JPH0533776A - Capacity control device for variable capacity type hydraulic pump - Google Patents
Capacity control device for variable capacity type hydraulic pumpInfo
- Publication number
- JPH0533776A JPH0533776A JP3213167A JP21316791A JPH0533776A JP H0533776 A JPH0533776 A JP H0533776A JP 3213167 A JP3213167 A JP 3213167A JP 21316791 A JP21316791 A JP 21316791A JP H0533776 A JPH0533776 A JP H0533776A
- Authority
- JP
- Japan
- Prior art keywords
- pressure
- pump
- control valve
- variable
- discharge
- 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
Landscapes
- Fluid-Pressure Circuits (AREA)
- Control Of Positive-Displacement Pumps (AREA)
Abstract
Description
【０００１】[0001]
【産業上の利用分野】本発明は、可変容量型油圧ポンプ
の容量を制御する装置に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for controlling the displacement of a variable displacement hydraulic pump.
【０００２】[0002]
【従来の技術】図１に示すように、可変容量型油圧ポン
プ１（以下可変ポンプ１という）は斜板２を傾転して容
量、つまり１回転当り吐出流量を変化するものであり、
この可変ポンプ１の吐出路３に方向制御弁４を介してア
クチュエータ５を設けた油圧回路において、前記斜板２
を傾転して容量を制御する装置としては可変制御弁６と
負荷検出弁７でポンプ吐出圧Ｐ0 を容量可変シリンダ８
の大径受圧室９に供給するものが知られている。すなわ
ち、可変制御弁６はバネ１０とポンプ吐出圧Ｐ0 でドレ
ーン位置Ａと圧油供給位置Ｂに切換えられ、ポンプ吐出
圧Ｐ0 が高くなると圧油供給位置Ｂとなってポンプ吐出
圧Ｐ0 を容量可変シリンダ８の大径受圧室９に供給して
小径受圧室１１との受圧面積差でピストン１２を左方向
に移動して斜板２を容量小方向に傾転し、可変ポンプ１
の１回転当り吐出流量を減少し、そのピストン１２の動
きを機械的フィードバック機構１３でバネ１０にフィー
ドバックしてバネ力を大きくして斜板２をポンプ吐出圧
Ｐ0 に見合う位置としてポンプ吐出圧×１回転当り吐出
流量を一定、つまりトルク一定制御する。負荷検出弁７
は方向制御弁４の上流側圧力Ｐ0 と負荷圧ＰLSの差圧△
ＰLS（△ＰLS＝Ｐ0 −ＰLS）が大きくなると圧油供給位
置Ｂとなって前述と同様に斜板２を容量・小方向に傾転
し、その差圧△ＰLSが小さくなるとドレーン位置Ａとな
って方向制御弁４の開度、つまり操作ストロークに応じ
て可変ポンプ１の容量を制御しアクチュエータ５の微操
作性、つまりファインコントロール性を向上している。2. Description of the Related Art As shown in FIG. 1, a variable displacement hydraulic pump 1 (hereinafter referred to as variable pump 1) tilts a swash plate 2 to change its capacity, that is, the discharge flow rate per rotation.
In the hydraulic circuit in which the actuator 5 is provided in the discharge passage 3 of the variable pump 1 via the direction control valve 4, the swash plate 2
As a device for tilting the cylinder to control the displacement, the variable control valve 6 and the load detection valve 7 are used to change the pump discharge pressure P 0 to the variable displacement cylinder 8
It is known to supply the pressure to the large diameter pressure receiving chamber 9. That is, the variable control valve 6 is switched between the drain position A and the pressure oil supply position B by the spring 10 and the pump discharge pressure P 0 , and when the pump discharge pressure P 0 becomes high, the variable control valve 6 becomes the pressure oil supply position B and the pump discharge pressure P 0. Is supplied to the large diameter pressure receiving chamber 9 of the variable volume cylinder 8 and the piston 12 is moved leftward by the pressure receiving area difference from the small diameter pressure receiving chamber 11 to tilt the swash plate 2 in the small volume direction, and the variable pump 1
The flow rate of the piston 12 is reduced and the movement of the piston 12 is fed back to the spring 10 by the mechanical feedback mechanism 13 to increase the spring force to set the swash plate 2 at a position commensurate with the pump discharge pressure P 0. The discharge flow rate per one rotation is controlled to be constant, that is, the torque is controlled to be constant. Load detection valve 7
Is the pressure difference Δ between the upstream pressure P 0 of the directional control valve 4 and the load pressure P LS .
When P LS (ΔP LS = P 0 −P LS ) becomes large, the pressure oil supply position B is reached and the swash plate 2 is tilted in the capacity / small direction as described above, and when the differential pressure ΔP LS becomes smaller. The drain position A is set, and the displacement of the variable pump 1 is controlled according to the opening of the directional control valve 4, that is, the operation stroke to improve the fine operability of the actuator 5, that is, the fine controllability.
【０００３】[0003]
【発明が解決しようとする課題】かかる容量制御装置で
あると、機械的フィードバック機構１３が必要であるか
ら、構造が複雑でコスト高となるし、機械的フィードバ
ック機構１３のガタなどにより制御精度が悪くなり、し
かも斜板位置を可変制御弁６にフィードバックするか
ら、可変ポンプ１自体の効率低下によって斜板位置によ
る実際の１回転当り吐出流量が理論１回転当り吐出流量
に対して誤差が生じ可変ポンプ吐出流量特性が悪くなる
し、可変制御弁６と負荷検出弁７を必要とするから構造
複雑となる。In such a capacity control device, since the mechanical feedback mechanism 13 is required, the structure is complicated and the cost is high, and the control accuracy is increased due to the looseness of the mechanical feedback mechanism 13 and the like. In addition, since the swash plate position is fed back to the variable control valve 6, the efficiency of the variable pump 1 itself deteriorates, and the actual discharge flow rate per revolution due to the swash plate position varies with respect to the theoretical discharge flow rate per revolution and varies. The pump discharge flow rate characteristics are deteriorated, and the variable control valve 6 and the load detection valve 7 are required, which complicates the structure.
【０００４】そこで、本発明は前述の課題を解決できる
ようにした可変容量型油圧ポンプの容量制御装置を提供
することを目的とする。Therefore, an object of the present invention is to provide a displacement control device for a variable displacement hydraulic pump, which can solve the above-mentioned problems.
【０００５】[0005]
【課題を解決するための手段】可変容量型油圧ポンプ２
０の斜板２４を容量大・小方向に傾転する容量可変シリ
ンダ２５と、可変容量型油圧ポンプ２０の流量変化及び
可変容量型油圧ポンプ２０の吐出路２１に設けた方向切
換弁２２の開度変化を検出する第１の手段と、可変容量
型油圧ポンプ２０の回転数変化及びポンプ吐出圧変化を
検出する第２の手段と、前記第１の手段の出力信号と第
２の手段の出力信号とによって容量可変シリンダ２５に
ポンプ吐出圧を供給する制御弁３０より構成した可変容
量型油圧ポンプの容量制御装置。[Means for Solving the Problems] Variable displacement hydraulic pump 2
A variable capacity cylinder 25 that tilts the swash plate 24 of 0 in the direction of large capacity and small capacity, a flow rate change of the variable capacity hydraulic pump 20, and an opening of the direction switching valve 22 provided in the discharge passage 21 of the variable capacity hydraulic pump 20. Degree detecting means, second means detecting the rotational speed change and pump discharge pressure change of the variable displacement hydraulic pump 20, an output signal of the first means and an output of the second means. A displacement control device for a variable displacement hydraulic pump configured by a control valve 30 that supplies pump discharge pressure to a displacement variable cylinder 25 according to a signal.
【０００６】[0006]
【作 用】可変容量型油圧ポンプ２０の流量変化及び
回転数変化、ポンプ吐出圧変化、方向制御弁の開度変化
により制御弁３０を切換えるから機械的フィードバック
機構を用いずにトルク一定制御できるし、方向切換弁の
通過流量を回転数に応じて増減してアクチュエータのフ
ァインコントロール性を向上できる。[Operation] Since the control valve 30 is switched by changing the flow rate and the rotating speed of the variable displacement hydraulic pump 20, the pump discharge pressure, and the opening of the directional control valve, constant torque control can be performed without using a mechanical feedback mechanism. The fine controllability of the actuator can be improved by increasing or decreasing the passage flow rate of the directional control valve according to the number of revolutions.
【０００７】[0007]
【実 施 例】図２に示すように、可変ポンプ２０の吐
出路２１には複数の方向切換弁２２を介して複数のアク
チュエータ２３が接続され、その可変ポンプ２０の容
量、つまり１回転当り吐出流量ｑを増減する斜板２４は
容量可変シリンダ２５で容量大・小方向に傾転され、こ
の容量可変シリンダ２５の小径受圧室２６は通路２７で
吐出路２１に接続し、大径受圧室２８は通路２９で制御
弁３０に接続している。前記可変ポンプ２０とともに駆
動される固定ポンプ３３の吐出路３４には絞り３５が設
けてあると共に、その吐出路３４における絞り３５前後
を短絡するバイパス路３６にはバイパス弁３７が設けら
れ、このバイパス弁３７はバネ３８で閉じ方向に押さ
れ、受圧部３９に作用する可変ポンプ２０のポンプ吐出
圧Ｐ0 で開方向に押されてバイパス弁３７の開度はポン
プ吐出圧Ｐ0 に比例して大きくなる。前記制御弁３０は
ドレーン位置Ａと圧油供給位置Ｂを備え、弱いバネ４０
でドレーン位置Ａに押され、前記可変制御弁３０は第１
受圧部４１に作用する圧力で圧油供給位置Ｂに向けて押
され、第２受圧部４２に作用する圧力でドレーン位置Ａ
に向けて押され、その第１受圧部４１は可変ポンプ２０
の吐出路２１に設けた絞り４３の上流側に第１パイロッ
ト通路４４で接続し、第２受圧部４２は方向制御弁２２
の下流側にシャトル弁４５、第２パイロット通路４６を
介して接続してあり、可変制御弁３０は絞り４３の上流
側圧力Ｐ0 と負荷圧（方向制御弁２２の下流側圧力）Ｐ
LSの差圧に比例した第１の力Ｆ1 で圧油供給位置Ｂに向
けて押される。前記制御弁３０は第３受圧部４７に作用
する圧力でドレーン位置Ａに向けて押され、第４受圧部
４８に作用する圧力で圧油供給位置Ｂに向けて押され、
その第３受圧部４７は第３パイロット通路５０で固定ポ
ンプ３３の吐出路３４の絞り３５の上流側に接続し、第
４受圧部４８は第４パイロット通路４９で絞り３５の下
流側に接続して可変制御弁３１は絞り３５前後の差圧△
ＰC （△ＰC ＝Ｐ2 −Ｐ3 ）に比例した第２の力Ｆ2 で
ドレーン位置Ａに向けて押される。[Example] As shown in FIG. 2, a plurality of actuators 23 are connected to a discharge passage 21 of a variable pump 20 through a plurality of directional switching valves 22. The swash plate 24 for increasing / decreasing the flow rate q is tilted in the large / small capacity direction by the variable capacity cylinder 25, and the small diameter pressure receiving chamber 26 of the variable capacity cylinder 25 is connected to the discharge passage 21 by the passage 27 and the large diameter pressure receiving chamber 28. Is connected to the control valve 30 by a passage 29. The discharge passage 34 of the fixed pump 33 driven together with the variable pump 20 is provided with a throttle 35, and the bypass passage 36 for short-circuiting the throttle passage 35 in the discharge passage 34 is provided with a bypass valve 37. The valve 37 is pushed in the closing direction by the spring 38, and is pushed in the opening direction by the pump discharge pressure P 0 of the variable pump 20 acting on the pressure receiving portion 39, and the opening degree of the bypass valve 37 is proportional to the pump discharge pressure P 0. growing. The control valve 30 includes a drain position A and a pressure oil supply position B, and a weak spring 40.
Is pushed to the drain position A, and the variable control valve 30 is moved to the first position.
The pressure acting on the pressure receiving portion 41 is pushed toward the pressure oil supply position B, and the pressure acting on the second pressure receiving portion 42 is applied to the drain position A.
The first pressure receiving portion 41 is pushed toward the variable pump 20.
Is connected to the upstream side of the throttle 43 provided in the discharge passage 21 of the first pilot passage 44, and the second pressure receiving portion 42 is connected to the directional control valve 22.
Is connected to the downstream side of the throttle valve 45 and the second pilot passage 46, and the variable control valve 30 controls the upstream pressure P 0 of the throttle 43 and the load pressure (downstream pressure of the directional control valve 22) P.
It is pushed toward the pressure oil supply position B by the first force F 1 proportional to the differential pressure of LS . The control valve 30 is pushed toward the drain position A by the pressure acting on the third pressure receiving portion 47, and is pushed toward the pressure oil supply position B by the pressure acting on the fourth pressure receiving portion 48,
The third pressure receiving portion 47 is connected to the upstream side of the throttle 35 in the discharge passage 34 of the fixed pump 33 by the third pilot passage 50, and the fourth pressure receiving portion 48 is connected to the downstream side of the throttle 35 in the fourth pilot passage 49. The variable control valve 31 adjusts the differential pressure Δ before and after the throttle 35.
The second force F 2 proportional to P C (ΔP C = P 2 −P 3 ) is pushed toward the drain position A.
【０００８】次に可変ポンプ２０の容量制御動作を説明
する。 可変ポンプ２０の回転数及び方向制御弁２２の開度が
一定でポンプ吐出圧が変化した時。 ポンプ吐出圧Ｐ0 がバイパス弁３７のセット圧以下であ
るとバイパス弁３７が閉となって、固定ポンプ３３の吐
出圧油は全量が絞り３５を通過するから、その絞り３５
前後の差圧△ＰC が大きくなり、制御弁３０に作用する
第２の力Ｆ2 が第１の力Ｆ1 より大きくなって制御弁３
０はドレーン位置Ａとなり、容量可変シリンダ２５の大
径受圧室２８が通路２９，５１を通ってタンク５２に通
過するから小径受圧室２６に作用するポンプ吐出圧Ｐ0
で容量可変シリンダ２５は右方向に移動して斜板２４は
容量大方向に傾転し、可変ポンプ２０の１回転当り吐出
流量が増加して単位時間当り吐出流量が増大するから絞
り４３前後の差圧が大きくなり、しかも方向制御弁２２
の開度が一定であるから絞り４３の上流側圧力と方向制
御弁２２の下流側圧力の差圧が大きくなって第１の力Ｆ
1 が大きくなり、この第１の力Ｆ1 と第２の力Ｆ2 がつ
り合ったところで斜板２４の位置が保持される。つま
り、絞り４３前後の差圧が可変ポンプ１の流量検出手段
となって制御弁３０にフィードバックされる。前述の状
態においてポンプ吐出圧Ｐ0がバイパス弁３７のセット
圧以上となるとバイパス弁３７が開き作動して固定ポン
プ３３の吐出圧油の一部がバイパス路３６を流れるから
絞り３５を流れる流量が減少してその絞り３５前後の差
圧△ＰC が低下し、制御弁３０の第２の力Ｆ2 が小さく
なるから制御弁３０は圧油供給位置Ｂとなり、ポンプ吐
出圧Ｐ0 が通路５３，２９から容量可変シリンダ２５の
大径受圧室２８に供給されて受圧面積差によって容量可
変シリンダ２５は左方向に移動して斜板２４を容量小方
向に傾転する。これにより、可変ポンプ２０の１回転当
り吐出流量が減少して単位時間当り吐出流量も減少する
から絞り４３前後の差圧が小さくなって絞り４３の上流
側圧力と方向制御弁２２の出力側圧力との差圧も小さく
なって第１の力Ｆ1 も小さくなり、この第１の力Ｆ1と
第２の力Ｆ2 がつり合ったところで斜板２４の位置が保
持される。Next, the displacement control operation of the variable pump 20 will be described. When the rotation speed of the variable pump 20 and the opening degree of the direction control valve 22 are constant and the pump discharge pressure changes. When the pump discharge pressure P 0 is equal to or lower than the set pressure of the bypass valve 37, the bypass valve 37 is closed, and the discharge pressure oil of the fixed pump 33 entirely passes through the throttle 35.
The differential pressure ΔP C between the front and rear becomes large, the second force F 2 acting on the control valve 30 becomes larger than the first force F 1 , and the control valve 3
0 becomes the drain position A, and the large diameter pressure receiving chamber 28 of the variable capacity cylinder 25 passes through the passages 29 and 51 to the tank 52, so that the pump discharge pressure P 0 acting on the small diameter pressure receiving chamber 26 is reached.
The variable volume cylinder 25 moves to the right and the swash plate 24 tilts toward the large volume direction, and the discharge flow rate per one rotation of the variable pump 20 increases and the discharge flow rate per unit time increases. The differential pressure becomes large and the directional control valve 22
Since the opening degree of is constant, the differential pressure between the upstream pressure of the throttle 43 and the downstream pressure of the directional control valve 22 becomes large, and the first force F
1 increases, and the position of the swash plate 24 is held when the first force F 1 and the second force F 2 are balanced. That is, the differential pressure before and after the throttle 43 serves as flow rate detection means of the variable pump 1 and is fed back to the control valve 30. In the above-mentioned state, when the pump discharge pressure P 0 becomes equal to or higher than the set pressure of the bypass valve 37, the bypass valve 37 is opened and a part of the discharge pressure oil of the fixed pump 33 flows through the bypass passage 36, so that the flow rate of the throttle 35 increases. As the differential pressure ΔP C before and after the throttle 35 decreases and the second force F 2 of the control valve 30 decreases, the control valve 30 moves to the pressure oil supply position B, and the pump discharge pressure P 0 changes to the passage 53. , 29 to the large-diameter pressure receiving chamber 28 of the variable capacity cylinder 25, the variable capacity cylinder 25 moves leftward due to the difference in pressure receiving area, and tilts the swash plate 24 in the small capacity direction. As a result, the discharge flow rate per one rotation of the variable pump 20 decreases and the discharge flow rate per unit time also decreases, so the differential pressure before and after the throttle 43 decreases, and the upstream pressure of the throttle 43 and the output pressure of the directional control valve 22. And the first force F 1 also decreases, and the position of the swash plate 24 is maintained when the first force F 1 and the second force F 2 are balanced.
【０００９】前述の状態からポンプ吐出圧Ｐ0 が更に高
くなると、バイバス弁３７が更に開き作動して通過流量
が増えるから絞り３５を流れる流量が減少して絞り３５
前後の差圧△ＰC が更に小さくなるので、制御弁３０に
作用する第２の力Ｆ2 が更に小さくなって制御弁３０は
圧油供給位置Ｂとなって前述と同様にして容量可変シリ
ンダ２５が左方向に移動して斜板２４が容量小方向に傾
転して１回転当り吐出流量が減少して単位時間当り吐出
流量が減少し、前述と同様に絞り４３前後の差圧が小さ
くなって第１の力Ｆ1も小さくなり、この第１の力Ｆ1
と第２の力Ｆ2 がつり合ったところで斜板２４の位置が
保持される。以上のように、可変ポンプ２０の回転数が
一定で方向制御弁２２の開度が一定の時にはポンプ吐出
圧Ｐ0 によって斜板２４の位置が決定されてポンプ吐出
圧Ｐ0 ×１回転当り吐出流量ｑが一定、つまりトルク一
定に制御される。When the pump discharge pressure P 0 further increases from the above-mentioned state, the bypass valve 37 is further opened and the flow rate of passage increases, so the flow rate through the throttle 35 decreases and the throttle 35 increases.
Since the differential pressure ΔP C between the front and the rear is further reduced, the second force F 2 acting on the control valve 30 is further reduced, and the control valve 30 is at the pressure oil supply position B. 25 moves to the left, the swash plate 24 tilts toward the small capacity direction, the discharge flow rate per rotation decreases, the discharge flow rate per unit time decreases, and the differential pressure before and after the throttle 43 decreases as described above. As a result, the first force F 1 also decreases, and the first force F 1
Then, the position of the swash plate 24 is maintained when the second force F 2 is balanced. As described above, the position of the swash plate 24 by the pump discharge pressure P 0 when the rotational speed is the degree of opening of the directional control valve 22 is constant at a certain variable pump 20 is determined pump discharge pressure P 0 × 1 rotation per discharge The flow rate q is controlled to be constant, that is, the torque is constant.
【００１０】可変ポンプ２０のポンプ吐出圧及び方向
制御便２２の開度が一定で回転数が変化した時。 ある値のポンプ吐出圧Ｐ0 で斜板２４位置が決定されて
いる状態で可変ポンプ２０の回転数が増加すると１回転
当り吐出流量が同じでも単位時間当り吐出流量が増加し
て絞り４３前後の差圧が大きくなって絞り４３の上流側
圧力と方向制御弁２２の出力側圧力との差圧が大きくな
るが、可変ポンプ２０とともに駆動される固定ポンプ３
３の単位時間当り吐出流量も増大して絞り３５前後の差
圧△ＰC も大きくなり、制御弁３０に作用する第１の力
Ｆ1 と第２の力Ｆ2 は等しくなって可変制御弁３１はつ
り合ったままとなって斜板２４の位置は変化せずに可変
ポンプ２０の１回転当り吐出流量は変化しない。このこ
とは可変ポンプ２０の回転数が低下した時も同様となる
から、可変ポンプ２０の容量をトルク一定制御できる。
すなわち、固定ポンプ３３と絞り３５とバイパス弁３７
が可変ポンプ回転数検出手段となる。When the pump discharge pressure of the variable pump 20 and the opening degree of the direction control stool 22 are constant and the number of revolutions changes. When the number of rotations of the variable pump 20 increases while the swash plate 24 position is determined by a certain value of the pump discharge pressure P 0 , the discharge flow rate per unit time increases even if the discharge flow rate per rotation is the same, and the front and rear of the throttle 43 are reduced. Although the differential pressure increases and the differential pressure between the upstream pressure of the throttle 43 and the output pressure of the directional control valve 22 increases, the fixed pump 3 driven together with the variable pump 20.
3, the discharge flow rate per unit time also increases, the differential pressure ΔP C before and after the throttle 35 also increases, and the first force F 1 and the second force F 2 acting on the control valve 30 become equal, and the variable control valve 31 They remain balanced and the position of the swash plate 24 does not change, and the discharge flow rate per one rotation of the variable pump 20 does not change. This also applies when the rotational speed of the variable pump 20 is reduced, so that the capacity of the variable pump 20 can be controlled to a constant torque.
That is, the fixed pump 33, the throttle 35, and the bypass valve 37.
Is the variable pump rotation speed detection means.
【００１１】可変ポンプ２０の回転数及びポンプ吐出
圧Ｐ0 が一定の時。 制御弁３０は固定ポンプ３３の吐出路３４に設けた絞り
３５前後の差圧△ＰC による第２の力Ｆ2 と絞り４３上
流側圧力と方向制御弁２２の出力側圧力、つまり最高負
荷圧ＰLSの差圧による第１の力Ｆ1が等しくなる位置と
なり、それによって可変ポンプ２０の斜板２４の位置が
決定される。前記絞り４３の上流側圧力と最高負荷圧Ｐ
LSの差圧は、可変ポンプ２０の単位時間当り吐出流量が
一定であれば方向制御弁２２の開度、つまり操作ストロ
ークに比例するので、操作ストロークが小さい時には前
記絞り４３の上流側圧力と最高負荷圧ＰLSの差圧が大き
く、制御弁３０に作用する第１の力Ｆ1 が前記絞り３５
前後の差圧△ＰC による第２の力Ｆ2 より大きくなって
制御弁３０は圧油供給位置Ｂとなり、通路５３，２９よ
り容量可変シリンダ２５の大径受圧室２８はポンプ吐出
圧Ｐ0 が供給されるから前述と同様に斜板２４は容量小
方向に傾転して１回転当り吐出流量が減少して単位時間
当り流量が減少し、方向制御弁２２を通過する流量が減
少して前記の絞り４３上流側圧力と最高負荷圧ＰLSとの
差圧が小さくなって第１の力Ｆ1 が低下し、その第１の
力Ｆ1 と第２の力Ｆ2 がつり合った位置で斜板２４の位
置が決定される。同様に方向制御弁２２の操作ストロー
クが大きい時には前記差圧が小さく、可変ポンプ２０の
斜板２４の位置は前述の場合よりも容量大方向の位置と
なる。これにより、可変ポンプ２０の単位時間当り吐出
流量は方向制御弁２２の操作ストロークが小さい時には
少なく、大きい時には多くなるので、最高負荷圧によら
ず方向制御弁２２の操作ストロークに見合った流量制御
ができてアクチュエータ２３の微操作性、つまりファイ
ンコントロール性を向上できる。When the rotation speed of the variable pump 20 and the pump discharge pressure P 0 are constant. The control valve 30 includes a second force F 2 due to the differential pressure ΔP C before and after the throttle 35 provided in the discharge passage 34 of the fixed pump 33, the upstream pressure of the throttle 43, and the output pressure of the directional control valve 22, that is, the maximum load pressure. It becomes a position where the first force F 1 due to the differential pressure of P LS becomes equal, and thereby the position of the swash plate 24 of the variable pump 20 is determined. The pressure on the upstream side of the throttle 43 and the maximum load pressure P
The differential pressure of LS is proportional to the opening of the directional control valve 22, that is, the operation stroke if the discharge flow rate per unit time of the variable pump 20 is constant. The differential pressure of the load pressure P LS is large, and the first force F 1 acting on the control valve 30 is the throttle 35.
The control valve 30 becomes the pressure oil supply position B when it becomes larger than the second force F2 due to the differential pressure ΔP C between the front and rear, and the pump discharge pressure P 0 is supplied to the large diameter pressure receiving chamber 28 of the variable capacity cylinder 25 from the passages 53 and 29. Since it is supplied, as described above, the swash plate 24 tilts in the small capacity direction, the discharge flow rate per rotation decreases, the flow rate per unit time decreases, and the flow rate passing through the direction control valve 22 decreases. At the position where the pressure difference between the upstream side pressure of the throttle 43 and the maximum load pressure P LS becomes small, the first force F 1 decreases, and the first force F 1 and the second force F 2 balance each other. The position of the swash plate 24 is determined. Similarly, when the operation stroke of the directional control valve 22 is large, the differential pressure is small, and the position of the swash plate 24 of the variable pump 20 is a position in the larger capacity direction than in the case described above. As a result, the discharge flow rate per unit time of the variable pump 20 is small when the operation stroke of the directional control valve 22 is small, and is large when it is large, so that the flow rate control suitable for the operation stroke of the directional control valve 22 can be performed regardless of the maximum load pressure. As a result, the fine operability of the actuator 23, that is, the fine controllability can be improved.
【００１２】可変ポンプ２０の回転数が変化した時。 可変ポンプ２０の回転数が変化すると固定ポンプ３３の
回転数も変化するために、前記絞り３５前後の差圧△Ｐ
C が絞り４３の上流側圧力と最高負荷圧ＰLSの差圧と同
様に変化するので、斜板２４の位置は変化しないが、回
転数変化により可変ポンプ２０の単位時間当り吐出流量
が増減するから、方向制御弁２２を通過する流量が回転
数変化により変化して絞り４３の上流側圧力と最高負荷
圧ＰLSの差回転数変化の２乗だけ変化するので、方向制
御弁２２の同一操作ストロークに対する通過流量は回転
数変化だけ変化し可変ポンプ２０の回転数に比例した流
量制御ができる。例えば、可変ポンプ２０の回転数が１
／２となると前記差圧は１／４となり、方向制御弁２２
の同一ストロークに対する通過流量は１／２となる。When the rotational speed of the variable pump 20 changes. When the rotation speed of the variable pump 20 changes, the rotation speed of the fixed pump 33 also changes, so that the differential pressure ΔP before and after the throttle 35.
Since C changes in the same manner as the pressure difference between the upstream side pressure of the throttle 43 and the maximum load pressure P LS , the position of the swash plate 24 does not change, but the discharge flow rate per unit time of the variable pump 20 increases / decreases due to the change in rotation speed. Therefore, since the flow rate passing through the directional control valve 22 changes due to the change in the rotation speed and changes by the square of the difference in rotation speed change between the upstream pressure of the throttle 43 and the maximum load pressure P LS , the same operation of the directional control valve 22 is performed. The passing flow rate with respect to the stroke changes only by the change in the number of revolutions, so that the flow rate can be controlled in proportion to the number of revolutions of the variable pump 20. For example, the rotation speed of the variable pump 20 is 1
When it becomes / 2, the differential pressure becomes 1/4, and the directional control valve 22
The flow rate for the same stroke is 1/2.
【００１３】[0013]
【発明の効果】可変容量型油圧ポンプ２０の容量をトル
ク一定として制御できるし、機械的フィードバック機構
が不要となって構造簡単でコスト安となるばかりか、ト
ルク一定制御の精度を向上できるし、可変容量型油圧ポ
ンプ２０の効率が低下しても可変ポンプ吐出流量特性の
性能が向上する。また、可変容量型油圧ポンプ２０の回
転数変化に応じて方向制御弁の通過流量を制御してアク
チュエータの微操作性を向上できる。また、前述の制御
を１つの制御弁３０で行なえるから構造簡単でコストを
安くできる。As described above, the displacement of the variable displacement hydraulic pump 20 can be controlled with a constant torque, a mechanical feedback mechanism is not required, the structure is simple and the cost is low, and the accuracy of the constant torque control can be improved. Even if the efficiency of the variable displacement hydraulic pump 20 is reduced, the performance of the variable pump discharge flow rate characteristic is improved. Further, the flow rate of passage of the directional control valve can be controlled according to the change in the rotational speed of the variable displacement hydraulic pump 20, and the fine operability of the actuator can be improved. Further, since the above control can be performed by one control valve 30, the structure is simple and the cost can be reduced.
【図１】従来例の線図的構成説明図である。FIG. 1 is a diagrammatic explanatory diagram of a conventional example.
【図２】本発明の実施例を示す線図的構成説明図であ
る。FIG. 2 is a diagrammatic configuration explanatory view showing an embodiment of the present invention.
２０ 可変容量型油圧ポンプ、２１ 吐出路、２２ 方
向制御弁、２３ アクチュエータ、２４ 斜板、２５
容量可変シリンダ、２６ 小径受圧室、２８大径受圧
室、３０ 制御弁、３３ 固定ポンプ、３４ 吐出路、
３５ 絞り、３７ バイパス弁、４３ 絞り。20 variable displacement hydraulic pump, 21 discharge passage, 22 directional control valve, 23 actuator, 24 swash plate, 25
Variable capacity cylinder, 26 small diameter pressure chamber, 28 large diameter pressure chamber, 30 control valve, 33 fixed pump, 34 discharge passage,
35 throttle, 37 bypass valve, 43 throttle.
Claims (1)
容量大・小方向に傾転する容量可変シリンダ２５と、可
変容量型油圧ポンプ２０の流量変化及び前記可変容量型
油圧ポンプ２０の吐出路２１に設けた方向切換弁２２の
開度変化を検出する第１の手段と、可変容量型油圧ポン
プ２０の回転数変化及びポンプ吐出圧変化を検出する第
２の手段と、前記第１の手段の出力信号と第２の手段の
出力信号とによって容量可変シリンダ２５にポンプ吐出
圧を供給する制御弁３０より構成した可変容量型油圧ポ
ンプの容量制御装置。Claim: What is claimed is: 1. A variable capacity cylinder 25 for tilting a swash plate 24 of a variable capacity hydraulic pump 20 in a large capacity / small capacity direction, a flow rate change of the variable capacity hydraulic pump 20, and the variable capacity. Means for detecting a change in the opening degree of the direction switching valve 22 provided in the discharge passage 21 of the hydraulic pump 20, and a second means for detecting a change in the rotational speed of the variable displacement hydraulic pump 20 and a change in the pump discharge pressure. And a control valve 30 for supplying pump discharge pressure to the variable displacement cylinder 25 by the output signal of the first means and the output signal of the second means.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP3213167A JPH0533776A (en) | 1991-07-31 | 1991-07-31 | Capacity control device for variable capacity type hydraulic pump |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP3213167A JPH0533776A (en) | 1991-07-31 | 1991-07-31 | Capacity control device for variable capacity type hydraulic pump |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH0533776A true JPH0533776A (en) | 1993-02-09 |
Family
ID=16634673
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP3213167A Pending JPH0533776A (en) | 1991-07-31 | 1991-07-31 | Capacity control device for variable capacity type hydraulic pump |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH0533776A (en) |
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO1998022717A1 (en) * | 1996-11-21 | 1998-05-28 | Hitachi Construction Machinery Co., Ltd. | Hydraulic drive apparatus |
| WO1998022716A1 (en) * | 1996-11-15 | 1998-05-28 | Hitachi Construction Machinery Co., Ltd. | Hydraulic drive apparatus |
| JPH10205501A (en) * | 1996-11-21 | 1998-08-04 | Hitachi Constr Mach Co Ltd | Hydraulic drive device |
| JP2008291731A (en) * | 2007-05-24 | 2008-12-04 | Kayaba Ind Co Ltd | Pump discharge rate control device |
| JP2011038316A (en) * | 2009-08-11 | 2011-02-24 | Hitachi Constr Mach Co Ltd | Pump tilting control unit of hydraulic working machine |
| WO2014156532A1 (en) * | 2013-03-27 | 2014-10-02 | カヤバ工業株式会社 | Pump discharge flow rate control device |
-
1991
- 1991-07-31 JP JP3213167A patent/JPH0533776A/en active Pending
Cited By (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO1998022716A1 (en) * | 1996-11-15 | 1998-05-28 | Hitachi Construction Machinery Co., Ltd. | Hydraulic drive apparatus |
| US6105367A (en) * | 1996-11-15 | 2000-08-22 | Hitachi Construction Machinery Co. Ltd. | Hydraulic drive system |
| WO1998022717A1 (en) * | 1996-11-21 | 1998-05-28 | Hitachi Construction Machinery Co., Ltd. | Hydraulic drive apparatus |
| JPH10205501A (en) * | 1996-11-21 | 1998-08-04 | Hitachi Constr Mach Co Ltd | Hydraulic drive device |
| US6192681B1 (en) | 1996-11-21 | 2001-02-27 | Hitachi Construction Machinery Co., Ltd. | Hydraulic drive apparatus |
| JP2008291731A (en) * | 2007-05-24 | 2008-12-04 | Kayaba Ind Co Ltd | Pump discharge rate control device |
| JP2011038316A (en) * | 2009-08-11 | 2011-02-24 | Hitachi Constr Mach Co Ltd | Pump tilting control unit of hydraulic working machine |
| WO2014156532A1 (en) * | 2013-03-27 | 2014-10-02 | カヤバ工業株式会社 | Pump discharge flow rate control device |
| CN105143669A (en) * | 2013-03-27 | 2015-12-09 | 萱场工业株式会社 | Pump discharge flow rate control device |
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