JPH02167934A - Hydraulic circuit of switch valve for attachment - Google Patents
Hydraulic circuit of switch valve for attachmentInfo
- Publication number
- JPH02167934A JPH02167934A JP63320370A JP32037088A JPH02167934A JP H02167934 A JPH02167934 A JP H02167934A JP 63320370 A JP63320370 A JP 63320370A JP 32037088 A JP32037088 A JP 32037088A JP H02167934 A JPH02167934 A JP H02167934A
- Authority
- JP
- Japan
- Prior art keywords
- valve
- switching valve
- attachment
- hydraulic pump
- switch valve
- 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.)
- Granted
Links
- 238000010586 diagram Methods 0.000 description 3
- 238000010276 construction Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000004891 communication Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 238000007789 sealing Methods 0.000 description 1
- 239000002699 waste material Substances 0.000 description 1
Classifications
-
- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02F—DREDGING; SOIL-SHIFTING
- E02F9/00—Component parts of dredgers or soil-shifting machines, not restricted to one of the kinds covered by groups E02F3/00 - E02F7/00
- E02F9/20—Drives; Control devices
- E02F9/22—Hydraulic or pneumatic drives
- E02F9/2221—Control of flow rate; Load sensing arrangements
- E02F9/2239—Control of flow rate; Load sensing arrangements using two or more pumps with cross-assistance
-
- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02F—DREDGING; SOIL-SHIFTING
- E02F9/00—Component parts of dredgers or soil-shifting machines, not restricted to one of the kinds covered by groups E02F3/00 - E02F7/00
- E02F9/20—Drives; Control devices
- E02F9/22—Hydraulic or pneumatic drives
- E02F9/2278—Hydraulic circuits
- E02F9/2292—Systems with two or more pumps
Landscapes
- Engineering & Computer Science (AREA)
- Mining & Mineral Resources (AREA)
- Civil Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Structural Engineering (AREA)
- Physics & Mathematics (AREA)
- Fluid Mechanics (AREA)
- Operation Control Of Excavators (AREA)
- Fluid-Pressure Circuits (AREA)
Abstract
Description
【発明の詳細な説明】
〔産業上の利用分野〕
この発明は、土木建設機械の油圧回路に係り、特にアタ
ッチメントを備える場合のアタッチメント用切換弁の油
圧回路の改良に関する。DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a hydraulic circuit for a civil engineering construction machine, and more particularly to an improvement in a hydraulic circuit for an attachment switching valve when an attachment is provided.
従来、土木建設機械、特にパワーショベルの油圧回路に
おいては、その操作性の便宜から、例えば第１の油圧ポ
ンプにより、旋回、アーム、走行（左（ＩＩ！Ｉ）の制
御を行い、第２の油圧ポンプにより、ブーム、バゲット
、走行（右Ｏｌ）の制御を行うよう構成したものが知ら
れている。しかるに、近年この種のパワーショベルでは
、アタッチメントとして油圧ブレーカや油圧ベンチャー
等を付加することから、その油圧回路にアタッチメント
用切換弁を常備する傾向にある。この場合、前述したよ
うに、パワーショベルの油圧回路では、油圧ポンプが旋
回系とブーム系に分けられているため、アタッチメント
用切換弁はいずれかの切換弁グループ（制御弁）内に設
置される。Conventionally, in the hydraulic circuit of civil engineering construction machines, especially power excavators, for convenience of operability, for example, the first hydraulic pump controls the swing, arm, and travel (left (II!I)), and the second It is known that a hydraulic pump is used to control the boom, baguette, and travel (right Ol).However, in recent years, this type of power excavator has started to add attachments such as hydraulic breakers and hydraulic ventures. In this case, as mentioned above, in the hydraulic circuit of a power excavator, the hydraulic pump is divided into the swing system and the boom system, so there is a tendency to always have a switching valve for the attachment in the hydraulic circuit. is installed in one of the switching valve groups (control valves).
例えば、第３図は、従来のアタッチメント用切換弁を常
備したパワーショベル等の油圧回路の構成例を示すもの
である。第３図において、参照符号１０は第１の油圧ポ
ンプを示し、１２は第２の油圧ポンプを示す、第１の油
圧ポンプ１０には、旋回用切換弁１４、アーム用切換弁
１６、走行（左り用切換弁１８、バイパス開閉弁２０が
それぞれ接続されて第１の制御弁２２を構成している。For example, FIG. 3 shows an example of the configuration of a hydraulic circuit for a power shovel or the like that is equipped with a conventional attachment switching valve. In FIG. 3, reference numeral 10 indicates a first hydraulic pump, and 12 indicates a second hydraulic pump. The left-hand switching valve 18 and the bypass on-off valve 20 are connected to each other to form a first control valve 22 .
また、第２の油圧ポンプ１２には、ブーム用切換弁２４
、パケット用切換弁２６、アタッチメント用切換弁２８
、走行（台間）用切換弁３０がそれぞれ接続されて第２
の制御弁３２を構成している。この場合、前記アタッチ
メント用切換弁２８は、第４図に示すように、第２の油
圧ポンプ１２に接続された供給油路３４が切換弁内部油
路３６と連通し、スプール３８の操作によってそれぞれ
給排ボート４０．４２を介してアタッチメントとの油路
の接続を行うよう構成される。なお、参照符号４４．４
６．４８はそれぞれセンタバイパスを禾すこのように、
従来においては、アタッチメント用切換弁を旋回系（第
１の制御弁２２）またはブーム系（第２の制御弁３２）
を構成する油圧回路のいずれの制御弁間に常備させても
問題はなかった。The second hydraulic pump 12 also includes a boom switching valve 24.
, packet switching valve 26, attachment switching valve 28
, travel (inter-machine) switching valves 30 are connected to the second
It constitutes a control valve 32. In this case, the attachment switching valve 28 has a supply oil passage 34 connected to the second hydraulic pump 12 communicating with the switching valve internal oil passage 36, as shown in FIG. It is configured to connect the oil passage with the attachment via the supply/discharge boat 40.42. In addition, reference number 44.4
6.48 each have a center bypass like this,
Conventionally, the attachment switching valve is either a swing system (first control valve 22) or a boom system (second control valve 32).
There was no problem even if it was permanently installed between any of the control valves in the hydraulic circuit that makes up the system.
しかしながら、近時アタッチメントの種類も増加し、特
殊な場合には、アタッチメントと該アタッチメント用切
換弁が付加されている制御弁内の他の切換弁に接続され
たアクチュエータとをそれぞれ独立に操作する要求が生
じるようになった。However, recently, the number of types of attachments has increased, and in special cases, there is a need to independently operate the attachment and the actuator connected to other switching valves in the control valve to which the switching valve for the attachment is attached. started to occur.
例えば、ブーム系の制御弁にアタッチメント用切換弁を
常備した油圧回路において、パケットとアタッチメント
とをそれぞれ独立して操作する場合等である。このよう
な場合、同一の油圧ポンプに接続したアクチュエータを
それぞれ独立して操作することは困難である。なお、バ
ンクタイプの制御弁では、他の油圧ポンプ圓にアタッチ
メント用切換弁を接続することも可能であるが、−殻内
なモノブロックタイプの制御弁では、例えば第５図に示
すように、一方の油圧系に常備されたアタッチメント用
切換弁を使用することなく、他方の油圧系に別に設けた
アタッチメント用切換弁を使用してアタッチメントを操
作しなければならない。For example, in a hydraulic circuit in which a boom system control valve is permanently equipped with an attachment switching valve, the packet and the attachment may be operated independently. In such a case, it is difficult to independently operate actuators connected to the same hydraulic pump. In addition, with a bank type control valve, it is also possible to connect an attachment switching valve to another hydraulic pump circle, but with an in-shell monoblock type control valve, for example, as shown in Fig. 5, Instead of using the attachment switching valve permanently provided in one hydraulic system, the attachment must be operated using a separate attachment switching valve provided in the other hydraulic system.
すなわち、第５図は、第３図に示すように、第２の油圧
ポンプ１２で構成されるブーム系にアタッチメント用切
換弁を常備した油圧回路であって、第１の油圧ポンプ１
０に別のアタッチメント用切換弁３４を接続し、バイパ
ス開閉弁２０の操作によって前記第１の油圧ポンプ１０
の圧油を前記アタッチメント用切換弁３４を介して所要
のアタッチメントへ供給するよう構成したものである。That is, FIG. 5 shows a hydraulic circuit in which a boom system consisting of a second hydraulic pump 12 is permanently equipped with an attachment switching valve, as shown in FIG.
0, another attachment switching valve 34 is connected to the first hydraulic pump 10 by operating the bypass on-off valve 20.
The pressure oil is supplied to a required attachment via the attachment switching valve 34.
これにより、パケットとアタッチメントとをそれぞれ独
立して操作することができる。しかし、この場合には、
前記ブーム系に常備したアタッチメント用切換弁２８は
全く機能せず、無駄な設備となる難点がある。This allows the packet and the attachment to be operated independently. However, in this case,
The attachment switching valve 28, which is always provided in the boom system, does not function at all and has the disadvantage of being a waste of equipment.
そこで、本発明の目的は、一方の油圧ポンプ側にバイパ
ス開閉弁を備えると共に他方の油圧ポンプ測にアタッチ
メント用切換弁を常備した油圧回路において、前記他方
の油圧ポンプ劇におけるアタッチメントと他のアクチュ
エータとをそれぞれ独立させて駆動制御する際に、簡単
な構成でしかもアタッチメント用切換弁を有効に使用し
てそれぞれ別の油圧ポンプの圧油により操作することが
できる省スペースで低コストに製造し得るアタッチメン
ト用切換弁の油圧回路を提供するにある。SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a hydraulic circuit equipped with a bypass on-off valve on one side of the hydraulic pump and a switching valve for an attachment on the side of the other hydraulic pump, in which the attachment and other actuators in the other hydraulic pump are connected. An attachment that has a simple configuration and can be manufactured at low cost in a space-saving manner by effectively using the switching valve for each attachment and operating each of them using pressure oil from a separate hydraulic pump. To provide hydraulic circuits for switching valves.
本発明に係るアタッチメント用切換弁の油圧回路は、第
１の油圧ポンプに接続されてバイパス開閉弁を備える第
１の制御弁と、第２の油圧ポンプに接続されてアタッチ
メント用切換弁を含む複数の切換弁を備える第２の制御
弁とからなる油圧回路において、
前記アタッチメント用切換弁のセンタバイパスを常時開
とすると共に第２の油圧ポンプと接続された供給油路か
ら前記アタッチメント用切換弁への油路を常時閉とする
よう構成し、
前記アタッチメント用切換弁の供給油路を第２の制御弁
の外部に設けてこれを第１の油圧ポンプに接続された供
給油路と接続し、前記アタッチメント用切換弁と連動さ
せて前記バイパス開閉弁を操作し該アタッチメント用切
換弁の供給油路に第Ｉの油圧ポンプの圧油を供給するよ
う構成することを特徴とする。A hydraulic circuit for an attachment switching valve according to the present invention includes a first control valve connected to a first hydraulic pump and provided with a bypass on-off valve, and a plurality of control valves connected to a second hydraulic pump and including an attachment switching valve. and a second control valve equipped with a switching valve, the center bypass of the attachment switching valve is always open, and a supply oil path connected to the second hydraulic pump is connected to the attachment switching valve. the oil passage of the attachment switching valve is configured to be always closed, and the supply oil passage of the attachment switching valve is provided outside the second control valve and is connected to the supply oil passage connected to the first hydraulic pump; The present invention is characterized in that the bypass on-off valve is operated in conjunction with the attachment switching valve to supply pressure oil of the I-th hydraulic pump to the supply oil path of the attachment switching valve.
本発明に係るアタッチメント用切換弁の油圧回路によれ
ば、第１の油圧ポンプに接続されてバイパス開閉弁を備
える第１の制御弁と、第２の油圧ポンプに接続されてア
タッチメント用切換弁を含む複数の切換弁を備える第２
の制御弁とからなる油圧回路において、前記第２の油圧
ポンプ圓に設けられるアタッチメントと他の切換弁に接
続されるアクチュエータとをそれぞれ独立して操作する
場合、前記アタッチメント用切換弁の操作に伴いバイパ
ス開閉弁が操作されて、第１の油圧ポンプの圧油が外部
油路を介してアタッチメント用切換弁に供給され、該ア
タッチメント用切換弁と他のアクチュエータ用切換弁と
をそれぞれ別の油圧ポンプの圧油で有効に制御すること
ができる。According to the hydraulic circuit for the attachment switching valve according to the present invention, the first control valve is connected to the first hydraulic pump and includes a bypass on-off valve, and the first control valve is connected to the second hydraulic pump and operates the attachment switching valve. a second valve comprising a plurality of switching valves including
In a hydraulic circuit consisting of a control valve, when the attachment provided in the second hydraulic pump circle and the actuator connected to the other switching valve are each independently operated, the When the bypass on-off valve is operated, pressure oil from the first hydraulic pump is supplied to the attachment switching valve via an external oil path, and the attachment switching valve and other actuator switching valves are connected to separate hydraulic pumps. It can be effectively controlled using pressurized oil.
次に、本発明に係るアタッチメント用切換弁の油圧回路
の実施例につき、添付図面を参照しながら以下詳細に説
明する。Next, an embodiment of a hydraulic circuit for an attachment switching valve according to the present invention will be described in detail below with reference to the accompanying drawings.
第１図は、本発明油圧回路の一実施例として、パワーシ
ョベルのアタッチメント用切換弁に適用した場合の油圧
回路を示す、従って、説明の便宜上前述した第３図に示
す従来の油圧回路と同一の構成部分については、同一の
参照符号を付しその詳細な説明は省略する。FIG. 1 shows, as an embodiment of the hydraulic circuit of the present invention, a hydraulic circuit when applied to a switching valve for an attachment of a power shovel. Therefore, for convenience of explanation, it is the same as the conventional hydraulic circuit shown in FIG. 3 described above. Components will be given the same reference numerals and detailed explanations will be omitted.
すなわち、第１図に示す実施例において、第１の油圧ポ
ンプ１０には、旋回用切換弁１４、アーム用切換弁１６
、走行（左開）用切換弁１８、バイパス開閉弁２０がそ
れぞれ接続されて第１の制御弁２２を構成している。ま
た、第２の油圧ポンプ１２には、ブーム用切換弁２４、
パケット用切換弁２６、アタッチメント用切換弁２８、
走行（右側）用切換弁３０がそれぞれ接続されて第２の
制御弁３２を構成している。これらの構成は、従来の油
圧回路と同じである。That is, in the embodiment shown in FIG. 1, the first hydraulic pump 10 includes a swing switching valve 14 and an arm switching valve 16.
, the travel (left-open) switching valve 18 , and the bypass on-off valve 20 are connected to each other to form a first control valve 22 . The second hydraulic pump 12 also includes a boom switching valve 24,
Packet switching valve 26, attachment switching valve 28,
The traveling (right side) switching valves 30 are connected to each other to form a second control valve 32 . These configurations are the same as conventional hydraulic circuits.
しかるに、本実施例においては、第２図に示すように、
アタッチメント用切換弁２８に設けられる切換弁内部油
路３６を、第２の油圧ポンプ１２（ブーム系）と接続さ
れる供給油路３４とは遮断して常時閉とし、後述する外
部配管と接続可能な圧油供給ボート５０と連通ずるよう
構成する。なお、本実施例のアタッチメント用切換弁２
８においては、スプール３８の操作に際してセンタバイ
パス４４．４６．４８が常時開となるようにスプール３
８の構造を設定する。そして、前記アタッチメント用切
換弁２８に設けた圧油供給ボート５０は、第１図に示す
ように、第１の油圧ポンプ１０（旋回系）と接続される
供給油路５２に対し、外部配管５４を介して連通接続し
てこれを常時開とする。また、本実施例においては、第
１の油圧ポンプ１０（旋回系）と接続されるバイパス開
閉弁２０につき、その操作部をアタッチメント用切換弁
２８の操作部と連動するようパイロット操作回路５６で
接続する。このように構成することにより、アタッチメ
ント用切換弁２８を操作する際には、これと同時にバイ
パス開閉弁２０が動作して第１の油圧ポンプ１０（旋回
系）の圧油を供給油路５２より外部配管５４を介してア
タッチメント用切換弁２８に供給することができる。However, in this example, as shown in FIG.
The switching valve internal oil passage 36 provided in the attachment switching valve 28 is always closed by being shut off from the supply oil passage 34 connected to the second hydraulic pump 12 (boom system), and can be connected to external piping described later. It is configured to communicate with a pressurized oil supply boat 50. Note that the attachment switching valve 2 of this embodiment
8, the spool 3 is set so that the center bypass 44, 46, 48 is always open when the spool 38 is operated.
Set up the structure of 8. As shown in FIG. 1, the pressure oil supply boat 50 provided in the attachment switching valve 28 is connected to an external piping 54 with respect to a supply oil path 52 connected to the first hydraulic pump 10 (swivel system). A communication connection is made through the 2-way terminal to keep it open at all times. In addition, in this embodiment, for the bypass on-off valve 20 connected to the first hydraulic pump 10 (swivel system), its operation section is connected by a pilot operation circuit 56 so as to be interlocked with the operation section of the attachment switching valve 28. do. With this configuration, when the attachment switching valve 28 is operated, the bypass on-off valve 20 is operated at the same time to supply pressure oil from the first hydraulic pump 10 (swivel system) from the supply oil path 52. It can be supplied to the attachment switching valve 28 via the external piping 54.
このようにして、本発明の油圧回路においては、パケッ
トとアタッチメントとをそれぞれ独立して操作する場合
、これらを駆動制御するためのブーム用切換弁２４とア
タッチメント用切換弁２８とは、それぞれ異なる油圧ポ
ンプによって独立して制御することができる。In this way, in the hydraulic circuit of the present invention, when the packet and the attachment are operated independently, the boom switching valve 24 and the attachment switching valve 28 for driving and controlling them are operated at different hydraulic pressures. Can be controlled independently by the pump.
前述した実施例から明らかなように、本発明によれば、
アタッチメント用切換弁のセンタバイパスを常時開とす
ると共に第２の油圧ポンプと接続された供給油路から前
記アタッチメント用切換弁への油路を常時閉とするよう
構成し、前記アタッチメント用切換弁と連動させてバイ
パス開閉弁を操作するよう構成することにより、アタッ
チメント用切換弁を常備した油圧回路の同一制御弁１Ｐ
Ｉ（例えばブーム系）における池の切換弁をそれぞれ独
立して制御する際に、対応するアタッチメントとアクチ
ュエータとを確実にしかも容易に駆動制御することがで
きる。As is clear from the embodiments described above, according to the present invention,
A center bypass of the attachment switching valve is always open, and an oil passage from the supply oil passage connected to the second hydraulic pump to the attachment switching valve is always closed, and the attachment switching valve and By configuring the bypass on-off valve to be operated in conjunction, the same control valve 1P in the hydraulic circuit is equipped with a switching valve for attachment.
When independently controlling the pond switching valves in I (eg, boom system), the corresponding attachments and actuators can be reliably and easily controlled.
特に、本発明によれば、実施例からも明らかなように、
従来のアタッチメント用切換弁の構造に大幅な変更を加
えることなく、例えば切換弁内部油路に簡単な封止部材
を設けて油路の切換えを行うことができ、またスプール
の一部を若干修正加工することにより容易に対応するこ
とができるので、低コストで製造することができる利点
がある。さらに、アタッチメント用切換弁の操作時には
、パイロット操作回路で常設のバイパス開閉弁を連動さ
せてこれを簡便に操作することができる。In particular, according to the present invention, as is clear from the examples,
Without making any major changes to the structure of conventional switching valves for attachments, for example, a simple sealing member can be installed in the oil passage inside the switching valve to switch the oil passage, and a part of the spool can also be slightly modified. Since it can be easily handled by processing, it has the advantage of being able to be manufactured at low cost. Furthermore, when operating the attachment switching valve, the pilot operating circuit can be used to interlock the permanently installed bypass on-off valve to easily operate it.
従って、本発明の油圧回路によれば、従来のものに比べ
てスペース的に縮小し得るばかりでなく、製作が容易で
あり、しかもコスト的にも低減することができる等多く
の利点を有する
以上、本発明の好適な実施例について説明したが、本発
明は前述した実施例に限定されることなく、本発明の精
神を逸脱しない範囲内において種々の設計変更をなし得
ることは勿論である。Therefore, the hydraulic circuit of the present invention not only has a smaller space than the conventional circuit, but also has many advantages such as being easy to manufacture and reducing costs. Although the preferred embodiments of the present invention have been described, the present invention is not limited to the above-described embodiments, and it goes without saying that various design changes can be made without departing from the spirit of the present invention.
第１図は本発明に係るアタッチメント用切換弁の油圧回
路の一実施例を示す油圧系統図、第２図は第１図に示す
アタッチメント用切換弁の構成例を示す要部断面図、第
３図は従来のアタッチメント用切換弁の油圧回路の構成
例を示す油圧系統図、第４図は第３図に示すアタッチメ
ント用切換弁の構成例を示す要部断面図、第５図は従来
のアタッチメント用切換弁の油圧回路の改善例を示す油
圧系統図である。
２２・・・第１の制御弁 ２４・・・ブーム用切換弁２
６・・・パケット用切換弁
２８・・・アタッチメント用切換弁
３０・・・走行用切換弁 ３２・・・第２の制御弁３４
・・・供給油路 ３６・・・切換弁内部油路３８・
・・スプール ５０・・・圧油供給ボート４０．４
２・・・給排ボート
４４．４６．４８・・・センタバイパス５２・・・供給
油路 ５４・・・外部配管５６・・・パイロット操
作回路
１０・・・第１の油圧ポンプ
１２・・・第２の油圧ポンプ
１４・・・旋回用切換弁 １６・・・アーム用切換弁１
８・・・走行用切換弁 ２０・・・バイパス開閉弁ＦＩ
Ｇ 、 １
ＦＩｏ ３
ＦＩｏ ２
ＦＩｏ ４FIG. 1 is a hydraulic system diagram showing one embodiment of the hydraulic circuit of the attachment switching valve according to the present invention, FIG. 2 is a sectional view of essential parts showing an example of the configuration of the attachment switching valve shown in FIG. The figure is a hydraulic system diagram showing an example of the configuration of a hydraulic circuit of a conventional attachment switching valve, Figure 4 is a sectional view of a main part showing an example of the configuration of the attachment switching valve shown in Figure 3, and Figure 5 is a conventional attachment switching valve. FIG. 3 is a hydraulic system diagram showing an example of an improved hydraulic circuit of a switching valve. 22... First control valve 24... Boom switching valve 2
6...Packet switching valve 28...Attachment switching valve 30...Traveling switching valve 32...Second control valve 34
...Supply oil path 36...Switching valve internal oil path 38.
... Spool 50 ... Pressure oil supply boat 40.4
2... Supply/discharge boat 44.46.48... Center bypass 52... Supply oil path 54... External piping 56... Pilot operation circuit 10... First hydraulic pump 12... Second hydraulic pump 14...Swivel switching valve 16...Arm switching valve 1
8... Travel switching valve 20... Bypass opening/closing valve FI
G, 1 FIo 3 FIo 2 FIo 4
Claims (1)
備える第１の制御弁と、第２の油圧ポンプに接続されて
アタッチメント用切換弁を含む複数の切換弁を備える第
２の制御弁とからなる油圧回路において、 前記アタッチメント用切換弁のセンタバイ パスを常時開とすると共に第２の油圧ポンプと接続され
た供給油路から前記アタッチメント用切換弁への油路を
常時閉とするよう構成し、 前記アタッチメント用切換弁の供給油路を 第２の制御弁の外部に設けてこれを第１の油圧ポンプに
接続された供給油路と接続し、 前記アタッチメント用切換弁と連動させて 前記バイパス開閉弁を操作し該アタッチメント用切換弁
の供給油路に前記第１の油圧ポンプの圧油を供給するよ
う構成することを特徴とするアタッチメント用切換弁の
油圧回路。(1) A first control valve connected to the first hydraulic pump and equipped with a bypass on-off valve; and a second control valve connected to the second hydraulic pump and equipped with a plurality of switching valves including an attachment switching valve. A hydraulic circuit comprising: a center bypass of the attachment switching valve is always open, and an oil passage from a supply oil path connected to a second hydraulic pump to the attachment switching valve is always closed. and a supply oil passage for the attachment switching valve is provided outside the second control valve and connected to a supply oil passage connected to the first hydraulic pump, and the oil supply passage for the attachment switching valve is interlocked with the attachment switching valve. A hydraulic circuit for an attachment switching valve, characterized in that it is configured to operate a bypass on-off valve to supply pressure oil from the first hydraulic pump to a supply oil path of the attachment switching valve.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP63320370A JP2642972B2 (en) | 1988-12-21 | 1988-12-21 | Hydraulic circuit of switching valve for attachment |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP63320370A JP2642972B2 (en) | 1988-12-21 | 1988-12-21 | Hydraulic circuit of switching valve for attachment |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH02167934A true JPH02167934A (en) | 1990-06-28 |
| JP2642972B2 JP2642972B2 (en) | 1997-08-20 |
Family
ID=18120720
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP63320370A Expired - Fee Related JP2642972B2 (en) | 1988-12-21 | 1988-12-21 | Hydraulic circuit of switching valve for attachment |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2642972B2 (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP2107170A3 (en) * | 1999-01-19 | 2009-11-11 | Hitachi Construction Machinery Co., Ltd. | Hydraulic driving device of civil engineering and construction machinery |
| JP2018053674A (en) * | 2016-09-30 | 2018-04-05 | 日立建機株式会社 | Civil engineering/construction machine |
-
1988
- 1988-12-21 JP JP63320370A patent/JP2642972B2/en not_active Expired - Fee Related
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP2107170A3 (en) * | 1999-01-19 | 2009-11-11 | Hitachi Construction Machinery Co., Ltd. | Hydraulic driving device of civil engineering and construction machinery |
| JP2018053674A (en) * | 2016-09-30 | 2018-04-05 | 日立建機株式会社 | Civil engineering/construction machine |
Also Published As
| Publication number | Publication date |
|---|---|
| JP2642972B2 (en) | 1997-08-20 |
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