JP4962143B2 - Hydraulic drive - Google Patents

Hydraulic drive Download PDF

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JP4962143B2
JP4962143B2 JP2007145068A JP2007145068A JP4962143B2 JP 4962143 B2 JP4962143 B2 JP 4962143B2 JP 2007145068 A JP2007145068 A JP 2007145068A JP 2007145068 A JP2007145068 A JP 2007145068A JP 4962143 B2 JP4962143 B2 JP 4962143B2
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pressure
valve
circuit
variable pump
switching valve
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JP2008298185A (en
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康治 岡崎
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Nachi Fujikoshi Corp
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本発明は、可変容量形油圧ポンプ（以下、可変ポンプとする）の吐出圧と複数のアクチュエータの最高負荷圧との差圧に応じて作動し、可変ポンプの吐出圧油をタンクに連通・遮断するアンロード弁を有する油圧駆動装置に関する。     The present invention operates according to the differential pressure between the discharge pressure of a variable displacement hydraulic pump (hereinafter referred to as a variable pump) and the maximum load pressure of a plurality of actuators. The present invention relates to a hydraulic drive device having an unloading valve.

従来技術、この種のアンロード弁にはポンプ圧と、複数のアクチュエータの最高負荷圧力を導くとともに、電磁比例減圧弁で制御する制御圧力を導いている。実機において、操作レバー（操作用バルブ）の操作に対しアクチュエータの応答性をよくするため、この電磁比例減圧弁の制御圧力によって予めアンロード開始圧を設定することができるようにしている。アンロード開始圧を希望の値に設定することで、予め可変ポンプの吐出流量を多くして、アクチュエータの応答性を高めている（例えば、特許文献１参照）。
特開平１１−３１５８０５号公報 In the prior art, this type of unload valve introduces the pump pressure and the maximum load pressure of a plurality of actuators, as well as the control pressure controlled by the electromagnetic proportional pressure reducing valve. In an actual machine, in order to improve the response of the actuator to the operation of the operation lever (operation valve), the unload start pressure can be set in advance by the control pressure of the electromagnetic proportional pressure reducing valve. By setting the unload start pressure to a desired value, the discharge flow rate of the variable pump is increased in advance to enhance the response of the actuator (see, for example, Patent Document 1).
JP-A-11-315805

しかしながら、特許文献１ではアンロード開始圧を設定するために、電磁比例減圧弁を余分に使用しており、該電磁比例減圧弁を制御するコントローラも必要であるのでコスト高になってしまう。
本発明は、電磁比例減圧弁等のバルブを追加することなく、実機操作レバーの操作に対してアクチュエータの応答性を高めるため、アクチュエータ毎に予め可変ポンプの吐出圧を設定するアンロード弁を有する油圧駆動装置を提供することを目的とする。 However, in Patent Document 1, an extra electromagnetic proportional pressure reducing valve is used to set the unloading start pressure, and a controller for controlling the electromagnetic proportional pressure reducing valve is also required, resulting in an increase in cost.
The present invention has an unload valve that sets the discharge pressure of the variable pump in advance for each actuator in order to increase the response of the actuator to the operation of the actual operation lever without adding a valve such as an electromagnetic proportional pressure reducing valve. An object is to provide a hydraulic drive device.

前記の目的を達成するために、本発明は、可変ポンプの吐出圧と少なくとも１つのアクチュエータの最高負荷圧との差圧に応じて可変ポンプの吐出圧油をタンクに導くアンロード弁を有する油圧駆動装置において、
前記アンドロード弁は、第一受圧部に作用する可変ポンプの吐出圧によって連通方向に作動し、第二受圧部に受ける最高負荷圧によって遮断方向に作動するように構成され、
操作切換弁は、スプールの中立位置では第１の回路、切換位置には第２の回路、第３の回路が構成され、かつ前記第２の回路及び第３の回路は所定面積だけ開口するよう構成され、さらにパイロットポンプの下流に第一の固定絞りを設け、該第一の固定絞りのタンクに連通する前記操作切換弁の回路の面積が、該操作切換弁の切換位置によって変化することで制御される制御圧が第三受圧部に作用して、前記操作切換弁の切換位置毎の回路の面積の設定により、操作切換弁の切換位置によって制御圧が変化して可変ポンプの吐出圧の高さの度合が変化することを特徴とする。
本発明によれば、操作切換弁がストロークしたときの第一の固定絞りの下流からタンクへの回路の面積を任意に設定することで、制御圧が異なり、その結果、作動させるアクチュエータに合わせて可変ポンプの吐出圧が設定できる。このためアクチュエータの負荷に合わせ適切な可変ポンプの吐出圧を設定できるので、該アクチュエータの応答性が高くなりすぎることによる実機のショックなどを防止できる。 In order to achieve the above-described object, the present invention provides a hydraulic pressure having an unload valve that guides the discharge pressure oil of the variable pump to the tank in accordance with the differential pressure between the discharge pressure of the variable pump and the maximum load pressure of at least one actuator. In the drive device,
The and load valve is configured to operate in a communication direction by a discharge pressure of a variable pump acting on a first pressure receiving part, and to operate in a blocking direction by a maximum load pressure received by the second pressure receiving part,
The operation switching valve includes a first circuit in the neutral position of the spool, a second circuit and a third circuit in the switching position, and the second circuit and the third circuit are opened by a predetermined area. is configured, further a first fixed throttle is provided downstream of the pilot pump, that area of the circuit of the operating switching valve communicating with the tank of the first fixed throttle is changed by the switching position of the operating selector valve The control pressure to be controlled acts on the third pressure receiving portion, and by setting the circuit area for each switching position of the operation switching valve, the control pressure changes depending on the switching position of the operation switching valve, and the discharge pressure of the variable pump is reduced. It is characterized in that the degree of height changes.
According to the present invention, by arbitrarily setting the area of the circuit from the downstream of the first fixed throttle to the tank when the operation switching valve is stroked, the control pressure differs, and as a result, the actuator is operated. Variable pump discharge pressure can be set. For this reason, an appropriate variable pump discharge pressure can be set in accordance with the load of the actuator, so that it is possible to prevent a shock of the actual machine due to an excessively high response of the actuator.

本発明は、作動させるアクチュエータに合わせて可変ポンプの吐出圧が設定できる。このためアクチュエータの負荷に合わせ適切な可変ポンプの吐出圧を設定できるので、該アクチュエータの応答性が高くなりすぎることによる実機のショックなどを防止できる。   In the present invention, the discharge pressure of the variable pump can be set according to the actuator to be operated. For this reason, an appropriate variable pump discharge pressure can be set in accordance with the load of the actuator, so that it is possible to prevent a shock of the actual machine due to an excessively high response of the actuator.

以下、本発明に係る油圧駆動装置につき好適の実施の形態を挙げ、添付図面を参照して詳細に説明する。
図１は、本発明の第一の実施の形態に係る油圧駆動装置１０の油圧回路図である。
図１に示す油圧駆動装置１０は、可変ポンプ１１の吐出圧Ｐと１つのアクチュエータ１７の最高負荷圧との差圧を検出する差圧減圧弁２５に応じ可変ポンプ１１の吐出圧油をタンク１８に導くアンロード弁１４を有する。
前記アンロード弁１４は、第一受圧部２１に作用する可変ポンプ１１の吐出圧Ｐが吐出ライン１３を経て連通方向（図１で左位置）に作動し、第二受圧部２２に受ける最高負荷圧ＰＬｍａｘによって遮断方向（図１で右位置）に作動するように構成されている。図１中、参照符号２４はリリーフ弁を示す。さらに、参照符号２６は圧力補償弁を示し、操作切換弁１９の前後の差圧を補償する機能を有する。 Preferred embodiments of the hydraulic drive apparatus according to the present invention will be described below in detail with reference to the accompanying drawings.
FIG. 1 is a hydraulic circuit diagram of a hydraulic drive apparatus 10 according to the first embodiment of the present invention.
The hydraulic drive device 10 shown in FIG. 1 supplies the discharge pressure oil of the variable pump 11 to the tank 18 in accordance with the differential pressure reducing valve 25 that detects the differential pressure between the discharge pressure P of the variable pump 11 and the maximum load pressure of one actuator 17. An unloading valve 14 leading to
The unload valve 14 is operated by the discharge pressure P of the variable pump 11 acting on the first pressure receiving portion 21 via the discharge line 13 in the communication direction (left position in FIG. 1), and the maximum load received by the second pressure receiving portion 22. It is configured to operate in the blocking direction (right position in FIG. 1) by the pressure PLmax. In FIG. 1, reference numeral 24 indicates a relief valve. Further, reference numeral 26 denotes a pressure compensation valve, which has a function of compensating for the differential pressure before and after the operation switching valve 19.

さらに、アクチュエータ（シリンダ）１７を作動する操作切換弁１９の上流に第一の固定絞り１６を設け、該第一の固定絞り１６の下流が操作切換弁１９によってタンク１８へ連通・遮断して、制御される制御圧Ｐｕがアンロード弁１４の第三受圧部２３に作用することで遮断方向に作動することを特徴としている。
図２は、操作切換弁１９の拡大回路図を示す。図２において、操作切換弁１９はスプール（図示しない）の中立位置では回路（第１の回路）２７ａ、切換位置、例えば左位置１９ａ及び右位置１９ｂには、油路面積が調整される回路（第２の回路）２７ｂ、回路（第３の回路）２７ｃが構成されている。前記左位置１９ａ、右位置１９ｂでは、第一の固定絞り１６の下流とタンク１８の油路を絞って連通される回路２７ｂ乃至２７ｃとなっており、中立位置では第一の固定絞り１６の下流とタンク１８を連通する回路２７ａとなっている。これによって、操作切換弁１９が中立のとき第一の固定絞り１６の上流側の圧力２０が一定ならアンロード弁１４の第三受圧部２３に作用する制御圧Ｐｕが操作切換弁１９の切換位置１９ａの回路２７ｂ，及び切換位置１９ｂの回路２７ｃの面積（図示せず）により変わることになる。
よって、シリンダ１７を作動させる操作切換弁１９の切換位置１９ａ，１９ｂのときは第三受圧部２３に作用する制御圧Ｐｕが高くなり、可変ポンプ１１の吐出圧Ｐが予め高く設定できシリンダ１７の応答性を高めることができる。

Further, a first fixed throttle 16 is provided upstream of the operation switching valve 19 that operates the actuator (cylinder) 17, and the downstream of the first fixed throttle 16 is communicated / blocked to the tank 18 by the operation switching valve 19, The control pressure Pu to be controlled acts on the third pressure receiving portion 23 of the unload valve 14 to operate in the shut-off direction.
FIG. 2 shows an enlarged circuit diagram of the operation switching valve 19. In FIG. 2, the operation switching valve 19 has a circuit (first circuit) 27a in a neutral position (not shown) of a spool (not shown ) 27a, and a circuit in which an oil passage area is adjusted ( for example, a left position 19a and a right position 19b ). The second circuit 27b and the circuit (third circuit) 27c are configured. In the left position 19a and the right position 19b, there are circuits 27b to 27c communicating with the downstream of the first fixed throttle 16 and the oil passage of the tank 18, and downstream of the first fixed throttle 16 in the neutral position. And a circuit 27 a that communicates with the tank 18. As a result, if the pressure 20 upstream of the first fixed throttle 16 is constant when the operation switching valve 19 is neutral, the control pressure Pu acting on the third pressure receiving portion 23 of the unloading valve 14 is changed to the switching position of the operation switching valve 19. It changes depending on the area (not shown) of the circuit 27b of 19a and the circuit 27c of the switching position 19b.
Therefore, at the switching positions 19a and 19b of the operation switching valve 19 for operating the cylinder 17, the control pressure Pu acting on the third pressure receiving portion 23 becomes high, and the discharge pressure P of the variable pump 11 can be set high in advance. Responsiveness can be improved.

図３は、アンロード弁１４を模写的に示した構造図である。図３においてアンロード弁１４は弁本体３２にスプール３３が摺動自在に嵌挿され、該弁本体３２の両端は栓３４，３５によって液密的に封止されている。スプール３３の一側（図３で左側）には、接触子３６がばね部材３７を介して当接している。前記ばね部材３７は栓３４と接触子３６との間に設けられている。スプール３３の他側（図３で右側）にはピストン３８が摺動自在に嵌挿されている。   FIG. 3 is a structural diagram schematically showing the unload valve 14. In FIG. 3, the unload valve 14 has a spool 33 slidably inserted into a valve body 32, and both ends of the valve body 32 are sealed fluid-tightly by plugs 34 and 35. A contact 36 is in contact with one side of the spool 33 (left side in FIG. 3) via a spring member 37. The spring member 37 is provided between the stopper 34 and the contact 36. A piston 38 is slidably fitted on the other side of the spool 33 (right side in FIG. 3).

図３において、ピストン３８の断面積、すなわちアンロード弁１４の第一受圧部２１の断面積をＡ１、スプール３３の第二受圧部２２の断面積をＡ２，第三受圧部２３の断面積をＡ３、ばね部材３７の弾発力Ｗｓｐとすると、
可変ポンプ１１の吐出ライン１３とタンクポート２８とを連通させる方向に作用する力は、 Ｐ×Ａ１・・・式１ で表わせる。
また、可変ポンプ１１の吐出ライン１３とタンクポート２８とを遮断させる方向に作用する力は、（Ｐｕ×Ａ３）＋（ＰＬ×Ａ２）＋Ｗｓｐ・・・式２ で表わせる。
従って、アンロード弁１４のスプール３３における圧力バランスは、
Ｗｓｐ＋（Ｐｕ×Ａ３）＋（ＰＬ×Ａ２）＝Ｐ×Ａ１・・・式３ となるように、アンロード弁１４が制御される。なお、ＰＬは負荷圧力、Ｐｕは制御圧を表わす。
ここで、Ａ１＝Ａ２＝Ａ３とすると、
操作切換弁１９が中立時（シリンダ１７に圧油の供給がない）は、ＰＬ＝０であることより、 式３は、Ｐ＝Ｐｕ＋Ｗｓｐ／Ａ１・・・式４ となる。
よって、アンロード状態の可変ポンプ１１のポンプ圧Ｐは、制御圧Ｐｕによって、変化することがわかる。 In FIG. 3, the cross-sectional area of the piston 38, that is, the cross-sectional area of the first pressure receiving portion 21 of the unload valve 14 is A1, the cross-sectional area of the second pressure receiving portion 22 of the spool 33 is A2, and the cross-sectional area of the third pressure receiving portion 23. Assuming that the elastic force Wsp of the spring member 37 is A3,
The force acting in the direction in which the discharge line 13 of the variable pump 11 and the tank port 28 communicate with each other can be expressed by P × A1.
Further, the force acting in the direction of blocking the discharge line 13 and the tank port 28 of the variable pump 11 can be expressed by (Pu × A3) + (PL × A2) + Wsp (Equation 2).
Therefore, the pressure balance in the spool 33 of the unload valve 14 is
The unload valve 14 is controlled so that Wsp + (Pu × A3) + (PL × A2) = P × A1 (Equation 3). Note that PL represents a load pressure and Pu represents a control pressure.
Here, if A1 = A2 = A3,
When the operation switching valve 19 is neutral (no pressure oil is supplied to the cylinder 17), since PL = 0, Equation 3 becomes P = Pu + Wsp / A1.
Therefore, it can be seen that the pump pressure P of the variable pump 11 in the unloaded state changes depending on the control pressure Pu.

次に制御圧Ｐｕの設定方法を図２により説明する。第一の固定絞り１６の上流側の圧力２０をＰｐとし、第一の固定絞り１６の面積をａ１、操作切換弁１９における該第一の固定絞り１６側の下流とタンク１８間の回路２７ａ乃至２７ｃの面積をａ２、タンク１８の圧力をＰｔとすると、面積ａ１，ａ２の流量はオリフィスの式より、
Ｑ＝ｃ×ａ１×√（Ｐｐ−Ｐｕ）・・・式５
Ｑ＝ｃ×ａ２×√（Ｐｕ−Ｐｔ）・・・式６で表わせる。
Ｐｔ＝０とすると、 ａ１×√（Ｐｐ−Ｐｕ）＝ａ２×√（Ｐｕ）
整理すると、Ｐｕ＝（ａ１２）／（ａ１２＋ａ２２）Ｐｐ・・・式７で表わせる。
よって、第一の固定絞り１６の上流側の圧力２０をＰｐの値と第一の固定絞り１６の面積ａ１と、操作切換弁１９における該第一の固定絞り１６の下流とタンク１８間の回路２７ａ乃至２７ｃの面積との関係で、制御圧Ｐｕは決まる。 Next, a method for setting the control pressure Pu will be described with reference to FIG. The pressure 20 on the upstream side of the first fixed throttle 16 is Pp, the area of the first fixed throttle 16 is a1, the circuit 27a to the circuit 18a between the downstream of the first fixed throttle 16 side of the operation switching valve 19 and the tank 18. Assuming that the area of 27c is a2 and the pressure of the tank 18 is Pt, the flow rates of the areas a1 and a2 are obtained from the orifice equation:
Q = c × a1 × √ (Pp−Pu) Equation 5
Q = c × a2 × √ (Pu−Pt) (6)
When Pt = 0, a1 × √ (Pp−Pu) = a2 × √ (Pu)
In summary, Pu = (a1 2 ) / (a1 2 + a2 2 ) Pp (7)
Therefore, the pressure 20 on the upstream side of the first fixed throttle 16 is the value of Pp, the area a1 of the first fixed throttle 16, and the circuit between the downstream of the first fixed throttle 16 and the tank 18 in the operation switching valve 19. The control pressure Pu is determined by the relationship with the areas 27a to 27c.

図４は操作切換弁１９（図１参照）の構造を示す要部拡大縦断面図で、該操作切換弁１９は弁本体３９のスプール穴４３にスプール４０が摺動自在に嵌挿されている。前記スプール４０には、第一の固定絞り１６側の下流とタンク１８（図１参照）の間の回路２７ａ乃至２７ｃの形状が例えば、図５及び図６のように形成されている。
図５では、第一の固定絞り１６側，タンク１８側の連通孔４１，４２が間隔をおいて設けられ、該連通孔４１、４２に連通する内部環状溝４４、４５がスプール４０の外周面に臨んで弁本体３９に設けられている。スプール４０の軸心方向には内部環状溝４４、４５の幅の一側端面（図５で内部環状溝４４の右側及び内部環状溝４５の左側を指す）に対してアンダーラップ量Ｘ１を有する段付面４６、４７が形成され、該段付面４６、４７は環状溝４８により連通している。 FIG. 4 is an enlarged longitudinal sectional view showing a main part of the structure of the operation switching valve 19 (see FIG. 1). The operation switching valve 19 has a spool 40 slidably inserted into a spool hole 43 of the valve body 39. . In the spool 40, the shapes of the circuits 27a to 27c between the downstream on the first fixed throttle 16 side and the tank 18 (see FIG. 1) are formed as shown in FIGS. 5 and 6, for example.
In FIG. 5, communication holes 41, 42 on the first fixed throttle 16 side and tank 18 side are provided at intervals, and internal annular grooves 44, 45 communicating with the communication holes 41, 42 are outer peripheral surfaces of the spool 40. It is provided in the valve body 39 so as to face. A step having an underlap amount X1 in the axial direction of the spool 40 with respect to one end face of the width of the inner annular grooves 44, 45 (referring to the right side of the inner annular groove 44 and the left side of the inner annular groove 45 in FIG. Attached surfaces 46 and 47 are formed, and the stepped surfaces 46 and 47 communicate with each other by an annular groove 48.

前記段付面４６、４７はそれぞれスプール４０の軸径よりも若干小さい軸部４９、５０を形成している。このため、例えばスプール４０が図５で右方向にストロークした場合は、スプール穴４３と軸部４９との間に隙間５１が形成され、かつ隙間５１は図５で示す中立位置のスプール穴４３と軸部４８の隙間よりも小さいため連通孔４１より連通孔４２に流れる圧油の流量は絞られている。逆にスプール４０が図５で左方向にストロークした場合は、スプール穴４３と軸部５０との間に隙間５２が形成され、かつ隙間５２も図５で示す中立位置のスプール穴４３と軸部４８の隙間よりも小さいため連通孔４１より連通孔４２に流れる圧油の流量は絞られている。また、隙間５１より隙間５２の方が小さく、スプール４０が左方向にストロークした方が、連通孔４１より連通孔４２に流れる圧油の流量はより絞られていることになる。   The stepped surfaces 46 and 47 form shaft portions 49 and 50 that are slightly smaller than the shaft diameter of the spool 40, respectively. Therefore, for example, when the spool 40 strokes in the right direction in FIG. 5, a gap 51 is formed between the spool hole 43 and the shaft portion 49, and the gap 51 is separated from the spool hole 43 in the neutral position shown in FIG. Since it is smaller than the clearance of the shaft portion 48, the flow rate of the pressure oil flowing from the communication hole 41 to the communication hole 42 is reduced. On the contrary, when the spool 40 strokes in the left direction in FIG. 5, a gap 52 is formed between the spool hole 43 and the shaft portion 50, and the gap 52 is also formed between the spool hole 43 and the shaft portion in the neutral position shown in FIG. 5. Since the clearance is smaller than 48, the flow rate of the pressure oil flowing from the communication hole 41 to the communication hole 42 is reduced. Further, when the gap 52 is smaller than the gap 51 and the spool 40 is stroked to the left, the flow rate of the pressure oil flowing from the communication hole 41 to the communication hole 42 is further reduced.

図６では、連通孔４１、４２に連通し、スプール４０の軸心方向に指向するノッチ５３、５４を間隔をおいて外周部に複数個設け、該ノッチ５３、５４の一端面と環状溝４４、４５の一側端面（図６で内部環状溝４４の右側及び内部環状溝４５の左側を指す）に対して距離Ｘ１を有する。ノッチ５３及び５４は環状溝４８により連通している。このため、例えばスプール４０が図６の右方向にストロークした場合は、ノッチ５３で連通孔４１より連通孔４２に流れる圧油の流量は絞られている。逆にスプール４０が図６の左方向にストロークした場合は、ノッチ５４で連通孔４１より連通孔４２に流れる圧油の流量は絞られている。また、ノッチ５３よりノッチ５４の方が深さが浅く、スプール４０が左方向にストロークした方が、連通孔４１より連通孔４２に流れる圧油の流量はより絞られていることになる。   In FIG. 6, a plurality of notches 53, 54 that communicate with the communication holes 41, 42 and that are oriented in the axial direction of the spool 40 are provided on the outer peripheral portion at intervals, and one end face of the notches 53, 54 and the annular groove 44 , 45 with a distance X1 with respect to one end face (referring to the right side of the inner annular groove 44 and the left side of the inner annular groove 45 in FIG. 6). Notches 53 and 54 communicate with each other by an annular groove 48. For this reason, for example, when the spool 40 strokes in the right direction of FIG. 6, the flow rate of the pressure oil flowing from the communication hole 41 to the communication hole 42 is reduced by the notch 53. Conversely, when the spool 40 strokes in the left direction in FIG. 6, the flow rate of the pressure oil flowing from the communication hole 41 to the communication hole 42 is reduced by the notch 54. Further, when the notch 54 is shallower than the notch 53 and the spool 40 is stroked to the left, the flow rate of the pressure oil flowing from the communication hole 41 to the communication hole 42 is further reduced.

図４に示す操作切換弁１９のスプール４０に設けた回路２７ａ乃至２７ｃにおいて、第一の固定絞り１６の下流とタンク１８への流路が絞られるまでの距離をＸ１とする。さらに、圧力ポートＰからシリンダ１７（図１参照）のポート（図示しない）への開口面積が開き始めるまでのストロークをＸ２とする。
ここで、Ｘ１＜Ｘ２の関係に設定すると、図７に示すように負荷圧力ＰＬが低い場合は
、該負荷圧力ＰＬに対し可変ポンプの吐出圧も高くする必要がなく、回路２７ｂ、２７ｃの面積を大きめにして、制御圧Ｐｕを低くすることで、可変ポンプ１１の吐出圧Ｐが低くできる。また、負荷圧ＰＬが高い場合は、回路２７ｂ、２７ｃの面積を小さめにして、制御圧Ｐｕを高くすることで可変ポンプ１１のポンプ圧Ｐを高くできる。負荷圧ＰＬの特性に合わせて、負荷圧ＰＬより可変ポンプ１１のポンプ圧Ｐを僅か高くできる。 In the circuits 27a to 27c provided on the spool 40 of the operation switching valve 19 shown in FIG. 4, the distance from the downstream of the first fixed throttle 16 to the throttle of the flow path to the tank 18 is X1. Furthermore, let X2 be the stroke until the opening area from the pressure port P to the port (not shown) of the cylinder 17 (see FIG. 1) begins to open.
Here, when the relationship X1 <X2 is set, when the load pressure PL is low as shown in FIG. 7, it is not necessary to increase the discharge pressure of the variable pump with respect to the load pressure PL, and the areas of the circuits 27b and 27c. The discharge pressure P of the variable pump 11 can be lowered by increasing the pressure and lowering the control pressure Pu. When the load pressure PL is high, the pump pressure P of the variable pump 11 can be increased by reducing the areas of the circuits 27b and 27c and increasing the control pressure Pu. In accordance with the characteristics of the load pressure PL, the pump pressure P of the variable pump 11 can be slightly higher than the load pressure PL.

図８は、従前の操作切換弁の開口面積と可変ポンプの吐出圧との関係を示す説明図である。図８では、操作切換弁１９のスプール４０（図４参照）の開口面積が開き始めるまでのストロークＸ２してから負荷圧力ＰＬが上昇し、それに伴い、可変ポンプのポンプ圧Ｐが遅れて上昇するので、Ｐ＜ＰＬのストローク範囲Ｘ３の間は、シリンダ１７（図１参照）は作動しない。
図９は本発明の第二の実施の形態に係る油圧駆動装置６０の油圧回路図を示す。図１０中、図１の構成要素と同一の構成要素は同一符号を付して詳細な説明を省略する。 以下、同様とする。
図９の油圧駆動装置６０は、パイロットポンプ１２の下流に第一の固定絞り１６とは別に第二の固定絞り６１を設け、第二の固定絞り６１の前後の差圧Ｐｒを検出する差圧減圧弁６２を設け、前後の差圧Ｐｒを第一の固定絞り１６へ供給し、該第一の固定絞り１６の下流とタンク１８への流路面積が操作切換弁１９の切換位置によって変化することで、制御される制御圧Ｐｕがアンロード弁１４の第三受圧部２３に作用することで遮断方向に作動することを特徴する。但し、原動機の回転で可変ポンプ１１のポンプ圧Ｐが変わる。なお、参照符号６３は第二の固定絞り６１の上流側の圧力ラインを示す。 FIG. 8 is an explanatory diagram showing the relationship between the opening area of the conventional operation switching valve and the discharge pressure of the variable pump. In FIG. 8, the load pressure PL increases after the stroke X2 until the opening area of the spool 40 (see FIG. 4) of the operation switching valve 19 starts to open, and accordingly, the pump pressure P of the variable pump increases with a delay. Therefore, the cylinder 17 (see FIG. 1) does not operate during the stroke range X3 where P <PL.
FIG. 9 shows a hydraulic circuit diagram of a hydraulic drive device 60 according to the second embodiment of the present invention. 10, the same components as those of FIG. 1 are denoted by the same reference numerals, and detailed description thereof is omitted. The same shall apply hereinafter.
9 is provided with a second fixed throttle 61 separately from the first fixed throttle 16 downstream of the pilot pump 12, and detects a differential pressure Pr before and after the second fixed throttle 61. A pressure reducing valve 62 is provided to supply the front and rear differential pressure Pr to the first fixed throttle 16, and the flow path area downstream of the first fixed throttle 16 and to the tank 18 varies depending on the switching position of the operation switching valve 19. Thus, the control pressure Pu to be controlled acts on the third pressure receiving portion 23 of the unload valve 14 to operate in the shut-off direction. However, the pump pressure P of the variable pump 11 changes with the rotation of the prime mover. Reference numeral 63 indicates a pressure line upstream of the second fixed throttle 61.

図１０は本発明の第三の実施の形態に係る油圧駆動装置７０の油圧回路図を示す。図１０の油圧駆動装置７０の特徴は、図１の油圧駆動装置１０に油圧モータ７１を付加して、該油圧モータ７１の操作を行う操作切換弁７２、圧力補償弁７３を設けている。
この油圧駆動装置７０では、操作切換弁１９、及び７２の切換ストロークに応じて、シリンダ１７及び油圧モータ７１に適した可変ポンプ１１の吐出圧Ｐに予め高めることができ、応答性を高めることができる。 FIG. 10 is a hydraulic circuit diagram of a hydraulic drive device 70 according to the third embodiment of the present invention. 10 is provided with an operation switching valve 72 and a pressure compensation valve 73 for operating the hydraulic motor 71 by adding a hydraulic motor 71 to the hydraulic drive apparatus 10 of FIG.
In the hydraulic drive device 70, the discharge pressure P of the variable pump 11 suitable for the cylinder 17 and the hydraulic motor 71 can be increased in advance according to the switching stroke of the operation switching valves 19 and 72, and the responsiveness can be improved. it can.

図１１は本発明の第四の実施の形態に係る油圧駆動装置８０の油圧回路図を示す。図１１の油圧駆動装置８０の特徴は、図９の油圧駆動装置６０に油圧モータ８１を付加して、該油圧モータ８１の操作を行う操作切換弁８２、圧力補償弁８３を設けている。   FIG. 11 shows a hydraulic circuit diagram of a hydraulic drive unit 80 according to the fourth embodiment of the present invention. 11 is provided with an operation switching valve 82 and a pressure compensation valve 83 for operating the hydraulic motor 81 by adding a hydraulic motor 81 to the hydraulic drive device 60 of FIG.

図１、図９乃至図１１に示す油圧駆動装置１０、６０、７０及び８０によれば、前記第一の固定絞りの断面積と前記操作切換弁によって制御されるタンクへの流路面積の設定条件によって、制御圧が選定可能であるので、操作切換弁が作動した際のタンクへの流路面積を任意に設定することで、制御圧が異なり、その結果、作動させるアクチュエータに合わせ可変ポンプの吐出圧を設定できる。このためアクチュエータの負荷に合わせ適切な可変ポンプの吐出圧を設定できるので、各アクチュエータとも応答性を高めることができ、かつ可変ポンプ吐出圧が高すぎることによる実機のショックを防止できる。また無駄ポンプ圧が高くなることもない。   According to the hydraulic drive devices 10, 60, 70 and 80 shown in FIGS. 1 and 9 to 11, the cross-sectional area of the first fixed throttle and the flow passage area to the tank controlled by the operation switching valve are set. Since the control pressure can be selected depending on the conditions, the control pressure differs by arbitrarily setting the flow path area to the tank when the operation switching valve is activated. The discharge pressure can be set. For this reason, it is possible to set an appropriate discharge pressure of the variable pump in accordance with the load of the actuator, so that the response of each actuator can be improved and the shock of the actual machine due to the variable pump discharge pressure being too high can be prevented. In addition, the waste pump pressure does not increase.

本発明の第一の実施の形態に係る油圧駆動装置の油圧回路図である。1 is a hydraulic circuit diagram of a hydraulic drive device according to a first embodiment of the present invention. 図１に示す操作切換弁の拡大油圧回路図である。FIG. 2 is an enlarged hydraulic circuit diagram of the operation switching valve shown in FIG. 1. 図１のアンロード弁の概略構造図である。FIG. 2 is a schematic structural diagram of the unload valve in FIG. 1. 図１の操作切換弁の要部拡大縦断面図である。FIG. 2 is an enlarged longitudinal sectional view of a main part of the operation switching valve in FIG. 1. 図４のスプールの拡大詳細図である。FIG. 5 is an enlarged detail view of the spool of FIG. 4. 図４のスプールの変形例を示す拡大詳細図である。FIG. 5 is an enlarged detail view showing a modified example of the spool of FIG. 4. 図１に示す操作切換弁の開口面積とアンロード弁の可変ポンプの吐出圧との関係を示す1 shows the relationship between the opening area of the operation switching valve shown in FIG. 1 and the discharge pressure of the variable pump of the unload valve. 従前の操作切換弁の開口面積と可変ポンプの吐出圧との関係を示す説明図である。It is explanatory drawing which shows the relationship between the opening area of a conventional operation switching valve, and the discharge pressure of a variable pump. 本発明の第二の実施の形態に係る油圧駆動装置の油圧回路図である。FIG. 4 is a hydraulic circuit diagram of a hydraulic drive device according to a second embodiment of the present invention. 本発明の第三の実施の形態に係る油圧駆動装置の油圧回路図である。FIG. 5 is a hydraulic circuit diagram of a hydraulic drive device according to a third embodiment of the present invention. 本発明の第四の実施の形態に係る油圧駆動装置の油圧回路図である。FIG. 6 is a hydraulic circuit diagram of a hydraulic drive device according to a fourth embodiment of the present invention.

符号の説明Explanation of symbols

１０、６０、７０，８０ 油圧駆動装置 １１ 可変ポンプ
１４ アンロード弁 １６、６１、 第一の固定絞り１
１９、７２、８２ 操作切換弁 ２１、２２、２３ 受圧部
２４ リリーフ弁 ２５、６２ 差圧減圧弁
２６、７３、８３ 圧力補償弁
10, 60, 70, 80 Hydraulic drive device 11 Variable pump 14 Unload valve 16, 61, First fixed throttle 1
19, 72, 82 Operation switching valve 21, 22, 23 Pressure receiving portion 24 Relief valve 25, 62 Differential pressure reducing valve 26, 73, 83 Pressure compensation valve

Claims (1)

可変ポンプの吐出圧と少なくとも１つのアクチュエータの最高負荷圧との差圧に応じて可変ポンプの吐出圧油をタンクに導くアンロード弁を有する油圧駆動装置において、
前記アンドロード弁は、第一受圧部に作用する可変ポンプの吐出圧によって連通方向に作動し、第二受圧部に受ける最高負荷圧によって遮断方向に作動するように構成され、
操作切換弁は、スプールの中立位置では第１の回路、切換位置には第２の回路、第３の回路が構成され、かつ前記第２の回路及び第３の回路は所定面積だけ開口するよう構成され、さらにパイロットポンプの下流に第一の固定絞りを設け、該第一の固定絞りのタンクに連通する前記操作切換弁の回路の面積が、該操作切換弁の切換位置によって変化することで制御される制御圧が第三受圧部に作用して、前記操作切換弁の切換位置毎の回路の面積の設定により、操作切換弁の切換位置によって制御圧が変化して可変ポンプの吐出圧の高さの度合が変化することを特徴とする油圧駆動装置。 In the hydraulic drive device having an unload valve for guiding the discharge pressure oil of the variable pump to the tank according to the differential pressure between the discharge pressure of the variable pump and the maximum load pressure of at least one actuator,
The and load valve is configured to operate in a communication direction by a discharge pressure of a variable pump acting on a first pressure receiving part, and to operate in a blocking direction by a maximum load pressure received by the second pressure receiving part,
The operation switching valve includes a first circuit in the neutral position of the spool, a second circuit and a third circuit in the switching position, and the second circuit and the third circuit are opened by a predetermined area. is configured, further a first fixed throttle is provided downstream of the pilot pump, that area of the circuit of the operating switching valve communicating with the tank of the first fixed throttle is changed by the switching position of the operating selector valve The control pressure to be controlled acts on the third pressure receiving portion, and by setting the circuit area for each switching position of the operation switching valve, the control pressure changes depending on the switching position of the operation switching valve, and the discharge pressure of the variable pump is reduced. A hydraulic drive device characterized in that the degree of height changes.
JP2007145068A 2007-05-31 2007-05-31 Hydraulic drive Expired - Fee Related JP4962143B2 (en)

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DE3644745A1 (en) * 1986-12-30 1988-07-14 Rexroth Mannesmann Gmbh CONTROL ARRANGEMENT FOR AT LEAST TWO HYDRAULIC CONSUMERS SUPPLIED BY AT LEAST ONE PUMP
JP3216816B2 (en) * 1991-01-23 2001-10-09 株式会社小松製作所 Pressure oil supply device
JPH0893706A (en) * 1994-09-29 1996-04-09 Toshiba Mach Co Ltd Hydraulic driving circuit
JP3859818B2 (en) * 1997-06-03 2006-12-20 株式会社タダノ Start-up prediction device for double-acting hydraulic actuator
JPH11315805A (en) * 1998-03-04 1999-11-16 Komatsu Ltd Unload valve
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