JPH06213206A - Pressure oil supplying device - Google Patents
Pressure oil supplying deviceInfo
- Publication number
- JPH06213206A JPH06213206A JP826793A JP826793A JPH06213206A JP H06213206 A JPH06213206 A JP H06213206A JP 826793 A JP826793 A JP 826793A JP 826793 A JP826793 A JP 826793A JP H06213206 A JPH06213206 A JP H06213206A
- Authority
- JP
- Japan
- Prior art keywords
- lever
- electric signal
- operation angle
- solenoid valve
- proportional solenoid
- 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.)
- Pending
Links
- 230000007423 decrease Effects 0.000 claims abstract description 15
- 239000012530 fluid Substances 0.000 claims description 4
- 230000003247 decreasing effect Effects 0.000 abstract description 12
- 230000007935 neutral effect Effects 0.000 description 4
- 230000001174 ascending effect Effects 0.000 description 2
- 230000002457 bidirectional effect Effects 0.000 description 2
- 238000011144 upstream manufacturing Methods 0.000 description 1
Landscapes
- Fluid-Pressure Circuits (AREA)
Abstract
Description
【０００１】[0001]
【産業上の利用分野】本発明は、産業車両に荷役用シリ
ンダ等のアクチュエータに油圧ポンプの吐出圧油を供給
する圧油供給装置に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pressure oil supply device for supplying the discharge pressure oil of a hydraulic pump to an actuator such as a cargo handling cylinder for an industrial vehicle.
【０００２】[0002]
【従来の技術】産業車両に荷役用に油圧ポンプの吐出圧
油を供給する装置としては、油圧ポンプの吐出路に比例
電磁弁を設けると共に、この比例電磁弁に通電する電気
レバー装置を設け、その電気レバー装置のレバーを操作
することで比例電磁弁に通電し、その通電量に応じて開
閉動作することで油圧ポンプの吐出圧油を荷役用シリン
ダに供給するものが知られている。2. Description of the Related Art As a device for supplying the discharge pressure oil of a hydraulic pump to an industrial vehicle for cargo handling, a proportional solenoid valve is provided in a discharge passage of the hydraulic pump, and an electric lever device for energizing the proportional solenoid valve is provided. It is known that the proportional solenoid valve is energized by operating a lever of the electric lever device and is opened / closed in accordance with the amount of energization to supply the discharge pressure oil of the hydraulic pump to the cargo handling cylinder.
【０００３】[0003]
【発明が解決しようとする課題】比例電磁弁は弁本体に
スプールを嵌挿し、そのスプールをスプリングで閉位置
（制御流量ゼロ位置）に保持すると共に、ソレノイドに
通電することでスプールを開位置に作動し、その開口面
積（制御流量）はソレノイドの通電量に応じて増減す
る。In a proportional solenoid valve, a spool is fitted in a valve body, and the spool is held in a closed position (zero control flow rate position) by a spring, and the solenoid is energized to open the spool. It operates, and its opening area (control flow rate) increases or decreases according to the energization amount of the solenoid.
【０００４】このような比例電磁弁はスプールのヒステ
リシスにより図１のように、流量増加方向作動時は、電
気信号Ａ1 から流量制御が始まり、Ａ2 でＱ1 の流量と
なる。しかし、流量減少方向作動時はＡ2 からＡ´2 ま
で流量Ｑ1 は一定となるし、流量制御が完了する電気信
号はＡ´1 で前述のＡ1 よりゼロに近い値となる。In such a proportional solenoid valve, due to the hysteresis of the spool, as shown in FIG. 1, when the flow rate is increased, the flow rate control starts from the electric signal A 1, and the flow rate becomes Q 1 at A 2 . However, the flow rate Q 1 is constant from A 2 to A ′ 2 when the flow rate is reduced, and the electric signal for completing the flow rate control is A ′ 1 and has a value closer to zero than A 1 described above.
【０００５】また、電気レバー装置はレバーを流量増方
向、流量減方向に操作することでポテンションメータ等
を作動して電気信号を出力するものであり、レバー操作
角度に対する電気信号は図２に示すように流量増方向と
流量減方向で同一となる。Further, the electric lever device operates a potentiometer or the like by operating the lever in the flow increasing direction and the flow decreasing direction to output an electric signal. The electric signal corresponding to the lever operating angle is shown in FIG. As shown, the flow rate increases and decreases in the same direction.
【０００６】このようであるから、電気レバー装置のレ
バーを角度θ2 まで操作して電気信号Ａ2 を出力してＱ
1 の流量となった後流量を少し減らしたい時にレバー操
作角度をθ2 から少し戻しても電気信号がＡ´2 となら
ずに流量はＱ1 のまま変わらないので、オペレータの意
思通りに流量が変化しない問題がある。また、レバー操
作角度ゼロから角度θ1 までが制御流量がゼロの不感帯
となりオペレータにとってはレバーの遊びが大きく、操
作性が劣る問題がある。[0006] Since this be the case, it outputs an electric signal A 2 by operating the lever of the electric lever device to an angle theta 2 Q
Because even a little return the lever operation angle from θ 2 when you want a little to reduce the flow rate after becoming one of the flow rate as well as the electrical signal is A'2 and the flow rate remains unchanged of Q 1, the flow rate to the intention Street operator There is a problem that does not change. Further, from the lever operation angle of zero to the angle θ 1 , there is a dead zone in which the control flow rate is zero, and there is a large play of the lever for the operator, which causes a problem of poor operability.
【０００７】そこで、本発明は前述の課題を解決できる
ようにした圧油供給装置を提供することを目的とする。Therefore, an object of the present invention is to provide a pressure oil supply device capable of solving the above problems.
【０００８】[0008]
【課題を解決するための手段】油圧ポンプ１の吐出圧油
をアクチュエータに供給比例電磁弁４と、レバー１０の
操作角度に応じた電気信号を出力する電気レバー装置９
と、この電気レバー装置９の電気信号に基づいて比例電
磁弁４に制御電気信号を出力するコントローラ１１を備
え、前記コントローラ１１はレバー操作角度の増減時に
おける入力レバー操作角度と比例電磁弁への制御電気信
号の対応データをそれぞれ備え、レバー操作角度の増減
を判断して対応データより制御電気信号を選択して比例
電磁弁４に出力するものとした圧油供給装置。油圧ポン
プの吐出圧油をアクチュエータに供給する比例電磁弁４
と、レバー１０の操作角度に応じた電気信号を出力する
電気レバー装置９と、この電気レバー装置９の電気信号
に基いて比例電磁弁４に制御電気信号を出力するコント
ローラ１１を備え、前記コントローラ１１はレバー操作
角度の増減を判断してレバー操作角度に対応する電気信
号を増減して比例電磁弁の制御電気信号として出力する
ものとした圧油供給装置。[Problems to be Solved by the Invention] Discharge pressure oil of a hydraulic pump 1 is supplied to an actuator.
And a controller 11 that outputs a control electric signal to the proportional solenoid valve 4 based on the electric signal of the electric lever device 9, and the controller 11 changes the input lever operation angle and the proportional solenoid valve when the lever operation angle is increased or decreased. A pressure oil supply device, which is provided with corresponding data of control electric signals, selects a control electric signal from the corresponding data by judging increase or decrease of the lever operation angle, and outputs the selected control electric signal to the proportional solenoid valve 4. Proportional solenoid valve 4 that supplies the hydraulic fluid discharged from the hydraulic pump to the actuator
And an electric lever device 9 for outputting an electric signal according to an operation angle of the lever 10, and a controller 11 for outputting a control electric signal to the proportional solenoid valve 4 based on the electric signal of the electric lever device 9. Reference numeral 11 denotes a pressure oil supply device which determines whether the lever operation angle is increased or decreased and increases or decreases an electric signal corresponding to the lever operation angle and outputs the electric signal as a control electric signal for the proportional solenoid valve.
【０００９】[0009]
【作 用】電気レバー装置９のレバー１０を操作角度
増方向、操作角度減方向に操作した時、つまり比例電磁
弁４の制御流量増加方向作動時と制御流量減少方向作動
時に、その比例電磁弁４に出力される制御電気信号が補
正されてレバー操作角度に対する制御流量が両方向作動
時に常に同一となる。[Operation] When the lever 10 of the electric lever device 9 is operated in the operation angle increasing direction and the operation angle decreasing direction, that is, when the proportional solenoid valve 4 is operated in the control flow increasing direction and the control flow decreasing direction, the proportional solenoid valve is operated. The control electric signal output to 4 is corrected so that the control flow rate with respect to the lever operation angle is always the same during bidirectional operation.
【００１０】[0010]
【実 施 例】図３に示すように、モータＭで駆動され
る油圧ポンプ１の吐出路２はパイロット油圧用電磁弁３
を通って比例電磁弁４の第１・第２入口ポート５，６に
接続し、その比例電磁弁４のアクチュエータポート７は
アクチュエータ、例えば荷役用シリンダ８の上げ側室８
ａに接続している。電気レバー装置９はレバー１０を操
作することで電気信号を出力し、その電気信号はコント
ローラ１１に入力される。[Example] As shown in FIG. 3, the discharge passage 2 of the hydraulic pump 1 driven by the motor M has a pilot hydraulic solenoid valve 3
Connected to the first and second inlet ports 5 and 6 of the proportional solenoid valve 4, and the actuator port 7 of the proportional solenoid valve 4 is an actuator, for example, the raising side chamber 8 of the cargo handling cylinder 8.
It is connected to a. The electric lever device 9 outputs an electric signal by operating the lever 10, and the electric signal is input to the controller 11.
【００１１】次に各部の詳細とともに作動を説明する。
電気レバー装置９のレバー１０を中立位置Ａとした時に
は電気信号を出力せずにコントローラ１１は何らの信号
を出力しないので、パイロット油圧用電磁弁３、比例電
磁弁４は図３に示す連通位置Ｂ、中立位置Ｃとなる。こ
れにより、油圧ポンプ１の吐出圧油はパイロット油圧用
電磁弁３の連通位置Ｂ、比例電磁弁４の第１入口ポート
５、タンクポート１２よりタンク１３に流出するので、
油圧ポンプ１の吐出路２に圧力が発生しない。この時、
アクチュエータポート７は遮断されて荷役用シリンダ８
はその位置に保持される。Next, the operation will be described together with the details of each part.
When the lever 10 of the electric lever device 9 is set to the neutral position A, the controller 11 does not output an electric signal and does not output any signal. B, the neutral position C. As a result, the hydraulic fluid discharged from the hydraulic pump 1 flows out to the tank 13 from the communication position B of the pilot hydraulic solenoid valve 3, the first inlet port 5 of the proportional solenoid valve 4, and the tank port 12.
No pressure is generated in the discharge passage 2 of the hydraulic pump 1. At this time,
The actuator port 7 is blocked and the cargo handling cylinder 8
Is held in that position.
【００１２】電気レバー装置９のレバー１０を中立位置
Ａから上昇位置Ｄ又は下降位置Ｅに向けて操作すると電
気信号がコントローラ１１に入力され、コントローラ１
１は上昇用ソレノイド１４又は下降用ソレノイド１５に
通電して比例電磁弁４を中立位置Ｃから上昇位置Ｆ又は
下降位置Ｇに向けて作動して第２入口ポート６をアクチ
ュエータポート７に連通又はアクチュエータポート７を
主タンクポート１６に連通して荷役用シリンダ８を伸長
又は減少する。これと同時にパイロット油圧用電磁弁３
のソレノイド１７に通電して絞り位置Ｈとするから、油
圧ポンプ１の吐出圧油は絞られて上流側に圧力が発生
し、その圧力はパイロット管路１８で比例電磁弁４の上
昇用受圧部１９と下降用受圧部２０に供給され、上昇用
ソレノイド１４又は下降用ソレノイド１５の一方が通電
されることで上昇用受圧部１９又は下降用受圧部２０の
一方の油圧が上昇して切換えられる。When the lever 10 of the electric lever device 9 is operated from the neutral position A toward the raised position D or the lowered position E, an electric signal is input to the controller 11 and the controller 1
1 is energized to the ascending solenoid 14 or the descending solenoid 15 to operate the proportional solenoid valve 4 from the neutral position C toward the ascending position F or the descending position G to communicate the second inlet port 6 with the actuator port 7 or the actuator. The port 7 is connected to the main tank port 16 to extend or decrease the cargo handling cylinder 8. At the same time, the pilot hydraulic solenoid valve 3
Since the solenoid 17 is energized to the throttle position H, the hydraulic fluid discharged from the hydraulic pump 1 is throttled and pressure is generated on the upstream side. 19 and the lowering pressure receiving portion 20, and one of the raising solenoid 14 and the lowering solenoid 15 is energized to raise and switch the hydraulic pressure of one of the raising pressure receiving portion 19 and the lowering pressure receiving portion 20.
【００１３】前述の動作時にコントローラ１１はレバー
操作角度増加、減少を判断し、レバー操作角度増加時に
は図４におけるθ´1 ，Ａ1 とθ´2 ，Ａ2 を結ぶ直線
ａのように制御電気信号を上昇用、下降用ソレノイド１
４，１５に出力し、レバー操作角度減少時には図４にお
けるゼロ、ゼロとθ´2 とＡ´2 を結ぶ点線ｂのように
制御電気信号を上昇用・下降用ソレノイド１４，１５に
出力する。At the time of the above operation, the controller 11 judges whether the lever operation angle is increased or decreased, and when the lever operation angle is increased, the control electric like a straight line a connecting θ ′ 1 , A 1 and θ ′ 2 , A 2 in FIG. Solenoid for raising and lowering signal 1
Output to 4, 15, at the time of lever operation angle decreases and outputs zero, the elevating-lowering solenoid 15 a control electrical signal as shown by the dotted line b connecting the zero and [theta] & apos 2 and A'2 in FIG.
【００１４】このようであるから、レバー操作角度増加
時には角度θ´1 で制御電気信号Ａ1 となり角度Ｑ´2
で制御電気信号Ａ2 となって流量Ｑ1 となり、レバー操
作角度減少時には角度θ´2 で制御電気信号Ａ´2 とな
り流量Ｑ1 、角度θ´1 で制御電気信号Ａ´1 となって
制御流量がゼロとなる。この時の動作をフローチャート
で表わすと図５のようになる。したがって、レバー操作
角度増加時と減少時でレバー操作角度θに対する制御流
量Ｑが同じとなり、ファインコントロール性向上、レバ
ー操作角度減少による操作性向上が図れる。[0014] Since this be the case, the lever operation angle increases when the angle [theta] & apos 1 in the control electrical signal A 1 becomes the angle Q'2
Flow rate Q 1 becomes in a control electric signal A 2 in, at the time of lever operation angle decreases the angle [theta] & apos controlled by second electrical signals A'2 next flow Q 1, controlled by the angle [theta] & apos 1 electrical signals A'1 and is controlled The flow rate becomes zero. The operation at this time is shown in a flowchart in FIG. Therefore, the control flow rate Q with respect to the lever operation angle θ becomes the same when the lever operation angle increases and decreases, and the fine controllability is improved and the operability is improved by decreasing the lever operation angle.
【００１５】次に他の実施例を説明する。電気レバー装
置９のレバー操作角度θに対応する電気信号をコントロ
ーラ１１によって増減して制御電気信号として出力する
ようにしても良い。Next, another embodiment will be described. An electric signal corresponding to the lever operation angle θ of the electric lever device 9 may be increased or decreased by the controller 11 and output as a control electric signal.
【００１６】例えば図６に示すように、レバー操作角度
信号θが増加の時にそのレバー操作角度信号θに対応す
る電気信号Ａに定数αを加算して制御電気信号とし、レ
バー操作角度信号θが減少の時にはそのレバー操作角度
θに対応する電気信号Ａをそのまま制御電気信号とす
る。ここで、定数αは図１に示すＡ1 →Ａ2 とＡ´1 →
Ａ´2 の差の場合とレバー操作角度信号θと電気信号Ａ
の対応データより選択した場合の２通りである。For example, as shown in FIG. 6, when the lever operation angle signal θ increases, a constant α is added to the electric signal A corresponding to the lever operation angle signal θ to obtain a control electric signal. When decreasing, the electric signal A corresponding to the lever operation angle θ is used as it is as a control electric signal. Here, the constant α is A 1 → A 2 and A ′ 1 → shown in FIG.
For the difference between the A'2 and lever operating angle signal θ and the electrical signal A
There are two cases when selected from the corresponding data of.
【００１７】また、図７に示すようにレバー操作角度信
号θが減少の時にはそのレバー操作角度信号θに対応す
る電気信号Ａから定数αをマイナスして制御電気信号と
し、レバー操作角度信号θが増加の時にはそのレバー操
作角度信号θに対応する電気信号Ａをそのまま制御電気
信号とする。ここで、定数αは前述と同様である。Further, as shown in FIG. 7, when the lever operation angle signal θ decreases, a constant α is subtracted from the electric signal A corresponding to the lever operation angle signal θ to obtain a control electric signal. When increasing, the electric signal A corresponding to the lever operation angle signal θ is directly used as the control electric signal. Here, the constant α is the same as that described above.
【００１８】[0018]
【発明の効果】電気レバー装置９のレバー１０を操作角
度増方向、操作角度減方向に操作した時、つまり比例電
磁弁４の制御流量増加方向作動時と制御流量減少方向作
動時に、その比例電磁弁４に出力される制御電気信号が
補正されてレバー操作角度に対する制御流量が両方向作
動時に常に同一となる。したがって、比例電磁弁のスプ
ールのヒステリシスの影響をなくしてファインコントロ
ール性向上及び、不感帯減少によるレバー遊び角度低減
による操作性向上を図ることができる。When the lever 10 of the electric lever device 9 is operated in the operation angle increasing direction and the operation angle decreasing direction, that is, when the proportional solenoid valve 4 is operated in the control flow increasing direction and the control flow decreasing direction, the proportional electromagnetic The control electric signal output to the valve 4 is corrected so that the control flow rate with respect to the lever operation angle is always the same during bidirectional operation. Therefore, the influence of the hysteresis of the spool of the proportional solenoid valve can be eliminated to improve the fine controllability and the operability can be improved by reducing the lever play angle by reducing the dead zone.
【図１】比例電磁弁の制御電気信号と制御流量の関係を
示す図表である。FIG. 1 is a chart showing a relationship between a control electric signal of a proportional solenoid valve and a control flow rate.
【図２】電気レバー装置のレバー操作角度と電気信号の
関係を示す図表である。FIG. 2 is a table showing a relationship between a lever operation angle of an electric lever device and an electric signal.
【図３】本発明の実施例を示す構成説明図である。FIG. 3 is a configuration explanatory view showing an embodiment of the present invention.
【図４】レバー操作角度と制御電気信号の関係を示す図
表である。FIG. 4 is a chart showing a relationship between a lever operation angle and a control electric signal.
【図５】動作フローチャートである。FIG. 5 is an operation flowchart.
【図６】動作フローチャートである。FIG. 6 is an operation flowchart.
【図７】動作フローチャートである。FIG. 7 is an operation flowchart.
１…油圧ポンプ、２…吐出路、３…パイロット油圧用電
磁弁、４…比例電磁弁、８…荷役用シリンダ、９…電気
レバー装置、１０…レバー、１１…コントローラ。DESCRIPTION OF SYMBOLS 1 ... Hydraulic pump, 2 ... Discharge passage, 3 ... Pilot hydraulic solenoid valve, 4 ... Proportional solenoid valve, 8 ... Cargo handling cylinder, 9 ... Electric lever device, 10 ... Lever, 11 ... Controller.
Claims (2)
タに供給する比例電磁弁４と、レバー１０の操作角度に
応じた電気信号を出力する電気レバー装置９と、この電
気レバー装置９の電気信号に基づいて比例電磁弁４に制
御電気信号を出力するコントローラ１１を備え、 前記コントローラ１１はレバー操作角度の増減時におけ
る入力レバー操作角度と比例電磁弁への制御電気信号の
対応データをそれぞれ備え、レバー操作角度の増減を判
断して対応データより制御電気信号を選択して比例電磁
弁４に出力するものとした圧油供給装置。1. A proportional solenoid valve 4 for supplying hydraulic fluid discharged from a hydraulic pump 1 to an actuator, an electric lever device 9 for outputting an electric signal according to an operation angle of a lever 10, and an electric signal for this electric lever device 9. A controller 11 that outputs a control electric signal to the proportional solenoid valve 4 based on the above, and the controller 11 includes the corresponding data of the input lever operation angle when the lever operation angle increases and decreases and the control electric signal corresponding to the proportional solenoid valve, respectively. A pressure oil supply device configured to determine whether to increase or decrease the lever operation angle, select a control electric signal from corresponding data, and output the control electric signal to the proportional solenoid valve 4.
に供給する比例電磁弁４と、レバー１０の操作角度に応
じた電気信号を出力する電気レバー装置９と、この電気
レバー装置９の電気信号に基づいて比例電磁弁４に制御
電気信号を出力するコントローラ１１を備え、 前記コントローラ１１はレバー操作角度の増減を判断し
てレバー操作角度に対応する電気信号を増減して比例電
磁弁の制御電気信号として出力するものとした圧油供給
装置。2. A proportional solenoid valve 4 for supplying pressure oil discharged from a hydraulic pump to an actuator, an electric lever device 9 for outputting an electric signal according to an operation angle of a lever 10, and an electric signal for the electric lever device 9. The controller 11 outputs a control electric signal to the proportional solenoid valve 4 based on the controller 11. The controller 11 determines increase / decrease of the lever operation angle and increases / decreases the electric signal corresponding to the lever operation angle to increase / decrease the control electric signal of the proportional solenoid valve. A pressure oil supply device that outputs as.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP826793A JPH06213206A (en) | 1993-01-21 | 1993-01-21 | Pressure oil supplying device |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP826793A JPH06213206A (en) | 1993-01-21 | 1993-01-21 | Pressure oil supplying device |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH06213206A true JPH06213206A (en) | 1994-08-02 |
Family
ID=11688392
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP826793A Pending JPH06213206A (en) | 1993-01-21 | 1993-01-21 | Pressure oil supplying device |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH06213206A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2001261295A (en) * | 2000-03-17 | 2001-09-26 | Komatsu Forklift Co Ltd | Control device for lift cylinder of forklift truck |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5857505A (en) * | 1981-10-02 | 1983-04-05 | Hitachi Constr Mach Co Ltd | Controller for electric-hydraulic converting valve |
| JPH0328586A (en) * | 1989-06-23 | 1991-02-06 | Harman Co Ltd | Control device for proportional valve |
-
1993
- 1993-01-21 JP JP826793A patent/JPH06213206A/en active Pending
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5857505A (en) * | 1981-10-02 | 1983-04-05 | Hitachi Constr Mach Co Ltd | Controller for electric-hydraulic converting valve |
| JPH0328586A (en) * | 1989-06-23 | 1991-02-06 | Harman Co Ltd | Control device for proportional valve |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2001261295A (en) * | 2000-03-17 | 2001-09-26 | Komatsu Forklift Co Ltd | Control device for lift cylinder of forklift truck |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US5537819A (en) | Hydraulic device for working machine | |
| JP3948122B2 (en) | Hydraulic actuator control device | |
| KR20030092121A (en) | Hydraulic system with three electrohydraulic valves for controlling fluid flow to a load | |
| JP4247986B2 (en) | Vehicle steering control device | |
| JPH0674204A (en) | Hydraulic type controller for plurality of consuming equipment | |
| EP3896550A1 (en) | Digital proportional pressure controller | |
| JP2001019391A (en) | Tilt controller for forklift | |
| JPH06213206A (en) | Pressure oil supplying device | |
| JPH07190006A (en) | Pressure compensation type oil pressure control circuit | |
| JPH03219180A (en) | Magnet valve with exciting current controller | |
| JP2903909B2 (en) | Construction machine control circuit | |
| JP3018788B2 (en) | Hydraulic pump control circuit | |
| US5315827A (en) | Apparatus for switching flow rate for attachment | |
| JPH07293508A (en) | Hydraulic control device | |
| JPH04285303A (en) | Hydraulic circuit for improving operability in load sensing system | |
| JP3714713B2 (en) | Hydraulic control device | |
| JP3248549B2 (en) | Auto accelerator device | |
| JPH04285304A (en) | Hydraulic circuit for improving operability in load sensing system | |
| JPS5825163B2 (en) | fluid control device | |
| JP3444506B2 (en) | Pressure oil supply device | |
| JPH06213208A (en) | Oil pressure controller | |
| JP4082928B2 (en) | Fluid pressure circuit | |
| JP4671408B2 (en) | Hydraulic circuit with unload valve | |
| JPH02125031A (en) | Pressure compensation type fluid pressure control system | |
| JPH0281897A (en) | Hydraulic controller for cargo in industrial vehicle |