Abstract:
Hydraulic system for actuating the hydraulic actuators (2) of a working machine, the hydraulic system (1) has a delivery (3), a discharge (5), a drainage line (25), a signal line (21), a main slide valve (9) which actuates a corresponding hydraulic actuator (2), a safety slide valve (24) integral with the main slide valve (9) and adapted for opening or closing the drainage line (25) itself, and a pressure compensator (10) presenting a frontal chamber (13) connectable by way of the main slide valve (9) to the delivery (3) and a rear chamber (14) connected to the signal line (21); the drainage line (25) connecting a node (28) of the signal line (21) to the discharge (5).
Abstract:
Die Erfindung geht aus von einer hydraulischen Steueranordnung in Load-Sensing Technik mit einem ersten Wegeventil, über das Druckmittel einem ersten hydraulischen Verbraucher zuführbar ist, und mit mindestens einem weiteren Wegeventil, über das Druckmittel einem weiteren hydraulischen Verbraucher zuführbar ist und das vorzugsweise mit dem ersten Wegeventil zu einem Ventilblock zusammengefasst ist, mit einer Lastmeldeleitung, über die eine Steuerseite eines Load-Sensing-Regelventils mit einem vom höchsten Lastdruck der betätigten hydraulischen Verbraucher abhängigen Steuerdruck beaufschlagbar ist und die einen dem Regelventil nächsten, ersten Leitungsabschnitt mit dem Steuerdruck und wenigstens einen weiteren Leitungsabschnitt aufweist, wobei jeweils ein Leitungsabschnitt über ein Wechselventil mit dem folgenden Leitungsabschnitt oder einem individuellen Meldekanal eines Wegeventils verbindbar ist, und mit einer Vorsteuerventilanordnung, durch die der Steuerdruck auf einen Grenzdruck begrenzt ist. Der Lastdruck am weiteren hydraulische Verbraucher soll auf kostengünstige Weise auf einen niedrigeren Wert als am ersten hydraulischen Verbraucher begrenzt werden. Das angestrebte Ziel wird erfindungsgemäss dadurch erreicht, dass die Vorsteuerventilanordnung bei einem bestimmten, in einem weiteren Leitungsabschnitt der Lastmeldeleitung anstehenden Druck von einem hohen, ersten Grenzdruck auf einen niedrigeren, zweiten Grenzdruck einstellbar ist und die individuellen Meldekanäle, vom ersten Leitungsabschnitt der Lastmeldeleitung aus betrachtet, nach fallendem maximalen Lastdruck der hydraulischen Verbraucher mit den aufeinanderfolgenden Leitungsabschnitten der Lastmeldeleitung verbindbar sind.
Abstract:
This disclosure provides for pressure limiting a hydraulic system (100, 200) to a desired pressure value by a particular circuit by controlling and closing the compensator when the desired pressure setting is achieved. Closing the compensator will reduced the pressure head and flow in the circuit resulting in improved efficiency. One illustrated embodiment of the disclosure provides a relief valve (30) in the pilot signal for a compensator. The method relates to limiting the pressure on an open side (202a) of the compensator, such that the pressure on the other side closes the compensator thereby limiting the pressure and also flow in the hydraulic circuit. In other words, the pressure on the open side (202a) is limited by the relief valve (30). Thus, the pressure on the other side increases thereby regulating the flow and pressure through the compensator. In another embodiment of the disclosure, instead of reducing the pressure on the open side (202a), the pressure on the closed side (202b) is increased, thereby controlling the flow and pressure of the hydraulic circuit. The pressure can be increased by a pump (12) or any other suitable mode.
Abstract:
A valve assembly (40) has a flow summation node (74) coupled to a displacement control (39) port of the first pump (50). Each valve (41-47) in the assembly has a variable metering orifice (75) controlling flow from an inlet (70) to a hydraulic actuator and has a variable source orifice (64) conveying fluid from a supply conduit (58) to a flow summation node. The source orifice enlarges as the metering orifice shrinks. Each valve includes a variable bypass orifice (80) and the bypass orifices of all the control valves are connected in series forming a bypass passage (85) between a bypass node (55) and a tank (53). The bypass node is coupled to the flow summation node and receives fluid from a second pump (51). At each valve, a source check valve (68) conveys fluid from the supply conduit to the inlet and a bypass supply check valve (89) conveys fluid from the bypass passage to the inlet.
Abstract:
The invention relates to a hydraulic valve device (1) including a high pressure connection (P') and a low pressure connection (T'); at least one motor port connection (A') that is connectable to a motor port (A) on a hydraulic motor (M), preferably a hydraulic cylinder; a flow control valve (F), which is arranged between the high pressure connection (P') and the motor port connection (A') and which includes a flow opening ( 18) that is adjustable between a fully closed position and a fully open position; and a pressure regulator (R) that is arranged between the high pressure connection (P') and the flow regulating valve (F), wherein a regulator pressure (PR) that acts at a first connection point (3) between the pressure regulator (R) and the flow regulating valve (F) acts on the pressure regulator (R) via a first control conduit (4) to close the same. A second control conduit (5) including a first restrictor (6), is arranged to convey a load pressure (PL) that acts at the motor port connection (A') from a second connection point (7) positioned between the flow regulating valve (F) and the motor port connection (A') via the first restrictor (6) to a third connection point (8) at which a first control pressure (Pc) acts and which third connection point (8) is connected to the pressure regulator (R) to act on the same in the opening direction by means of said first control pressure (Pc), wherein the third connection point (8) is connected to the low pressure connection (T), via an adjustable second restrictor (9).
Abstract:
The invention relates to a hydraulic system (20) for a working machine (1). The hydraulic system is a load sensing (LS) system and comprises a first hydraulic actuator (24) and a first control valve (25) for controlling the flow of hydraulic fluid from a pump (21) to the first hydraulic actuator and for draining hydraulic fluid from the first hydraulic actuator, respectively, and a second hydraulic actuator (26) and a second control valve (27) for controlling the flow of hydraulic fluid from the pump to the second hydraulic actuator and for draining hydraulic fluid from the second hydraulic actuator, respectively. The hydraulic system further comprises a first hydraulic circuit (28) for providing an LS pressure for the first actuator (24) and a second hydraulic circuit (29) for providing an LS pressure for the second actuator (26). At least one of the first and second hydraulic circuits (28, 29) comprises an offset valve (30a, 30b) for changing the LS pressure before providing the LS pressure to the pump (21).
Abstract:
Hydraulic system for actuating the hydraulic actuators (2) of a working machine, the hydraulic system (1) has a delivery (3), a discharge (5), a drainage line (25), a signal line (21), a main slide valve (9) which actuates a corresponding hydraulic actuator (2), a safety slide valve (24) integral with the main slide valve (9) and adapted for opening or closing the drainage line (25) itself, and a pressure compensator (10) presenting a frontal chamber (13) connectable by way of the main slide valve (9) to the delivery (3) and a rear chamber (14) connected to the signal line (21); the drainage line (25) connecting a node (28) of the signal line (21) to the discharge (5).
Abstract:
Offenbart wird eine Lasterkennungsschaltung mit einem Lasterkennungsventil (8), das an seinen beiden Steuerseiten (20,22) mit dem Druck in den Kammern eines Zylinders (1) als Verbraucher beaufschlagt ist, wobei je nachdem, ob eine ziehende oder drückende Last eine Zylinderstange des Zylinders beaufschlagt, an einer der beiden Steuerseiten ein entsprechender Last- (über-) druck anliegt, wodurch einer von zwei Zug- oder Drucklast anzeigenden Ausgängen (16,18) des Lasterkennungsventils mit dem die Nettolast repräsentierenden Druck als Referenzdruck beaufschlagt wird.
Abstract:
The invention relates to an arrangement for controlling a work vehicle comprising a hydraulic system (22), which comprises at least one pump (18, 180) and at least one actuator (4, 5, 8, 9, 10) operatively driven by hydraulic fluid delivered from said pump, wherein at least a first pump (18) is a variable displacement pump. The system (22) is of load-sensing type in that the pump displacement is controlled by a pilot pressure representing a load exerted on the system. The arrangement comprises means (63) for reducing the pilot pressure delivered to the first pump (18) so that the first pump displacement is regulated down when there is a need for limiting hydraulic power consumption.
Abstract:
A hydraulic system includes a first pump and a plurality of valves that control fluid flow from the first pump to several actuators. Variable source orifices in the control valves are connected in parallel between the first pump and a node, and variable bypass orifices in the control valves are connected in series between the node and a tank. Pressure at the node controls displacement of the first pump. Each control valve also has a metering orifice for varying fluid flow between the node and one of the actuators. A hydrostatic pump-motor, coupled between two ports of a given actuator, is driven in a motoring mode by fluid exiting one of those ports. In a pumping mode, the hydrostatic pump-motor forces lower pressure fluid exhausting from one port into the other port of the given actuator.