JP3571443B2

JP3571443B2 - Work vehicle support leg interlock device

Info

Publication number: JP3571443B2
Application number: JP00149396A
Authority: JP
Inventors: 健一速水; 大二郎佐野
Original assignee: Shinmaywa Industries Ltd
Current assignee: Shinmaywa Industries Ltd
Priority date: 1996-01-09
Filing date: 1996-01-09
Publication date: 2004-09-29
Anticipated expiration: 2016-01-09
Also published as: JPH09188230A

Description

【０００１】
【発明の属する技術分野】
本発明は、高所で作業を行うブームなどの作業装置を装着した車台を前輪および後輪に代わって伸長時に支持する支持脚を備えた作業車の支持脚インタロック装置に関するものである。
【０００２】
【従来の技術】
一般に、ブーム先端のバケットにより高所で作業を行う作業装置などを車台に装着した作業車においては、この車台の前後に、それぞれ伸長時に該車台を前輪および後輪に代わって支持する伸縮自在なジャッキなどからなる左右一対の支持脚が設けられている。上記後輪は、上記前輪が車台に制動力を作用させないフリーな車輪に構成されているのに対し、車台に制動力を作用させる制動輪に構成されており、前側の支持脚の伸長時に前輪が、後側の支持脚の伸長時に後輪がそれぞれ持ち上げられて、高所での作業が安定した状態で行われるようにしている。この場合、各支持脚は、その伸縮動作が前後いずれからでも任意に行えるようになっている。
【０００３】
【発明が解決しようとする課題】
ところが、上記作業車は、各支持脚の伸縮動作時に後輪の制動力のみにより停止状態に保たれるので、その作業車を停止させた接地面が作業車の進退方向に傾斜している場合などには、制動輪（後輪）の制動力を接地面に対して確実に作用させる必要がある。しかし、各支持脚は前後いずれからでも伸縮動作が行えるようになっているため、前後の支持脚を伸縮動作させる順番が不適切であると、制動輪の制動力を利用できないことがある。つまり、各支持脚の伸縮動作の順番を誤ると、制動輪を持ち上げている後側の支持脚と、フリーな前輪とによって車台が一時的に支持されることがあり、これでは、車台を停止させるに必要な制動力が不十分となり、作業車が接地面の傾斜方向に移動するといった欠点がある。
【０００４】
本発明はかかる点に鑑みてなされたもので、その目的とするところは、前後の支持脚を制動輪による制動力が効率良く得られる順番で伸縮動作させるようにすることで、支持脚の伸縮動作時における作業車の移動を確実に防止することにある。
【０００５】
【課題を解決するための手段】
上記目的を達成するため、請求項１記載の発明が講じた解決手段は、作業車の支持脚インタロック装置として、作業装置が装着された車台の前後に、それぞれ伸長時に該車台を前輪および後輪に代わって支持する伸縮自在な左右一対の支持脚が設けられ、上記車台は、後輪の制動力により停止するように構成されており、上記前側の支持脚の伸長時に前輪が、上記後側の支持脚の伸長時に後輪がそれぞれ持ち上げられるようにした作業車を前提とする。そして、上記前側の支持脚により前輪が持ち上げられていることを検出する前輪持ち上げ状態検出手段と、該前輪持ち上げ状態検出手段からの信号を受け、前側の左右の支持脚のうちの少なくとも一方により前輪が持ち上げられているときにのみ上記後側の支持脚の伸長動作を許容する伸長動作許容手段とを設ける。さらに、上記前輪持ち上げ状態検出手段は、前側の支持脚の伸縮量を検出する伸縮量検出手段と、前側の支持脚が接地面に対して接地したことを検出する接地状態検出手段とを備え、これら両検出手段の検出信号によって前輪の持ち上げ状態を検出するようになっている構成としたものである。
【０００６】
この構成により、請求項１記載の発明では、各車輪を持ち上げて車台を接地面に対して支持脚により支持する場合、先ず、前側の左右の支持脚のうちの少なくとも一方により前輪を持ち上げ、この前側の少なくとも一方の支持脚による制動力と、後輪（制動輪）による制動力との車台前後両側の制動力によって作業車が停止状態に保たれる。その後、制動輪に代わって後側の支持脚による車台後側の支持がなされるが、この後側の支持脚の伸長時にはフリーな前輪に代わる前側の少なくとも一方の支持脚の制動力により車台は停止状態に保たれることから、各支持脚の接地面が作業車の進退方向に傾斜していても作業車が移動することはない。しかも、後側の支持脚の伸長動作が、前側の少なくとも一方の支持脚により前輪が持ち上げられているときにのみ許容されることから、前後の支持脚を伸長動作させる順番を誤ることはない。さらに、前側の支持脚の伸長量および接地面への接地との両検出信号によって前輪の持ち上げ状態が検出され、前側の支持脚が不十分な伸長量で接地面上の石などの障害物に接地していたり、十分に伸長しているにも拘らず接地面の凹部に入り込んで接地していない等の前側の支持脚の一方の検出信号のみによる前輪持ち上げ状態の誤検出が確実に防止されるとともに、傾斜する接地面上での各支持脚の伸長動作時における作業車の移動がより確実に防止される。
【０００７】
請求項２記載の発明が講じた解決手段は、請求項１記載の発明の構成要件に加えて、後側の支持脚により後輪が持ち上げられていることを検出する後輪持ち上げ状態検出手段と、前輪持ち上げ状態検出手段および後輪持ち上げ状態検出手段からの信号を受け、前側の少なくとも一方の支持脚により前輪が持ち上げられているときでかつ後側の支持脚により後輪が持ち上げられていないときに前側の支持脚の収縮動作を許容する収縮動作許容手段とを設ける構成としたものである。
【０００８】
この構成により、請求項２記載の発明では、各支持脚による車台の支持を解除して各車輪を接地面に降す場合、先ず、後側の支持脚を収縮させて制動輪を接地面に降し、この制動輪の制動力と、前側の支持脚による制動力との車台前後両側からの制動力によって作業車を停止させておく。その後、前側の支持脚に代わって前輪が接地面に降されるが、この前側の支持脚の収縮動作は、前側の支持脚により前輪が持ち上げられているときでかつ後側の支持脚により後輪が持ち上げられていないとき、つまり先に制動輪が接地して制動輪の制動力により車台を停止させているときに許容されることから、各支持脚の接地面が作業車の進退方向に傾斜していても、制動輪の制動力が十分に作用している状態で前側の支持脚の収縮動作が行われ、前側の支持脚の収縮時に作業車が移動することはない。しかも、前側の支持脚の収縮動作が、制動輪が接地しているときにのみ許容されて、前後の支持脚の収縮動作の順番を誤ることはない。これによって、前後の支持脚は、制動輪による制動力が効率良く得られる順番で伸縮動作され、支持脚の伸縮動作時における作業車の移動が確実に防止される。
【０００９】
【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いて説明する。
【００１０】
図４は作業車を示し、１は作業車Ａの車体、２はこの車体１に起伏、旋回可能に設置された作業装置としてのブーム、３は高所作業時に上記車体１を浮上状態に支持する支持脚としてのジャッキである。
【００１１】
上記車体１は車台１ｃと、該車台１ｃ上に設けられた荷台１ａと、上記車台１ｃに一体的に連結された車室部１ｂとからなり、この車体１は前後に一対ずつの前輪４ａおよび後輪４ｂを備え、前輪４ａがフリーな従動輪とされ、後輪４ｂが走行時の駆動輪とされ、また、この後輪４ｂが、車体１の停車時にハンドブレーキ（図示せず）の操作により制動力が作用する制動輪に構成されている。また、上記ブーム２は、上記車台１ｃに垂直軸Ｖ回りに回転可能に支持された旋回支柱２ａと、この旋回支柱２ａの上端に水平軸Ｈ回りに回転可能に連結されるとともに、起伏用シリンダ２ｂにより起伏可能に連結された伸縮管２ｃと、この伸縮管２ｃの先端に設けられた作業用バケット２ｄとからなり、上記バケット２ｄに作業者が乗って上記起伏用シリンダ２ｂを伸長作動させることにより、そのバケット２ｄが上記車台１ｃに対して相対的に上昇するようになっている。
【００１２】
上記ジャッキ３は、車台１ｃ前側（前輪４ａの直後方）に設けられた左右一対の前側ジャッキ３ａと、車台１ｃ後側（後輪４ｂの直後方）に設けられた左右一対の後側ジャッキ３ｂとからなる。
【００１３】
上記前側および後側ジャッキ３ａ，３ｂは、図２および図３にも示すように、上記車台１ｃに対して鉛直線方向に伸縮自在なジャッキ部５により構成されている。該ジャッキ部５は、上記車台１ｃに固定した有底四角筒状の外筒５ａと、この外筒５ａ内に摺動可能に挿入された四角筒状の内筒５ｂと、一端がこの内筒５ｂの下端に、他端が上記外筒５ａの上端にそれぞれ連結されたシリンダ５ｃと、上記内筒５ｂの下端に車体１左右方向向きに略水平に延びるピン部材５ｄを介して揺動自在に支持されたブラケット５ｅと、該ブラケット５ｅの下端に固定され、下面が接地面Ｓに当接（接地）する水平板状の当接片５ｆとを備えている。上記シリンダ５ｃは、圧油によって伸縮する油圧シリンダに構成されている。また、上記ジャッキ部５のシリンダ５ｃの上端には、車体１左右方向向きに互いに対向する左右の対向片を有する断面略コ字状のコ字状ブラケット６が設けられており、該コ字状ブラケット６は、その底部が外筒５ａの後面より後方に位置するように設けられている。このコ字状ブラケット６の左右両対向片先端（反底部側）には、外筒５ａの左右両辺の上端間に取り付けられたピン７に対して遊嵌状態で嵌合する円形状の孔部６ａ，６ａが設けられ、シリンダ５ｃは、その自重により各孔部６ａの周方向上端部が外筒５ａのピン７の周方向上端部に当接した状態で、該各孔部６ａの半径方向に移動可能な間隙を存して支持されている。そして、この各ジャッキ部５では、上記シリンダ５ｃの伸長動作により上記内筒５ｂが外筒５ａから突出し当接片５ｆが接地面Ｓに当接してから下方に押し下げられて車体１を浮上させる張出し状態（図４に一点鎖線で示す状態）にされ、収縮動作により上記内筒５ｂが上記外筒５ａ内に没入して車輪（前輪４ａおよび後輪４ｂ）が接地面Ｓに接地した格納状態（同図に実線で示す状態）にされるようになっている。なお、図２ないし図４には車体左側のジャッキ部５のみを示すが、車体右側のものも上記左側のそれと同様に構成されている。
【００１４】
この場合、前側ジャッキ３ａおよび後側ジャッキ３ｂのジャッキ部５の伸長動作は、図示しない前側および後側ジャッキ張出しスイッチのＯＦＦ位置からＯＮ位置への切り換えにより行われるようになっており、前側ジャッキ３ａのジャッキ部５の伸長時に前輪４ａが、上記後側ジャッキ３ｂのジャッキ部５の伸長時に後輪４ｂがそれぞれ個別に持ち上げられるようになっている。また、前側ジャッキ３ａおよび後側ジャッキ３ｂのジャッキ部５の収縮動作も、図示しない前側および後側ジャッキ格納スイッチのＯＦＦ位置からＯＮ位置への切り換えにより行われるようになっている。
【００１５】
そして、図１に示すように、上記前側ジャッキ３ａのジャッキ部５には、該ジャッキ部５により前輪４ａが持ち上げられていることを検出する前輪持ち上げ状態検出手段１１が設けられている。この前輪持ち上げ状態検出手段１１からの信号は、前側および後側ジャッキ３ａ，３ｂのジャッキ部５のシリンダ５ｃの伸縮動作を順番通りに行わせる支持脚インタロック装置としてのジャッキインタロック回路１２に入力され、このジャッキインタロック回路１２には、前側ジャッキ３ａの左右のジャッキ部５のうちの少なくとも一方（右側又は左側）により前輪４ａが持ち上げられているときに上記後側ジャッキ３ｂのジャッキ部５の伸長動作を許容する伸長動作許容手段としての伸長動作許容回路１３が設けられている。本発明の特徴部分として、上記前輪持ち上げ状態検出手段１１は、左右の前側ジャッキ３ａ（ジャッキ部５）のシリンダ５ｃの伸縮量を左右個別に検出する左前側および右前側伸縮量検出手段１４Ｌ，１４Ｒと、左右の前側ジャッキ３ａのジャッキ部５の当接片５ｆが接地面Ｓに対して接地（当接）したことを左右個別に検出する左前側および右前側接地状態検出手段１５Ｌ，１５Ｒ（接地状態検出手段）とにより構成されている。また、上記伸長動作許容回路１３は、上記左前側および右前側伸縮量検出手段１４Ｌ，１４Ｒからの出力信号、つまり検出条件を満たす信号（後述するリミットスイッチ２１ｃからの検出位置ａ信号）“１”又は検出条件を満たさない信号（後述のリミットスイッチ２１ｃからの非検出位置ｂ信号）“０”を入力する第１オア回路１３ａと、上記左前側および右前側接地状態検出手段１５Ｌ，１５Ｒからの出力信号、つまり検出条件を満たす信号（後述するリミットスイッチ２３ｄからのＯＦＦ信号）“１”又は検出条件を満たさない信号（後述のリミットスイッチ２３ｄからのＯＮ信号）“０”を入力する第１アンド回路１３ｂと、上記第１オア回路１３ａおよび第１アンド回路１３ｂからの出力信号を入力し、該両回路１３ａ，１３ｂの出力信号が共に“１”であるときのみ信号を出力する第２アンド回路１３ｃとからなり、この第２アンド回路１３ｃからの出力信号は、後側ジャッキ３ｂ（ジャッキ部５）のシリンダ５ｃを伸長させる指令信号として後側ジャッキ３ｂのシリンダ伸縮用油圧切換弁（図示せず）に出力され、この油圧切換弁が後側ジャッキ３ｂを伸長させる伸長位置に切換えられる。つまり、第２アンド回路１３ｃからの指令信号は、後側ジャッキ張出しスイッチのＯＮ位置への切換えにより、伸長動作許容回路１３の各回路１３ａ〜１３ｃの検出条件が全て満たされて左右の前側ジャッキ３ａのうちの一方のジャッキ部５により前輪４ａが持ち上げられているときにのみ後側ジャッキ３ｂのシリンダ伸縮用油圧切換弁に出力され、該伸長動作許容回路１３の各回路１３ａ〜１３ｃの検出条件を全て満たしていないとき（前輪４ａが持ち上げられていないとき）には後側ジャッキ３ｂのシリンダ伸縮用油圧切換弁に指令信号が出力されないようになっている。この場合、前側ジャッキ３ａのシリンダ５ｃを伸長させる指令信号は、前側ジャッキ張出しスイッチのＯＮ位置への切り換えと同時にジャッキインタロック回路１２を迂回する迂回回路（図示せず）を介して前側ジャッキ３ａのシリンダ伸縮用油圧切換弁（図示せず）にダイレクトに出力され、この油圧切換弁が伸長位置に切換えられる。
【００１６】
一方、上記後側ジャッキ３ｂのジャッキ部５には、該ジャッキ部５により後輪４ｂが持ち上げられていることを検出する後輪持ち上げ状態検出手段１６が設けられている。この後輪持ち上げ状態検出手段１６からの信号は、上記ジャッキインタロック回路１２に入力されるようになっており、該ジャッキインタロック回路１２には、後輪４ｂのみが接地面Ｓに接地しているとき、つまり前側ジャッキ３ａのジャッキ部５により前輪４ａが持ち上げられているときでかつ後側ジャッキ３ｂのジャッキ部５により後輪４ｂが左右共に持ち上げられていないときに、前側ジャッキ３ａ（ジャッキ部５）のシリンダ５ｃの収縮動作を許容する収縮動作許容手段としての収縮動作許容回路１７が設けられている。上記後輪持ち上げ状態検出手段１６は、左右の後側ジャッキ３ｂのジャッキ部５の当接片５ｆが接地面Ｓに対して接地したことを左右個別に検出する左後側および右後側接地状態検出手段１８Ｌ，１８Ｒにより構成されている。また、上記収縮動作許容回路１７は、上記左後側および右後側接地状態検出手段１８Ｌ，１８Ｒからの出力信号、つまり検出条件を満たす信号“１”又は検出条件を満たさない信号“０”を入力する第２オア回路１７ａと、該第２オア回路１７ａからの出力信号“１”又は“０”を入力するノット回路１７ｂと、上記第２オア回路１７ａの出力信号および上記第２アンド回路１３ｃからの出力信号“１”又は“０”を入力する第３アンド回路１７ｃと、該第３アンド回路１７ｃの出力信号および上記ノット回路１７ｂの出力信号“１”又は“０”を入力する第３オア回路１７ｄとからなり、この第３オア回路１７ｄからの出力信号は、前側ジャッキ３ａ（ジャッキ部５）のシリンダ５ｃを収縮させる指令信号として前側ジャッキ３ａのシリンダ伸縮用油圧切換弁に出力され、この油圧切換弁が前側ジャッキ３ａを収縮させる収縮位置に切換えられる。つまり、第３オア回路１７ｄからの指令信号は、前側ジャッキ格納スイッチのＯＮ位置への切換えにより、収縮動作許容回路１７の各回路１７ａ〜１７ｄの検出条件が全て満たされて左右の前側ジャッキ３ａのうちの一方のジャッキ部５により前輪４ａが持ち上げられているときでかつ左右の後側ジャッキ３ｂのジャッキ部５により後輪４ｂが持ち上げられていないときにのみ前側ジャッキ３ａのシリンダ伸縮用油圧切換弁に出力され、該収縮動作許容回路１７の各回路１７ａ〜１７ｄの検出条件を全て満たしていないとき（前輪４ａが持ち上げられていないときでかつ左右の後輪４ｂのうちの一方が持ち上げられているとき）には後側ジャッキ３ｂのシリンダ伸縮用油圧切換弁に指令信号が出力されないようになっている。この場合、後側ジャッキ３ａのシリンダ５ｃを収縮させる指令信号は、後側ジャッキ格納スイッチのＯＮ位置への切り換えと同時にインタロック回路１２を迂回する迂回回路（図示せず）を介して後側ジャッキ３ｂのシリンダ伸縮用油圧切換弁にダイレクトに出力され、該油圧切換弁が収縮位置に切換えられる。
【００１７】
上記左前側および右前側伸縮量検出手段１４Ｌ，１４Ｒは、内筒５ｂの一辺上端より外方（外筒５ａの一辺側）に突出する突片２１ａと、外筒５ａの一辺中央下部位置寄りにピン軸２１ｂ回りに揺動自在に取り付けられ、該突片２１ａとの当接により検出位置ａと非検出位置ｂとに切換わるリミットスイッチ２１ｃとからなり、シリンダ５ｃが最伸長位置付近まで伸長したときにリミットスイッチ２１ｃが検出位置ａに切換わって前側ジャッキ３ａの伸長状態が、シリンダ５ｃが最伸長位置から収縮したときにリミットスイッチ２１ｃが非検出位置ｂに切換わって前側ジャッキ３ａの収縮状態がそれぞれ検出されるようになっている。また、上記左前側および右前側接地状態検出手段１５Ｌ，１５Ｒ（同一構成となるので、左後側および右後側接地状態検出手段１８Ｌ，１８Ｒについては符号のみを付してその説明は省略する）は、シリンダ５ｃ上端のコ字状ブラケット６の底部にステー２３ｂを介して取り付けられたボルト状部材２３ｃと、該ボルト状部材２３ｃの脚部先端に対応する外筒５ａの上端部にブラケット２３ａを介して取り付けられ、該ボルト状部材２３ｃの脚部先端との接触または非接触によりＯＮ／ＯＦＦ位置に切換わるリミットスイッチ２３ｄとからなり、シリンダ５ｃの伸長により当接片５ｆが接地面Ｓに接地してシリンダ５ｃ上端のコ字状ブラケット６の各孔部６ａの周方向下端部がその自重に抗して外筒５ａのピン７の周方向下端部に当接したときにボルト状部材２３ｃの脚部先端とリミットスイッチ２３ｄとが離れて非接触となるＯＦＦ位置への切換えによって前側ジャッキ３ａ（後側ジャッキ３ｂ）の接地状態が、シリンダ５ｃの収縮により当接片５ｆが接地面Ｓから離れてコ字状ブラケット６の各孔部６ａの周方向上端部がその自重により外筒５ａのピン７の周方向上端部に当接したときにボルト状部材２３ｃの脚部先端とリミットスイッチ２３ｄとが接触するＯＮ位置への切換えによって前側ジャッキ３ａ（後側ジャッキ３ｂ）の非接地状態がそれぞれ検出されるようになっている。この場合、前側ジャッキ３ａの伸長時における左前側および右前側伸縮量検出手段１４Ｌ，１４Ｒの伸長状態の検出つまりリミットスイッチ２１ｃの検出位置ａへの切換えは、左前側および右前側接地状態検出手段１５Ｌ，１５Ｒ（左後側および右後側接地状態検出手段１８Ｌ，１８Ｒ）のボルト状部材２３ｃとリミットスイッチ２３ｄとが非接触（ＯＦＦ位置）となる接地状態の検出後に行われる一方、前側ジャッキ３ａの収縮時における左前側および右前側伸縮量検出手段１４Ｌ，１４Ｒの収縮状態の検出つまりリミットスイッチ２１ｃの非検出位置ｂへの切換えは、左前側および右前側接地状態検出手段１５Ｌ，１５Ｒのボルト状部材２３ｃとリミットスイッチ２３ｄとが接触（ＯＮ位置）となる非接地状態の検出前に先行して行われる。
【００１８】
次に、上記作業車Ａのジャッキインタロック回路１２による前側および後側ジャッキ３ａ，３ｂの伸縮動作を図１の電気回路図に基づいて説明する。
【００１９】
先ず、ブーム２により高所作業を行う場合、高所作業を行う場所に作業車Ａを停止させ、ハンドブレーキにより後輪４ｂを制動させた後、前側ジャッキ張出しスイッチをＯＮ位置に切り換える。すると、迂回回路を介して前側ジャッキ３ａ（ジャッキ部５）のシリンダ５ｃを伸長させる指令信号が前側ジャッキ３ａのシリンダ伸縮用油圧切換弁に出力されて該油圧切換弁が伸長位置に切換わり、前側ジャッキ３ａが伸長する。このとき、後側ジャッキ張出しスイッチを誤ってＯＮ位置に切り換えても、左前側および右前側伸縮量検出手段１４Ｌ，１４Ｒからの出力信号並びに左前側および右前側接地状態検出手段１５Ｌ，１５Ｒからの出力信号が全て“０”となって前輪４ａが持ち上げられていないので、ジャッキインタロック回路１２の各回路には信号が流れず、後側ジャッキ３ｂの伸長動作が行われることはない。そして、この前側ジャッキ３ａの伸長動作は、前側ジャッキ３ａの伸長動作が左前側および右前側伸縮量検出手段１４Ｌ，１４Ｒからの出力信号のうちのいずれか一方が“１”で、かつ左前側および右前側接地状態検出手段１５Ｌ，１５Ｒからの出力信号が共に“１”となるときに、左右の前側ジャッキ３ａのうちの少なくとも一方により前輪４ａが持ち上げられていることが前輪持ち上げ状態検出手段１１により検出される。次いで、この左右の前側ジャッキ３ａのうちの少なくとも一方により前輪４ａが持ち上げられた状態で、上記前側ジャッキ張出しスイッチをＯＦＦ位置に切り換えた後、後側ジャッキ張出しスイッチをＯＮ位置に切り換えると、第２アンド回路１３ｃからの指令信号“１”が後側ジャッキ３ｂのシリンダ伸縮用油圧切換弁に出力されて該油圧切換弁が伸長位置に切換わり、後側ジャッキ３ｂのシリンダ５ｃが伸長して、前後のジャッキ３ａ，３ｂによる車台１ｃの支持が完了する。その後、後側ジャッキ張出しスイッチをＯＦＦ位置に切り換える。
【００２０】
これにより、各車輪４ａ，４ｂを持ち上げて車台１ｃを接地面Ｓに対してジャッキ３により支持する場合には、前側ジャッキ３ａのうちの少なくとも一方により前輪４ａを持ち上げて、前側の少なくとも一方のジャッキ３ａによる制動力と、後輪４ｂ（制動輪）による制動力との車台１ｃ前後両側の制動力によって作業車Ａを停止状態に保った後、制動輪に代わって後側ジャッキ３ｂによる車台１ｃ後側の支持がなされるが、この後側ジャッキ４ａの伸長時にはフリーな前輪４ａに代わる前側の少なくとも一方のジャッキ３ａの制動力により車台１ｃは停止状態に保たれることから、ジャッキ３の接地面Ｓが作業車Ａの進退方向に傾斜していても作業車Ａが移動することがなく、ジャッキ３の伸長動作時における作業車Ａの移動を確実に防止することができる。しかも、後側ジャッキ３ｂの伸長動作が、前側の少なくとも一方のジャッキ３ａにより前輪４ａが持ち上げられているときにのみ許容されることから、前側ジャッキ張出しスイッチよりも先に後側ジャッキ張出しスイッチをＯＮ位置に切換えて前後のジャッキ３ａ，３ｂを伸長動作させる順番を誤ったとしても、後側ジャッキ３ｂが前側ジャッキ３ａに先行して伸長動作することはなく、前後のジャッキ３ａ，３ｂの伸長動作時の誤動作を確実に防止することができる。
【００２１】
一方、前後のジャッキ３ａ，３ｂを格納して作業車Ａを走行状態に戻す場合、後側ジャッキ格納スイッチをＯＮ位置に切り換えると、迂回回路を介した後側ジャッキ３ｂのシリンダ伸縮用油圧切換弁を収縮位置に切り替える指令信号により後側ジャッキ３ｂが収縮し始める。このとき、前側ジャッキ格納スイッチを誤ってＯＮ位置に切り換えると、ジャッキインタロック回路１２の各回路にも信号が流れて前側ジャッキ３ａの伸縮用油圧切換弁を収縮位置に切換える指令信号が出力されて前側ジャッキ３ａが収縮し始めるが、この前側ジャッキ３ａの収縮動作は、左前側および右前側伸縮量検出手段１４Ｌ，１４Ｒからの出力信号のうちのいずれか一方が“１”から“０”に切換わることで停止する。そして、後側ジャッキ３ｂの収縮動作に伴い後輪４ｂが左右共に接地面Ｓに接地すると、左後側および右後側伸縮量検出手段１８Ｌ，１８Ｒからの出力信号が共に“０”となって左後側および右後側接地状態検出手段１８Ｌ，１８Ｒによる左右の後側ジャッキ３ｂの非接地状態が検出される。次いで、この後輪４ｂが左右共に接地面Ｓに接地したとき、つまり前側の少なくとも一方のジャッキ３ａにより前輪４ａが持ち上げられているときでかつ後側ジャッキ３ｂにより後輪４ｂが持ち上げられていないときに、上記後側ジャッキ格納スイッチをＯＦＦ位置に切り換えた後、前側ジャッキ格納スイッチをＯＮ位置に切り換えると、第３オア回路１７ｄからの指令信号“１”が前側ジャッキ３ａのシリンダ伸縮用油圧切換弁に出力されて該油圧切換弁が収縮位置に切換わり、前側ジャッキ３ａのシリンダ５ｃが収縮して、前後のジャッキ３ａ，３ｂが格納され、前後輪４ａ，４ｂによる車台１ｃの支持が完了する。その後、ジャッキ収縮スイッチをＯＦＦ位置に切り換える。
【００２２】
これにより、ジャッキ３による車台１ｃの支持を解除して前後輪４ａ，４ｂを接地面Ｓに降す場合には、後側ジャッキ３ｂを収縮させて制動輪（後輪４ｂ）を接地面Ｓに降し、この制動輪の制動力と、前側ジャッキ３ａによる制動力との車台１ｃ前後両側からの制動力によって作業車Ａを停止させておいた後、前側ジャッキ３ａに代わって前輪４ａが接地面Ｓに降されるが、この前側ジャッキ３ａの収縮動作は、前側ジャッキ３ａにより前輪４ａが持ち上げられているときでかつ後側ジャッキ３ｂにより後輪４ｂが持ち上げられていないとき、つまり先に制動輪が接地して制動輪の制動力により車台１ｃを停止させているときに許容されることから、ジャッキ３の接地面Ｓが作業車Ａの進退方向に傾斜していても、制動輪の制動力が十分に作用している状態で前側ジャッキ３ａの収縮動作が行われ、前側ジャッキ３ａの収縮時に作業車Ａが移動することがなく、ジャッキ３の収縮動作時における作業車Ａの移動を確実に防止することができる。しかも、前側ジャッキ３ａの収縮動作が、制動輪が接地しているときにのみ許容されることから、後側ジャッキ張出しスイッチよりも先に前側ジャッキ張出しスイッチをＯＮ位置に切換えて前後のジャッキ３ａ，３ｂを収縮動作させる順番を誤ったとしても、左前側および右前側伸縮量検出手段１４Ｌ，１４Ｒからの出力信号のうちのいずれか一方が“１”から“０”に切換わった時点（左前側および右前側接地状態検出手段１５Ｌ，１５Ｒからの出力信号が“１”に保持されて前側ジャッキ３ａによる支持が行われている状態）で前側ジャッキ３ａの収縮動作が停止し、該前側ジャッキ３ａが後側ジャッキ３ｂに先行して収縮動作することはなく、前後のジャッキ３ａ，３ｂの収縮動作時の誤動作を確実に防止することができる。
【００２３】
また、前輪持ち上げ状態検出手段１１が、左右の前側ジャッキ３ａの伸縮量を左右個別に検出する左前側および右前側伸縮量検出手段１４Ｌ，１４Ｒと、左右の前側ジャッキ３ａが接地面Ｓに対して接地したことを左右個別に検出する左前側および右前側接地状態検出手段１５Ｌ，１５Ｒとで構成されているので、前側ジャッキ３ａの伸長量および接地面Ｓへの接地との両検出信号によって前輪４ａの持ち上げ状態が検出され、前側ジャッキ３ａが不十分な伸長量で接地面Ｓ上の石などの障害物に接地していたり、十分に伸長しているにも拘らず接地面Ｓの凹部に入り込んで接地していない等の前側ジャッキ３ａの一方の検出信号のみによる前輪持ち上げ状態の誤検出を確実に防止することができるとともに、傾斜する接地面Ｓ上でのジャッキ３の伸長動作時における作業車Ａの移動をより確実に防止することができる。
【００２４】
尚、本発明は上記実施の形態に限定されるものではなく、その他種々の変形形態を包含するものである。例えば、上記実施の形態では、支持脚としてジャッキ３を適用したが、内筒の先端に車輪を有する支持脚であっても良く、この場合、内筒先端の車輪のうちの少なくとも前側支持脚の車輪に制動装置が設けられる。
【００２５】
また、上記実施の形態では、ジャッキ３を鉛直線方向に延ばしたが、前側ジャッキを下方に行くに従い前方に位置するように傾斜させるとともに、後側ジャッキを下方に行くに従い後方に位置するように傾斜させて、前後のジャッキが車体側面視で略ハの字状になるように配置しても良い。しかも、上記実施の形態では、作業装置としてブーム２を適用したが、クレーンや重量物の積替装置などの作業装置であっても良い。
【００２６】
さらに、上記実施の形態では、前側および後側のジャッキ張出しスイッチおよびジャッキ格納スイッチのＯＮ位置への切換えにより前後のジャッキ３ａ，３ｂをジャッキインタロック回路１２に基づいて伸縮動作させたが、前後のジャッキを統括して伸縮動作させる単一のジャッキ張出しスイッチおよびジャッキ格納スイッチにより、該各スイッチのＯＮ位置への切換え時に前後のジャッキがジャッキインタロック回路に基づく順番通りに伸縮動作するようにしても良い。また、ジャッキインタロック回路に基づく前後のジャッキの伸縮動作を有効または無効とする選択スイッチを付設して、ジャッキ伸縮時に作業車の移動不能な平坦な接地面上でのジャッキの伸縮動作が前後いずれからでも行えるようにしても良い。
【００２７】
しかも、上記実施の形態では、ブーム２を起伏および旋回可能に構成したが、ブームが起伏、伸縮および旋回可能に構成された作業装置であっても良い。
【００２８】
また、上記実施の形態では、シリンダ５ｃ側のコ字状ブラケット６の各孔部６ａを外筒５ａ側のピン７に対して遊嵌状態で嵌合させる該各孔部６ａの半径方向への移動可能な間隙を利用して、前後のジャッキ３ａ，３ｂの接地状態を検出する左右前側および左右後側の接地状態検出手段１５Ｌ，１５Ｒ，１８Ｌ，１８Ｒを構成したが、圧力センサを用いて前後左右のジャッキの接地状態をそれぞれ個別に検出する接地状態検出手段が構成されていても良い。さらに、上記実施の形態では、リミットスイッチ２１ｃを内筒５ｂ側の突片２１ａとの当接によりシリンダ５ｃの伸縮量を直接的に検出する左前側および右前側伸縮量検出手段１４Ｌ，１４Ｒを構成したが、光学的センサによるシリンダの伸縮時の通過位置、またはシリンダの伸縮動作時間などでシリンダの伸縮量を間接的に検出する左前側および右前側伸縮量検出手段が構成されていても良い。
【００２９】
【発明の効果】
以上の如く、請求項１記載の発明における作業車の支持脚インタロック装置によれば、前側の少なくとも一方の支持脚により前輪が持ち上げられていることを車輪持ち上げ状態検出手段で検出したときに後側の支持脚の伸長動作を許容するので、前側の少なくとも一方の支持脚による制動力と制動輪による制動力との車台前後両側からの制動力によって作業車を停止させ、この前側の少なくとも一方の支持脚による制動力を作用させた状態で、制動輪に代わる後側の支持脚の伸長動作を行え、作業車の進退方向に傾斜する接地面上において車輪を持ち上げて車台を支持する各支持脚の伸長動作時における作業車の移動を確実に防止することができるとともに、前後の支持脚の伸長動作時の誤動作を確実に防止することができる。さらに、前輪持ち上げ状態検出手段を前側の支持脚の伸縮量検出手段および接地状態検出手段により構成し、これら両検出手段の検出信号によって前輪の持ち上げ状態を検出するようにしたので、前側の支持脚の一方の検出手段からの検出信号のみによる前輪の持ち上げ状態の誤検出を確実に防止することができるとともに、傾斜する接地面上での各支持脚の伸長動作時における作業車の移動をより確実に防止することができる。
【００３０】
請求項２記載の発明における作業車の支持脚インタロック装置によれば、後側の支持脚により後輪が持ち上げられていないことを後輪持ち上げ状態検出手段で検出したときに前側の支持脚の収縮動作を許容するので、制動輪の制動力と前側の支持脚による制動力とによって作業車を停止させ、この制動輪の制動力を作用させた状態で、前側支持脚に代わってフリーな前輪を接地し、同様に傾斜する接地面上に車輪を降ろす各支持脚の収縮動作時における作業車の移動を確実に防止することができるとともに、前後の支持脚の収縮動作時の誤動作を確実に防止することができ、よって制動輪による制動力を効率良く得る順番で前後の支持脚を伸縮動作させて支持脚の伸縮動作時における作業車の移動を確実に防止できる。
【図面の簡単な説明】
【図１】本発明の実施の形態に係るジャッキインタロック回路図である。
【図２】左前側ジャッキの縦断側面図である。
【図３】左前側ジャッキの後面図である。
【図４】作業車の側面図である。
【符号の説明】
１ｃ車台
２ブーム（作業装置）
３ジャッキ（支持脚）
３ａ前側ジャッキ（前側支持脚）
３ｂ後側ジャッキ（後側支持脚）
４ａ前輪
４ｂ後輪
１１前輪持ち上げ状態検出手段
１２ジャッキインタロック回路（支持脚インタロック装置）
１３伸長動作許容回路（伸長動作許容手段）
１４Ｌ，１４Ｒ伸縮量検出手段
１５Ｌ，１５Ｒ前側接地状態検出手段（接地状態検出手段）
１６後輪持ち上げ状態検出手段
１７収縮動作許容回路（収縮動作許容手段）
Ｓ接地面[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a support leg interlock device for a work vehicle having a support leg for supporting a chassis on which a work device such as a boom that works at a high place is mounted at the time of extension instead of a front wheel and a rear wheel.
[0002]
[Prior art]
In general, in a work vehicle equipped with a work device or the like that performs work at a high place by a bucket at the end of a boom, a telescopic device that supports the vehicle chassis in place of front and rear wheels when the vehicle is extended before and after the chassis, respectively. A pair of left and right support legs, such as jacks, are provided. The rear wheel is configured as a braking wheel that applies a braking force to the chassis, whereas the front wheel is configured as a free wheel that does not apply a braking force to the chassis. However, the rear wheels are lifted when the rear support legs are extended, so that work at a high place is performed in a stable state. In this case, each support leg can be arbitrarily extended or retracted from either front or rear.
[0003]
[Problems to be solved by the invention]
However, since the work vehicle is kept stopped only by the braking force of the rear wheels during the expansion and contraction operation of each support leg, when the contact surface where the work vehicle is stopped is inclined in the forward and backward directions of the work vehicle. For example, it is necessary to reliably apply the braking force of the braking wheel (rear wheel) to the ground contact surface. However, since each support leg can be extended and retracted from both front and rear, if the order of extending and retracting the front and rear support legs is inappropriate, the braking force of the braking wheel may not be used. In other words, if the order of expansion and contraction of each support leg is incorrect, the chassis may be temporarily supported by the rear support leg that lifts the braking wheel and the free front wheel. There is a disadvantage that the braking force required for the operation is insufficient, and the work vehicle moves in the direction of inclination of the ground contact surface.
[0004]
The present invention has been made in view of such a point, and an object of the present invention is to extend and contract the support legs by extending and retracting the front and rear support legs in the order in which the braking force by the braking wheel can be efficiently obtained. An object of the present invention is to reliably prevent the work vehicle from moving during operation.
[0005]
[Means for Solving the Problems]
In order to achieve the above object, a solution taken by the invention according to claim 1 is as a support leg interlocking device for a working vehicle, the front and rear of the chassis when the working device is mounted, before and after the chassis, respectively, when extended. A pair of extendable left and right support legs for supporting the wheels is provided, and the undercarriage is configured to stop by the braking force of the rear wheels. It is assumed that the working vehicle is configured such that the rear wheels can be lifted when the supporting legs on the side are extended. A front wheel lifting state detecting means for detecting that the front wheel is lifted by the front supporting leg; and a signal from the front wheel lifting state detecting means, and receiving at least one of the front left and right supporting legs, Extension operation permitting means for permitting the extension operation of the rear support leg only when the arm is lifted.. Further, the front wheel lifting state detecting means includes an expansion / contraction amount detecting means for detecting an expansion / contraction amount of the front support leg, and a ground contact state detecting means for detecting that the front support leg is in contact with the ground surface, The lifting state of the front wheel is detected by the detection signals of these two detecting means.It is configured.
[0006]
With this configuration, according to the first aspect of the invention, when each wheel is lifted and the chassis is supported on the ground surface by the support legs, first, the front wheels are lifted by at least one of the left and right support legs on the front side. The work vehicle is kept stopped by the braking force on both the front and rear sides of the chassis including the braking force by at least one of the front support legs and the braking force by the rear wheels (braking wheels). After that, the rear of the chassis is supported by the rear support legs in place of the braking wheels.When the rear support legs are extended, the chassis is moved by the braking force of at least one of the front support legs instead of the free front wheels. Since the stationary state is maintained, the work vehicle does not move even if the contact surface of each support leg is inclined in the forward and backward directions of the work vehicle. In addition, since the extension operation of the rear support leg is allowed only when the front wheel is lifted by at least one of the front support legs, the order in which the front and rear support legs are extended is not mistaken.Further, the lifting state of the front wheel is detected based on the detection signals of the amount of extension of the front support leg and the contact to the ground contact surface, and the front support leg is not sufficiently extended by obstacles such as stones on the contact surface. The detection of the front wheel lifting state by only one detection signal of the front support leg, such as the fact that it is in contact with the concave part of the ground contact surface and not grounded even though it is grounded or fully extended, is reliably prevented. In addition, the movement of the work vehicle during the extension operation of each support leg on the inclined contact surface is more reliably prevented.
[0007]
According to a second aspect of the present invention, in addition to the constituent features of the first aspect of the invention, a rear wheel lifting state detecting means for detecting that the rear wheel is lifted by the rear support leg is provided. Receiving signals from the front wheel lifting state detecting means and the rear wheel lifting state detecting means, when the front wheel is lifted by at least one of the front support legs, and when the rear wheel is not lifted by the rear support legs. And a contraction operation permitting means for permitting the front support leg to contract.
[0008]
With this configuration, according to the second aspect of the present invention, when releasing the support of the chassis by each support leg and lowering each wheel to the ground contact surface, first, the rear support leg is contracted to move the braking wheel to the ground contact surface. The work vehicle is stopped by the braking force from both the front and rear sides of the chassis, including the braking force of the braking wheel and the braking force of the front support legs. After that, the front wheel is lowered to the ground contact surface in place of the front support leg, but the contraction operation of the front support leg is performed when the front wheel is lifted by the front support leg and rearward by the rear support leg. When the wheels are not lifted, that is, when the brake wheels touch the ground first and the chassis is stopped by the braking force of the brake wheels, the grounding surface of each support leg is moved in the forward and backward directions of the work vehicle. Even if it is inclined, the contraction operation of the front support leg is performed in a state where the braking force of the braking wheel is sufficiently applied, and the work vehicle does not move when the front support leg contracts. Moreover, the contraction operation of the front support leg is allowed only when the braking wheel is in contact with the ground, and the order of contraction operation of the front and rear support legs is not erroneous. Thereby, the front and rear support legs are extended and contracted in the order in which the braking force by the braking wheel is efficiently obtained, and the movement of the work vehicle during the extension and contraction operation of the support legs is reliably prevented..
[0009]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0010]
FIG. 4 shows a work vehicle, 1 is a body of the work vehicle A, 2 is a boom as a work device installed on the body 1 so as to be able to undulate and turn, and 3 is a support device for supporting the body 1 in a floating state at the time of work at a high place. It is a jack as a supporting leg.
[0011]
The vehicle body 1 includes a chassis 1c, a carrier 1a provided on the chassis 1c, and a vehicle compartment 1b integrally connected to the chassis 1c. The vehicle body 1 has a pair of front and rear front wheels 4a and The vehicle has a rear wheel 4b, the front wheel 4a is a free driven wheel, the rear wheel 4b is a driving wheel for traveling, and the rear wheel 4b operates a handbrake (not shown) when the vehicle body 1 is stopped. Thus, a braking wheel on which a braking force acts is configured. The boom 2 is connected to the chassis 1c so as to be rotatable around a vertical axis V, and is connected to the upper end of the swivel column 2a so as to be rotatable around a horizontal axis H. The telescopic tube 2c is connected to the top and bottom of the telescopic tube 2c so as to be undulated by a work 2b, and a worker rides on the bucket 2d to extend the undulating cylinder 2b. Thereby, the bucket 2d rises relatively to the chassis 1c.
[0012]
The jack 3 includes a pair of left and right front jacks 3a provided on the front side of the chassis 1c (immediately behind the front wheels 4a) and a pair of left and right rear jacks 3b provided on the rear side of the chassis 1c (immediately behind the rear wheels 4b). Consists of
[0013]
As shown in FIGS. 2 and 3, the front and rear jacks 3a and 3b are each constituted by a jack portion 5 that can expand and contract in the vertical direction with respect to the chassis 1c. The jack part 5 includes a bottomed square cylindrical outer cylinder 5a fixed to the chassis 1c, a square cylindrical inner cylinder 5b slidably inserted into the outer cylinder 5a, and one end of the inner cylinder 5b. A cylinder 5c having the other end connected to the upper end of the outer cylinder 5a at the lower end of the cylinder 5b, and a pin member 5d extending substantially horizontally in the left-right direction of the vehicle body 1 at the lower end of the inner cylinder 5b so as to be swingable. The bracket 5e includes a supported bracket 5e, and a horizontal plate-shaped contact piece 5f fixed to a lower end of the bracket 5e and having a lower surface abutting (grounding) on the ground surface S. The cylinder 5c is configured as a hydraulic cylinder that expands and contracts with pressure oil. At the upper end of the cylinder 5c of the jack portion 5, a U-shaped bracket 6 having a substantially U-shaped cross section having left and right opposing pieces facing each other in the left-right direction of the vehicle body 1 is provided. The bracket 6 is provided such that its bottom is located behind the rear surface of the outer cylinder 5a. A circular hole which is fitted in a free-fit state with a pin 7 attached between the upper ends of the left and right sides of the outer cylinder 5a is formed at the tip (opposite bottom side) of the left and right opposed pieces of the U-shaped bracket 6. 6a, 6a are provided, and the cylinder 5c is arranged such that the upper end in the circumferential direction of each hole 6a abuts on the upper end in the circumferential direction of the pin 7 of the outer cylinder 5a by its own weight in the radial direction of each hole 6a. It is supported with a movable gap. In each of the jack portions 5, the extension of the cylinder 5c causes the inner cylinder 5b to protrude from the outer cylinder 5a, and the contact piece 5f to be brought into contact with the ground surface S, and then pushed downward to cause the vehicle body 1 to float. The inner cylinder 5b is immersed in the outer cylinder 5a by the contracting operation, and the wheels (the front wheels 4a and the rear wheels 4b) are in the retracted state (the state shown by the one-dot chain line in FIG. 4). The state shown by the solid line in FIG. 2 to 4 show only the jack portion 5 on the left side of the vehicle body, the one on the right side of the vehicle body has the same configuration as that on the left side.
[0014]
In this case, the extension operation of the jack portions 5 of the front jack 3a and the rear jack 3b is performed by switching the front and rear jack extension switches (not shown) from the OFF position to the ON position. The front wheel 4a is individually lifted when the jack portion 5 is extended, and the rear wheel 4b is individually lifted when the jack portion 5 of the rear jack 3b is extended. The contraction operation of the jack portions 5 of the front jack 3a and the rear jack 3b is also performed by switching the front and rear jack storage switches (not shown) from the OFF position to the ON position.
[0015]
And, FigureAs shown in FIG. 1, the jack portion 5 of the front jack 3a is provided with a front wheel lifting state detecting means 11 for detecting that the front wheel 4a is being lifted by the jack portion 5. The signal from the front wheel lifting state detecting means 11 is input to a jack interlock circuit 12 as a support leg interlock device for sequentially performing the expansion and contraction operation of the cylinder 5c of the jack portion 5 of the front and rear jacks 3a and 3b. The jack interlock circuit 12 includes the jack 5 of the rear jack 3b when the front wheel 4a is lifted by at least one (right or left) of the left and right jacks 5 of the front jack 3a. An extension operation permitting circuit 13 is provided as extension operation permitting means for permitting the extension operation.As a characteristic part of the present invention,The front wheel lifting state detecting means 11 includes left and right front-side expansion / contraction detecting means 14L and 14R for individually detecting left and right expansion / contraction of the cylinder 5c of the left and right front jacks 3a (jack portion 5), and left and right front-side jacks 3a. The left and right front contact state detecting means 15L and 15R (ground contact state detecting means) which individually detect that the contact piece 5f of the jack portion 5 of the contact portion 5f contacts (contacts) with the contact surface S. Have been. The extension operation permitting circuit 13 outputs signals from the left front and right front expansion / contraction amount detecting means 14L and 14R, that is, a signal satisfying the detection condition (a detection position a signal from a limit switch 21c described later) "1". Alternatively, a first OR circuit 13a that inputs a signal (a non-detection position b signal from a limit switch 21c to be described later) “0” that does not satisfy a detection condition, and outputs from the left front and right front ground state detection means 15L and 15R A first AND circuit that inputs a signal, that is, a signal (OFF signal from a limit switch 23d described later) that satisfies the detection condition “1” or a signal that does not satisfy the detection condition (ON signal from a limit switch 23d described later) “0” 13b and output signals from the first OR circuit 13a and the first AND circuit 13b. A second AND circuit 13c that outputs a signal only when both of the force signals are "1". The output signal from the second AND circuit 13c extends the cylinder 5c of the rear jack 3b (jack section 5). As a command signal to cause the rear jack 3b to extend, the hydraulic switching valve is switched to an extension position for extending the rear jack 3b. In other words, the command signal from the second AND circuit 13c is changed over to the ON position of the rear jack extension switch so that all the detection conditions of the circuits 13a to 13c of the extension operation permitting circuit 13 are satisfied and the left and right front jacks 3a Only when the front wheel 4a is lifted by one of the jack portions 5, the output is output to the cylinder expansion / contraction hydraulic switching valve of the rear jack 3b, and the detection condition of each of the circuits 13a to 13c of the extension operation allowing circuit 13 When all of them are not satisfied (when the front wheel 4a is not lifted), no command signal is output to the cylinder expansion / contraction hydraulic switching valve of the rear jack 3b. In this case, a command signal for extending the cylinder 5c of the front jack 3a is supplied to the front jack 3a via a bypass circuit (not shown) that bypasses the jack interlock circuit 12 simultaneously with switching of the front jack extension switch to the ON position. The hydraulic pressure is directly output to a cylinder expansion / contraction hydraulic switching valve (not shown), and the hydraulic switching valve is switched to an extended position.
[0016]
On the other hand, the jack portion 5 of the rear jack 3b is provided with a rear wheel lifting state detecting means 16 for detecting that the rear wheel 4b is lifted by the jack portion 5. The signal from the rear wheel lifting state detecting means 16 is input to the jack interlock circuit 12, and only the rear wheel 4b is grounded to the ground plane S in the jack interlock circuit 12. When the front wheel 4a is lifted by the jack portion 5 of the front jack 3a and the rear wheel 4b is not lifted both right and left by the jack portion 5 of the rear jack 3b. A contraction operation permitting circuit 17 as contraction operation permitting means for permitting the contraction operation of the cylinder 5c of 5) is provided. The rear wheel lifting state detecting means 16 is a left rear side and right rear side grounding state that individually detects that the contact piece 5f of the jack portion 5 of the left and right rear jacks 3b is in contact with the ground surface S. It is constituted by detecting means 18L and 18R. The contraction operation permitting circuit 17 outputs an output signal from the left rear and right rear ground state detecting means 18L, 18R, that is, a signal "1" satisfying the detection condition or a signal "0" not satisfying the detection condition. A second OR circuit 17a for inputting, a knot circuit 17b for inputting an output signal "1" or "0" from the second OR circuit 17a, an output signal of the second OR circuit 17a, and the second AND circuit 13c A third AND circuit 17c for inputting an output signal "1" or "0" from the third circuit, and a third for inputting the output signal of the third AND circuit 17c and the output signal "1" or "0" of the knot circuit 17b. An output signal from the third OR circuit 17d is used as a command signal for contracting the cylinder 5c of the front jack 3a (jack portion 5) by the cylinder of the front jack 3a. Is output to the telescoping hydraulic switching valve, the hydraulic switching valve is switched to a retracted position for contracting the front jack 3a. In other words, the command signal from the third OR circuit 17d is switched to the ON position of the front jack storage switch, so that all the detection conditions of the circuits 17a to 17d of the contraction operation permitting circuit 17 are satisfied, and the left and right front jacks 3a are switched. Only when the front wheel 4a is lifted by one of the jack portions 5 and when the rear wheel 4b is not lifted by the jack portions 5 of the left and right rear jacks 3b, the hydraulic switching valve for cylinder expansion and contraction of the front jack 3a. And when all the detection conditions of the circuits 17a to 17d of the contraction operation permitting circuit 17 are not satisfied (when the front wheel 4a is not lifted and one of the left and right rear wheels 4b is lifted) In this case, no command signal is output to the cylinder expansion / contraction hydraulic switching valve of the rear jack 3b. In this case, a command signal for contracting the cylinder 5c of the rear jack 3a is transmitted to the rear jack via a bypass circuit (not shown) that bypasses the interlock circuit 12 simultaneously with switching of the rear jack storage switch to the ON position. The hydraulic pressure is directly output to the cylinder switching hydraulic switching valve 3b, and the hydraulic switching valve is switched to the contracted position.
[0017]
The left-front and right-front expansion / contraction amount detecting means 14L, 14R include a protruding piece 21a projecting outward (one side of the outer cylinder 5a) from an upper end of one side of the inner cylinder 5b, and a central lower position of one side of the outer cylinder 5a. A limit switch 21c is mounted so as to be swingable about the pin shaft 21b and switches between a detection position a and a non-detection position b by contact with the protruding piece 21a, and the cylinder 5c extends to near the maximum extension position. When the limit switch 21c is switched to the detection position a and the front jack 3a is in the extended state, when the cylinder 5c is contracted from the most extended position, the limit switch 21c is switched to the non-detection position b and the front jack 3a is in the contracted state. Are respectively detected. Further, the left front and right front contact state detecting means 15L and 15R (since they have the same configuration, the left rear and right rear contact state detection means 18L and 18R are denoted only by reference numerals and description thereof is omitted). A bolt 23c attached to the bottom of the U-shaped bracket 6 at the upper end of the cylinder 5c via a stay 23b, and a bracket 23a at the upper end of the outer cylinder 5a corresponding to the tip of the leg of the bolt 23c. And a limit switch 23d which is switched to an ON / OFF position by contact or non-contact with the tip of the leg of the bolt-like member 23c. The extension of the cylinder 5c causes the contact piece 5f to contact the ground plane S. Then, the circumferential lower end of each hole 6a of the U-shaped bracket 6 at the upper end of the cylinder 5c abuts against the circumferential lower end of the pin 7 of the outer cylinder 5a against its own weight. The front end of the front jack 3a (rear jack 3b) is switched to the OFF position where the leg tip of the bolt-shaped member 23c and the limit switch 23d are separated from each other to be out of contact, and the contact piece 5f is contracted by the contraction of the cylinder 5c. Of the bolt-shaped member 23c when the upper end in the circumferential direction of each hole 6a of the U-shaped bracket 6 comes into contact with the upper end in the circumferential direction of the pin 7 of the outer cylinder 5a due to its own weight. The non-ground state of the front jack 3a (rear jack 3b) is detected by switching to the ON position where the tip and the limit switch 23d are in contact with each other. In this case, the detection of the extension state of the left front and right front extension amount detecting means 14L and 14R when the front jack 3a is extended, that is, the switching to the detection position a of the limit switch 21c, is performed by the left front and right front contact state detecting means 15L. , 15R (the rear left and right rear contact state detecting means 18L, 18R) are carried out after the detection of the contact state in which the bolt-shaped member 23c and the limit switch 23d are not in contact (OFF position), while the front jack 3a The detection of the contraction state of the front left and right front expansion / contraction amount detecting means 14L and 14R at the time of contraction, that is, the switching of the limit switch 21c to the non-detection position b is performed by the bolt-shaped members of the front left and right front contact state detecting means 15L and 15R. This is performed before the detection of the non-ground state in which the contact 23c and the limit switch 23d come into contact (ON position). .
[0018]
Next, the expansion and contraction operation of the front and rear jacks 3a and 3b by the jack interlock circuit 12 of the work vehicle A will be described with reference to the electric circuit diagram of FIG.
[0019]
First, when performing high-altitude work using the boom 2, the work vehicle A is stopped at a place where high-altitude work is performed, and the rear wheel 4b is braked by hand brake. Then, the front jack extension switch is switched to the ON position. Then, a command signal for extending the cylinder 5c of the front jack 3a (jack portion 5) via the bypass circuit is output to the cylinder expanding / contracting hydraulic switching valve of the front jack 3a, and the hydraulic switching valve is switched to the extended position, and The jack 3a extends. At this time, even if the rear jack extension switch is erroneously switched to the ON position, the output signals from the left front and right front expansion / contraction amount detecting means 14L and 14R and the outputs from the left front and right front grounding state detecting means 15L and 15R are output. Since the signals are all "0" and the front wheel 4a is not lifted, no signal flows to each circuit of the jack interlock circuit 12, and the extension operation of the rear jack 3b is not performed. The extension operation of the front jack 3a is performed when the extension operation of the front jack 3a is such that one of the output signals from the left front side and the right front expansion / contraction amount detecting means 14L and 14R is “1” and the left front side When the output signals from the right front contact state detecting means 15L and 15R are both "1", the front wheel lifting state detecting means 11 indicates that the front wheel 4a has been lifted by at least one of the left and right front jacks 3a. Is detected. Next, in a state where the front wheel 4a is lifted by at least one of the left and right front jacks 3a, the front jack extension switch is switched to the OFF position, and then the rear jack extension switch is switched to the ON position. The command signal "1" from the AND circuit 13c is output to the cylinder expansion / contraction hydraulic switching valve of the rear jack 3b, the hydraulic switching valve is switched to the extended position, and the cylinder 5c of the rear jack 3b is extended and The support of the chassis 1c by the jacks 3a and 3b is completed. Thereafter, the rear jack extension switch is switched to the OFF position.
[0020]
Accordingly, when each of the wheels 4a and 4b is lifted and the chassis 1c is supported by the jack 3 on the ground surface S, the front wheel 4a is lifted by at least one of the front jacks 3a and at least one of the front jacks is lifted. After the work vehicle A is stopped by the braking force of the front and rear sides of the chassis 1c of the braking force by the rear wheel 4b (braking wheel) and the braking force by the rear wheel 4b (after the chassis 1c by the rear jack 3b instead of the braking wheel). When the rear jack 4a is extended, the chassis 1c is kept stopped by the braking force of at least one of the front jacks 3a in place of the free front wheel 4a. Even if S is inclined in the forward and backward directions of the work vehicle A, the work vehicle A does not move, and the movement of the work vehicle A during the extension operation of the jack 3 is reliably prevented. Rukoto can. In addition, since the extension operation of the rear jack 3b is permitted only when the front wheel 4a is lifted by at least one of the front jacks 3a, the rear jack extension switch is turned on before the front jack extension switch. Even if the position is switched and the order of extending the front and rear jacks 3a and 3b is incorrect, the rear jack 3b does not extend before the front jack 3a, and the front and rear jacks 3a and 3b do not extend. Can reliably be prevented from malfunctioning.
[0021]
On the other hand, when the front and rear jacks 3a, 3b are stored and the work vehicle A is returned to the running state, when the rear jack storage switch is switched to the ON position, the hydraulic switching valve for cylinder expansion and contraction of the rear jack 3b via the bypass circuit. Is switched to the contraction position, the rear jack 3b starts contracting. At this time, if the front jack storage switch is erroneously switched to the ON position, a signal also flows to each circuit of the jack interlock circuit 12, and a command signal for switching the telescopic hydraulic switching valve of the front jack 3a to the contracted position is output. The front jack 3a starts to contract. When the front jack 3a contracts, one of the output signals from the left front and right front expansion / contraction detecting means 14L, 14R is switched from "1" to "0". Stop by changing. When the rear wheel 4b touches both the right and left contact surfaces S with the contraction operation of the rear jack 3b, the output signals from the left rear and right rear expansion / contraction detecting means 18L and 18R both become "0". The left and right rear jacks 3b detect the non-ground state of the left and right rear jacks 3b by the left rear and right rear ground state detecting means 18L and 18R. Next, when the rear wheel 4b touches the ground surface S on both the left and right sides, that is, when the front wheel 4a is lifted by at least one of the front jacks 3a, and when the rear wheel 4b is not lifted by the rear jack 3b. Then, when the rear jack storage switch is switched to the OFF position and then the front jack storage switch is switched to the ON position, the command signal "1" from the third OR circuit 17d receives the hydraulic switching valve for cylinder expansion and contraction of the front jack 3a. And the hydraulic switching valve is switched to the contracted position, the cylinder 5c of the front jack 3a is contracted, the front and rear jacks 3a, 3b are stored, and the support of the chassis 1c by the front and rear wheels 4a, 4b is completed. Thereafter, the jack contraction switch is switched to the OFF position.
[0022]
Thus, when the support of the chassis 1c by the jack 3 is released and the front and rear wheels 4a and 4b are lowered to the ground surface S, the rear jack 3b is contracted to bring the braking wheel (rear wheel 4b) to the ground surface S. After the work vehicle A is stopped by the braking force of the braking wheel and the braking force of the front jack 3a from both the front and rear sides of the chassis 1c, the front wheel 4a replaces the front jack 3a with the ground surface. S, the contraction operation of the front jack 3a is performed when the front wheel 4a is lifted by the front jack 3a and the rear wheel 4b is not lifted by the rear jack 3b, that is, when the braking wheel is moved first. Is permitted when the chassis 1c is stopped by the braking force of the braking wheel due to contact with the ground, so that even if the grounding surface S of the jack 3 is inclined in the forward and backward directions of the work vehicle A, the braking force of the braking wheel Works enough In this state, the contraction operation of the front jack 3a is performed, the work vehicle A does not move when the front jack 3a contracts, and the movement of the work vehicle A during the contraction operation of the jack 3 can be reliably prevented. it can. In addition, since the contraction operation of the front jack 3a is allowed only when the braking wheel is in contact with the ground, the front jack extension switch is switched to the ON position prior to the rear jack extension switch, and the front and rear jacks 3a, Even if the order in which the 3b is contracted is erroneous, the time at which one of the output signals from the left-front and right-front expansion / contraction amount detecting means 14L, 14R is switched from "1" to "0" (left front And the output signals from the right front contact state detecting means 15L and 15R are held at "1" and the front jack 3a is supported, and the contraction operation of the front jack 3a is stopped, and the front jack 3a is turned off. The contraction operation is not performed prior to the rear jack 3b, and the malfunction of the front and rear jacks 3a and 3b during the contraction operation can be reliably prevented.
[0023]
In addition, the front wheel lifting state detecting means 11 detects left and right front and rear front jacks 3a independently of the amount of expansion and contraction of the left and right front jacks 3a, 14L and 14R. The front wheel 4a is formed by the left front side and right front side grounding state detecting means 15L and 15R for detecting right and left of the front wheel 4a separately from the amount of extension of the front jack 3a and the grounding on the ground surface S. Is lifted, and the front jack 3a is in contact with an obstacle such as a stone on the contact surface S with an insufficient extension amount, or enters the concave portion of the contact surface S despite being sufficiently extended. Erroneous detection of the lifting state of the front wheel based on only one detection signal of the front jack 3a such as not being grounded can be reliably prevented, and the jack on the inclined ground surface S can be prevented. It is possible to more reliably prevent the movement of the work vehicle A at 3 elongation operation.
[0024]
It should be noted that the present invention is not limited to the above-described embodiment, but encompasses various other modified forms. For example, in the above embodiment, the jack 3 is applied as the support leg, but a support leg having a wheel at the tip of the inner cylinder may be used. In this case, at least the front support leg of the wheel at the tip of the inner cylinder may be used. A braking device is provided on the wheel.
[0025]
In the above-described embodiment, the jack 3 is extended in the vertical direction. However, the front jack is inclined so as to be located forward as it goes down, and the rear jack is located as it goes backward as it goes down. The jacks may be inclined so that the front and rear jacks are substantially U-shaped when viewed from the side of the vehicle body. In addition, in the above-described embodiment, the boom 2 is applied as a working device, but a working device such as a crane or a heavy goods transfer device may be used.
[0026]
Further, in the above-described embodiment, the front and rear jacks 3a and 3b are expanded and contracted based on the jack interlock circuit 12 by switching the front and rear jack extension switches and the jack storage switches to the ON position. A single jack extension switch and a jack storage switch for controlling the jacks to extend and retract the jacks may cause the front and rear jacks to extend and contract in the order based on the jack interlock circuit when each switch is switched to the ON position. good. In addition, a selection switch that enables or disables the expansion and contraction of the front and rear jacks based on the jack interlock circuit is attached, so that the expansion and contraction of the jack on the flat ground surface where the work vehicle can not move You may be able to do it even from.
[0027]
In addition, in the above-described embodiment, the boom 2 is configured to be able to move up and down, and may be turned.
[0028]
Further, in the above embodiment, each hole 6a of the U-shaped bracket 6 on the cylinder 5c side is loosely fitted to the pin 7 on the outer cylinder 5a in the radial direction of each hole 6a. The left and right front and left and right rear contact state detecting means 15L, 15R, 18L, 18R for detecting the contact state of the front and rear jacks 3a, 3b using the movable gap are configured. Grounding state detecting means for individually detecting the grounding states of the left and right jacks may be configured. Further, in the above embodiment, the left and right front expansion / contraction detecting means 14L and 14R for directly detecting the expansion / contraction of the cylinder 5c by contacting the limit switch 21c with the protruding piece 21a on the inner cylinder 5b side are configured. However, a left-front-side and right-front-side expansion / contraction detecting means for indirectly detecting the amount of expansion / contraction of the cylinder based on the passage position when the cylinder expands / contracts by the optical sensor or the operation time of the cylinder expansion / contraction may be configured.
[0029]
【The invention's effect】
As described above, according to the work vehicle support leg interlock device of the first aspect of the present invention, when the wheel lifting state detecting means detects that the front wheel is lifted by at least one of the front support legs, The work vehicle is stopped by the braking force from both the front and rear sides of the chassis between the braking force by at least one of the front supporting legs and the braking force by the braking wheel, and the at least one of the front sides is allowed. Each support leg that can extend the rear support leg in place of the braking wheel while applying the braking force by the support leg, and lifts the wheel on the ground surface that is inclined in the forward and backward directions of the work vehicle to support the chassis. In addition, it is possible to reliably prevent the work vehicle from moving during the extension operation, and to reliably prevent the malfunction of the front and rear support legs during the extension operation.Further, the front wheel lifting state detecting means is constituted by the front support leg expansion / contraction amount detecting means and the ground contact state detecting means, and the front wheel lifting state is detected by the detection signals of these two detecting means. Erroneous detection of the lifting state of the front wheel based on only the detection signal from one of the detection means can be reliably prevented, and the movement of the work vehicle during the extension operation of each support leg on the inclined contact surface can be more reliably performed. Can be prevented .
[0030]
According to the support leg interlock device of the second aspect of the present invention, when the rear wheel lifting state detecting means detects that the rear wheel is not lifted by the rear supporting leg, the front supporting leg of the work vehicle is rotated. Since the contraction operation is allowed, the work vehicle is stopped by the braking force of the braking wheel and the braking force of the front support leg, and the free front wheel is used instead of the front support leg in a state where the braking force of the braking wheel is applied. Grounding and lowering the wheel on the similarly inclined contact surface can reliably prevent the work vehicle from moving during the contraction operation of each support leg, and ensure that the front and rear support legs do not malfunction during the contraction operation. Therefore, the front and rear support legs can be extended and contracted in the order in which the braking force by the braking wheel is efficiently obtained, and the movement of the work vehicle during the extension and contraction operation of the support legs can be reliably prevented..
[Brief description of the drawings]
FIG. 1 is a circuit diagram of a jack interlock circuit according to an embodiment of the present invention.
FIG. 2 is a vertical sectional side view of a left front jack.
FIG. 3 is a rear view of the left front jack.
FIG. 4 is a side view of the work vehicle.
[Explanation of symbols]
1c chassis
2 boom (work equipment)
3 jacks (supporting legs)
3a Front jack (front support leg)
3b Rear jack (rear support leg)
4a Front wheel
4b Rear wheel
11 Front wheel lifting state detection means
12. Jack interlock circuit (support leg interlock device)
13 Expansion operation allowable circuit (expansion operation allowable means)
14L, 14R Expansion / contraction detector
15L, 15R Front ground contact detection means (ground contact detection means)
16 Rear wheel lifting state detection means
17 Contraction operation permission circuit (contraction operation permission means)
S ground plane

Claims

A pair of extendable left and right support legs are provided before and after the chassis on which the working device is mounted to support the chassis in place of the front wheels and the rear wheels when extended, and the chassis is stopped by the braking force of the rear wheels. It is configured as
A work vehicle in which the front wheels are lifted when the front support legs are extended, and the rear wheels are lifted when the rear support legs are extended,
Front wheel lifting state detecting means for detecting that the front wheel is lifted by the front support leg,
Extension operation permitting means for receiving a signal from the front wheel lifting state detecting means and permitting the rear support leg to extend only when the front wheel is lifted by at least one of the left and right support legs on the front side; Is provided ,
The front wheel lifting state detecting means includes an expansion / contraction amount detecting means for detecting an expansion / contraction amount of the front support leg, and a contact state detecting means for detecting that the front support leg is in contact with the contact surface. A support leg interlock device for a work vehicle, wherein a lifting state of a front wheel is detected by a detection signal of a detection means .

Rear wheel lifting state detecting means for detecting that the rear wheel is lifted by the rear support leg,
Receiving signals from the front wheel lifting state detecting means and the rear wheel lifting state detecting means, when the front wheel is lifted by at least one of the front support legs, and the rear wheel is lifted by the rear support leg. 2. A support leg interlock device for a working vehicle according to claim 1, further comprising a contraction operation permitting means for permitting a contraction operation of said front support leg when not in operation .