JP3791842B2 - Hydraulic circuit for construction machinery - Google Patents

Hydraulic circuit for construction machinery Download PDF

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Publication number
JP3791842B2
JP3791842B2 JP2003074556A JP2003074556A JP3791842B2 JP 3791842 B2 JP3791842 B2 JP 3791842B2 JP 2003074556 A JP2003074556 A JP 2003074556A JP 2003074556 A JP2003074556 A JP 2003074556A JP 3791842 B2 JP3791842 B2 JP 3791842B2
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Prior art keywords
switching valve
valve
oil
output
oil passage
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JP2004278241A (en
Inventor
雅敏 中根
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Sumitomo SHI Construction Machinery Co Ltd
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Sumitomo SHI Construction Machinery Co Ltd
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Description

【０００１】
【発明の属する技術分野】
この発明は、建設機械の油圧回路に関するものである。更に詳細には、予備切換弁と旋回切換弁を一の油圧ポンプのセンタ油路に接続した場合の操作性を向上させた建設機械の油圧回路に関する。
【０００２】
【従来技術】
油圧ショベル等の建設機械の油圧回路にブレーカ又は破砕機等を制御するための予備切換弁を接続した従来の油圧回路は多数ある。このような油圧回路を掲載した公報としては例えば、公開特許公報、同特開平４−３１２６３０号、同特開平８−６０７１０号、同特開平８−６８０７７号等がある。また、旋回モータを制御する旋回切換弁を接続した従来の油圧回路も多数にある。このような油圧回路を掲載した公報としては例えば、公開特許公報、同特開平４−３１２６３０号がある。しかし、予備切換弁と旋回切換弁とを同一油圧ポンプに接続した油圧回路、特にブレーカ又は破砕機等と旋回モータとを同時に使用する場合の制御性を考慮した油圧回路は殆ど公開されていない。
【０００３】
しかし、油圧回路の構成上から同一油圧ポンプのセンタ油路に（又は同一のグループに）予備切換弁と旋回切換弁を同一油圧ポンプのセンタ油路に接続する場合もある。例えば、公開特許公報、特開平１１−２２９４２２号には同一の油圧ポンプに予備切換弁と旋回切換弁とがパラレル接続されている。このような油圧回路では、旋回中に予備操作（ブレーカ又は破砕機の操作）をしたり、中止したりすると旋回が急減速したり、急加速したりする。また、予備操作中に旋回操作をすると旋回の動きが緩慢になり、操作性が劣化するという課題がある。
【０００４】
【発明が解決しようとする課題】
本発明は、上記事実に鑑みなされたものであり、同一の油圧ポンプのセンタ油路に予備切換弁と旋回切換弁とを接続した回路で、同時操作しても上記した不具合が生じない建設機械の油圧回路を提供することを課題とする。
【０００５】
【課題を解決するための手段】
本発明は上記の課題を解決するための手段として以下の構成を採用している。即ち、
請求項１に記載の発明は、ブレーカ又は破砕機等を接続して制御する予備切換弁と旋回モータを制御する旋回切換弁を一の油圧ポンプのセンタ油路に接続した建設機械の油圧回路において、該予備切換弁と旋回切換弁を同時に操作したときに他の油圧ポンプから油圧を供給可能にするために、該他の油圧ポンプのセンタ油路にカット弁を設けると共に、該カット弁の上流に分岐油路を設けて前記予備切換弁の入力油路に合流接続したことを特徴している。
本発明は同時操作において圧油の供給不足になる状態を回避したことを主な特徴としている。
【０００６】
また、請求項２に記載の発明は、請求項１に記載の油圧回路において、前記一の油圧ポンプから前記予備切換弁の油圧供給路に絞り抵抗を備えた絞り切換弁を設けると共に、前記旋回用リモコン弁の操作検出回路を設け、該操作検出回路の出力により該絞り切換弁の絞り抵抗を増減させて前記旋回モータの油圧供給を確保するように構成したことを特徴としている。
本発明は同時操作において、旋回動作の円滑な操作を可能にしたことを主な特徴としている。
【０００７】
請求項３に記載の発明は、請求項１又は請求項２に記載の油圧回路において、前記分岐油路を前記旋回切換弁の入力油路に更に合流接続したことを特徴としている。
【０００８】
【発明の実施の形態】
以下本発明の実施形態を図に基づいて説明する。
図１は本願発明の第１実施形態を示す油圧回路図である。図１において、第１油圧ポンプ（一の油圧ポンプ）１１のセンタ油路１２に旋回切換弁１３及び予備切換弁１４がパラレルに接続されている。旋回切換弁１３のパイロットポートにはリモコン弁１５がパイロット油圧路１５ａ、１５ｂにより接続されている。また、パイロット油圧路１５ａ、１５ｂの両油路間にシャトル弁１７が接続されている。さらに、旋回切換弁１３の出力ポートには旋回用油圧モータ（以下旋回モータという）１９が接続されている。
【０００９】
同様に、予備切換弁１４のパイロットポートにはリモコン弁１６がパイロット油圧路１６ａ、１６ｂにより接続され、パイロット油圧路１６ａ、１６ｂは上記パイロットポートに接続される他にパイロット油圧路１６ａ、１６ｂ間にシャトル弁１８が接続されている。シャトル弁１８の出力ポートには圧力スイッチ（操作検出回路）２１を接続している。また、予備切換弁１４の出力ポートにはブレーカ（又は破砕機）のアクチュエータ２０が接続されている。
【００１０】
一方、第２油圧ポンプ（他の油圧ポンプ）３１のセンタ油路３２の下流にはカットオフ用の切換弁（カット弁）３３が挿入されている。カット弁３３の制御ポートには電磁切換弁３５の出力ポートに接続され、電磁切換弁３５の入力ポートは油タンクＴと、パイロット油路３６を介してシャトル弁１７の出力ポートに夫々接続されている。電磁切換弁３５のソレノイド２１ａは圧力スイッチ２１の出力端に接続されている。また、カット弁３３の上流に分岐油路３４を設けて、分岐油路３４の他端を予備切換弁１４の入力油路１４ｃにチェック弁を利用して合流接続する。又入力油路１４ｃには絞り抵抗を備えた絞り切換弁２２が挿入されている。絞り切換弁２２は連通油路と絞り油路とを備え、絞り切換弁２２の制御ポートはシャトル弁１７の出力ポートに接続されている。
【００１１】
本実施形態は上記構成により以下のように機能する。即ち、旋回リモコン弁１５を操作するとシャトル弁１７の出力ポートがパイロット油圧となり、このパイロット油圧により絞り切換弁２２の制御ポートに印加して絞り切換弁２２を絞り側に切換える。更に、上記のパイロット油圧は電磁切換弁３５の入力ポートに印加する。この場合に予備切換弁１４のリモコン弁１６を操作するとシャトル弁１８にパイロット油圧が現れ、圧力スイッチ２１をオンにする。これにより、電磁切換弁３５のソレノイドに電流が流れ、電磁切換弁３５は連通状態に切り換る。従って、カット弁３３がカット状態になり、第２油圧ポンプ３１の圧油がセンタ油路３２、分岐油路３４を経て予備切換弁１４の入力油路１４ｃに合流される。
【００１２】
なお、この場合において、旋回リモコン弁１５のパイロット圧により絞り切換弁２２が絞り側に切換えられているために、旋回モータ１９にも十分な作動油が第１油圧ポンプ１１から供給されると共に、ブレーカ（又は破砕機）のアクチュエータ２０には第１油圧ポンプ１１からの作動油の供給と第２油圧ポンプ３１からの作動油の供給が同時に行われるために十分な供給を受けて円滑な操作が可能になる。
【００１３】
上記の場合において、予備切換弁１４のリモコン弁１６を操作しなければ電磁切換弁３５の出力は油タンク圧となり、カット弁３３は連通状態にあるために、第２油圧ポンプ３１の圧油は分岐油路３４に流れない。また、絞り弁２２は絞り状態に切り換るが、旋回モータ１９にもブレーカ（又は破砕機）のアクチュエータ２０にも何らの不都合も生じない。同様に、ブレーカ（又は破砕機）のアクチュエータ２０を単独に操作する場合は従来回路と同様な回路構成となり、何らの不都合も生じない。
【００１４】
図２は上記した実施形態の一部を変更した第２実施形態である。第２実施形態は図２と図１との比較から明らかなように、第２油圧ポンプ３１のセンタ油路３２の分岐油路３４を第１油圧ポンプ１１の共通な供給油路１２ｃに合流させた点で異なる。なお、図２の油圧回路の代わり、分岐油路３４を旋回切換弁１３の入力油路１３ｃ、予備切換弁１４の入力油路１４ｃの夫々に合流接続してもよい。
【００１５】
この実施形態は上記第１実施形態の説明からも推測できるように、旋回リモコン弁１５と予備リモコン弁１６を同時に操作した場合にのみ第２油圧ポンプ３１からの油圧が旋回切換弁１３の入力油路１３ｃ、予備切換弁１４の入力油路１４ｃの夫々に供給される。旋回リモコン弁１５又は予備リモコン弁１６のみを単独に操作した場合は従来の油圧回路（第２油圧ポンプ３１からの油圧を分岐油路３４を介して旋回切換弁１３の入力油路１３ｃ、予備切換弁１４の入力油路１４ｃの何れにも合流接続していない油圧回路）と機能的には同一である。
【００１６】
以上本発明の実施形態を図面に基づいて詳述してきたが、本発明の技術的範囲はこれに限られるものではない。
【００１７】
【発明の効果】
予備操作と旋回操作とを同時に操作した場合でも旋回操作を円滑に操作できるという効果がある。
【図面の簡単な説明】
【図１】 本発明を実施する実施形態を示す。
【図２】 本発明の別の実施形態を示す。
【符号の説明】
１１ 第１油圧ポンプ（一の油圧ポンプ）
１３ 旋回切換弁
１４ 予備切換弁
１５ 旋回用リモコン弁
１６ 予備用リモコン弁
１７ シャトル弁（第１シャトル弁）
１８ シャトル弁（第２シャトル弁）
１９ 旋回モータ
２０ ブレーカ又は破砕機等のアクチュエータ
２１ 圧力スイッチ
２２ 絞り切換弁
３１ 第２油圧ポンプ（他の油圧ポンプ）
３３ カット弁
３５ 電磁弁[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a hydraulic circuit of a construction machine. More specifically, the present invention relates to a hydraulic circuit for a construction machine that improves operability when a preliminary switching valve and a swing switching valve are connected to a center oil passage of one hydraulic pump.
[0002]
[Prior art]
There are many conventional hydraulic circuits in which a standby switching valve for controlling a breaker or a crusher is connected to a hydraulic circuit of a construction machine such as a hydraulic excavator. For example, Japanese Patent Laid-Open No. 4-31630, Japanese Patent Laid-Open No. 8-60710, and Japanese Patent Laid-Open No. 8-68077 disclose such a hydraulic circuit. There are also a number of conventional hydraulic circuits connected to a turning switching valve for controlling the turning motor. For example, Japanese Patent Laid-Open No. 4-31630 and Japanese Patent Laid-Open No. 4-31630 disclose such a hydraulic circuit. However, a hydraulic circuit in which a preliminary switching valve and a swing switching valve are connected to the same hydraulic pump, in particular, a hydraulic circuit in consideration of controllability when a breaker or a crusher or the like and a swing motor are used simultaneously has not been disclosed.
[0003]
However, in some cases, the preliminary switching valve and the swing switching valve are connected to the center oil passage of the same hydraulic pump in the center oil passage of the same hydraulic pump (or in the same group) due to the configuration of the hydraulic circuit. For example, in Japanese Patent Laid-Open No. 11-229422, a preliminary switching valve and a turning switching valve are connected in parallel to the same hydraulic pump. In such a hydraulic circuit, when a preliminary operation (operation of a breaker or a crusher) is performed during a turn or when the turn is stopped, the turn is suddenly decelerated or accelerated. In addition, if the turning operation is performed during the preliminary operation, there is a problem that the turning movement becomes slow and the operability is deteriorated.
[0004]
[Problems to be solved by the invention]
The present invention has been made in view of the above facts, and is a construction machine in which the above-mentioned problems do not occur even when operated simultaneously in a circuit in which a preliminary switching valve and a turning switching valve are connected to the center oil passage of the same hydraulic pump. It is an object of the present invention to provide a hydraulic circuit.
[0005]
[Means for Solving the Problems]
The present invention employs the following configuration as means for solving the above-described problems. That is,
The invention according to claim 1 is a hydraulic circuit of a construction machine in which a preliminary switching valve for controlling by connecting a breaker or a crusher and a swing switching valve for controlling a swing motor are connected to a center oil passage of one hydraulic pump. In order to supply hydraulic pressure from another hydraulic pump when the preliminary switching valve and the swing switching valve are operated simultaneously, a cut valve is provided in the center oil passage of the other hydraulic pump, and upstream of the cut valve. A branching oil passage is provided in the main oil passage and joined to the input oil passage of the preliminary switching valve.
The main feature of the present invention is that it avoids a situation where pressure oil is insufficiently supplied during simultaneous operation.
[0006]
According to a second aspect of the present invention, in the hydraulic circuit according to the first aspect, a throttle switching valve having a throttle resistance is provided in the hydraulic pressure supply path of the preliminary switching valve from the one hydraulic pump, and the turning An operation detection circuit for the remote control valve is provided, and the throttle resistance of the throttle switching valve is increased / decreased by the output of the operation detection circuit to ensure the hydraulic pressure supply of the swing motor.
The main feature of the present invention is that it is possible to smoothly perform a turning operation in the simultaneous operation.
[0007]
According to a third aspect of the present invention, in the hydraulic circuit according to the first or second aspect, the branch oil passage is further joined and connected to an input oil passage of the turning switching valve.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a hydraulic circuit diagram showing a first embodiment of the present invention. In FIG. 1, a turning switching valve 13 and a standby switching valve 14 are connected in parallel to a center oil passage 12 of a first hydraulic pump (one hydraulic pump) 11. A remote control valve 15 is connected to the pilot port of the turning switching valve 13 through pilot hydraulic passages 15a and 15b. A shuttle valve 17 is connected between the two oil passages of the pilot hydraulic passages 15a and 15b. Further, a turning hydraulic motor (hereinafter referred to as a turning motor) 19 is connected to the output port of the turning switching valve 13.
[0009]
Similarly, a remote control valve 16 is connected to the pilot port of the preliminary switching valve 14 through pilot hydraulic passages 16a and 16b. The pilot hydraulic passages 16a and 16b are connected to the pilot hydraulic passages 16a and 16b in addition to being connected to the pilot port. A shuttle valve 18 is connected. A pressure switch (operation detection circuit) 21 is connected to the output port of the shuttle valve 18. A breaker (or crusher) actuator 20 is connected to the output port of the preliminary switching valve 14.
[0010]
On the other hand, a cut-off switching valve (cut valve) 33 is inserted downstream of the center oil passage 32 of the second hydraulic pump (other hydraulic pump) 31. The control port of the cut valve 33 is connected to the output port of the electromagnetic switching valve 35. The input port of the electromagnetic switching valve 35 is connected to the output port of the shuttle valve 17 via the oil tank T and the pilot oil passage 36, respectively. Yes. The solenoid 21 a of the electromagnetic switching valve 35 is connected to the output end of the pressure switch 21. A branch oil passage 34 is provided upstream of the cut valve 33, and the other end of the branch oil passage 34 is joined and connected to the input oil passage 14c of the auxiliary switching valve 14 using a check valve. A throttle switching valve 22 having a throttle resistance is inserted in the input oil passage 14c. The throttle switching valve 22 includes a communication oil path and a throttle oil path, and the control port of the throttle switching valve 22 is connected to the output port of the shuttle valve 17.
[0011]
This embodiment functions as follows by the above configuration. That is, when the swing remote control valve 15 is operated, the output port of the shuttle valve 17 becomes the pilot hydraulic pressure, and the pilot hydraulic pressure is applied to the control port of the throttle switching valve 22 to switch the throttle switching valve 22 to the throttle side. Further, the pilot hydraulic pressure is applied to the input port of the electromagnetic switching valve 35. In this case, when the remote control valve 16 of the preliminary switching valve 14 is operated, the pilot hydraulic pressure appears in the shuttle valve 18 and the pressure switch 21 is turned on. Thereby, an electric current flows into the solenoid of the electromagnetic switching valve 35, and the electromagnetic switching valve 35 switches to a communication state. Accordingly, the cut valve 33 is in the cut state, and the pressure oil of the second hydraulic pump 31 is joined to the input oil passage 14c of the preliminary switching valve 14 via the center oil passage 32 and the branch oil passage 34.
[0012]
In this case, since the throttle switching valve 22 is switched to the throttle side by the pilot pressure of the swing remote control valve 15, sufficient hydraulic oil is supplied also to the swing motor 19 from the first hydraulic pump 11, The breaker (or crusher) actuator 20 is supplied with hydraulic oil from the first hydraulic pump 11 and hydraulic oil from the second hydraulic pump 31 at the same time. It becomes possible.
[0013]
In the above case, if the remote control valve 16 of the preliminary switching valve 14 is not operated, the output of the electromagnetic switching valve 35 becomes the oil tank pressure, and the cut valve 33 is in a communicating state. It does not flow into the branch oil passage 34. Although the throttle valve 22 is switched to the throttled state, neither inconvenience occurs in the swing motor 19 nor the actuator 20 of the breaker (or crusher). Similarly, when operating the actuator 20 of a breaker (or crusher) independently, it becomes a circuit structure similar to a conventional circuit, and no inconvenience arises.
[0014]
FIG. 2 shows a second embodiment in which a part of the above-described embodiment is changed. As apparent from the comparison between FIG. 2 and FIG. 1, in the second embodiment, the branch oil passage 34 of the center oil passage 32 of the second hydraulic pump 31 is joined to the common supply oil passage 12 c of the first hydraulic pump 11. It is different in point. Instead of the hydraulic circuit in FIG. 2, the branch oil passage 34 may be joined and connected to the input oil passage 13 c of the turning switching valve 13 and the input oil passage 14 c of the standby switching valve 14.
[0015]
In this embodiment, as can be inferred from the description of the first embodiment, the hydraulic pressure from the second hydraulic pump 31 is changed to the input oil of the swing switching valve 13 only when the swing remote control valve 15 and the spare remote control valve 16 are operated simultaneously. The oil is supplied to the passage 13c and the input oil passage 14c of the auxiliary switching valve 14, respectively. When only the swing remote control valve 15 or the spare remote control valve 16 is operated alone, the hydraulic circuit of the related art (the oil pressure from the second hydraulic pump 31 via the branch oil path 34, the input oil path 13c of the swing switching valve 13, the preliminary switching). This is functionally the same as a hydraulic circuit that is not joined and connected to any of the input oil passages 14c of the valve 14.
[0016]
Although the embodiment of the present invention has been described in detail with reference to the drawings, the technical scope of the present invention is not limited to this.
[0017]
【The invention's effect】
Even when the preliminary operation and the turning operation are simultaneously performed, there is an effect that the turning operation can be smoothly performed.
[Brief description of the drawings]
FIG. 1 shows an embodiment for carrying out the present invention.
FIG. 2 shows another embodiment of the present invention.
[Explanation of symbols]
11 First hydraulic pump (one hydraulic pump)
13 Rotation switching valve 14 Preliminary switching valve 15 Rotating remote control valve 16 Preliminary remote control valve 17 Shuttle valve (first shuttle valve)
18 Shuttle valve (second shuttle valve)
19 Rotating motor 20 Actuator 21 such as breaker or crusher 21 Pressure switch 22 Restriction switching valve 31 Second hydraulic pump (other hydraulic pump)
33 Cut valve 35 Solenoid valve

Claims (2)

ブレーカ又は破砕機等を接続して制御する予備切換弁と旋回モータを制御する旋回切換弁を一の油圧ポンプのセンタ油路に接続し、該予備切換弁と旋回切換弁を同時操作したときに他の油圧ポンプからの油圧を供給可能にした建設機械の油圧回路において、
前記一の油圧ポンプから前記予備切換弁への入力油路に連通油路と絞り油路とを切換える絞り切換弁を挿入し、該他の油圧ポンプのセンタ油路にカット弁を設け、該カット弁の上流側に分岐油路を設けて前記予備切換弁の入力油路に合流接続し、該カット弁の制御ポートに電磁切換弁の出力ポートを接続し、該電磁切換弁の入力ポートには油タンクと前記旋回切換弁用リモコン弁の２出力油路間に設けた第１シャトル弁の出力を接続し、該電磁切換弁のソレノイドに前記予備切換弁用リモコン弁の２出力油路間に設けた第２シャトル弁の出力を圧力スイッチを介して接続し、更に、第１シャトル弁の出力を前記絞り切換弁の制御ポートに接続し、
第１シャトル弁の出力及び第２シャトル弁の出力が各々パイロット圧になったときはカット弁の油路が閉じ、他の油圧ポンプの圧油が前記予備切換弁の入力油路に合流されると共に一の油圧ポンプから前記予備切換弁の入力油路への圧油供給が絞られるように構成したことを特徴とする建設機械の油圧回路。When a spare switching valve for controlling by connecting a breaker or a crusher or the like and a turning switching valve for controlling a turning motor are connected to the center oil passage of one hydraulic pump, and the preliminary switching valve and the turning switching valve are operated simultaneously In the hydraulic circuit of construction machinery that can supply hydraulic pressure from other hydraulic pumps,
Inserting a throttle switching valve for switching between a communication oil path and a throttle oil path into the input oil path from the one hydraulic pump to the preliminary switching valve, and providing a cut valve in the center oil path of the other hydraulic pump, A branch oil passage is provided on the upstream side of the valve and joined to the input oil passage of the preliminary switching valve, and the output port of the electromagnetic switching valve is connected to the control port of the cut valve, and the input port of the electromagnetic switching valve The output of the first shuttle valve provided between the oil tank and the two output oil paths of the swivel switching valve remote control valve is connected, and the solenoid of the electromagnetic switching valve is connected between the two output oil paths of the spare switching valve remote control valve. Connecting the output of the provided second shuttle valve via a pressure switch, and further connecting the output of the first shuttle valve to the control port of the throttle switching valve;
When the output of the first shuttle valve and the output of the second shuttle valve reach the pilot pressure, the oil passage of the cut valve is closed, and the pressure oil of the other hydraulic pump is joined to the input oil passage of the preliminary switching valve. And a hydraulic circuit for a construction machine, characterized in that the pressure oil supply from one hydraulic pump to the input oil passage of the preliminary switching valve is restricted . ブレーカ又は破砕機等を接続して制御する予備切換弁と旋回モータを制御する旋回切換弁を一の油圧ポンプのセンタ油路に接続し、該予備切換弁と旋回切換弁を同時操作したときに他の油圧ポンプからの油圧を供給可能にした建設機械の油圧回路において、
前記一の油圧ポンプから前記予備切換弁への入力油路に連通油路と絞り油路とを切換える絞り切換弁を挿入し、該他の油圧ポンプのセンタ油路にカット弁を設け、該カット弁の上流側に分岐油路を設けて前記絞り切換弁の入力側油路に合流接続し、該カット弁の制御ポートに電磁切換弁の出力ポートを接続し、該電磁切換弁の入力ポートには油タンクと前記旋回切換弁用リモコン弁の２出力油路間に設けた第１シャトル弁の出力を接続し、該電磁切換弁のソレノイドに前記予備切換弁用リモコン弁の２出力油路間に設けた第２シャトル弁の出力を圧力スイッチを介して接続し、更に、第１シャトル弁の出力を前記絞り切換弁の制御ポートに接続し、
第１シャトル弁の出力及び第２シャトル弁の出力が各々パイロット圧になったときはカット弁の油路が閉じ、他の油圧ポンプの圧油が前記絞り切換弁の入力側油路に合流されると共に合流された圧油供給が絞られるように構成したことを特徴とする建設機械の油圧回路。When a spare switching valve for controlling by connecting a breaker or a crusher or the like and a turning switching valve for controlling a turning motor are connected to the center oil passage of one hydraulic pump, and the preliminary switching valve and the turning switching valve are operated simultaneously In the hydraulic circuit of construction machinery that can supply hydraulic pressure from other hydraulic pumps,
Inserting a throttle switching valve for switching between a communication oil path and a throttle oil path into the input oil path from the one hydraulic pump to the preliminary switching valve, and providing a cut valve in the center oil path of the other hydraulic pump, A branch oil passage is provided on the upstream side of the valve and joined to the input oil passage of the throttle switching valve. The output port of the electromagnetic switching valve is connected to the control port of the cut valve, and the input port of the electromagnetic switching valve is connected. Is connected to the output of the first shuttle valve provided between the oil tank and the two output oil paths of the swivel switching valve remote control valve, and the solenoid of the electromagnetic switching valve is connected between the two output oil paths of the spare switching valve remote control valve. The output of the second shuttle valve provided on the pressure switch is connected via a pressure switch, and the output of the first shuttle valve is connected to the control port of the throttle switching valve,
When the output of the first shuttle valve and the output of the second shuttle valve reach the pilot pressure, the oil passage of the cut valve is closed, and the pressure oil of the other hydraulic pump is joined to the input side oil passage of the throttle switching valve. construction machine hydraulic circuit, characterized in that Rutotomoni merging been pressurized oil supply is configured such that squeezed.
JP2003074556A 2003-03-18 2003-03-18 Hydraulic circuit for construction machinery Expired - Fee Related JP3791842B2 (en)

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