装置を備えた作業車として、例えば特許文献１に開示されているように、動力が第１伝動系（特許文献１の図２中のＧ９）を介して伝達され、第１伝動系が右及び左の第２伝動系（特許文献１の図２中の２０Ｒ，２０Ｌ，２１Ｒ，２１Ｌ）に分岐され、右及び左の第２伝動系を介して右及び左の走行装置（特許文献１の図２中の１Ｒ，１Ｌ）に伝達されるように構成している。これにより、第１伝動系、右及び左の第２伝動系を介して、同方向及び同速度の動力が右及び左の走行装置に伝達されて機体は直進（前進又は後進）する。
【０００３】
特許文献１の構造では、右又は左の走行装置の一方に右又は左の走行装置の他方と同方向で且つ右又は左の走行装置の他方よりも低速に減速された動力を伝達可能な旋回機構（特許文献１の図２中のＣ，２７Ｒ，２７Ｌ，２５Ｒ，２５Ｌ）を備えている。これにより、例えば第１伝動系及び左の第２伝動系を介して、正転の動力が左の走行装置が伝達されている状態で、旋回機構により動力を右の走行装置に伝達すると、左の走行装置よりも低速の正転の動力が右の走行装置に伝達されて、右及び左の走行装置の速度差により機体は前進しながら右に旋回していく。
【０００４】
【特許文献１】
特開２００１−１９３８３５号公報（図２，４，１１，１２）
【０００５】
【発明が解決しようとする課題】
特許文献１の構造では［従来の技術］に記載の旋回機構に加えて、右及び左の走行装置を制動可能な制動機構（特許文献１の図２中のＢ）を備えている。これにより、例えば第１伝動系及び左の第２伝動系を介して正転の動力が左の走行装置が伝達されている状態で、制動機構により右の走行装置に制動を掛けると、右の走行装置が停止した状態で左の走行装置が駆動される状態となって、［従来の技術］に記載のように、前進（後進）しながら右に旋回する場合に比べて小さな旋回が行われる。
【０００６】
前述のように制動機構を使用すると小さな旋回が可能であるが、右（左）の走行装置が停止した状態で左（右）の走行装置が駆動されることにより、小さな旋回が行われるので、停止した右（左）の走行装置が移動せずにその場で向きを変えるような状態となり、停止した右（左）の走行装置により地面の土が横に大きく押し退けられるような状態となって、地面が荒らされることが多くある。
本発明は、右及び左の走行装置を備えた作業車の走行伝動構造において、右及び左の走行装置の速度差により前進（後進）しながら右（左）に旋回する場合の利点を残して、できるだけ地面の荒れを抑えて小さな旋回が行えるように構成することを目的としている。
【０００７】
【課題を解決するための手段】
［Ｉ］請求項１の特徴によると、伝動上手側の第１伝動系から伝達される動力を、右及び左に分岐して伝動下手側に伝える第２伝動系を介して、右及び左の走行装置を駆動するように構成してある作業車の走行伝動構造において、
前記右又は左の走行装置の一方に前記右又は左の走行装置の他方と同方向で且つ第１減速比によって前記右又は左の走行装置の他方よりも低速に減速された動力を伝達可能な第１旋回機構と、
前記第１旋回機構によって動力が伝達される右又は左の走行装置と同じ一方の走行装置に対して、前記右又は左の走行装置の他方と同方向で且つ前記第１減速比よりも低速の第２減速比によって前記右又は左の走行装置の他方よりも低速に減速された動力を伝達可能な第２旋回機構とを備え、
前記第１伝動系から第２伝動系への動力伝達系とは別に、前記第１伝動系から前記第１旋回機構及び第２旋回機構へ動力を分岐伝動する分岐伝動機構を備え、
前記分岐伝動機構を、第１伝動系の動力が伝達される伝動ギヤの両側に一体形成した一対の出力ギヤによって構成するとともに、各出力ギヤから前記第１旋回機構及び第２旋回機構へ伝える動力の減速比が、各出力ギヤ同士で互いに異なるように設定してある。
【０００８】
請求項１の特徴によると、所定の旋回半径で旋回を行う場合、第１旋回機構を作動させればよい。これにより、例えば第１伝動系及び左の第２伝動系を介して正転の動力が左の走行装置が伝達されている状態で、第１旋回機構により左の走行装置と同方向で且つ第１減速比によって左の走行装置よりも低速に減速された動力が右の走行装置に伝達されて、右及び左の走行装置の速度差により機体は前進しながら右に旋回していく。
【０００９】
請求項１の特徴によると、前述の所定の旋回半径での旋回よりも小さな旋回を行う場合、第２旋回機構を作動させればよい。これにより、例えば第１伝動系及び左の第２伝動系を介して正転の動力が左の走行装置が伝達されている状態で、第２旋回機構により左の走行装置と同方向で且つ第１減速比よりも低速の第２減速比によって左の走行装置よりも低速に減速された動力が右の走行装置に伝達される。第１旋回機構の第１減速比よりも第２旋回機構の第２減速比が低速に設定されているので、第１旋回機構の場合に比べて右及び左の走行装置の速度差が大きなものとなり、第１旋回機構の場合に比べて小さな旋回半径で機体は前進しながら右に旋回していく。
【００１０】
この場合、請求項１の特徴によると、第２旋回機構の第２減速比を充分に低速に設定すれば、右及び左の走行装置の速度差が大きなものとなって小さな旋回半径での旋回が可能になるのであるが、第２旋回機構により動力が伝達される右（左）の走行装置（旋回中心側の走行装置）は、停止するのではなく他方の走行装置と同方向に駆動されている。
これにより、第２旋回機構を作動させた旋回では、第２旋回機構により動力が伝達される右（左）の走行装置（旋回中心側の走行装置）が、その場で向きを変えるような状態になることはなく、停止した右（左）の走行装置により地面の土が横に大きく押し退けられるような状態は生じ難いので、地面が荒らされることが少ない。
【００１１】
【００１２】
右及び左の第２伝動系に分岐する前の第１伝動系の部分から、第１及び第２旋回機構を介して右又は左の走行装置に動力が伝達されており、共通の部分と言ってよい第１伝動系から、第１及び第２旋回機構を介して右又は左の走行装置に動力が伝達されているので、別々の部分から動力を分岐させ、第１及び第２旋回機構を介して右又は左の走行装置に動力が伝達されように構成する場合に比べて、構造が複雑なものになり難い。
【００１３】
【００１４】
【００１５】
［ＩＩ］請求項２の特徴によると、請求項１の場合と同様に前項［Ｉ］に記載の「作用」を備えており、これに加えて以下のような「作用」を備えている。
請求項２の特徴によると、摩擦式の多板クラッチを備えて第１及び第２旋回機構を構成しているので、第１及び第２旋回機構を介して右又は左の走行装置に動力を伝達する場合、右又は左の走行装置への伝動及び遮断を滑らかに行うことができる。
【００１６】
【発明の実施の形態】
［１］
図１に示すように、クローラ式の右及び左の走行装置１によって支持された機体の前部の左部に刈取部２、機体の前部の右部に運転部３が備えられ、機体の後部の左部に脱穀装置４、機体の後部の右部にグレンタンク５が備えられて、作業車の一例である稲用のコンバインが構成されている。これにより、圃場の穀稈が刈取部２によって刈り取られ、脱穀装置４により脱穀処理されて、脱穀装置４で回収された穀粒がグレンタンク５に供給される。
【００１７】
図２に示すように、走行用のミッションケース６が備えられて、前進側及び後進側に変速自在な静油圧式無段変速装置７がミッションケース６に連結されており、エンジン８の出力軸８ａの動力が、ベルト式のテンションクラッチ９を介して静油圧式無段変速装置７の入力軸７ａに伝達される。静油圧式無段変速装置７の出力軸７ｂの動力が出力軸１０に伝達され、ベルト式のテンションクラッチ１１を介して刈取部２に伝達される。
【００１８】
［２］
次に、ミッションケース６の内部に備えられた伝動系において、直進（前進又は後進）の伝動系について説明する。
図２に示すように、ミッションケース６の内部に伝動軸１２が備えられ、出力軸１０に固定された伝動ギヤ１３が、伝動軸１２に固定された伝動ギヤ１４に咬合している。伝動軸１２に低速ギヤ１５、中速ギヤ１６及び高速ギヤ１７が相対回転自在に外嵌されており、シフト部材１８，１９がスプライン構造により一体回転及びスライド自在に伝動軸１２に外嵌されている。
【００１９】
図２に示すように、ミッションケース６の内部に伝動軸２０が備えられて、伝動軸２０に固定された低速ギヤ２１、中速ギヤ２２及び高速ギヤ２３が低速ギヤ１５、中速ギヤ１６及び高速ギヤ１７に咬合している。これにより、シフト部材１８，１９をスライド操作して低速ギヤ１５、中速ギヤ１６及び高速ギヤ１７に咬合させることにより、伝動軸１２から伝動軸２０に伝達される動力を３段に変速することができる。
【００２０】
図２及び図３に示すように、ミッションケース６の内部に支持軸２４が回転自在に支持されて、支持軸２４の中央に伝動ギヤ２５が固定されており、中速ギヤ２２と伝動ギヤ２５とが咬合している。支持軸２４に右及び左のサイドギヤ２６が相対回転自在及びスライド自在に外嵌されており、右及び左の走行装置１に動力を伝達する右及び左の伝動ギヤ２７が、右及び左のサイドギヤ２６のスライド操作に関係なく右及び左のサイドギヤ２６に常時咬合している。
【００２１】
図２及び図３に示すように、右及び左のサイドギヤ２６と支持軸２４との間に右及び左の油室４３が構成されており、バネ３９により右及び左のサイドギヤ２６が伝動ギヤ２５に向けて付勢されている。これにより、バネ３９の付勢力により右及び左のサイドギヤ２６が伝動ギヤ２５の咬合部２５ｃに咬合しており、右及び左の油室４３に作動油を供給すると、バネ３９に抗して右及び左のサイドギヤ２６がスライド操作されて伝動ギヤ２５の咬合部２５ｃから離れる。
【００２２】
以上の構造により、図２及び図３に示すように、右及び左のサイドギヤ２６を伝動ギヤ２５の咬合部２５ｃに咬合させると、伝動軸２０の動力が中速ギヤ２２及び伝動ギヤ２５、右及び左のサイドギヤ２６、右及び左の伝動ギヤ２７を介して右及び左の走行装置１に伝達される。これにより、同方向及び同速度の動力が右及び左の走行装置１に伝達されて、機体は直進（前進又は後進）する。次に右（左）のサイドギヤ２６をスライド操作して伝動ギヤ２５の咬合部２５ｃから離すと、伝動ギヤ２５から右（左）の走行装置１への動力が遮断される。このように、伝動ギヤ２５の咬合部２５ｃと右及び左のサイドギヤ２６との間で、右及び左のサイドクラッチ３７が構成されている。
すなわち、サイドクラッチ３７で分岐される直前の上記伝動ギヤ２５に至るまでの上手側の伝動系が第１伝動系を構成するものであり、伝動ギヤ２５から分岐された下手側の伝動系が第２伝動系を構成している。
【００２３】
［３］
次に、ミッションケース６の内部に備えられた伝動系において、旋回の伝動系について説明する。
図２及び図３に示すように、ミッションケース６の内部に伝動軸２８が備えられて、第１旋回クラッチ２９及び第２旋回クラッチ３０が伝動軸２８に備えられている。第１及び第２旋回クラッチ２９，３０は、伝動軸２８に固定されたケース部材３１、伝動軸２８に相対回転自在に外嵌された小径の第１旋回ギヤ３２及び大径の第２旋回ギヤ３３、ケース部材３１と第１及び第２旋回ギヤ３２，３３との間に配置された摩擦板３４、摩擦板３４を押圧するピストン部材３５等を備えて、油圧多板型式に構成されている。
【００２４】
図２及び図３に示すように、伝動ギヤ２５に大径の第１出力ギヤ２５ａ及び小径の第２出力ギヤ２５ｂが一体的に備えられており、第１出力ギヤ２５ａと第１旋回ギヤ３２とが咬合し、第２出力ギヤ２５ｂと第２旋回ギヤ３３とが咬合している。伝動軸２８に右及び左の伝動ギヤ３６が固定されている。
上記伝動ギヤ２５と一体に形成された大径の第１出力ギヤ２５ａと、小径の第２出力ギヤ２５ｂとが、前記第１伝動系から第２伝動系への動力伝達系とは別に、前記第１伝動系から後述する前記第１旋回機構及び第２旋回機構へ動力を分岐伝動する分岐伝動機構を構成している。
【００２５】
図２及び図３に示すように、右及び左のサイドギヤ２６と右及び左の伝動ギヤ３６との間に、右及び左の伝動クラッチ３８が備えられている。右及び左の伝動クラッチ３８は、支持軸２４に相対回転自在に外嵌されたケース部材４０、ケース部材４０と右及び左のサイドギヤ２６との間に配置された摩擦板４１、摩擦板４１を押圧するピストン部材４２等を備えて、油圧多板型式に構成されている。
ケース部材４０の外周部にギヤ歯が備えられており、右及び左の伝動ギヤ３６が右及び左の伝動クラッチ３８のケース部材４０のギヤ歯に咬合している。
【００２６】
以上の構造により、前項［２］に記載のように、右及び左のサイドギヤ２６が伝動ギヤ２５の咬合部２５ｃに咬合し、伝動軸２０の動力が右及び左のサイドギヤ２６を介して右及び左の走行装置１に伝達されて、機体が直進（前進又は後進）している状態において、第１及び第２旋回クラッチ２９，３０、右及び左の伝動クラッチ３８が遮断状態に操作されている。
【００２７】
前述の状態において、例えば図３に示すように、左のサイドギヤ２６をスライド操作して伝動ギヤ２５の咬合部２５ｃから離し（左のサイドクラッチ３７の遮断状態）、第１旋回クラッチ２９及び左の伝動クラッチ３８を伝動状態に操作すると、伝動ギヤ２５の動力が第１出力ギヤ２５ａ、第１旋回クラッチ２９、伝動軸２８、左の伝動ギヤ３６及び左の伝動クラッチ３８を介して左のサイドギヤ２６に伝達される。これにより、第１出力ギヤ２５ａと第１旋回ギヤ３２との間で低速に減速（第１減速比）された動力（右の走行装置１と同方向）が、左の走行装置１に伝達されて、右及び左の走行装置１の速度差（例えば左の走行装置１の速度が右の走行装置１の速度の１／３）により、機体は前進（後進）しながら左に旋回していく。
上記第１出力ギヤ２５ａの動力が伝達される第１旋回ギヤ３２、第１旋回クラッチ２９、伝動軸２８、左の伝動ギヤ３６及び左の伝動クラッチ３８によって、前記右又は左の走行装置１の一方に前記右又は左の走行装置１の他方と同方向で、且つ前記右又は左の走行装置１の他方よりも低速の第１減速比によって減速された動力を伝達可能な第１旋回機構が構成されている。
【００２８】
次に前述の状態において、第２旋回クラッチ３０及び左の伝動クラッチ３８を伝動状態に操作すると、伝動ギヤ２５の動力が第２出力ギヤ２５ｂ、第２旋回クラッチ３０、伝動軸２８、左の伝動ギヤ３６及び左の伝動クラッチ３８を介して左のサイドギヤ２６に伝達される。これにより、第２出力ギヤ２５ｂと第２旋回ギヤ３３との間で低速に減速（第２減速比）された動力（右の走行装置１と同方向）が、左の走行装置１に伝達されて、右及び左の走行装置１の速度差（例えば左の走行装置１の速度が右の走行装置１の速度の１／８〜１／１０）により、機体は前進（後進）しながら左に旋回していく。
上記第２出力ギヤ２５ｂの動力が伝達される第２旋回ギヤ３３と、第２旋回クラッチ３０、伝動軸２８、左の伝動ギヤ３６及び左の伝動クラッチ３８によって、前記右又は左の走行装置１の一方に前記右又は左の走行装置１の他方と同方向で、且つ前記第１減速比よりも低速の第２減速比によって減速された動力を伝達可能な第２旋回機構が構成されている。
【００２９】
この場合、図３に示すように、第１出力ギヤ２５ａと第１旋回ギヤ３２との間の第１減速比に比べて、第２出力ギヤ２５ｂと第２旋回ギヤ３３との間の第２減速比が低速に設定されているので、第１旋回クラッチ２９を使用した場合の右及び左の走行装置１の速度差に比べて、第２旋回クラッチ３０を使用した場合の右及び左の走行装置１の速度差が大きなものとなり、第１旋回クラッチ２９を使用した場合に比べて、第２旋回クラッチ３０を使用した場合の方が、小さな旋回半径で機体は前進（後進）しながら右に旋回していく。前述のように左の伝動クラッチ３８を伝動状態に操作した場合と同様に、右の伝動クラッチ３８を伝動状態に操作した場合も同じ状態が生じる。
【００３０】
［４］
次に、右及び左のサイドクラッチ２６、右及び左の伝動クラッチ３８、第１及び第２旋回クラッチ２９，３０の操作並びに油圧回路構造について説明する。
図４に示すように、油圧ポンプ４４の作動油が、３位置切換式の方向切換弁４５から油路４６，４７を介して右及び左の油室４３、右及び左の伝動クラッチ３８に供給されている。右及び左の油室４３からの油路４８が旋回選択弁５０に接続され、旋回選択弁５０の作動油が第１及び第２旋回クラッチ２９，３０に供給されるように構成されており、旋回選択弁５０に可変リリーフ弁４９が接続されている。操向レバー５１が運転部３に備えられて、操向レバー５１と方向切換弁４５及び可変リリーフ弁４９とが、連係機構５２を介して連係されている。
【００３１】
図４に示す状態は、旋回選択弁５０を第１旋回位置５０ａに操作し、操向レバー５１を中立位置Ｎに操作している状態であり、方向切換弁４５が中立位置４５Ｎに操作され、可変リリーフ弁４９が開位置に操作されている。この状態で右及び左の油室４３に作動油は供給されず、右及び左の伝動クラッチ３８、第１及び第２旋回クラッチ２９，３０が遮断状態に操作されている。
【００３２】
これによって、図２及び図３に示すように、右及び左のサイドギヤ２６が伝動ギヤ２５の咬合部２５ｃに咬合して（右及び左のサイドクラッチ３７の伝動状態）、伝動軸２０の動力が中速ギヤ２２及び伝動ギヤ２５、右及び左のサイドギヤ２６、右及び左の伝動ギヤ２７を介して右及び左の走行装置１に伝達され、同方向及び同速度の動力が右及び左の走行装置１に伝達されて、機体は直進（前進又は後進）する。
【００３３】
図２及び図４に示すように、操向レバー５１を中立位置Ｎから右第１旋回位置Ｒ１（左第１旋回位置Ｌ１）に操作すると、方向切換弁４５が右旋回位置４５Ｒ（左旋回位置４５Ｌ）に操作され、作動油が右（左）の油室４３及び右（左）の伝動クラッチ３８に供給されて、右（左）のサイドギヤ２６がスライド操作されて伝動ギヤ２５の咬合部２５ｃから離れ（右（左）のサイドクラッチ３７の遮断状態）、右（左）の伝動クラッチ３８が伝動状態に操作される。この場合、第１及び第２旋回クラッチ２９，３０が遮断状態に操作されているので（可変リリーフ弁４９が開位置に操作されていることによる）、右（左）の走行装置１が自由回転する状態となって、機体は右（左）に緩やかに向きを変える。
【００３４】
図２及び図４に示すように、操向レバー５１を右第１旋回位置Ｒ１（左第１旋回位置Ｌ１）から、右第２旋回位置Ｒ２（左第２旋回位置Ｌ２）に操作していくと、前述の状態から可変リリーフ弁４９が開位置から次第に閉位置に操作されていくので、第１旋回クラッチ２９が遮断状態から次第に伝動状態に操作されていく。これにより、前項［３］に記載のように、第１出力ギヤ２５ａと第１旋回ギヤ３２との間で低速に減速（第１減速比）された動力が右（左）の走行装置１に伝達されていき、右及び左の走行装置１の速度差により、機体は前進（後進）しながら右（左）に旋回していくのであり、操向レバー５１を右第２旋回位置Ｒ２（左第２旋回位置Ｌ２）に操作すると、第１旋回クラッチ２９が完全な伝動状態となる。
【００３５】
図２及び図４に示すように、操向レバー５１を右第１旋回位置Ｒ１（左第１旋回位置Ｌ１）から、右第２旋回位置Ｒ２（左第２旋回位置Ｌ２）に操作していく際、事前に旋回選択弁５０を第２旋回位置５０ｂに操作しておくと、前述の状態から可変リリーフ弁４９が開位置から次第に閉位置に操作されていけば、第２旋回クラッチ３０が遮断状態から次第に伝動状態に操作されていく。これにより、前項［３］に記載のように、第２出力ギヤ２５ｂと第２旋回ギヤ３３との間で低速に減速（第２減速比）された動力が右（左）の走行装置１に伝達されていき、右及び左の走行装置１の速度差により、機体は前進（後進）しながら右（左）に旋回していくのであり、操向レバー５１を右第２旋回位置Ｒ２（左第２旋回位置Ｌ２）に操作すると、第２旋回クラッチ３０が完全な伝動状態となる。
【００３６】
この場合に、図３に示すように、第１出力ギヤ２５ａと第１旋回ギヤ３２との間の第１減速比に比べて、第２出力ギヤ２５ｂと第２旋回ギヤ３３との間の第２減速比が低速に設定されているので、旋回選択弁５０を第１旋回位置５０ａに操作した状態で操向レバー５１を右第２旋回位置Ｒ２（左第２旋回位置Ｌ２）に操作した場合に比べて、旋回選択弁５０を第２旋回位置５０ｂに操作した状態で操向レバー５１を右第２旋回位置Ｒ２（左第２旋回位置Ｌ２）に操作した場合の方が、小さな旋回半径で機体は前進（後進）しながら右（左）に旋回していく。
【００３７】
［発明の実施の第１別形態］
前述の［発明の実施の形態］において、操向レバー５１と旋回選択弁５０とを連係して、以下のように構成してもよい。
図５に示すように、操向レバー５１を中立位置Ｎに操作していると、右及び左のサイドクラッチ３７が伝動状態に操作され、操作レバー５１を中立位置Ｎから右第１旋回位置Ｒ１（左第１旋回位置Ｌ１）に操作すると、右（左）のサイドクラッチ３７が遮断状態に操作されて、右（左）の伝動クラッチ３８が伝動状態に操作される。
【００３８】
図５に示すように、操向レバー５１を右第１旋回位置Ｒ１（左第１旋回位置Ｌ１）から右第２旋回位置Ｒ２（左第２旋回位置Ｌ２）に操作していくと、第１旋回クラッチ２９が遮断状態から次第に伝動状態に操作されていき、操向レバー５１を右第２旋回位置Ｒ２（左第２旋回位置Ｌ２）に操作すると、第１旋回クラッチ２９が完全な伝動状態に操作される。操向レバー５１を右第２旋回位置Ｒ２（左第２旋回位置Ｌ２）から右第３旋回位置Ｒ３（左第３旋回位置Ｌ３）に操作していくと、第１旋回クラッチ２９が直ちに遮断状態に操作され、第２旋回クラッチ３０が遮断状態から次第に伝動状態に操作されていき、操向レバー５１を右第３旋回位置Ｒ３（左第３旋回位置Ｌ３）に操作すると、第２旋回クラッチ３０が完全な伝動状態に操作される。
【００３９】
【００４０】
【００４１】
【００４２】
［発明の実施の第２別形態］
前述の［発明の実施の形態］〜［発明の実施の第１別形態］において、第２出力ギヤ２５ｂと第２旋回ギヤ３３との間の第２減速比よりも低速の第３減速比を備えた第３旋回クラッチ（図示せず）を、図２及び図３に示す伝動軸２８に備えて、第２旋回クラッチ３０及び第３旋回クラッチにより第２旋回機構を構成してもよい。操向レバー５１に代えて、一般の乗用車のような丸型の操縦ハンドル（図示せず）を使用してもよい。
本発明はクローラ式の右及び左の走行装置１ばかりではなく、操向操作されない走行車輪を右に複数個備え左に複数個備えて、右及び左の走行装置１を構成した作業車にも適用できる。
【００４３】
【発明の効果】
請求項１の特徴によると、右及び左の走行装置を備えた作業車の走行伝動構造において、右又は左の走行装置の一方に右又は左の走行装置の他方と同方向で且つ第１減速比（第２減速比）によって右又は左の走行装置の他方よりも低速に減速された動力を伝達可能な第１旋回機構（第２旋回機構）を備えることにより、地面の荒れを少なくしながら、所定の旋回半径での旋回及び所定の旋回半径での旋回よりも小さな旋回を行うことができるようになって、作業車の旋回性能を向上させることができた。
【００４４】
共通の部分と言ってよい第１伝動系から、第１及び第２旋回機構を介して右又は左の走行装置に動力が伝達されており、別々の部分から動力を分岐させ、第１及び第２旋回機構を介して右又は左の走行装置に動力が伝達されように構成する場合に比べて、構造が複雑なものになり難いので、構造の簡素化の面で有利なものとなった。
【００４５】
【００４６】
請求項２の特徴によると、摩擦式の多板クラッチを備えて第１及び第２旋回機構を構成しており、第１及び第２旋回機構を介して右又は左の走行装置に動力を伝達する場合、右又は左の走行装置への伝動及び遮断を滑らかに行うことができるようになって、作業車の旋回性能を向上させることができた。
【図面の簡単な説明】
【図１】コンバインの全体側面図
【図２】ミッションケースの内部を示す概略図
【図３】ミッションケースの第１及び第２旋回クラッチ、右及び左のサイドクラッチ（サイドギヤ）の付近の縦断正面図
【図４】右及び左のサイドクラッチ（サイドギヤ）、右及び左の伝動クラッチ、第１及び第２旋回クラッチの油圧回路図
【図５】発明の実施の第１別形態における操向レバーを示す図
【符号の説明】
１走行装置
２５第１伝動系
２６，２７第２伝動系
２８，３６第３伝動系
２９第１旋回機構
３０第２旋回機構[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a traveling transmission structure for a work vehicle including right and left traveling apparatuses.
[0002]
[Prior art]
As a work vehicle equipped with right and left traveling devices, for example, as disclosed in Patent Document 1, power is transmitted via a first transmission system (G9 in FIG. 2 of Patent Document 1), The transmission system is branched into right and left second transmission systems (20R, 20L, 21R, and 21L in FIG. 2 of Patent Document 1), and right and left traveling devices ( It is configured to be transmitted to 1R, 1L in FIG. As a result, the power in the same direction and speed is transmitted to the right and left traveling devices via the first transmission system and the right and left second transmission systems, and the aircraft moves straight (forward or reverse).
[0003]
In the structure of Patent Document 1, turning that can transmit power to one of the right and left traveling devices in the same direction as the other of the right or left traveling device and at a lower speed than the other of the right or left traveling device. A mechanism (C, 27R, 27L, 25R, 25L in FIG. 2 of Patent Document 1) is provided. Thus, for example, when the power for forward rotation is transmitted to the left traveling device via the first transmission system and the left second transmission system, when the power is transmitted to the right traveling device by the turning mechanism, The forward rotation power slower than that of the traveling device is transmitted to the right traveling device, and the aircraft turns to the right while moving forward due to the speed difference between the right and left traveling devices.
[0004]
[Patent Document 1]
JP 2001-193835 A (FIGS. 2, 4, 11, 12)
[0005]
[Problems to be solved by the invention]
The structure of Patent Document 1 includes a braking mechanism (B in FIG. 2 of Patent Document 1) capable of braking the right and left traveling devices in addition to the turning mechanism described in [Prior Art]. Thus, for example, when the right traveling device is braked by the braking mechanism in the state where the left traveling device is transmitting the forward rotation power via the first transmission system and the left second transmission system, When the traveling device is stopped, the left traveling device is driven, and as described in [Prior Art], a small turn is performed as compared with the case where the vehicle turns to the right while moving forward (reverse). .
[0006]
As described above, a small turn is possible when the braking mechanism is used, but a small turn is made by driving the left (right) travel device with the right (left) travel device stopped. The stopped right (left) traveling device does not move and changes its direction on the spot, and the stopped right (left) traveling device causes the ground soil to largely push away sideways. The ground is often roughed.
The present invention has the advantage of turning right (left) while moving forward (reverse) due to the speed difference between the right and left traveling devices in a traveling transmission structure of a work vehicle equipped with right and left traveling devices. The purpose is to make it possible to make a small turn while suppressing the rough surface as much as possible.
[0007]
[Means for Solving the Problems]
[I] According to the feature of claim 1, the power transmitted from the first transmission system on the upper transmission side is branched to the right and left and transmitted to the lower transmission side via the second transmission system. In the traveling transmission structure of the work vehicle configured to drive the traveling device ,
One of the right and left traveling devices can transmit power decelerated in the same direction as the other of the right or left traveling devices and at a lower speed than the other of the right or left traveling devices by the first reduction ratio. A first turning mechanism;
For the same traveling device as the right or left traveling device to which power is transmitted by the first turning mechanism, the traveling device is in the same direction as the other of the right or left traveling device and is slower than the first reduction gear ratio. A second turning mechanism capable of transmitting power decelerated at a lower speed than the other of the right or left traveling device by a second reduction ratio;
In addition to the power transmission system from the first transmission system to the second transmission system, a branch transmission mechanism for branching power from the first transmission system to the first turning mechanism and the second turning mechanism is provided.
The branch transmission mechanism is constituted by a pair of output gears integrally formed on both sides of the transmission gear to which the power of the first transmission system is transmitted, and the power transmitted from each output gear to the first turning mechanism and the second turning mechanism. Are set so that the output gears are different from each other .
[0008]
According to the feature of claim 1, when turning with a predetermined turning radius, the first turning mechanism may be operated. Thus, for example, in the state in which the left traveling device is transmitting the forward rotation power via the first transmission system and the left second transmission system, the first turning mechanism is arranged in the same direction as the left traveling device and the second traveling device. The power decelerated at a lower speed than the left traveling device by the 1 reduction ratio is transmitted to the right traveling device, and the aircraft turns to the right while moving forward due to the speed difference between the right and left traveling devices.
[0009]
According to the first aspect of the present invention, the second turning mechanism may be operated when turning smaller than the turning with the predetermined turning radius. Thus, for example, in a state in which the left traveling device is transmitted the forward rotation power through the first transmission system and the left second transmission system, the second turning mechanism is arranged in the same direction as the left traveling device and the second traveling device. The power decelerated to a speed lower than that of the left travel device by the second speed reduction ratio lower than the first speed reduction ratio is transmitted to the right travel device. Since the second reduction ratio of the second turning mechanism is set to be lower than the first reduction ratio of the first turning mechanism, the speed difference between the right and left traveling devices is larger than that of the first turning mechanism. Thus, the aircraft turns to the right while moving forward with a small turning radius compared to the case of the first turning mechanism.
[0010]
In this case, according to the feature of claim 1, if the second reduction gear ratio of the second turning mechanism is set to a sufficiently low speed, the difference in speed between the right and left traveling devices becomes large, and turning with a small turning radius. However, the right (left) traveling device (the traveling device on the turning center side) to which power is transmitted by the second turning mechanism is not stopped but driven in the same direction as the other traveling device. ing.
As a result, in a turn in which the second turning mechanism is operated, a state in which the right (left) traveling device (the traveling device on the turning center side) to which power is transmitted by the second turning mechanism changes its direction on the spot. It is unlikely that the ground soil will be greatly pushed away by the stopped right (left) travel device, so the ground is rarely roughened.
[0011]
[0012]
Power is transmitted from the part of the first transmission system before branching to the right and left second transmission system to the right or left traveling device via the first and second turning mechanisms, which is called a common part. Since the power is transmitted from the first transmission system to the right or left traveling device via the first and second turning mechanisms, the power is branched from separate parts, and the first and second turning mechanisms are Compared to a configuration in which power is transmitted to the right or left traveling device through the structure, the structure is less likely to be complicated.
[0013]
[0014]
[0015]
[II] According to the feature of claim 2 , as in the case of claim 1, the “action” described in the preceding item [I] is provided, and in addition to this, the following “action” is provided.
According to the second aspect of the present invention, since the first and second turning mechanisms are configured with the friction type multi-plate clutch, power is supplied to the right or left traveling device via the first and second turning mechanisms. In the case of transmission, transmission to the right or left traveling device and interruption can be smoothly performed.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
[1]
As shown in FIG. 1, a cutting part 2 is provided on the left part of the front part of the airframe supported by the crawler type right and left traveling devices 1, and a driving part 3 is provided on the right part of the front part of the airframe. A threshing device 4 is provided on the left side of the rear part, and a grain tank 5 is provided on the right part of the rear part of the machine body to constitute a combine for rice, which is an example of a work vehicle. As a result, the grain culm in the field is cut by the reaping unit 2, threshing is performed by the threshing device 4, and the grains recovered by the threshing device 4 are supplied to the glen tank 5.
[0017]
As shown in FIG. 2, a traveling transmission case 6 is provided, and a hydrostatic continuously variable transmission 7 that can be shifted forward and backward is connected to the transmission case 6. The power of 8a is transmitted to the input shaft 7a of the hydrostatic continuously variable transmission 7 through the belt-type tension clutch 9. The power of the output shaft 7 b of the hydrostatic continuously variable transmission 7 is transmitted to the output shaft 10 and is transmitted to the cutting unit 2 via the belt-type tension clutch 11.
[0018]
[2]
Next, in the transmission system provided in the inside of the mission case 6 , a linear (forward or reverse) transmission system will be described.
As shown in FIG. 2, a transmission shaft 12 is provided inside the transmission case 6, and a transmission gear 13 fixed to the output shaft 10 is engaged with a transmission gear 14 fixed to the transmission shaft 12. A low-speed gear 15, a medium-speed gear 16 and a high-speed gear 17 are externally fitted to the transmission shaft 12 so as to be relatively rotatable, and shift members 18 and 19 are externally fitted to the transmission shaft 12 so as to be integrally rotatable and slidable by a spline structure. Yes.
[0019]
As shown in FIG. 2, a transmission shaft 20 is provided inside the transmission case 6, and a low-speed gear 21, a medium-speed gear 22, and a high-speed gear 23 fixed to the transmission shaft 20 are a low-speed gear 15, a medium-speed gear 16, and It meshes with the high speed gear 17. Thus, the power transmitted from the transmission shaft 12 to the transmission shaft 20 is shifted in three stages by sliding the shift members 18 and 19 to engage with the low speed gear 15, the medium speed gear 16 and the high speed gear 17. Can do.
[0020]
As shown in FIGS. 2 and 3, a support shaft 24 is rotatably supported inside the transmission case 6, and a transmission gear 25 is fixed to the center of the support shaft 24. And bite. Right and left side gears 26 are fitted on the support shaft 24 so as to be relatively rotatable and slidable, and right and left transmission gears 27 that transmit power to the right and left traveling devices 1 are provided with right and left side gears. The right and left side gears 26 are always engaged regardless of the sliding operation of the 26.
[0021]
As shown in FIGS. 2 and 3, right and left oil chambers 43 are formed between the right and left side gears 26 and the support shaft 24, and the right and left side gears 26 are transmitted to the transmission gear 25 by springs 39. It is energized towards. As a result, the right and left side gears 26 are engaged with the engagement portion 25c of the transmission gear 25 by the biasing force of the spring 39, and when hydraulic oil is supplied to the right and left oil chambers 43, The left side gear 26 is slid to be separated from the occlusal portion 25 c of the transmission gear 25.
[0022]
With the above structure, as shown in FIGS. 2 and 3, when the right and left side gears 26 are engaged with the engagement portion 25c of the transmission gear 25, the power of the transmission shaft 20 is changed to the medium speed gear 22, the transmission gear 25, and the right side. Then, it is transmitted to the right and left traveling devices 1 via the left side gear 26 and the right and left transmission gears 27. As a result, power in the same direction and at the same speed is transmitted to the right and left traveling apparatuses 1, and the aircraft moves straight (forward or reverse). Next, when the right (left) side gear 26 is slid and separated from the engagement portion 25c of the transmission gear 25, the power from the transmission gear 25 to the right (left) traveling device 1 is cut off. As described above, the right and left side clutches 37 are configured between the occlusal portion 25 c of the transmission gear 25 and the right and left side gears 26.
That is, the upper transmission system until reaching the transmission gear 25 immediately before branching by the side clutch 37 constitutes the first transmission system, and the lower transmission system branched from the transmission gear 25 is the first transmission system. 2 constitutes the transmission system.
[0023]
[3]
Next, in the transmission system provided inside the mission case 6 , the turning transmission system will be described.
As shown in FIGS. 2 and 3, the transmission shaft 28 is provided inside the transmission case 6, and the first turning clutch 29 and the second turning clutch 30 are provided on the transmission shaft 28. The first and second swing clutches 29 and 30 are a case member 31 fixed to the transmission shaft 28, a small-diameter first swing gear 32 and a large-diameter second swing gear that are externally fitted to the transmission shaft 28 so as to be relatively rotatable. 33, a friction plate 34 disposed between the case member 31 and the first and second swivel gears 32, 33, a piston member 35 that presses the friction plate 34, and the like, are configured in a hydraulic multi-plate type. .
[0024]
As shown in FIGS. 2 and 3, the transmission gear 25 is integrally provided with a first output gear 25 a having a large diameter and a second output gear 25 b having a small diameter, and the first output gear 25 a and the first turning gear 32 are provided. And the second output gear 25b and the second turning gear 33 are engaged. Right and left transmission gears 36 are fixed to the transmission shaft 28.
A large-diameter first output gear 25a integrally formed with the transmission gear 25 and a small-diameter second output gear 25b are separated from the power transmission system from the first transmission system to the second transmission system. A branch transmission mechanism is configured to branch and transmit power from the first transmission system to the first and second turning mechanisms described later.
[0025]
As shown in FIGS. 2 and 3, right and left transmission clutches 38 are provided between the right and left side gears 26 and the right and left transmission gears 36. The right and left transmission clutches 38 include a case member 40 that is externally fitted to the support shaft 24 so as to be relatively rotatable, a friction plate 41 that is disposed between the case member 40 and the right and left side gears 26, and a friction plate 41. The piston member 42 to be pressed is provided, and the hydraulic multi-plate type is configured.
Gear teeth are provided on the outer periphery of the case member 40, and the right and left transmission gears 36 mesh with the gear teeth of the case member 40 of the right and left transmission clutches 38.
[0026]
With the above structure, as described in [2] above, the right and left side gears 26 are engaged with the engagement portion 25c of the transmission gear 25, and the power of the transmission shaft 20 is transmitted to the right and left via the right and left side gears 26. The first and second swing clutches 29 and 30 and the right and left transmission clutches 38 are operated in a disconnected state in a state where the airframe is transmitted straight to the left traveling device 1 (forward or reverse). .
[0027]
In the above-described state, for example, as shown in FIG. 3, the left side gear 26 is slid to move away from the engagement portion 25c of the transmission gear 25 (the left side clutch 37 is disconnected), and the first swing clutch 29 and the left When the transmission clutch 38 is operated to the transmission state, the power of the transmission gear 25 is transmitted to the left side gear 26 via the first output gear 25a, the first turning clutch 29, the transmission shaft 28, the left transmission gear 36, and the left transmission clutch 38. Is transmitted to. As a result, the power (in the same direction as the right traveling device 1) that has been decelerated at a low speed (first reduction ratio) between the first output gear 25a and the first turning gear 32 is transmitted to the left traveling device 1. Due to the difference in speed between the right and left traveling devices 1 (for example, the speed of the left traveling device 1 is 1/3 of the speed of the right traveling device 1), the aircraft turns left while moving forward (reversing). .
The right or left traveling device 1 is controlled by the first turning gear 32, the first turning clutch 29, the transmission shaft 28, the left transmission gear 36, and the left transmission clutch 38 to which the power of the first output gear 25a is transmitted. A first turning mechanism capable of transmitting power decelerated by a first reduction ratio in the same direction as the other of the right or left traveling device 1 and at a lower speed than the other of the right or left traveling device 1; It is configured.
[0028]
Next, when the second turning clutch 30 and the left transmission clutch 38 are operated to the transmission state in the above-described state, the power of the transmission gear 25 is changed to the second output gear 25b, the second turning clutch 30, the transmission shaft 28, and the left transmission. It is transmitted to the left side gear 26 via the gear 36 and the left transmission clutch 38. As a result, the power (in the same direction as the right traveling device 1) that has been decelerated at a low speed (second reduction ratio) between the second output gear 25b and the second turning gear 33 is transmitted to the left traveling device 1. Due to the difference in speed between the right and left traveling devices 1 (for example, the speed of the left traveling device 1 is 1/8 to 1/10 of the speed of the right traveling device 1), the aircraft moves forward (reverse) and moves to the left. Turn around.
The right or left traveling device 1 is constituted by the second turning gear 33 to which the power of the second output gear 25b is transmitted, the second turning clutch 30, the transmission shaft 28, the left transmission gear 36, and the left transmission clutch 38. A second turning mechanism is configured that can transmit power decelerated by a second reduction ratio that is lower than the first reduction ratio in the same direction as the other of the right or left traveling device 1. .
[0029]
In this case, as shown in FIG. 3, the second reduction gear between the second output gear 25 b and the second turning gear 33 is compared with the first reduction ratio between the first output gear 25 a and the first turning gear 32. Since the reduction ratio is set to a low speed, the right and left travels when the second swing clutch 30 is used compared to the speed difference between the right and left travel devices 1 when the first swing clutch 29 is used. The speed difference of the device 1 becomes large, and when the second turning clutch 30 is used, the aircraft moves forward (reverse) with a small turning radius to the right when compared with the case where the first turning clutch 29 is used. Turn around. Similar to the case where the left transmission clutch 38 is operated in the transmission state as described above, the same state occurs when the right transmission clutch 38 is operated in the transmission state.
[0030]
[4]
Next, the operation of the right and left side clutches 26, the right and left transmission clutches 38, the first and second turning clutches 29 and 30, and the hydraulic circuit structure will be described.
As shown in FIG. 4, the hydraulic oil of the hydraulic pump 44 is supplied to the right and left oil chambers 43 and the right and left transmission clutches 38 through the oil passages 46 and 47 from the three-position switching type directional control valve 45. Has been. An oil passage 48 from the right and left oil chambers 43 is connected to the turning selection valve 50, and hydraulic oil of the turning selection valve 50 is configured to be supplied to the first and second turning clutches 29 and 30. A variable relief valve 49 is connected to the swing selection valve 50. A steering lever 51 is provided in the operating unit 3, and the steering lever 51, the direction switching valve 45, and the variable relief valve 49 are linked via a linkage mechanism 52.
[0031]
The state shown in FIG. 4 is a state in which the turning selection valve 50 is operated to the first turning position 50a and the steering lever 51 is operated to the neutral position N, the direction switching valve 45 is operated to the neutral position 45N, The variable relief valve 49 is operated to the open position. In this state, hydraulic oil is not supplied to the right and left oil chambers 43, and the right and left transmission clutches 38 and the first and second turning clutches 29 and 30 are operated in a disconnected state.
[0032]
As a result, as shown in FIGS. 2 and 3, the right and left side gears 26 are engaged with the engagement portions 25c of the transmission gear 25 (the transmission state of the right and left side clutches 37), and the power of the transmission shaft 20 is increased. Power is transmitted to the right and left traveling devices 1 via the medium speed gear 22 and the transmission gear 25, the right and left side gears 26, and the right and left transmission gears 27. Transmitted to the device 1, the aircraft goes straight (forward or reverse).
[0033]
2 and 4, when the steering lever 51 is operated from the neutral position N to the right first turning position R1 (left first turning position L1), the direction switching valve 45 is moved to the right turning position 45R (left turning). 45L), hydraulic oil is supplied to the right (left) oil chamber 43 and the right (left) transmission clutch 38, and the right (left) side gear 26 is slid to engage the engagement portion of the transmission gear 25. The right (left) transmission clutch 38 is operated to the transmission state, away from 25c (right (left) side clutch 37 is disconnected). In this case, since the first and second swing clutches 29 and 30 are operated in the disconnected state (due to the variable relief valve 49 being operated in the open position), the right (left) traveling device 1 rotates freely. The aircraft gradually turns to the right (left).
[0034]
2 and 4, the steering lever 51 is operated from the right first turning position R1 (left first turning position L1) to the right second turning position R2 (left second turning position L2). Then, since the variable relief valve 49 is gradually operated from the open position to the closed position from the above state, the first swing clutch 29 is gradually operated from the disconnected state to the transmission state. As a result, as described in [3] above, the power that has been decelerated at a low speed (first reduction ratio) between the first output gear 25a and the first turning gear 32 is applied to the right (left) traveling device 1. Due to the difference in speed between the right and left traveling devices 1, the aircraft turns to the right (left) while moving forward (reverse), and the steering lever 51 is moved to the right second turning position R2 (left When operated to the second turning position L2), the first turning clutch 29 is brought into a complete transmission state.
[0035]
2 and 4, the steering lever 51 is operated from the right first turning position R1 (left first turning position L1) to the right second turning position R2 (left second turning position L2). At this time, if the turning selection valve 50 is operated to the second turning position 50b in advance, the second turning clutch 30 is disconnected if the variable relief valve 49 is gradually moved from the open position to the closed position from the above state. It is gradually operated from the state to the transmission state. As a result, as described in [3] above, the power decelerated at low speed (second reduction ratio) between the second output gear 25b and the second turning gear 33 is transferred to the right (left) traveling device 1. Due to the difference in speed between the right and left traveling devices 1, the aircraft turns to the right (left) while moving forward (reverse), and the steering lever 51 is moved to the right second turning position R2 (left When operated to the second turning position L2), the second turning clutch 30 is in a complete transmission state.
[0036]
In this case, as shown in FIG. 3, the first reduction gear ratio between the first output gear 25a and the first turning gear 32 is larger than the first reduction gear ratio between the second output gear 25b and the second turning gear 33. 2. Since the reduction gear ratio is set to low speed, the steering lever 51 is operated to the right second turning position R2 (left second turning position L2) while the turning selection valve 50 is operated to the first turning position 50a. As compared with the above, when the steering lever 51 is operated to the right second turning position R2 (left second turning position L2) with the turning selection valve 50 being operated to the second turning position 50b, the turning radius is smaller. The aircraft turns to the right (left) while moving forward (reversing).
[0037]
[First Alternative Embodiment of the Invention]
In the above-mentioned [Embodiment of the invention], the steering lever 51 and the turning selection valve 50 may be linked together and configured as follows.
As shown in FIG. 5, when the steering lever 51 is operated to the neutral position N, the right and left side clutches 37 are operated to the transmission state, and the operation lever 51 is moved from the neutral position N to the right first turning position R1. When it is operated to (left first turning position L1), the right (left) side clutch 37 is operated to be disconnected, and the right (left) transmission clutch 38 is operated to be transmitted.
[0038]
As shown in FIG. 5, when the steering lever 51 is operated from the right first turning position R1 (left first turning position L1) to the right second turning position R2 (left second turning position L2), the first When the turning clutch 29 is gradually moved from the disconnected state to the transmission state and the steering lever 51 is operated to the right second turning position R2 (left second turning position L2), the first turning clutch 29 is brought into a complete transmission state. Operated. When the steering lever 51 is operated from the right second turning position R2 (left second turning position L2) to the right third turning position R3 (left third turning position L3), the first turning clutch 29 is immediately disconnected. When the second turning clutch 30 is gradually moved from the disconnected state to the transmission state, and the steering lever 51 is operated to the right third turning position R3 (left third turning position L3), the second turning clutch 30 is operated. Is operated in full transmission.
[0039]
[0040]
[0041]
[0042]
[ Second Embodiment of the Invention]
In the above-mentioned [Embodiment of the invention] to [ First alternative embodiment of the invention], the third reduction ratio that is lower than the second reduction ratio between the second output gear 25b and the second turning gear 33 is set. A third turning clutch (not shown) provided may be provided on the transmission shaft 28 shown in FIGS. 2 and 3, and the second turning mechanism may be configured by the second turning clutch 30 and the third turning clutch. Instead of the steering lever 51, a round steering handle (not shown) such as a general passenger car may be used.
The present invention is not limited to the crawler-type right and left traveling devices 1 but also to a work vehicle that includes a plurality of traveling wheels that are not steered on the right and a plurality on the left to form the right and left traveling devices 1. Applicable.
[0043]
【The invention's effect】
According to the first aspect of the present invention, in the traveling transmission structure of the work vehicle including the right and left traveling devices, one of the right and left traveling devices has the same direction as the other of the right or left traveling device and the first deceleration. By providing the first turning mechanism (second turning mechanism) capable of transmitting the power decelerated at a lower speed than the other of the right or left traveling device by the ratio (second reduction ratio), the roughness of the ground is reduced. Thus, turning with a predetermined turning radius and turning smaller than turning with a predetermined turning radius can be performed, and the turning performance of the work vehicle can be improved.
[0044]
Power is transmitted from the first transmission system, which may be said to be a common part, to the right or left traveling device via the first and second turning mechanisms, and the power is branched from the separate parts, and the first and second Compared to a configuration in which power is transmitted to the right or left traveling device via the two-turn mechanism, the structure is less likely to be complicated, which is advantageous in terms of simplification of the structure.
[0045]
[0046]
According to the second aspect of the present invention, the first and second turning mechanisms are configured with the friction type multi-plate clutch, and the power is transmitted to the right or left traveling device via the first and second turning mechanisms. In this case, transmission and shut-off to the right or left traveling device can be performed smoothly, and the turning performance of the work vehicle can be improved.
[Brief description of the drawings]
FIG. 1 is an overall side view of a combine. FIG. 2 is a schematic view showing the inside of a mission case. FIG. 3 is a longitudinal front view of the mission case near the first and second turning clutches and right and left side clutches (side gears). FIG. 4 is a hydraulic circuit diagram of right and left side clutches (side gears), right and left transmission clutches, and first and second swing clutches. FIG. 5 is a steering lever according to a first embodiment of the invention. Figure [Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Traveling device 25 1st transmission system 26, 27 2nd transmission system 28, 36 3rd transmission system 29 1st turning mechanism 30 2nd turning mechanism

Claims

It is configured to drive the right and left traveling devices via a second transmission system that branches power transmitted from the first transmission system on the upper transmission side to the right and left and transmits it to the lower transmission side. It is a traveling transmission structure of a work vehicle ,
Power that is decelerated in the same direction as the other of the right or left traveling device and at a lower speed than the other of the right or left traveling device by the first reduction ratio can be transmitted to one of the right or left traveling device. A first turning mechanism;
For the same traveling device as the right or left traveling device to which power is transmitted by the first turning mechanism, the traveling device is in the same direction as the other of the right or left traveling device and is slower than the first reduction gear ratio. A second turning mechanism capable of transmitting power decelerated at a lower speed than the other of the right or left traveling device by a second reduction ratio;
In addition to the power transmission system from the first transmission system to the second transmission system, a branch transmission mechanism for branching power from the first transmission system to the first turning mechanism and the second turning mechanism is provided.
The branch transmission mechanism is constituted by a pair of output gears integrally formed on both sides of the transmission gear to which the power of the first transmission system is transmitted, and the power transmitted from each output gear to the first turning mechanism and the second turning mechanism. The transmission transmission structure for a work vehicle is characterized in that the reduction gear ratio is set to be different for each output gear .

The traveling transmission structure for a work vehicle according to claim 1, wherein a frictional multi-plate clutch is provided to constitute the first and second turning mechanisms.