JP3626145B2

JP3626145B2 - Agricultural tractor steering device

Info

Publication number: JP3626145B2
Application number: JP2002069117A
Authority: JP
Inventors: 功前田; 勝美藤木
Original assignee: セイレイ工業株式会社
Priority date: 2002-03-13
Filing date: 2002-03-13
Publication date: 2005-03-02
Anticipated expiration: 2015-11-17
Also published as: JP2002316662A

Description

【０００１】
【発明の属する技術分野】
本発明は、農業用トラクタの操向装置に関する。
【０００２】
【従来の技術】
従来、農業用トラクタにおいて、左右走行部にそれぞれ連動連結した無段変速機の駆動速度を異ならせて、機体を旋回させるようにしたものがある。
【０００３】
【発明が解決しようとする課題】
ところが、左右無段変速機にそれぞれ左右操向レバーを連動連結して、左右無段変速機を個別に操作するように構成されているため操向操作が難しく、更に、左右無段変速機の個体差や、左右無段変速機を操作する左右操作機構の不揃いやガタが原因で、直進性が悪く、また、左右無段変速機が相互関連なく制御されているので、旋回が円滑に行われず、そのため圃場面を傷めるという問題がある。
【０００４】
【課題を解決するための手段】
そこで、本発明では、エンジンに走行用無段変速機を連動連結し、同走行用無段変速機に左右走行部の各駆動軸を連動連結して、各駆動軸を走行用無段変速機により相互に同一回転方向に駆動させる一方、エンジンに操向用無段変速機を連動連結し、同操向用無段変速機に左右走行部の各駆動軸を連動連結して、各駆動軸を操向用無段変速機により相互に逆回転方向に駆動させて、両変速機により各駆動軸の回転数を増減させて機体を旋回増減速可能とした農業用トラクタであって、ステアリングホイールを操向用増減速機構を介して操向用無段変速機に連動連結する一方、前後進変速レバーを走行用無段変速機に連動連結すると共に、前後進変速レバーの前・後進側操作に連動する前後進切換機構を設けて、同前後進切換機構により、ステアリングホイールの回動方向と機体の旋回方向とを一致させ、しかも、前記操向用増減速機構と前後進切換機構とをステアリングギヤボックスの内部に配設したことを特徴とする農業用トラクタの操向装置を提供するものである。
【０００５】
【発明の実施の形態】
本発明の実施の形態について図面を参照して説明する。
【０００６】
図１は、本発明に係る走行駆動装置ＤＲを具備する農業用トラクタＴＲの側面図であり、同農業用トラクタＴＲはクローラ式の左右走行部１Ｌ，１Ｒを装備した機体フレーム２の上面前部に原動機部３を載設し、その後方にキャビン４を載設して、同キャビン４中に運転部５を配置している。
【０００７】
運転部５は前部にステアリングホイール６を操向回動自在に配置し、その後方に所定間隔を保持して座席７を配置し、同座席の右側方に前後進変速レバー８を前後傾動自在に立設している。図中、９は走行部フレーム、１０は履帯、１１は駆動輪、１２は遊動輪、１３は下部転輪、１４は上部転輪、１５はロアリンク、１６は作業機昇降機構である。
【０００８】
図２及び図３は走行駆動装置ＤＲの配置を示しており、機体の前後中心線に沿って、前方から原動機部３に搭載したエンジン１７、フロントミッション１８、リアミッション１９の順に配置して、フロントミッション１８の後面に、可変容量型油圧ポンプと定容量型油圧モータとで構成した静油圧式の操向用無段変速機２０を取付け、リアミッション１９の前面に、可変容量型油圧ポンプと定容量型油圧モータとで構成した走行用変速機としての静油圧式の走行用無段変速機２１を取付けており、動力伝達の順に走行駆動装置ＤＲの各部について説明する。
【０００９】
図４及び図５はフロントミッション１８、図６はリアミッション１９を示しており、エンジン１７とダブルフックジョイント２２を介して連動連結したフロントミッション入力軸２３を、ギヤトレイン２５を介して前記操向用無段変速機２０の入力軸２０ａに連動連結し、同入力軸２０ａの後端を、フロントミッション１８とリアミッション１９との間に設けたユニバーサルジョイント２６，２６と第１連動軸２７とを介し、前記走行用無段変速機２１の入力軸２１ａの前端に連動連結しており、同入力軸２１ａの後端は、リアミッション１９中に設けた動力取出しクラッチ２９と中立及び２段変速可能の動力取出し変速部３０と噛合減速歯車３０ａとを介して動力取出し軸３１に連動連結している。
【００１０】
一方、走行用無段変速機２１の出力軸２１ｂは、走行用クラッチ３２と中立及び３段変速可能の副変速部３３を介してリアミッション出力軸３４に連動連結しており、リアミッション出力軸３４の前端は、ユニバーサルジョイント２６，２６と第２連動軸３５とを介し、フロントミッション１８の後面に軸支した前入力軸３６の後端に連動連結しており、前入力軸３６の前端に形成した走行用噛合傘歯車３７を介し、左右走行部駆動軸３８Ｌ，３８Ｒの間に軸支した中間軸３９に連動連結している。
【００１１】
上記左右走行部駆動軸３８Ｌ，３８Ｒは、中間軸３９の左右側に配設した左右遊星歯車機構４０Ｌ，４０Ｒの左右プラネタリギヤ４１Ｌ，４１Ｒと左右ケージ４２Ｌ，４２Ｒとを介し、左右走行部１Ｌ，１Ｒの左右駆動輪１１Ｌ，１１Ｒにそれぞれ連動連結しており、中間軸３９の左右両端に上記左右遊星歯車機構４０Ｌ，４０Ｒの左右アウタギヤ４３Ｌ，４３Ｒを嵌着している。
【００１２】
一方、操向用無段変速機２０の出力軸２０ｂの前端に操向用原動傘歯車４５を形成し、同操向用原動傘歯車４５に、左右操向軸４６Ｌ，４６Ｒの内側端に嵌着した左右操向用受動傘歯車４７Ｌ，４７Ｒを噛合させて差動歯車機構４８を構成しており、左右操向軸４６Ｌ，４６Ｒの外側端と左右遊星歯車機構４０Ｌ，４０Ｒの左右サンギヤ４９Ｌ，４９Ｒとを左右操向用噛合歯車５０Ｌ，５０Ｒを介してそれぞれ連動連結しており、左右操向軸４６Ｌ，４６Ｒの内側端に形成したスプライン５１Ｌ，５１Ｒと、同スプライン５１Ｌ，５１Ｒに嵌合可能のスリーブ５１ａよりなるデフロック機構５１を設けて、左右操向軸４６Ｌ，４６Ｒの回動を阻止できるようにしている。図６中、５２はブレーキである。
【００１３】
次に、図７〜図１１を参照して操向装置ＳＴについて説明する。
【００１４】
操向装置ＳＴは、図７及び図８で示すように、キャビン４の前側内面にステー５４を突設し、同ステー５４の後端に前低後高の傾斜状態で固着したステアリングポスト５５に、上端にステアリングホイール６を取付けたステアリング軸５６を回動自在に挿通し、ステアリング軸５６の下端をユニバーサルジョイント２６，２６と延長軸５７とを介し、キャビン４の床の下面に取付けたステアリングボックス５８の上面から突出した操作入力軸５９に連動連結している。
【００１５】
ステアリングボックス５８の内部には操向用増減速機構ＳＡを設けて、操向用無段変速機２０の回転速度をステアリングホイール６の操作量に比例させるようにしている。
【００１６】
操向用増減速機構ＳＡは、図９〜図１１で示すように、同ステアリングボックス５８中にラック支持軸６０を左右方向に架設し、ラック支持軸６０の前面にラック６１を取付けたラック支持体６１ａを左右摺動自在に外嵌し、同ラック６１に前記操作入力軸５９の下端に形成したピニオン６２を噛合させると共に、同ラック支持体６１ａの下面に、断面が下方開口略コ字形状の傾動体６３の中央部を左右回動自在に枢着すると共に、ステアリングボックス５８の底壁を挿通した作動軸６４の内側端に連設した内部作動レバー６５の先端部に突設した作動ピン６６を、上記傾動体６３の開口内部にボールベアリング６７を介して挿入し、作動軸６４の外側端に外部作動レバー６８を連設し、同外部作動レバー６８を連結ロッド６９と操向変速レバー７０ａとを介して前記操向用無段変速機２０の操向用変速操作軸７０に連動連結している。
【００１７】
また、ステアリングボックス５８中に左右方向に伸延した螺杆７１を架設し、同螺杆７１に復座付勢体７２を外嵌しており、復座付勢体７２は上記ラック６１に固着した筒体７３にコイルスプリング７４を収納し、同コイルスプリング７４の両端をそれぞれワッシャ７５，７５と止め輪７６，７６とで内側方向には摺動自在、外側方向には摺動不可に固定し、螺杆７１の上記ワッシャ７５，７５の外側位置に螺着した調整ナット７７，７７により復座付勢体７２を支持している。
【００１８】
また、ステアリングボックス５８中に前後進切換機構ＳＢを設けて、後述する前後進変速レバー８の前後傾動に連動して、操向用無段変速機２０出力の回転方向を反転させることにより、前後進に関係なくステアリングホイール６の回動方向に機体を旋回させるようにしている。
【００１９】
前後進切換機構ＳＢは、左右方向に伸延した傾動軸７８を回動自在に架設し、同傾動軸７８にボールスプライン７９を介して摺動体８０を左右摺動自在に外嵌し、同摺動体８０の下方延設部８０ａと前記傾動体６３とを連結杆８１を介して連動連結すると共に、傾動軸７８の突出端部に傾動操作レバー８２を連設し、同傾動操作レバー８２に固定端を機体フレーム２に枢着した傾動用油圧シリンダ８３の作動端と、傾動軸７８を中立位置に復帰させる復座機構８４を連動連結している。
【００２０】
また、図７及び図８で示すように、機体フレーム２の座席７の右側方に立設した前後進変速レバー支持体８５の上端部を挿通した支軸８６を介して前後進変速レバー８を前後傾動自在に軸支し、同支軸８６に略逆Ｔ字形状の前後進変速板８７を連設し、前後進変速板８７の後端を第１前後進変速ロッド８８、ベルクランク８８ａ、第２前後進変速ロッド８８ｂ及び走行速度操作レバー８９を介して走行用無段変速機２１の走行速度操作軸９０に連動連結している。
【００２１】
また、上記前後進変速板８７の前端には、前後進変速レバー８を中立位置に復帰させる復座機構８４を連結している。なお、上記復座機構８４は、前記復座付勢体７２と略同様に構成されており、筒体側が機体フレーム２に固定され、螺杆側を前後進変速板８７に連結した点で前記とは異なる。
【００２２】
また、前後進変速レバー８には前後進検出センサＳＥが連動連結しており、同前後進検出センサＳＥは、上記前後進変速レバー支持体８５の上端部にスイッチ支持板９１を連設し、同スイッチ支持板９１に前進スイッチ９３と後進スイッチ９４とを取付けて、前後進変速レバー８が前進側に操作されたときには、前後進変速板８７の前端部と前進スイッチ９３とが当接して前進スイッチ９３だけがＯＮし、前後進変速レバー８が後進側に操作されたときには、前後進変速板８７の後端部と後進スイッチ９４とが当接して後進スイッチ９４だけがＯＮし、中立位置では両方のスイッチ９３，９４がＯＦＦするようにしており、各スイッチ９３，９４を前記傾動用油圧シリンダ８３に連通連結した電磁油圧方向制御弁９２に接続して、各スイッチ９３，９４の検出出力により電磁油圧方向制御弁９２の油路を切換えて、傾動用油圧シリンダ８３に伸縮作動させるようにしている。
【００２３】
本発明の実施形態は上記のように構成されており、エンジン１７により走行用無段変速機２１と操向用無段変速機２０とに動力を伝達しておき、前後進変速レバー８を操作すると、走行用無段変速機２１が、前後進変速レバー８の操作量に対応した速度でリアミッション１９の副変速部３３と、フロントミッション１８の左右遊星歯車機構４０Ｌ，４０Ｒとを介し、左右走行部１Ｌ，１Ｒの左右駆動輪１１Ｌ，１１Ｒを駆動して、前後進変速レバー８の操作量に対応した速度で農業用トラクタＴＲを前後進させることができる。
【００２４】
また、副変速部３３を操作して変速比を変更することにより、走行用無段変速機２１の効率のよい回転数範囲内で、広い範囲の走行速度に対応することができる。
【００２５】
また、ステアリングホイール６を操作して操向用無段変速機２０を作動させると、差動歯車機構４８の作用により、左右遊星歯車機構４０Ｌ，４０Ｒの左右サンギヤ４９Ｌ，４９Ｒが互いに逆方向に回動するので、左右駆動輪１１Ｌ，１１Ｒの回転速度を相補的に増減させて農業用トラクタＴＲを旋回させることができる。
【００２６】
次に操向装置ＳＴの作用について説明する。ステアリングホイール６を操作すると、ステアリング軸５６下端のピニオン６２と噛合したラック６１がステアリングホイール６の操作方向に対応した方向に摺動する。
【００２７】
このとき、前後進変速レバー８の操作方向により、前後進スイッチ９３，９４のいずれかがＯＮして、電磁油圧方向制御弁９２を介し傾動用油圧シリンダ８３を作動させ、傾動軸７８とボールスプライン７９とを介し、ステアリングボックス５８中の傾動体６３を傾斜させているので、傾動体６３の開口部に挿入した作動ピン６６が、上記ラック６１の移動軌跡に略直交する軌跡で、かつ、ステアリングホイール６の操作量に対応した量だけ移動し、内部作動レバー６５、作動軸６４、外部作動レバー６８及び連結ロッド６９を介して操向用無段変速機２０の操向用変速操作軸７０に伝達され、それまで中立状態にあって吐出量がゼロであった可変容量型油圧ポンプから、ステアリングホイール６の操作量に対応した回転数で操向用無段変速機２０が出力し、差動歯車機構４８を介して左右遊星歯車機構４０Ｌ，４０Ｒの左右サンギヤ４９Ｌ，４９Ｒを回動させる。
【００２８】
このように、ステアリングホイール６の操作を、前後進変速レバー８の操作方向に応じて傾動方向を変化させる傾動体６３を介して操向用無段変速機２０の操向用変速操作軸７０に伝達することにより、農業用トラクタＴＲの前後進に関係なくステアリングホイール６の回動方向と同一方向に農業用トラクタＴＲを旋回させることができる。
【００２９】
なお、傾動体６３を介せずにステアリングホイール６を操向用無段変速機の操向用変速操作軸７０に連動連結すると、前後進のいずれかの場合に、ステアリングホイール６の回動方向と農業用トラクタＴＲの旋回方向とが逆になり、操向操作が極めて難しくなる。
【００３０】
また、前後進変速レバー８が中立状態、即ち、機体が停止しているときは、前後進検出センサＳＥの前後進スイッチ９３，９４が両方とも出力しないので、傾動用油圧シリンダ８３内の油圧が開放されて、復座機構８４により傾動軸７８が中立位置に復帰する。この状態では傾動体６３が前後進いずれの側にも傾斜していないので、ステアリングホイール６を回動させても作動ピン６６が中立位置を保持するので、操向用無段変速機２０が停止状態を保持し、従って、機体の旋回は行われないことになる。
【００３１】
また、差動歯車機構４８のデフロック機構５１により、左右サンギヤ４９Ｌ，４９Ｒを固定させて、左右駆動輪１１Ｌ，１１Ｒの回動速度を同一にすることにより、農業用トラクタＴＲの直進性を向上することができる。
【００３２】
【発明の効果】
本発明によれば、次のような効果を得ることができる。
【００３３】
すなわち、本発明では、エンジンに走行用無段変速機を連動連結し、同走行用無段変速機に左右走行部の各駆動軸を連動連結して、各駆動軸を走行用無段変速機により相互に同一回転方向に駆動させる一方、エンジンに操向用無段変速機を連動連結し、同操向用無段変速機に左右走行部の各駆動軸を連動連結して、各駆動軸を操向用無段変速機により相互に逆回転方向に駆動させて、両変速機により各駆動軸の回転数を増減させて機体を旋回増減速可能とした農業用トラクタであって、ステアリングホイールを操向用増減速機構を介して操向用無段変速機に連動連結する一方、前後進変速レバーを走行用無段変速機に連動連結すると共に、前後進変速レバーの前・後進側操作に連動する前後進切換機構を設けて、同前後進切換機構により、ステアリングホイールの回動方向と機体の旋回方向とを一致させ、しかも、前記操向用増減速機構と前後進切換機構とをステアリングギヤボックスの内部に配設している。
【００３４】
従って、走行用変速機により左右走行部の回転方向を、例えば、正回転駆動させて、機体を前進走行させている状態で、操向用無段変速機により左走行部の回転方向を、例えば、正回転駆動させると共に、右走行部の回転方向を逆回転駆動させると、左走行部は両変速機により増速駆動されると共に、右走行部は両変速機により減速駆動されて、円滑に機体を右旋回させることができる。
【００３５】
この際、左右走行部は、機体の旋回操作時に、両変速機により相補的に増減速させることができるために、機体を緩旋回から急旋回にわたって円滑に旋回させることができると共に、旋回時に左右走行部により圃場を傷めるという不具合の発生を防止することができる。
【００３６】
そして、一個のステアリングホイールで機体の旋回を制御することができて操作が容易になり、しかも、前述した左右操作機構の不揃いやガタに起因する不具合が解消されるので、直進性が良くなり、更に、ステアリングホイールでは微妙な操向操作が可能であるから、任意の旋回半径で、しかも、円滑に機体を旋回させることができる。
【００３７】
しかも、前後進変速レバーの前・後進側操作に連動する前後進切換機構を設けて、同前後進切換機構により、ステアリングホイールの回動方向と機体の旋回方向とを一致させるようにしている。
【００３８】
このように、ステアリングホイールの回動方向と機体の旋回方向とを一致させたことによって、機体の前後進行方向に関係なく旋回したい方向にステアリングホイールを回動操作すれば良いので、操向操作が容易になり、安全性を高めることができる。
【図面の簡単な説明】
【図１】本発明に係る走行部駆動装置を具備する農業用トラクタの全体側面図。
【図２】上記走行部駆動装置の概略構成を示す模式平面図。
【図３】上記走行部駆動装置の構成を示す平面図。
【図４】フロントミッションの構成を示す一部断面側面図。
【図５】フロントミッションの構成を示す一部断面平面図。
【図６】リヤミッションの構成を示す一部断面側面図。
【図７】操向装置の側面図。
【図８】操向装置の正面図。
【図９】ステアリングギヤボックスの断面側面図。
【図１０】ステアリングギヤボックスの断面正面図。
【図１１】ステアリングギヤボックスの断面平面図。
【符号の説明】
ＤＲ走行駆動装置
ＳＡ操向用増減速機構
ＳＢ前後進切換機構
ＳＥ前後進検出センサ
１Ｌ，１Ｒ左右走行部
６ステアリングホイール
８前後進変速レバー
２０操向用無段変速機
２１走行用無段変速機
５８ステアリングボックス[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a steering device for an agricultural tractor.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, there is an agricultural tractor in which the body is turned by varying the driving speed of a continuously variable transmission that is linked and connected to the left and right traveling units.
[0003]
[Problems to be solved by the invention]
However, the left and right continuously variable transmissions are linked to the left and right steering levers, and the left and right continuously variable transmissions are individually operated. Due to individual differences and unevenness and backlash of the left and right operating mechanisms that operate the left and right continuously variable transmission, the straight travel is poor, and the left and right continuously variable transmissions are controlled independently of each other, so turning is smooth. Therefore, there is a problem that the field scene is damaged.
[0004]
[Means for Solving the Problems]
Therefore, in the present invention, the driving continuously variable transmission is linked to the engine, the drive shafts of the left and right traveling portions are linked to the driving continuously variable transmission, and the driving shafts are connected to the driving continuously variable transmission. The steering continuously variable transmission is linked to the engine, and the drive shafts of the left and right traveling parts are linked to the steering continuously variable transmission. An agricultural tractor that can be driven in a reverse rotation direction by a steering continuously variable transmission and that can increase / decrease the speed of the vehicle by turning the speed of each drive shaft with both transmissions. Is linked to the steering continuously variable transmission via the steering speed increase / decrease mechanism, while the forward / reverse shift lever is linked to the traveling continuously variable transmission, and the forward / reverse operation of the forward / reverse shift lever is operated. A forward / reverse switching mechanism linked to the Is matched with the turning direction of the turning direction and the fuselage of the ring wheel, moreover, the agricultural tractor, characterized in that disposed between the forward-reverse switching mechanism the steering for acceleration and deceleration mechanism inside the steering gear box A steering device is provided.
[0005]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described with reference to the drawings.
[0006]
FIG. 1 is a side view of an agricultural tractor TR provided with a traveling drive apparatus DR according to the present invention. The agricultural tractor TR is an upper front portion of a body frame 2 equipped with crawler-type left and right traveling sections 1L and 1R. The motor unit 3 is mounted on the rear side, the cabin 4 is mounted on the rear side, and the driving unit 5 is disposed in the cabin 4.
[0007]
The driving unit 5 has a steering wheel 6 disposed at the front thereof so that the steering wheel 6 can be freely rotated, a seat 7 is disposed behind the steering wheel 6 with a predetermined interval, and a forward / reverse speed change lever 8 can be tilted forward and backward on the right side of the seat. Is standing. In the figure, 9 is a traveling unit frame, 10 is a crawler belt, 11 is a drive wheel, 12 is an idler wheel, 13 is a lower wheel, 14 is an upper wheel, 15 is a lower link, and 16 is a work implement lifting mechanism.
[0008]
2 and 3 show the arrangement of the travel drive device DR, arranged in the order of the engine 17, the front mission 18, the rear mission 19 mounted on the prime mover unit 3 from the front along the front-rear center line of the aircraft, A hydrostatic steering continuously variable transmission 20 composed of a variable displacement hydraulic pump and a constant displacement hydraulic motor is mounted on the rear surface of the front mission 18, and a variable displacement hydraulic pump and A hydrostatic traveling continuously variable transmission 21 as a traveling transmission constituted by a constant displacement hydraulic motor is attached, and each part of the traveling drive apparatus DR will be described in the order of power transmission.
[0009]
4 and 5 show a front mission 18 and FIG. 6 shows a rear mission 19. The front mission input shaft 23 linked to the engine 17 via a double hook joint 22 is connected to the steering via a gear train 25. Universally connected to the input shaft 20a of the continuously variable transmission 20 and universal joints 26 and 26 provided between the front mission 18 and the rear mission 19 at the rear end of the input shaft 20a and the first interlocking shaft 27. Via the front end of the input shaft 21a of the continuously variable transmission 21 for traveling, the rear end of the input shaft 21a is capable of neutral and two-stage shifting with a power take-off clutch 29 provided in the rear mission 19. Are connected to a power take-off shaft 31 through a power take-off transmission 30 and a meshing reduction gear 30a.
[0010]
On the other hand, the output shaft 21b of the traveling continuously variable transmission 21 is linked to the rear mission output shaft 34 via the traveling clutch 32 and a sub-transmission unit 33 capable of neutral and three-speed shifting, and the rear mission output shaft. The front end of 34 is linked to the rear end of the front input shaft 36 pivotally supported on the rear surface of the front mission 18 via the universal joints 26 and 26 and the second interlocking shaft 35. And an intermediate shaft 39 that is pivotally supported between the left and right traveling unit drive shafts 38L and 38R via a traveling meshing bevel gear 37 formed in the above.
[0011]
The left and right traveling unit drive shafts 38L and 38R are connected to the left and right traveling units 1L and 1R via the left and right planetary gears 41L and 41R and the left and right cages 42L and 42R of the left and right planetary gear mechanisms 40L and 40R disposed on the left and right sides of the intermediate shaft 39, respectively. The left and right drive wheels 11L and 11R are connected to each other, and the left and right outer gears 43L and 43R of the left and right planetary gear mechanisms 40L and 40R are fitted to the left and right ends of the intermediate shaft 39, respectively.
[0012]
On the other hand, a steering driving bevel gear 45 is formed at the front end of the output shaft 20b of the steering continuously variable transmission 20, and the steering driving bevel gear 45 is fitted to the inner ends of the left and right steering shafts 46L and 46R. The left and right steering passive bevel gears 47L and 47R are meshed to form a differential gear mechanism 48, and the outer ends of the left and right steering shafts 46L and 46R and the left and right sun gears 49L of the left and right planetary gear mechanisms 40L and 40R, 49R and the left and right steering gears 50L and 50R are interlocked and connected to each other, and can be fitted to the splines 51L and 51R formed on the inner ends of the left and right steering shafts 46L and 46R and the splines 51L and 51R. A differential lock mechanism 51 comprising a sleeve 51a is provided to prevent the left and right steering shafts 46L and 46R from rotating. In FIG. 6, 52 is a brake.
[0013]
Next, the steering apparatus ST will be described with reference to FIGS.
[0014]
As shown in FIGS. 7 and 8, the steering device ST has a stay 54 that protrudes from the inner surface of the front side of the cabin 4, and is attached to a steering post 55 that is fixed to the rear end of the stay 54 in a tilted state of front and rear and rear height. The steering shaft 56 with the steering wheel 6 attached to the upper end is rotatably inserted, and the lower end of the steering shaft 56 is attached to the lower surface of the cabin 4 via the universal joints 26, 26 and the extension shaft 57. An operation input shaft 59 protruding from the upper surface of 58 is interlocked and connected.
[0015]
A steering acceleration / deceleration mechanism SA is provided inside the steering box 58 so that the rotational speed of the steering continuously variable transmission 20 is proportional to the operation amount of the steering wheel 6.
[0016]
As shown in FIGS. 9 to 11, the steering speed increasing / decreasing mechanism SA has a rack support shaft 60 in which a rack support shaft 60 is installed in the left-right direction in the steering box 58, and a rack 61 is attached to the front surface of the rack support shaft 60. The body 61a is slidably fitted to the left and right, and the rack 61 is engaged with a pinion 62 formed at the lower end of the operation input shaft 59, and the lower surface of the rack support 61a has a substantially U-shaped cross section. The center part of the tilting body 63 is pivotally pivoted in the left-right direction, and the operating pin projecting from the tip of the internal operating lever 65 connected to the inner end of the operating shaft 64 inserted through the bottom wall of the steering box 58 is provided. 66 is inserted into the opening of the tilting body 63 via a ball bearing 67, and an external operating lever 68 is connected to the outer end of the operating shaft 64. The external operating lever 68 and the connecting rod 69 are steered and shifted. Via the bar 70a is operatively connected to the steering gear shifting operation shaft 70 of the steering for a continuously variable transmission 20.
[0017]
Further, a screw 71 extending in the left-right direction is installed in the steering box 58, and a reverse seat biasing body 72 is externally fitted to the screw 71, and the reverse seat biasing body 72 is a cylindrical body fixed to the rack 61. The coil spring 74 is housed in 73, and both ends of the coil spring 74 are fixed to the inside by means of washers 75, 75 and retaining rings 76, 76 so as to be slidable in the inner direction and non-slidable in the outer direction. The reverse seat urging body 72 is supported by adjusting nuts 77 and 77 screwed to the outer positions of the washers 75 and 75.
[0018]
Further, by providing a forward / reverse switching mechanism SB in the steering box 58 and reversing the rotation direction of the steering continuously variable transmission 20 in conjunction with the forward / backward tilting of the forward / reverse transmission lever 8 to be described later, The body is turned in the turning direction of the steering wheel 6 regardless of the advance.
[0019]
The forward / reverse switching mechanism SB includes a tilting shaft 78 extending in the left-right direction so as to be rotatable, and a sliding body 80 is externally fitted to the tilting shaft 78 via a ball spline 79 so as to be slidable left and right. A downward extending portion 80a of 80 and the tilting body 63 are interlocked and connected via a connecting rod 81, and a tilting operation lever 82 is connected to the protruding end portion of the tilting shaft 78, and the tilting operation lever 82 is fixed to the fixed end. The operating end of the tilting hydraulic cylinder 83 pivotally attached to the body frame 2 and the reverse seat mechanism 84 for returning the tilting shaft 78 to the neutral position are interlocked and connected.
[0020]
Further, as shown in FIGS. 7 and 8, the forward / reverse speed change lever 8 is moved via a support shaft 86 inserted through the upper end portion of the forward / reverse speed change lever support body 85 erected on the right side of the seat 7 of the body frame 2. A forward / reverse transmission plate 87 having a substantially inverted T shape is connected to the support shaft 86 so as to freely tilt forward and backward, and a rear end of the forward / rearward transmission plate 87 is connected to a first forward / reverse transmission rod 88, a bell crank 88a, The second forward / reverse speed change rod 88 b and the travel speed operation lever 89 are linked to the travel speed operation shaft 90 of the continuously variable transmission 21 for travel.
[0021]
Further, a reverse seat mechanism 84 for returning the forward / reverse transmission lever 8 to the neutral position is connected to the front end of the forward / reverse transmission plate 87. The reverse seating mechanism 84 is configured in substantially the same manner as the reverse seat biasing body 72, and the cylinder side is fixed to the body frame 2 and the screw side is connected to the forward / reverse transmission plate 87. Is different.
[0022]
A forward / reverse detection sensor SE is linked to the forward / reverse transmission lever 8, and the forward / reverse detection sensor SE is provided with a switch support plate 91 at the upper end of the forward / reverse transmission lever support 85. When a forward switch 93 and a reverse switch 94 are attached to the switch support plate 91 and the forward / reverse transmission lever 8 is operated to the forward side, the forward end of the forward / reverse transmission plate 87 and the forward switch 93 come into contact to advance. When only the switch 93 is turned on and the forward / reverse transmission lever 8 is operated to the reverse side, the rear end portion of the forward / reverse transmission plate 87 and the reverse switch 94 come into contact with each other, and only the reverse switch 94 is turned on. Both switches 93, 94 are turned OFF, and each switch 93, 94 is connected to an electrohydraulic direction control valve 92 communicatively coupled to the tilting hydraulic cylinder 83. The detection output of 93 and 94 by switching the oil passage electromagnetic hydraulic directional control valve 92, so as to stretch activated tilt hydraulic cylinder 83.
[0023]
The embodiment of the present invention is configured as described above. Power is transmitted to the traveling continuously variable transmission 21 and the steering continuously variable transmission 20 by the engine 17, and the forward / reverse shift lever 8 is operated. Then, the continuously variable transmission 21 for traveling passes through the auxiliary transmission portion 33 of the rear mission 19 and the left and right planetary gear mechanisms 40L and 40R of the front mission 18 at a speed corresponding to the operation amount of the forward / reverse transmission lever 8. By driving the left and right drive wheels 11L, 11R of the traveling portions 1L, 1R, the agricultural tractor TR can be moved forward and backward at a speed corresponding to the operation amount of the forward / reverse shift lever 8.
[0024]
Further, by operating the auxiliary transmission unit 33 and changing the gear ratio, it is possible to cope with a wide range of traveling speeds within the efficient rotational speed range of the continuously variable transmission 21 for traveling.
[0025]
Further, when the steering continuously variable transmission 20 is operated by operating the steering wheel 6, the left and right sun gears 49L and 49R of the left and right planetary gear mechanisms 40L and 40R rotate in opposite directions due to the action of the differential gear mechanism 48. Therefore, the agricultural tractor TR can be turned by increasing or decreasing the rotational speeds of the left and right drive wheels 11L and 11R in a complementary manner.
[0026]
Next, the operation of the steering device ST will be described. When the steering wheel 6 is operated, the rack 61 engaged with the pinion 62 at the lower end of the steering shaft 56 slides in a direction corresponding to the operation direction of the steering wheel 6.
[0027]
At this time, one of the forward / reverse switches 93 and 94 is turned on by the operation direction of the forward / reverse shift lever 8 to operate the tilting hydraulic cylinder 83 via the electromagnetic hydraulic direction control valve 92, and the tilting shaft 78 and the ball spline are operated. 79, the tilting body 63 in the steering box 58 is tilted, so that the operating pin 66 inserted into the opening of the tilting body 63 has a trajectory substantially perpendicular to the movement trajectory of the rack 61 and the steering. It moves by an amount corresponding to the operation amount of the wheel 6, and moves to the steering shift operation shaft 70 of the steering continuously variable transmission 20 via the internal operation lever 65, the operation shaft 64, the external operation lever 68 and the connecting rod 69. Steering continuously variable transmission at a rotational speed corresponding to the operation amount of the steering wheel 6 from the variable displacement hydraulic pump that has been transmitted and was neutral until then and the discharge amount was zero The machine 20 outputs and rotates the left and right sun gears 49 L, 49 R of the left and right planetary gear mechanisms 40 L, 40 R via the differential gear mechanism 48.
[0028]
In this way, the steering wheel 6 is operated to the steering shift operation shaft 70 of the steering continuously variable transmission 20 via the tilting body 63 that changes the tilting direction according to the operation direction of the forward / reverse shift lever 8. By transmitting, the agricultural tractor TR can be turned in the same direction as the turning direction of the steering wheel 6 regardless of the forward / backward movement of the agricultural tractor TR.
[0029]
If the steering wheel 6 is linked to the steering speed change operation shaft 70 of the steering continuously variable transmission without using the tilting body 63, the turning direction of the steering wheel 6 in either case of forward / reverse travel. And the turning direction of the agricultural tractor TR is reversed, and the steering operation becomes extremely difficult.
[0030]
Further, when the forward / reverse shift lever 8 is in a neutral state, that is, when the aircraft is stopped, both the forward / reverse switches 93 and 94 of the forward / reverse detection sensor SE do not output, so the hydraulic pressure in the tilting hydraulic cylinder 83 is reduced. The tilting shaft 78 is returned to the neutral position by the reverse seating mechanism 84. In this state, since the tilting body 63 is not tilted forward or backward, the operating pin 66 holds the neutral position even when the steering wheel 6 is rotated, so that the steering continuously variable transmission 20 is stopped. The state is maintained, and therefore the aircraft is not turned.
[0031]
Further, the right and left sun gears 49L and 49R are fixed by the differential lock mechanism 51 of the differential gear mechanism 48 and the rotation speeds of the left and right drive wheels 11L and 11R are made the same, thereby improving the straightness of the agricultural tractor TR. be able to.
[0032]
【The invention's effect】
According to the present invention, the following effects can be obtained.
[0033]
That is, according to the present invention, the driving continuously variable transmission is linked to the engine, the drive shafts of the left and right traveling parts are linked to the driving continuously variable transmission, and the driving shafts are connected to the driving continuously variable transmission. The steering continuously variable transmission is linked to the engine, and the drive shafts of the left and right traveling parts are linked to the steering continuously variable transmission. An agricultural tractor that can be driven in a reverse rotation direction by a steering continuously variable transmission and that can increase / decrease the speed of the vehicle by turning the speed of each drive shaft with both transmissions. Is linked to the steering continuously variable transmission via the steering speed increase / decrease mechanism, while the forward / reverse shift lever is linked to the traveling continuously variable transmission, and the forward / reverse operation of the forward / reverse shift lever is operated. A forward / reverse switching mechanism linked to the Is matched with the turning direction of the turning direction and the fuselage of the A ring wheel, moreover, it is disposed and the forward-reverse switching mechanism the acceleration and deceleration mechanism for steering the interior of the steering gear box.
[0034]
Accordingly, the rotational direction of the left and right traveling parts is driven by the traveling transmission, for example, in the state of being driven to rotate forward and the aircraft is traveling forward, and the rotational direction of the left traveling part is controlled by the continuously variable transmission for steering, for example. When the right traveling unit is driven to rotate in the forward direction and the rotational direction of the right traveling unit is rotated in the reverse direction, the left traveling unit is driven to increase the speed by both transmissions, and the right traveling unit is driven to decelerate by both transmissions to smoothly The aircraft can be turned to the right.
[0035]
At this time, since the left and right traveling units can be complementarily increased / decreased by both transmissions during the turning operation of the airframe, the airframe can smoothly turn from a slow turn to a sudden turn, Generation | occurrence | production of the malfunction of damaging a farm field by a traveling part can be prevented.
[0036]
And it is possible to control the turning of the aircraft with a single steering wheel, and the operation is easy, and the problems caused by the unevenness and backlash of the left and right operation mechanism described above are eliminated, so the straightness is improved, Further, since the steering wheel can perform a delicate steering operation, the airframe can be smoothly turned with an arbitrary turning radius.
[0037]
In addition, a forward / reverse switching mechanism that interlocks with forward / reverse operation of the forward / reverse speed change lever is provided so that the turning direction of the steering wheel coincides with the turning direction of the machine body.
[0038]
In this way, by making the turning direction of the steering wheel coincide with the turning direction of the airframe, the steering wheel can be turned in the direction in which it wants to turn regardless of the forward / backward direction of the airframe. It becomes easy and can increase safety.
[Brief description of the drawings]
FIG. 1 is an overall side view of an agricultural tractor provided with a traveling unit driving device according to the present invention.
FIG. 2 is a schematic plan view showing a schematic configuration of the traveling unit driving device.
FIG. 3 is a plan view showing a configuration of the traveling unit driving device.
FIG. 4 is a partial cross-sectional side view showing a configuration of a front mission.
FIG. 5 is a partial cross-sectional plan view showing a configuration of a front mission.
FIG. 6 is a partial cross-sectional side view showing a configuration of a rear mission.
FIG. 7 is a side view of the steering device.
FIG. 8 is a front view of the steering device.
FIG. 9 is a cross-sectional side view of a steering gear box.
FIG. 10 is a cross-sectional front view of a steering gear box.
FIG. 11 is a cross-sectional plan view of a steering gear box.
[Explanation of symbols]
DR Traveling drive device SA Steering acceleration / deceleration mechanism SB Forward / reverse switching mechanism SE Forward / reverse detection sensor 1L, 1R Left / right traveling unit 6 Steering wheel 8 Forward / reverse shifting lever 20 Steering continuously variable transmission 21 Traveling continuously variable transmission 58 Steering box

Claims

The driving continuously variable transmission (21) is linked to the engine (17), and the drive shafts (38L) (38R) of the left and right traveling parts (1L) (1R) are connected to the continuously variable transmission (21). The drive shafts (38L) and (38R) are driven in the same rotational direction by the traveling continuously variable transmission (21) while being linked to each other, while the engine (17) is driven by the continuously variable transmission (20). Are linked to each other, and the drive shafts (38L) (38R) of the left and right traveling parts (1L) (1R) are linked to the continuously variable transmission (20) for the same steering, so that each drive shaft (38L) (38R ) Are driven in the reverse rotation direction by the steering continuously variable transmission (20), and the rotational speed of each drive shaft (38L) (38R) is increased or decreased by both transmissions (21) (20). Agricultural tractor (B) capable of turning and decelerating
While the steering wheel (6) is linked to the steering continuously variable transmission (20) via the steering acceleration / deceleration mechanism (SA),
The forward / reverse transmission lever (8) is linked to the continuously variable transmission (21) for driving, and a forward / reverse switching mechanism (SB) is provided that is linked to the forward / reverse operation of the forward / reverse transmission lever (8). By the same forward / reverse switching mechanism (SB), the turning direction of the steering wheel (6) and the turning direction of the fuselage are matched ,
In addition, the steering tractor steering apparatus according to claim 1 , wherein the steering acceleration / deceleration mechanism (SA) and the forward / reverse switching mechanism (SB) are arranged in a steering gear box (58) .