JP2594686Y2 - Traveling hydraulic circuit - Google Patents
Traveling hydraulic circuitInfo
- Publication number
- JP2594686Y2 JP2594686Y2 JP1993028077U JP2807793U JP2594686Y2 JP 2594686 Y2 JP2594686 Y2 JP 2594686Y2 JP 1993028077 U JP1993028077 U JP 1993028077U JP 2807793 U JP2807793 U JP 2807793U JP 2594686 Y2 JP2594686 Y2 JP 2594686Y2
- Authority
- JP
- Japan
- Prior art keywords
- pressure
- valve
- switching valves
- variable displacement
- load
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
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- Fluid-Pressure Circuits (AREA)
Description
【０００１】[0001]
【産業上の利用分野】本考案は、パワーショベルなどの
装軌式作業車における左右走行油圧モータに１つの油圧
ポンプの吐出圧油を供給して走行する走行用油圧回路に
関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a traveling hydraulic circuit which travels by supplying hydraulic pressure discharged from one hydraulic pump to left and right traveling hydraulic motors of a tracked work vehicle such as a power shovel.
【０００２】[0002]
【従来の技術】パワーショベルとしては、下部走行体に
上部車体を旋回油圧モータで旋回可能に設け、この上部
車体にブーム、アーム、バケットを含む作業機リンク機
構を設置しブームシリンダ、アームシリンダ、バケット
シリンダで上下揺動自在に設け、前記下部走行体は左右
走行油圧モータで左右履帯を駆動する装軌式としたもの
が知られている。2. Description of the Related Art As a power shovel, an upper body is provided on a lower traveling body so as to be able to turn by a turning hydraulic motor, and a work machine link mechanism including a boom, an arm, and a bucket is installed on the upper body, and a boom cylinder, an arm cylinder, It is known that a bucket cylinder is provided so as to be able to swing up and down, and the lower traveling body is of a track type in which left and right crawler belts are driven by left and right traveling hydraulic motors.
【０００３】かかるパワーショベルの各油圧アクチュエ
ータに１つの油圧ポンプの吐出圧油を供給する油圧回路
としては、例えば特開平４−２４４６０４号公報に示す
ように油圧アクチュエータの負荷圧とポンプ吐出圧の差
圧が一定となるように容量制御される１つの可変容量油
圧ポンプと、この可変容量油圧ポンプの吐出側に接続さ
れて各油圧アクチュエータに圧油を供給する複数の方向
切換弁と、各方向切換弁の入口側にそれぞれ設けられ、
ロードチェック弁と負荷圧に抗して下流側圧力によりロ
ードチェック弁を閉じ方向に押す減圧弁より成る複数の
圧力補償弁を備えたものが知られている。[0003] As a hydraulic circuit for supplying the discharge pressure oil of one hydraulic pump to each hydraulic actuator of such a power shovel, for example, as disclosed in JP-A-4-244604, the difference between the load pressure of the hydraulic actuator and the discharge pressure of the pump is disclosed. One variable displacement hydraulic pump whose capacity is controlled so that the pressure is constant, a plurality of direction switching valves connected to the discharge side of the variable displacement hydraulic pump to supply pressure oil to each hydraulic actuator, Each is provided on the inlet side of the valve,
2. Description of the Related Art There is known a load check valve including a plurality of pressure compensating valves including a load check valve and a pressure reducing valve that pushes the load check valve in a closing direction by a downstream pressure against the load pressure.
【０００４】前述の油圧回路により走行用油圧回路を構
成すると例えば、図１に示すようになる。つまり可変容
量油圧ポンプ１の吐出路２に左右走行油圧モータ３，４
に圧油を供給する左右方向切換弁５，６を設け、この左
右方向切換弁５，６の入口側に、ロードチェック弁７
と、負荷圧に抗して下流側圧力によりロードチェック弁
を閉じ方向に押す減圧弁８より成る圧力補償弁９をそれ
ぞれ設け、左右方向切換弁５，６の負荷圧検出ポート５
ａ，６ａを各圧力補償弁９の減圧弁８に接続し、減圧弁
８の下流側圧力を負荷圧導入路１０を経て容量制御弁１
１に供給して容量制御シリンダ１２で可変容量油圧ポン
プ１の容量を負荷圧とポンプ吐出圧の差圧が一定となる
ように制御し、各圧力補償弁９で左右方向切換弁５，６
のメータイン差圧を制御するようになる。１３はカウン
タバランス弁である。[0004] When the traveling hydraulic circuit is constituted by the above-mentioned hydraulic circuit, for example, it becomes as shown in FIG. That is, the right and left traveling hydraulic motors 3 and 4
Left and right switching valves 5 and 6 for supplying pressure oil are provided, and a load check valve 7 is provided at the inlet side of the left and right switching valves 5 and 6.
And a pressure compensating valve 9 composed of a pressure reducing valve 8 that pushes the load check valve in the closing direction by the downstream pressure against the load pressure.
a, 6a are connected to the pressure reducing valves 8 of the pressure compensating valves 9, and the pressure on the downstream side of the pressure reducing valves 8 is passed through the load pressure introducing passage 10 to the capacity control valve 1.
The displacement of the variable displacement hydraulic pump 1 is controlled by the displacement control cylinder 12 so that the differential pressure between the load pressure and the pump discharge pressure is kept constant.
Is controlled. 13 is a counter balance valve.
【０００５】かかる油圧回路において左右方向切換弁
５，６のメータイン開口面積を異ならせて左右走行油圧
モータ３，４の回転数を異ならせることで左右旋回走行
する際に走行速度が低下する。すなわち、左右に旋回走
行する際には旋回抵抗大のために、内側走行モータ（被
駆動側）は制動状態となり駆動圧はゼロ（又はカウンタ
ーバランス弁セット圧）となり、外側走行モータ（駆動
側）の駆動圧は走行抵抗、旋回抵抗に対応する高圧にな
る。このために内側走行モータと外側走行モータの差圧
が大きくなり、内側走行モータへの流れはエネルギー損
失となり通常、馬力制御が作動し可変容量油圧ポンプ１
の容量が低下して外側走行モータへの流量が減少して走
行速度が低下する。In such a hydraulic circuit, the traveling speed is reduced when the vehicle turns left and right by making the meter-in opening areas of the left and right direction switching valves 5 and 6 different and making the rotation speeds of the left and right traveling hydraulic motors 3 and 4 different. That is, when turning left and right, the inner traveling motor (the driven side) is in a braking state because the turning resistance is large, the driving pressure becomes zero (or the counterbalance valve set pressure), and the outer traveling motor (the driving side). Becomes high pressure corresponding to running resistance and turning resistance. As a result, the differential pressure between the inner traveling motor and the outer traveling motor increases, and the flow to the inner traveling motor becomes an energy loss.
, The flow rate to the outer traveling motor decreases, and the traveling speed decreases.
【０００６】例えば、左右方向切換弁５，６を右側位置
Ａとし、かつ左方向切換弁５のメータイン開口面積を大
で右方向切換弁６のメータイン開口面積を小として左走
行油圧モータ３を駆動側、右走行油圧モータ４を被駆動
側として矢印ａ方向に旋回走行する場合に、右走行油圧
モータ４は制動状態となり駆動圧ＰＬ２はカウンタバラ
ンス弁１３のセット圧となるし、左走行油圧モータ３の
駆動圧ＰＬ１は走行抵抗、旋回抵抗に対応する高圧とな
るから、駆動側の圧力補償弁９の減圧弁８は負荷圧ＰＬ
１で右方に押されてロードチェック弁７の開度が大とな
り、被駆動側の圧力補償弁９の減圧弁８は駆動側の負荷
圧ＰＬ１で左に押されてロードチェック弁７を閉じ側に
押し、ロードチェック弁７の開度は小さくなる。この開
度は駆動圧の差圧ＰＬ１−ＰＬ２に反比例する。このた
めに、右方向切換弁６のメータイン開口面積が小さく駆
動圧の差圧が大きい時にはそれにともなって可変容量油
圧ポンプ１の吐出圧が大きくなって馬力一定制御が働い
て容量が減少し、駆動側の走行油圧モータに流入する流
量が減少して車速が低下する。For example, the left traveling hydraulic motor 3 is driven by setting the left and right switching valves 5 and 6 to the right position A, increasing the meter-in opening area of the left switching valve 5 and reducing the meter-in opening area of the right switching valve 6. When the vehicle travels in the direction of arrow a with the right and left traveling hydraulic motors 4 as driven sides, the right traveling hydraulic motor 4 enters a braking state, and the driving pressure PL2 becomes the set pressure of the counter balance valve 13, and the left traveling hydraulic motor 3 is a high pressure corresponding to the running resistance and the turning resistance, the pressure reducing valve 8 of the driving side pressure compensating valve 9 is set to the load pressure PL.
1, the pressure check valve 7 is pushed to the right to increase the opening degree of the load check valve 7, and the pressure reducing valve 8 of the pressure compensation valve 9 on the driven side is pushed to the left by the load pressure PL1 on the drive side to close the load check valve 7. Side, the opening of the load check valve 7 decreases. This opening is inversely proportional to the differential pressure PL1-PL2 of the driving pressure. For this reason, when the meter-in opening area of the right direction switching valve 6 is small and the differential pressure of the drive pressure is large, the discharge pressure of the variable displacement hydraulic pump 1 is accordingly increased, the constant horsepower control is performed, and the displacement is reduced. The flow rate flowing into the side traveling hydraulic motor decreases, and the vehicle speed decreases.
【０００７】そこで、本出願人は先に前述の課題を解決
できるようにした走行用油圧回路を出願した。Accordingly, the present applicant has previously filed an application for a traveling hydraulic circuit capable of solving the above-mentioned problems.
【０００８】すなわち、図２、図３、図４に示すように
可変容量油圧ポンプ１と、この可変容量油圧ポンプ１の
吐出圧油を左右走行油圧モータ３，４に供給する左右方
向切換弁５，６と、前記可変容量油圧ポンプ１の容量を
左右走行油圧モータ３，４の負荷圧とポンプ吐出圧の差
圧が一定となるように制御する容量制御部材１１，１２
と、前記左右方向切換弁５，６の上流側に設けられてロ
ードチェック弁７と、負荷圧に抗して下流側圧力により
ロードチェック弁７を閉じ方向に押す減圧弁８より成る
圧力補償弁９を備え、左右方向切換弁５，６の戻り回路
２１，２２を補助リリーフ弁２４とタンク２５に接続制
御する切換弁２３を設け、この補助リリーフ弁２４の入
口側をチェック弁２７を介して左右方向切換弁５，６の
上流側回路２８，２９に接続し、前記切換弁２３を左右
方向切換弁５，６をメータイン開口面積を異ならせて操
作した時に高圧側の戻り回路２１，２２を補助リリーフ
弁２４に接続する位置となるようにした走行用油圧回
路。That is, as shown in FIGS. 2, 3 and 4, a variable displacement hydraulic pump 1 and a left / right switching valve 5 for supplying discharge pressure oil of the variable displacement hydraulic pump 1 to left and right traveling hydraulic motors 3, 4 are provided. , 6 and displacement control members 11, 12 for controlling the displacement of the variable displacement hydraulic pump 1 so that the differential pressure between the load pressure of the left and right traveling hydraulic motors 3, 4 and the pump discharge pressure is constant.
A pressure check valve 7 provided on the upstream side of the left and right direction switching valves 5 and 6, and a pressure reducing valve 8 for pressing the load check valve 7 in a closing direction by a downstream pressure against the load pressure. 9, a switching valve 23 for controlling the connection of the return circuits 21 and 22 of the left and right switching valves 5 and 6 to the auxiliary relief valve 24 and the tank 25, and the inlet side of the auxiliary relief valve 24 via the check valve 27. The high-pressure side return circuits 21 and 22 are connected to the upstream side circuits 28 and 29 of the left and right switching valves 5 and 6, respectively, and the switching valve 23 is operated when the left and right switching valves 5 and 6 are operated with different meter-in opening areas. A traveling hydraulic circuit that is located at a position connected to the auxiliary relief valve 24.
【０００９】つまり、図２においては切換弁２３は上流
側回路２８，２９に接続した左右回路３２，３３の圧力
差によりドレーン位置Ｂから左位置Ｃ又は右位置Ｄに切
換えられる。That is, in FIG. 2, the switching valve 23 is switched from the drain position B to the left position C or the right position D by the pressure difference between the left and right circuits 32, 33 connected to the upstream circuits 28, 29.
【００１０】図３においては、切換弁２３の左右受圧部
３０，３１を左右方向切換弁５，６の負荷圧検出ポート
５ａ，６ａに接続して、切換弁２３を左右走行油圧モー
タ３，４の負荷圧に差が生じた時に左右位置Ｃ，Ｄに切
換えられるようにしてある。In FIG. 3, the right and left pressure receiving portions 30, 31 of the switching valve 23 are connected to the load pressure detecting ports 5a, 6a of the left and right switching valves 5, 6, and the switching valve 23 is connected to the left and right traveling hydraulic motors 3, 4. Are switched to the left and right positions C and D when there is a difference between the load pressures.
【００１１】図４においては、左右方向切換弁５，６を
切換える左右パイロット弁４０，４１の第１・第２回路
４２，４３を高圧優先弁４４で左右回路４５，４６にそ
れぞれ接続し、この左右回路４５，４６を切換弁２３の
左右受圧部３０，３１に接続して、切換弁２３を左右方
向切換弁５，６を切換えるパイロット圧油を利用して切
換えられるようにしてある。In FIG. 4, first and second circuits 42 and 43 of left and right pilot valves 40 and 41 for switching left and right switching valves 5 and 6 are connected to left and right circuits 45 and 46 by a high pressure priority valve 44, respectively. The left and right circuits 45 and 46 are connected to the left and right pressure receiving portions 30 and 31 of the switching valve 23 so that the switching valve 23 can be switched using pilot pressure oil for switching the left and right switching valves 5 and 6.
【００１２】かかる走行用油圧回路であれば、左右方向
切換弁５，６を右側位置Ａとし、かつ左方向切換弁５の
メータイン開口面積を大で右方向切換弁６のメータイン
開口面積を小として左走行油圧モータ３を駆動側、右走
行油圧モータ４を被駆動側として矢印ａ方向に旋回走行
する場合に、右走行油圧モータ４は制動状態となり駆動
圧ＰＬ２はカウンタバランス弁１３にセット圧となる
し、左走行油圧モータ３は駆動圧ＰＬ１は走行抵抗、旋
回抵抗に対応する高圧となるから、左方向切換弁５の入
口圧Ｐ１は右方向切換弁６の入口圧Ｐ２よりも高くな
る。これにより、切換弁２３は入口圧Ｐ１によって左位
置Ｃとなり、左方向切換弁５の戻り回路２１が補助リリ
ーフ弁２４の入口側に接続し、右方向切換弁６の戻り回
路２２はタンク２５に直接流出する。In this traveling hydraulic circuit, the left and right switching valves 5 and 6 are set to the right position A, the meter-in opening area of the left switching valve 5 is large, and the meter-in opening area of the right switching valve 6 is small. When the vehicle travels in the direction of arrow a with the left traveling hydraulic motor 3 as the driving side and the right traveling hydraulic motor 4 as the driven side, the right traveling hydraulic motor 4 is in a braking state, and the driving pressure PL2 is set to the counterbalance valve 13 by the set pressure. In other words, since the driving pressure PL1 of the left traveling hydraulic motor 3 becomes a high pressure corresponding to the traveling resistance and the turning resistance, the inlet pressure P1 of the leftward switching valve 5 becomes higher than the inlet pressure P2 of the rightward switching valve 6. Thereby, the switching valve 23 is brought to the left position C by the inlet pressure P1, the return circuit 21 of the leftward switching valve 5 is connected to the inlet side of the auxiliary relief valve 24, and the return circuit 22 of the rightward switching valve 6 is connected to the tank 25. Spills directly.
【００１３】補助リリーフ弁２４の入口側はセット圧Ｐ
３まで上昇し、その圧油は回路２６、チェック弁２７よ
り右方向切換弁６の上流側回路２９に流入する。これに
より、被駆動側のロードチェック弁７が閉じて可変容量
油圧ポンプ１からロードチェック弁７を介して右走行油
圧モータ４へ流入する流量が減少する。よって、可変容
量油圧ポンプ１の吐出圧油の大部分が左走行モータ３へ
供給されて、馬力制御により可変容量油圧ポンプ１の容
量低下がおきないから、駆動側である左走行油圧モータ
３への流量が減少せずに車速が低下しない。The inlet side of the auxiliary relief valve 24 has a set pressure P
3 and the pressure oil flows from the circuit 26 and the check valve 27 into the upstream circuit 29 of the rightward switching valve 6. As a result, the load check valve 7 on the driven side is closed, and the flow rate flowing from the variable displacement hydraulic pump 1 to the right traveling hydraulic motor 4 via the load check valve 7 decreases. Therefore, most of the discharge pressure oil of the variable displacement hydraulic pump 1 is supplied to the left traveling motor 3, and the displacement of the variable displacement hydraulic pump 1 is not reduced by the horsepower control. The vehicle speed does not decrease because the flow rate of the vehicle does not decrease.
【００１４】また、図５に示すように可変容量油圧ポン
プ１と、この可変容量油圧ポンプ１の吐出圧油を左右走
行油圧モータ３，４に供給する左右方向切換弁５，６
と、前記可変容量油圧ポンプ１の容量を左右走行油圧モ
ータ３，４の負荷圧とポンプ吐出圧の差圧が一定となる
ように制御する容量制御部材１０と、前記左右方向切換
弁５，６の上流側に設けられて負荷圧と上流側圧力によ
って左右方向切換弁５，６のメータイン差圧を制御する
圧力補償弁９とを備え、前記左右方向切換弁５，６の戻
り回路２１，２２を補助リリーフ弁２４とタンク２５に
接続制御する切換弁２３を設け、この補助リリーフ弁２
４の入口側をチェック弁２７を介して左右方向切換弁
５，６の上流側回路２８，２９に接続し、前記切換弁２
３の左右受圧部３０，３１に上流側回路２８，２９に接
続した左右回路３２，３３に接続し、左右方向切換弁
５，６をメータイン開口面積を異ならせて操作した時に
切換弁２３が高圧側の戻り回路２１，２２を補助リリー
フ弁２４に接続する位置となるようにした走行用油圧回
路を先に提案した。As shown in FIG. 5, a variable displacement hydraulic pump 1 and left and right direction switching valves 5 and 6 for supplying discharge hydraulic oil of the variable displacement hydraulic pump 1 to left and right traveling hydraulic motors 3 and 4 are provided.
A displacement control member 10 for controlling the displacement of the variable displacement hydraulic pump 1 so that the differential pressure between the load pressure of the left and right traveling hydraulic motors 3 and 4 and the pump discharge pressure is constant; And a pressure compensating valve 9 provided on the upstream side for controlling the meter-in differential pressure of the left and right switching valves 5 and 6 by the load pressure and the upstream pressure, and the return circuits 21 and 22 of the left and right switching valves 5 and 6 are provided. And a switching valve 23 for controlling connection between the auxiliary relief valve 24 and the tank 25.
4 is connected via a check valve 27 to upstream circuits 28, 29 of the left / right directional switching valves 5, 6;
3 are connected to the left and right circuits 32, 33 connected to the upstream circuits 28, 29 to the left and right pressure receiving parts 30, 31, respectively, and when the left and right switching valves 5, 6 are operated with different meter-in opening areas, the switching valve 23 becomes high pressure. A traveling hydraulic circuit in which the return circuits 21 and 22 on the side are connected to the auxiliary relief valve 24 has been previously proposed.
【００１５】この走行用油圧回路であれば、左右方向切
換弁５，６を右側位置Ａとし、かつ左方向切換弁５のメ
ータイン開口面積を大で右方向切換弁６のメータイン開
口面積を小として左走行油圧モータ３を駆動側、右走行
油圧モータ４を被駆動側として矢印ａ方向に旋回走行す
る場合に、右走行油圧モータ４は制動状態となり駆動圧
ＰＬ２はカウンタバランス弁のセット圧となるし、左走
行油圧モータ３の駆動圧ＰＬ１は走行抵抗、旋回抵抗に
対応する高圧となるから、左方向切換弁５の入口圧Ｐ１
は右方向切換弁６の入口圧Ｐ２よりも高くなる。これに
より、切換弁２３は入口圧Ｐ１によって右位置Ｄとな
り、右方向切換弁５の戻り回路２１が補助リリーフ弁２
４の入口側に接続し、右方向切換弁６の戻り回路２２は
タンク２５に直接流出する。In this traveling hydraulic circuit, the left and right switching valves 5 and 6 are set to the right position A, the meter-in opening area of the left switching valve 5 is made large, and the meter-in opening area of the right switching valve 6 is made small. When the vehicle travels in the direction of arrow a with the left traveling hydraulic motor 3 as the driving side and the right traveling hydraulic motor 4 as the driven side, the right traveling hydraulic motor 4 enters a braking state and the driving pressure PL2 becomes the set pressure of the counterbalance valve. Since the driving pressure PL1 of the left traveling hydraulic motor 3 becomes a high pressure corresponding to the traveling resistance and the turning resistance, the inlet pressure P1 of the left direction switching valve 5 is increased.
Becomes higher than the inlet pressure P2 of the rightward switching valve 6. Thereby, the switching valve 23 is brought to the right position D by the inlet pressure P1, and the return circuit 21 of the rightward switching valve 5 is connected to the auxiliary relief valve 2
4, the return circuit 22 of the right-way switching valve 6 flows directly to the tank 25.
【００１６】補助リリーフ弁２４の入口側はセット圧Ｐ
3 まで上昇し、その圧油は回路２６、チェック弁２７よ
り右方向切換弁６の入口側回路２９に流入する。この
時、右方向切換弁６の下流側回路３４の圧力はカウンタ
バランス弁１１のセット圧ＰＬ２となり、上流側回路２
９の圧力Ｐ2 は右方向切換弁６の圧力補償弁７によって
きまる。このようであるから、補助リリーフ弁２４のセ
ット圧Ｐ3 が右方向切換弁６の下流側圧力＋差圧以上、
つまり右方向切換弁６のメータイン差圧と下流側圧力に
よって決定される上流側圧力が補助リリーフ弁２４のセ
ット圧Ｐ3 以下となると補助リリーフ弁２４の入口側の
圧油がチェック弁２７より右方向制御弁６の入口側回路
２９に流入し、上流側圧力Ｐ2 によって圧力補償弁７が
閉じ、可変油圧ポンプ１の吐出圧油が圧力補償弁７より
右走行油圧モータ４に供給しなくなる。右方向切換弁６
のメータイン開口面積が著しく小さく下流側圧力がカウ
ンタバランス弁セット圧＋メータイン差圧までしか上昇
しない時には可変容量油圧ポンプ１の吐出圧油は全量が
左走行油圧モータ３に供給されて駆動側流量低下が起き
ずに走行速度が低下することを防止する。The inlet side of the auxiliary relief valve 24 has a set pressure P
The pressure oil rises to 3, and flows from the circuit 26 and the check valve 27 into the inlet-side circuit 29 of the rightward switching valve 6. At this time, the pressure of the downstream circuit 34 of the rightward switching valve 6 becomes the set pressure PL2 of the counter balance valve 11, and the pressure of the upstream circuit 2
The pressure P 2 at 9 is determined by the pressure compensating valve 7 of the rightward switching valve 6. Since this be the case, the set pressure P 3 of the auxiliary relief valve 24 is in the right direction switching valve 6 downstream pressure + difference on pressure or,
That is, when the upstream pressure determined by the meter-in differential pressure of the rightward switching valve 6 and the downstream pressure becomes equal to or less than the set pressure P 3 of the auxiliary relief valve 24, the pressure oil on the inlet side of the auxiliary relief valve 24 becomes rightward from the check valve 27. After flowing into the inlet side circuit 29 of the direction control valve 6, the pressure compensating valve 7 is closed by the upstream pressure P 2 , and the pressure oil discharged from the variable hydraulic pump 1 is not supplied to the right traveling hydraulic motor 4 from the pressure compensating valve 7. Right direction switching valve 6
When the meter-in opening area is extremely small and the downstream pressure rises only up to the counterbalance valve set pressure + meter-in differential pressure, the entire discharge pressure oil of the variable displacement hydraulic pump 1 is supplied to the left traveling hydraulic motor 3 and the drive side flow rate decreases. The traveling speed is prevented from being reduced without causing the occurrence of the traveling speed.
【００１７】[0017]
【考案が解決しようとする課題】かかる先に提案した各
走行用油圧回路であると、外側走行モータ（駆動側）の
戻り油を内側走行モータ（被駆動側）へ回生する時の回
生油の圧力（内側走行モータへ押し込む圧力）は補助リ
リーフ弁２４で決定しているので車速（流量）によらず
回生時はその圧力はほぼ一定に保持される。In each of the previously proposed traveling hydraulic circuits, the return oil of the outer traveling motor (drive side) is regenerated to the inner traveling motor (driven side). Since the pressure (pressure to be pushed into the inner running motor) is determined by the auxiliary relief valve 24, the pressure is maintained substantially constant during regeneration regardless of the vehicle speed (flow rate).
【００１８】しかし車速（流量）が大きいほど回生油の
流量が多く流路抵抗による圧力損失は大となり、補助リ
リーフ弁２４部の回生流の圧力も大となるので、その分
リリーフ流量が大となって内側走行モータへの回生流量
が少なくなる。すなわち、先に提案した走行用油圧回路
では車速が大ほど回生流量が小となるから、その分可変
容量油圧ポンプ１の吐出量を増加する必要がある。However, as the vehicle speed (flow rate) increases, the flow rate of the regenerative oil increases, the pressure loss due to the flow path resistance increases, and the pressure of the regenerative flow at the auxiliary relief valve 24 increases, so that the relief flow rate increases accordingly. As a result, the regenerative flow to the inner traveling motor decreases. That is, in the traveling hydraulic circuit proposed earlier, the higher the vehicle speed, the smaller the regenerative flow rate. Therefore, it is necessary to increase the discharge amount of the variable displacement hydraulic pump 1 accordingly.
【００１９】このことを図表で示すと図６の（ａ），
（ｂ）となり、流量（車速）大の時には図６の（ａ）の
ように回生流量Ｑ3 が小となるから内側走行モータへの
流量Ｑ2 を可変容量油圧ポンプ１の吐出圧油で補償する
ことになる。なお、Ｑ1 が外側走行モータへの流量であ
る。This is shown in the form of a table in FIG.
(B) next, regenerative flow Q 3 is compensated flow rate Q 2 of the inner traveling motor from the small at the discharge pressure oil of the variable displacement hydraulic pump 1 as the flow rate (speed) in FIG. 6 when sized (a) Will do. Incidentally, Q 1 is a flow to the outer traveling motor.
【００２０】そこで、本考案は前述の課題を解決できる
ようにした走行用油圧回路を提供することを目的とす
る。Accordingly, an object of the present invention is to provide a traveling hydraulic circuit capable of solving the above-mentioned problems.
【００２１】[0021]
【課題を解決するための手段】可変容量油圧ポンプ１
と、この可変容量油圧ポンプ１の吐出圧油を左右走行油
圧モータ３，４に供給する左右方向切換弁５，６と、前
記可変容量油圧ポンプ１の容量を左右走行油圧モータ
３，４の負荷圧とポンプ吐出圧の差圧が一定となるよう
に制御する容量制御部材と、前記左右方向切換弁５，６
の上流側に設けられてロードチェック弁７と、負荷圧に
抗して下流側圧力によりロードチェック弁７を閉じ方向
に押す減圧弁８より成る圧力補償弁９を備え、左右方向
切換弁５，６の戻り回路２１，２２を補助リリーフ弁２
４とタンク２５に接続制御する切換弁２３を設け、この
補助リリーフ弁２４の入口側をチェック弁２７を介して
左右方向切換弁５，６の上流側回路２８，２９に接続
し、前記切換弁２３を左右方向切換弁５，６をメータイ
ン開口面積を異ならせて操作した時に高圧側の戻り回路
２１，２２を補助リリーフ弁２４に接続し、かつ絞りを
介してタンクに連通する位置となるようにした走行用油
圧回路。可変容量油圧ポンプ１と、この可変容量油圧ポ
ンプ１の吐出圧油を左右走行油圧モータ３，４に供給す
る左右方向切換弁５，６と、前記可変容量油圧ポンプ１
の容量を左右走行油圧モータ３，４の負荷圧とポンプ吐
出圧の差圧が一定となるように制御する容量制御部材１
０と、前記左右方向切換弁５，６の上流側に設けられて
負荷圧と上流側圧力によって左右方向切換弁５，６のメ
ータイン差圧を制御する圧力補償弁９とを備え、前記左
右方向切換弁５，６の戻り回路２１，２２を補助リリー
フ弁２４とタンク２５に接続制御する切換弁２３を設
け、この補助リリーフ弁２４の入口側をチェック弁２７
を介して左右方向切換弁５，６の上流側回路２８，２９
に接続し、前記切換弁２３を左右方向切換弁５，６をメ
ータイン開口面積を異ならせて操作した時に高圧側の戻
り回路２１，２２を補助リリーフ弁２４に接続し、かつ
絞りを介してタンクに連通する位置となるようにした走
行油圧回路。A variable displacement hydraulic pump 1 is provided.
Left and right direction switching valves 5 and 6 for supplying the discharge pressure oil of the variable displacement hydraulic pump 1 to the left and right traveling hydraulic motors 3 and 4; A pressure control member for controlling the pressure difference between the pressure and the pump discharge pressure to be constant;
And a pressure compensating valve 9 comprising a load check valve 7 provided on the upstream side and a pressure reducing valve 8 for pushing the load check valve 7 in the closing direction by a downstream pressure against the load pressure. 6 to the auxiliary relief valve 2
A switching valve 23 for controlling connection between the switching valve 4 and the tank 25 is provided, and an inlet side of the auxiliary relief valve 24 is connected to upstream circuits 28 and 29 of the left and right switching valves 5 and 6 via a check valve 27. When the left and right directional control valves 5 and 6 are operated with different meter-in opening areas, the return circuits 21 and 22 on the high pressure side are connected to the auxiliary relief valve 24 and communicate with the tank via the throttle. Traveling hydraulic circuit. A variable displacement hydraulic pump 1; left and right direction switching valves 5 and 6 for supplying discharge pressure oil of the variable displacement hydraulic pump 1 to left and right traveling hydraulic motors 3 and 4;
Control member 1 for controlling the displacement of the pump so that the differential pressure between the load pressure of the left and right traveling hydraulic motors 3 and 4 and the pump discharge pressure becomes constant.
0, and a pressure compensating valve 9 provided upstream of the left-right switching valves 5 and 6 to control the meter-in differential pressure of the left-right switching valves 5 and 6 by a load pressure and an upstream pressure. A switching valve 23 for controlling connection of the return circuits 21 and 22 of the switching valves 5 and 6 to the auxiliary relief valve 24 and the tank 25 is provided.
Upstream circuits 28, 29 of the left and right switching valves 5, 6
When the switching valve 23 is operated with the left and right switching valves 5 and 6 having different meter-in opening areas, the return circuits 21 and 22 on the high pressure side are connected to the auxiliary relief valve 24 and the tank is connected via a throttle. A traveling hydraulic circuit that is in a position to communicate with the vehicle.
【００２２】[0022]
【作 用】左右方向切換弁５，６をメータイン開口面
積が異なるように操作した時に駆動側の戻り圧油は所定
圧力に上昇して被駆動側の上流側回路に供給され、被駆
動側の圧力補償弁９のロードチェック弁７が閉じて、可
変容量油圧ポンプ１の容量が低下しないので、駆動側の
走行用油圧モータに十分な容量の圧油が供給されて車速
が低下することがないし、車速が大の時には被駆動側の
上流側回路に供給される油、つまり回生油の流量を大に
できるから可変容量油圧ポンプ１の容量を大幅に減らす
ことができる。左右方向切換弁５，６をメータイン開口
面積が異なるように操作した時に被駆動側の方向切換弁
における上流側回路に低圧油が供給されて圧力補償弁９
を閉じて可変容量油圧ポンプ１の吐出圧油が被駆動側の
走行油圧モータに供給されなくなるから、可変容量油圧
ポンプ１の吐出圧油は全量が駆動側の走行油圧モータに
全量供給されて走行速度が低下することを防止できる
し、車速が大の時には被駆動側の上流側回路に供給され
る油、つまり回生油の流量を大にできるから可変容量油
圧ポンプ１の容量を大幅に減らすことができる。[Operation] When the left and right direction switching valves 5 and 6 are operated so that the meter-in opening areas are different, the return pressure oil on the drive side rises to a predetermined pressure and is supplied to the upstream circuit on the driven side, and is supplied to the upstream circuit on the driven side. Since the load check valve 7 of the pressure compensating valve 9 is closed and the capacity of the variable displacement hydraulic pump 1 does not decrease, a sufficient amount of pressure oil is supplied to the driving hydraulic motor on the driving side, and the vehicle speed does not decrease. When the vehicle speed is high, the flow rate of the oil supplied to the driven-side upstream circuit, that is, the flow rate of the regenerative oil can be increased, so that the capacity of the variable displacement hydraulic pump 1 can be greatly reduced. When the left and right direction switching valves 5 and 6 are operated so as to have different meter-in opening areas, low pressure oil is supplied to the upstream circuit in the driven side direction switching valve and the pressure compensating valve 9 is supplied.
Is closed and the discharge hydraulic oil of the variable displacement hydraulic pump 1 is no longer supplied to the driven hydraulic motor on the driven side, so that the entire discharge hydraulic oil of the variable displacement hydraulic pump 1 is fully supplied to the drive hydraulic motor on the drive side and travels. It is possible to prevent the speed from decreasing, and when the vehicle speed is high, the flow rate of the oil supplied to the upstream circuit on the driven side, that is, the flow rate of the regenerative oil can be increased, so that the capacity of the variable displacement hydraulic pump 1 can be greatly reduced. Can be.
【００２３】[0023]
【実 施 例】次に本考案の実施例を説明する。なお、
従来と同一部材は符号を同一とする。図７は本考案の第
１実施例を示し、先に提案した図２に示すものと切換弁
２３が相違し、他の構成は同一である。前記切換弁２３
は図８に示すように、弁本体４０のスプール孔４１にス
プール４２を摺動自在に嵌挿して成り、そのスプール孔
４１には出口ポート４３を境として左右に第１・第２タ
ンクポート４４，４５と第１・第２ポート４６，４７が
形成され、その出口ポート４３は補助リリーフ弁２４の
入口側とチェック弁２７の入口側にそれぞれ連通し、第
１・第２タンクポート４４，４５はタンクポート４８に
それぞれ連通し、第１ポート４６は戻り回路２１に連通
し、第２ポート４７は戻り回路２２に連通している。[Embodiment] Next, an embodiment of the present invention will be described. In addition,
The same members as those in the related art have the same reference numerals. FIG. 7 shows a first embodiment of the present invention, in which the switching valve 23 is different from the previously proposed one shown in FIG. 2, and the other configuration is the same. The switching valve 23
As shown in FIG. 8, a spool 42 is slidably fitted in a spool hole 41 of a valve body 40, and the spool hole 41 has a first and second tank port 44 on the left and right with an outlet port 43 as a boundary. , 45 and first and second ports 46, 47 are formed, and the outlet port 43 thereof communicates with the inlet side of the auxiliary relief valve 24 and the inlet side of the check valve 27, respectively, and the first and second tank ports 44, 45 are formed. Are connected to the tank port 48, the first port 46 is connected to the return circuit 21, and the second port 47 is connected to the return circuit 22.
【００２４】前記スプール４２には第１ポート４６を出
口ポート４３と第１タンクポート４４に連通・遮断する
第１ランド部４９及び第２ポート４７を出口ポート４３
と第２タンクポート４５に連通・遮断する第２ランド部
５０を有し、この第１・第２ランド部４９，５０には第
１・第２切欠５１，５２がそれぞれ形成されている。そ
してスプール４２は左右のばね５３，５４でドレーン位
置Ｂに保持され、左受圧部３０の高圧油により左位置Ｃ
に押され、右受圧部３１の高圧油により右位置Ｄに押さ
れる。The spool 42 has a first land portion 49 and a second port 47 for connecting / disconnecting the first port 46 to / from the outlet port 43 and the first tank port 44.
And a second land portion 50 that communicates with and blocks the second tank port 45. First and second cutouts 51 and 52 are formed in the first and second land portions 49 and 50, respectively. The spool 42 is held at the drain position B by the left and right springs 53 and 54, and is moved to the left position C by the high pressure oil of the left pressure receiving portion 30.
And is pushed to the right position D by the high pressure oil of the right pressure receiving portion 31.
【００２５】スプール４２がドレーン位置の時には第１
ポート４６が第１タンクポート４４に連通し、かつ第１
ポート４６と出口ポート４３が遮断され、第２ポート４
７が第２タンクポート４５に連通しかつ第２ポート４７
と出口ポート４３が遮断する。スプール４２が左位置の
時には第１ポート４６と出口ポート４３が連通し、かつ
第２ポート４７と第２ポート４５が連通し、第１ポート
４６が切欠５１，５２でタンクポート４８に連通する。
スプール４２が右位置の時には第２ポート４７が出口ポ
ート４３に連通し、第１ポート４６と第１タンクポート
４４が連通し、第２ポート４７が切欠５１，５２でタン
クポート４８に連通する。When the spool 42 is at the drain position, the first
Port 46 communicates with the first tank port 44 and
The port 46 and the outlet port 43 are shut off, and the second port 4
7 communicates with the second tank port 45 and the second port 47
And the outlet port 43 is shut off. When the spool 42 is at the left position, the first port 46 communicates with the outlet port 43, the second port 47 communicates with the second port 45, and the first port 46 communicates with the tank port 48 through the notches 51 and 52.
When the spool 42 is at the right position, the second port 47 communicates with the outlet port 43, the first port 46 communicates with the first tank port 44, and the second port 47 communicates with the tank port 48 through the cutouts 51 and 52.
【００２６】このようであるから、左右方向切換弁５，
６を右側位置Ａとし、かつ左方向切換弁５のメータイン
開口面積を大で右方向切換弁６のメータイン開口面積を
小として左走行油圧モータ３を駆動側、右走行油圧モー
タ４を被駆動側として矢印ａ方向に旋回する場合に、右
走行油圧モータ４は制動状態となり駆動圧ＰＬ２はカウ
ンタバランス弁１３のセット圧となるし、左走行油圧モ
ータ３の駆動圧ＰＬ１は走行抵抗、旋回抵抗に対応する
高圧となるから、左走行油圧モータ５の入口圧Ｐ１は右
方向切換弁６の入口圧Ｐ２よりも高くなる。これによ
り、切換弁２３は入口圧Ｐ１によって左位置Ｃとなり、
左方向切換弁５の戻り回路２が補助リリーフ弁２４の入
口側に接続し、右方向切換弁６の戻り回路２２はタンク
２５に直接流出する。Because of this, the left / right directional control valve 5,
6, the left traveling hydraulic motor 3 is driven on the right side, and the right traveling hydraulic motor 4 is driven on the right side by setting the meter-in opening area of the left direction switching valve 5 to be large and the meter-in opening area of the right direction switching valve 6 to be small. When turning in the direction of arrow a, the right traveling hydraulic motor 4 is in a braking state, the driving pressure PL2 is the set pressure of the counterbalance valve 13, and the driving pressure PL1 of the left traveling hydraulic motor 3 is a driving resistance and a turning resistance. Since the pressure becomes correspondingly high, the inlet pressure P1 of the left traveling hydraulic motor 5 becomes higher than the inlet pressure P2 of the right direction switching valve 6. Thereby, the switching valve 23 is set to the left position C by the inlet pressure P1, and
The return circuit 2 of the leftward switching valve 5 is connected to the inlet side of the auxiliary relief valve 24, and the return circuit 22 of the rightward switching valve 6 flows directly to the tank 25.
【００２７】補助リリーフ弁２４の入口側はセット圧Ｐ
３まで上昇し、その圧油は回路２６、チェック弁２７よ
り右方向切換弁６の上流側回路２９に流入する。これに
より、被駆動側のロードチェック弁７が閉じて可変容量
油圧ポンプ１からロードチェック弁７を介して右走行油
圧モータ４へ流入する流量が減少する。よって、可変容
量油圧ポンプ１の吐出圧油の大部分が左走行モータ３へ
供給されて、馬力制御による可変容量油圧ポンプの容量
低下がおきないから、駆動側である左走行油圧モータ３
への流量が減少せずに車速が低下しない。The inlet side of the auxiliary relief valve 24 has a set pressure P
3 and the pressure oil flows from the circuit 26 and the check valve 27 into the upstream circuit 29 of the rightward switching valve 6. As a result, the load check valve 7 on the driven side is closed, and the flow rate flowing from the variable displacement hydraulic pump 1 to the right traveling hydraulic motor 4 via the load check valve 7 decreases. Therefore, most of the discharge pressure oil of the variable displacement hydraulic pump 1 is supplied to the left traveling motor 3 and the capacity of the variable displacement hydraulic pump is not reduced by the horsepower control.
The vehicle speed does not decrease without decreasing the flow rate to the vehicle.
【００２８】以上の説明は図２に示す先に提案したもの
と同様であり、次に切換弁２３に切欠５１、切欠５２を
設けたことによる作動を説明する。第１ポート４６に流
入した戻り油の一部は切欠５１、切欠５２より第１・第
２タンクポート４４，４５を経てタンクポート４８より
タンク２５に流出し、その流出量は車速（流量）によら
ずほぼ一定であるから大流量が流入した時より、小流量
が流入した時の方が回生流量（＝流入量−流出量）が少
なくなる。The above description is the same as the previously proposed one shown in FIG. 2. Next, the operation of the switching valve 23 provided with the notches 51 and 52 will be described. A part of the return oil that has flowed into the first port 46 flows out of the notch 51, the notch 52, through the first and second tank ports 44 and 45, and out of the tank port 48 to the tank 25, and the amount of the outflow depends on the vehicle speed (flow rate). Since the flow rate is almost constant, the regenerative flow rate (= inflow rate-outflow rate) is smaller when the small flow rate flows in than when the large flow rate flows in.
【００２９】図１０、図１１、図１２は本考案の第２、
第３、第４実施例を示し、先に提案した図３、図４、図
５に対応するものであり、切換弁２３の形状が異なるの
みであるから詳細な説明を省略する。FIGS. 10, 11 and 12 show the second embodiment of the present invention.
This shows the third and fourth embodiments and corresponds to FIGS. 3, 4 and 5 proposed earlier, and only the shape of the switching valve 23 is different, so detailed description is omitted.
【００３０】[0030]
【考案の効果】左右方向切換弁５，６をメータイン開口
面積が異なるように操作した時に駆動側の戻り圧油を所
定圧力に上昇して被駆動側の上流側回路に供給され、被
駆動側の圧力補償弁９のロードチェック弁７が閉じて、
可変容量油圧ポンプ１の容量が低下しないので、駆動側
の走行油圧モータに十分な容量の圧油が供給されて車速
が低下することがない。しかも、車速が大の時には被駆
動側の上流側回路に供給される油、つまり回生油の流量
を大にできるから可変容量油圧ポンプ１の容量を大幅に
減らすことができる。左右方向切換弁５，６をメータイ
ン開口面積が異なるように操作した時に被駆動側の方向
切換弁における上流側回路に低圧油が供給されて圧力補
償弁９を閉じて可変容量油圧ポンプ１の吐出圧油が被駆
動側の走行油圧モータに供給されなくなるから、可変容
量油圧ポンプ１の吐出圧油は全量が駆動側の走行油圧モ
ータに全量供給されて走行速度が低下することを防止で
きる。しかも、車速が大の時には被駆動側の上流側回路
に供給される油、つまり回生油の流量を大にできるから
可変容量油圧ポンプ１の容量を大幅に減らすことができ
る。When the left and right switching valves 5 and 6 are operated so as to have different meter-in opening areas, the return pressure oil on the drive side is raised to a predetermined pressure and supplied to the upstream circuit on the driven side, and is supplied to the driven side. The load check valve 7 of the pressure compensating valve 9 is closed,
Since the capacity of the variable displacement hydraulic pump 1 does not decrease, a sufficient amount of pressure oil is supplied to the traveling hydraulic motor on the driving side, and the vehicle speed does not decrease. In addition, when the vehicle speed is high, the flow rate of the oil supplied to the driven-side upstream circuit, that is, the flow rate of the regenerative oil can be increased, so that the capacity of the variable displacement hydraulic pump 1 can be greatly reduced. When the left and right direction switching valves 5 and 6 are operated so as to have different meter-in opening areas, low-pressure oil is supplied to the upstream circuit in the driven side direction switching valve to close the pressure compensating valve 9 and discharge the variable displacement hydraulic pump 1. Since the pressurized oil is no longer supplied to the driven hydraulic motor on the driven side, it is possible to prevent the entire amount of the discharge hydraulic oil from the variable displacement hydraulic pump 1 from being supplied to the driven hydraulic motor on the drive side, thereby preventing the traveling speed from decreasing. In addition, when the vehicle speed is high, the flow rate of the oil supplied to the driven-side upstream circuit, that is, the flow rate of the regenerative oil can be increased, so that the capacity of the variable displacement hydraulic pump 1 can be greatly reduced.
【図１】従来の油圧回路図である。FIG. 1 is a conventional hydraulic circuit diagram.
【図２】先に提案した油圧回路図である。FIG. 2 is a hydraulic circuit diagram proposed earlier.
【図３】先に提案した油圧回路図である。FIG. 3 is a hydraulic circuit diagram proposed earlier.
【図４】先に提案した油圧回路図である。FIG. 4 is a hydraulic circuit diagram proposed earlier.
【図５】先に提案した油圧回路図である。FIG. 5 is a hydraulic circuit diagram proposed earlier.
【図６】流量と回生流量の関係を示す図表である。FIG. 6 is a table showing a relationship between a flow rate and a regenerative flow rate.
【図７】本考案の第１実施例を示す油圧回路図である。FIG. 7 is a hydraulic circuit diagram showing the first embodiment of the present invention.
【図８】切換弁の断面図である。FIG. 8 is a sectional view of a switching valve.
【図９】流量と回生流量の関係を示す図表である。FIG. 9 is a table showing a relationship between a flow rate and a regenerative flow rate.
【図１０】本考案の第２実施例を示す油圧回路図であ
る。FIG. 10 is a hydraulic circuit diagram showing a second embodiment of the present invention.
【図１１】本考案の第３実施例を示す油圧回路図であ
る。FIG. 11 is a hydraulic circuit diagram showing a third embodiment of the present invention.
【図１２】本考案の第４実施例を示す油圧回路図であ
る。FIG. 12 is a hydraulic circuit diagram showing a fourth embodiment of the present invention.
１…可変容量油圧ポンプ、２…吐出路、３…左走行油圧
モータ、４…右走行油圧モータ、５…左方向切換弁、６
…右方向切換弁、９…圧力補償弁、２１…戻り回路、２
２…戻り回路、２３…切換弁、２４…補助リリーフ弁、
２５…タンク、２７…チェック弁、２８…上流側回路、
２９…上流側回路。DESCRIPTION OF SYMBOLS 1 ... Variable displacement hydraulic pump, 2 ... Discharge path, 3 ... Left traveling hydraulic motor, 4 ... Right traveling hydraulic motor, 5 ... Left direction switching valve, 6
... Right direction switching valve, 9 ... Pressure compensation valve, 21 ... Return circuit, 2
2: return circuit, 23: switching valve, 24: auxiliary relief valve,
25 tank, 27 check valve, 28 upstream circuit
29 ... upstream circuit.
───────────────────────────────────────────────────── フロントページの続き (58)調査した分野(Int.Cl.6，ＤＢ名) E02F 9/22 F15B 11/00 F15B 11/05 ──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. 6 , DB name) E02F 9/22 F15B 11/00 F15B 11/05
Claims (2)
油圧ポンプ１の吐出圧油を左右走行油圧モータ３，４に
供給する左右方向切換弁５，６と、前記可変容量油圧ポ
ンプ１の容量を左右走行油圧モータ３，４の負荷圧とポ
ンプ吐出圧の差圧が一定となるように制御する容量制御
部材と、前記左右方向切換弁５，６の上流側に設けられ
たロードチェック弁７と、負荷圧に抗して下流側圧力に
よりロードチェック弁７を閉じ方向に押す減圧弁８より
成る圧力補償弁９を備え、 左右方向切換弁５，６の戻り回路２１，２２を補助リリ
ーフ弁２４とタンク２５に接続制御する切換弁２３を設
け、この補助リリーフ弁２４の入口側をチェック弁２７
を介して左右方向切換弁５，６の上流側回路２８，２９
に接続し、前記切換弁２３を左右方向切換弁５，６をメ
ータイン開口面積を異ならせて操作した時に高圧側の戻
り回路２１，２２を補助リリーフ弁２４に接続し、かつ
絞りを介してタンクに連通する位置となるようにした走
行用油圧回路。1. A variable displacement hydraulic pump 1; left and right direction switching valves 5 and 6 for supplying discharge hydraulic oil of the variable displacement hydraulic pump 1 to left and right traveling hydraulic motors 3 and 4; And a load check valve 7 provided upstream of the left and right direction switching valves 5 and 6 to control the pressure difference between the load pressures of the left and right traveling hydraulic motors 3 and 4 and the pump discharge pressure to be constant. And a pressure compensating valve 9 comprising a pressure reducing valve 8 which pushes the load check valve 7 in the closing direction by a downstream pressure against the load pressure. The return circuits 21 and 22 of the left and right directional switching valves 5 and 6 are auxiliary relief valves. A switching valve 23 for controlling the connection between the auxiliary relief valve 24 and the tank 25 is provided.
Upstream circuits 28, 29 of the left and right switching valves 5, 6
When the switching valve 23 is operated with the left and right switching valves 5 and 6 having different meter-in opening areas, the return circuits 21 and 22 on the high pressure side are connected to the auxiliary relief valve 24 and the tank is connected via a throttle. A traveling hydraulic circuit that is in a position that communicates with the vehicle.
油圧ポンプ１の吐出圧油を左右走行油圧モータ３，４に
供給する左右方向切換弁５，６と、前記可変容量油圧ポ
ンプ１の容量を左右走行油圧モータ３，４の負荷圧とポ
ンプ吐出圧の差圧が一定となるように制御する容量制御
部材１０と、前記左右方向切換弁５，６の上流側に設け
られて負荷圧と上流側圧力によって左右方向切換弁５，
６のメータイン差圧を制御する圧力補償弁９とを備え、 前記左右方向切換弁５，６の戻り回路２１，２２を補助
リリーフ弁２４とタンク２５に接続制御する切換弁２３
を設け、この補助リリーフ弁２４の入口側をチェック弁
２７を介して左右方向切換弁５，６の上流側回路２８，
２９に接続し、前記切換弁２３を左右方向切換弁５，６
をメータイン開口面積を異ならせて操作した時に高圧側
の戻り回路２１，２２を補助リリーフ弁２４に接続し、
かつ絞りを介してタンクに連通する位置となるようにし
た請求項１記載の走行油圧回路。2. A variable displacement hydraulic pump 1; left and right direction switching valves 5 and 6 for supplying discharge hydraulic oil of the variable displacement hydraulic pump 1 to left and right traveling hydraulic motors 3 and 4; And a displacement control member 10 for controlling the differential pressure between the load pressure of the left and right traveling hydraulic motors 3 and 4 and the pump discharge pressure to be constant, and the load pressure provided upstream of the left and right direction switching valves 5 and 6. Left / right directional control valve 5, due to upstream pressure
6, a pressure compensating valve 9 for controlling the meter-in differential pressure, and a switching valve 23 for controlling connection of the return circuits 21 and 22 of the left-right switching valves 5 and 6 to an auxiliary relief valve 24 and a tank 25.
The inlet side of the auxiliary relief valve 24 is connected via a check valve 27 to an upstream circuit 28 of the
29, and the switching valve 23 is connected to the left and right switching valves 5, 6
Are operated with different meter-in opening areas, the return circuits 21 and 22 on the high pressure side are connected to the auxiliary relief valve 24,
2. The travel hydraulic circuit according to claim 1, wherein the travel hydraulic circuit is located at a position communicating with the tank via a throttle.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP1993028077U JP2594686Y2 (en) | 1993-05-27 | 1993-05-27 | Traveling hydraulic circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP1993028077U JP2594686Y2 (en) | 1993-05-27 | 1993-05-27 | Traveling hydraulic circuit |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH0687466U JPH0687466U (en) | 1994-12-22 |
| JP2594686Y2 true JP2594686Y2 (en) | 1999-05-10 |
Family
ID=12238714
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP1993028077U Expired - Lifetime JP2594686Y2 (en) | 1993-05-27 | 1993-05-27 | Traveling hydraulic circuit |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2594686Y2 (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP3736657B2 (en) * | 1997-04-25 | 2006-01-18 | 株式会社小松製作所 | Hydraulic motor drive system |
-
1993
- 1993-05-27 JP JP1993028077U patent/JP2594686Y2/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| JPH0687466U (en) | 1994-12-22 |
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