摘要:
Pressure compensating valves not fully closing at the stroke end are employed, and upon the operator's operation for the traveling, pilot primary pressure is reduced and the reduced pilot primary pressure is supplied to remote control valves 34c - 34h of non-travel operating devices. With this configuration and operation, the inflow of the hydraulic fluid into non-travel actuators is suppressed and a necessary amount of hydraulic fluid for travel motors is secured in travel combined operation. Accordingly, when saturation occurs in a construction machine's hydraulic drive system performing the load sensing control due to combined operation with a great load pressure difference between two actuators, deceleration/stoppage of an actuator on the low load pressure side is prevented by preventing full closure of the pressure compensating valve on the low load pressure side, while also preventing deceleration/stoppage of a high load pressure actuator by securing a necessary amount of hydraulic fluid for the high load pressure actuator. Consequently, excellent operability in the combined operation is achieved.
摘要:
Hydraulic section (1) for use in a hydraulic distributor (10), comprising: a valve body (2); a main spool (3); pressure compensator (5) housed in a first hole in the valve body (2); a piston (11) housed in the first hole; an intermediate chamber (16) in fluid communication with the feed line (Pal), the intermediate chamber (16) extending at least partially in the first hole and being delimited by the rod (12) of the piston (11); two limiters (6, 7) and a drainage channel (18) pertaining to the intermediate chamber (16) for altering the pressure thereof and close the compensator (5).
摘要:
A control pressure switching valve (57) is disposed between a displacement regulator (26) and a pressure control valve (44). The control pressure switching valve (57) is switched between a control position (j), in which a load sensing control pressure (PLS) is permitted to be outputted from the pressure control valve (44) to the displacement regulator (26), and a control release position (k), in which the load sensing control pressure (PLS) to be outputted to the displacement regulator (26) is reduced to a prescribed low pressure value. When the regeneration of a filter (19) is determined to be necessary, the controller (61) switches the control pressure switching valve (57) to the control release position (k). When the load sensing control pressure (PLS) is reduced to the low pressure value with the control pressure switching valve (57) switched to the control release position (k), the displacement regulator (26) increases a delivery displacement of a hydraulic pump (13), thereby increasing rotational load of an engine (10).
摘要:
Disclosed is a control system for controlling flow so as to allow simultaneous usage of a parallel flow path and a tandem flow path thereby reducing loss of pressure inside a control valve, when simultaneously operating work devices having different operating pressures. A control system for operating the work device, according to the present invention, provides the control system for operating the work device for a construction machine, comprising: first and second hydraulic pumps that are connected to an engine; a revolution control valve, an arm control valve, and a left driving control valve, which are installed on a first center bypass path of the first hydraulic pump, and each of which is connected via the parallel flow path; a boom control valve, a bucket control valve, and a right driving valve, which are installed on a second center bypass path of the second hydraulic pump, and each of which is connected via the parallel flow path; a pressure generation device; a bleed flow path, which is formed on a control spool at a lower side of a boom of the boom control valve, for maintaining an open state of the second center bypass path without closing same, when the boom control valve is switched so as to lower the boom; and a center bypass switch valve, which is installed on the lowermost side of the second center bypass path and is switched by means of a control signal for switching the boom control valve.
摘要:
Système hydraulique comportant : - un dispositif restricteur de débit (LS) disposé dans un canal de pression (10, 10'), entre une pompe (1) à débit variable et un récepteur hydraulique (R), ledit dispositif restricteur étant réglé à la valeur de commande dudit récepteur hydraulique, - un canal de régulation (20, 20') permettant de transmettre la pression de charge réelle (Pu) du récepteur hydraulique à un dispositif de commande (C) taré à une valeur de pression et ajustant la pression de refoulement de la pompe en fonction de ladite pression de charge et de ladite pression de tarage, - un dispositif correcteur (A) configuré pour commander le dispositif de commande avec une pression de charge (Pu2) différente de la pression de charge réelle du récepteur hydraulique, ledit dispositif correcteur consistant en un distributeur avec tiroir de manoeuvre (30) à deux positions et ressort de tarage (310), ledit distributeur comportant au moins un orifice de sortie (S) relié au dispositif de commande par le canal de régulation, dans lequel - une première extrémité (31) du tiroir de manoeuvre est soumise à la pression (Pu) au niveau de l'orifice de sortie du dispositif restricteur de débit et à la pression du ressort de tarage (310), - une seconde extrémité (32) du tiroir de manoeuvre est soumise à la pression (P LS ) au niveau de l'orifice d'entrée du dispositif restricteur de débit.
摘要:
The invention relates to a hydraulic control arrangement that is used particularly for controlling hydraulic consumers of a mobile machine tool. Said hydraulic control arrangement comprises a load signaling line to which the maximum load pressure of several hydraulic consumers that are simultaneously triggered via one respective main control valve can be applied, and a final section of which can be connected to a pump regulator. The hydraulic control arrangement further comprises a pressure relief valve which allows the control pressure to be limited in the final section of the load signaling line. In order to be able to easily and inexpensively control the pressure also for several hydraulic consumers, the pressure relief valve can be displaced in accordance with the level of a pilot signal that is used for triggering a main control valve.