A control system for controlling a work machine including a working unit including elements and actuators that drives the elements includes: a first hydraulic pump and a second hydraulic pump each of which supplies operating oil to at least one of the actuators; and a control device that calculates a distribution flow rate of operating oil distributed to each of the actuators based on an operating state of the working unit and switches, based on the calculated distribution flow rate, between a first state in which the operating oil supplied from both the first hydraulic pump and the second hydraulic pump is supplied to the actuators and a second state in which the actuator to which the operating oil is supplied from the first hydraulic pump is different from the actuator to which the operating oil is supplied from the second hydraulic pump.

In one aspect, a system for controlling the supply of hydraulic fluid to an implement of a work vehicle may generally include a pump, a control valve coupled to the pump and first and second fluid lines provided in flow communication with output ports of the control valve. The system may also include a pressure control valve provided in flow communication with the second fluid line that is configured to regulate a fluid pressure of the hydraulic fluid being supplied to a hydraulic cylinder of the implement. Additionally, the system may include a bypass fluid line configured to provide a flow path for hydraulic fluid between the pump and the second fluid line that is independent of the control valve and a load sensing line configured to provide an indication of the fluid pressure of the hydraulic fluid being supplied to the hydraulic cylinder.

A method is provided for compensating for the flow rate of a variable capacity-type hydraulic pump such that, when a manipulation lever is manipulated, a discontinuous section, which has no change in the discharge flow rate of the hydraulic pump, is eliminated.

Modular directional valve with two or more crossing elements (E1 . . . En) able, acting only on the entry side, to manage a variable displacement pump (PA) of the load sensing type.

In particular, this management allows in a single drive, unlike the conventional crossing distributors, to make the flow rate to the utility independent of the load and allows setting a maximum flow rate at the end of the stroke; in multiple drives, it ensures that the sum of the required flow rates is independent of the loads.

A compensated flow rate regulator is placed in the entry side so as to act only on the bypass line LC upstream of the first element (E1 . . . En) while a proportional choke is placed on the load line consisting of a 2-way 2-position tray.

Modular directional valve with two or more crossing elements (E1 . . . En) fed by a variable displacement (PA), negative control or load sensing pump.

A pressure regulator (5) is placed in the entry side and only on the bypass line and upstream of the first element (E1 . . . En).

In the single drive, it makes the flow rate to the utility independent of the load and allows setting a maximum flow rate at the end of the stroke; in multiple drives, it ensures that the sum of the required flow rates is independent of the loads.

The present application relates to a crane hydraulic system and a controlling method of the system, wherein the crane hydraulic system includes a load sensing subsystem, and the subsystem includes a variable pump, a variable pump oil inlet line, a load feedback line, an oil return line and a pressure compensator; the pressure compensator is provided with an oil inlet, an oil outlet, a first control oil port, a second control oil port and a control spring; the oil inlet communicates with the variable pump oil inlet line, the oil outlet communicates with the oil return line, the first control oil port communicates with the load feedback line, and the second control oil port also communicates with the variable pump oil inlet line; and wherein the control spring and the first control oil port are located on the same end of the pressure compensator, and a set pressure of the control spring is greater than a pressure difference of the variable pump. According to the present application, since the load sensing subsystem is arranged, at the start and stop moments of a winch system, the pressure compensator can be opened, and the variable pump oil inlet line communicates with the oil return line to realize pressure relief, so as to reduce the pressure impact.

Open centre hydraulic distributor, comprising: a free circulation line connecting a supply line from a negative control pump to a discharge; a delivery line connecting the supply line to users; at least one directional valve that intercepts the free circulation line and the delivery line, so that it narrows a transit area of the free circulation line and opens a transit area of the delivery line, and vice versa; a slide valve arranged on the free circulation line downstream of the directional valve; a valve device that is activated when a threshold value of a pressure delta between upstream and downstream of the directional valve is reached, and maintains this pressure delta equal to the threshold value; a negative control line to pick up a pressure signal from the free circulation line downstream of the directional valve and upstream of the slide valve.

A control system for controlling a work machine including a working unit including elements and actuators that drives the elements includes: a first hydraulic pump and a second hydraulic pump each of which supplies operating oil to at least one of the actuators; and a control device that calculates a distribution flow rate of operating oil distributed to each of the actuators based on an operating state of the working unit and switches, based on the calculated distribution flow rate, between a first state in which the operating oil supplied from both the first hydraulic pump and the second hydraulic pump is supplied to the actuators and a second state in which the actuator to which the operating oil is supplied from the first hydraulic pump is different from the actuator to which the operating oil is supplied from the second hydraulic pump.

A control method for controlling retraction of a boom is applied to a hydraulic system which combines retraction of the boom by self-weight with retraction of the boom by pressure. The control method includes: when the boom is retracted, controlling the self-weight retraction proportional valve to be at a maximum opening; obtaining an actual speed at which the boom is retracted; controlling a rotation speed of the pressure retraction motor to rise or an opening degree of the pressure retraction proportional valve to increase when the actual speed is less than a preset speed; and controlling the rotation speed of the pressure retraction motor to reduce or the opening degree of the pressure retraction proportional valve to decrease when the actual speed is greater than the preset speed.

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).