An apparatus for monitoring the pressurisation of a control valve for a hydraulic actuator and a control valve. The apparatus including a spool movable along an axis (X), wherein the spool is configured to control the flow of hydraulic fluid through the control valve based on its position along the axis (X), and wherein in an unpressurised state of the control valve the spool occupies a first axial position, and in a pressurised state of the control valve the spool occupies a second, different axial position. The apparatus also including a position sensor configured to monitor the position of the spool within the control valve and detect whether the spool occupies the first axial position or the second axial position, wherein the first axial position and the second axial position correspond to neutral positions of the spool.

[Object] To make it possible to detect, with a single pressure sensor, a malfunction of two solenoid valves for switching flow paths and to quickly and reliably exhaust residual pressure in an air device through a solenoid valve.

[Solution] A residual pressure exhaust air circuit 1 includes: a main flow path 9 through which air from an air source 2 is supplied to an air cylinder 100; an exhaust flow path 10 through which air in the air cylinder 100 is exhausted; a first sensor 8 for detecting a malfunction of solenoid valves 12, 13; a detection flow path 11 through which air from the air source 2 is supplied to the first sensor 8; and the two solenoid valves 12, 13 that switch communication states among the main flow path 9, the exhaust flow path 10, and the detection flow path 11. The two solenoid valves 12, 13 are formed of two-position valves having first positions 12a, 13a at the time of OFF and second positions 12b, 13b at the time of ON and are synchronously ON/OFF controlled. When the two solenoid valves 12, 13 do not operate in synchronization with each other, the air from the air source 2 is supplied to the first sensor 8 to detect a malfunction of the two solenoid valves 12, 13, and at the same time, the air in the air cylinder 100 is exhausted through the solenoid valve 12, 13.

A hydraulic module with a switch valve for controlling a flow of a hydraulic fluid in a connecting rod for an internal combustion engine with variable compression with an eccentric element adjustment arrangement for adjusting an effective connecting rod length, wherein the eccentrical element adjustment arrangement includes a first cylinder and a second cylinder configured as hydraulic chambers, wherein a first inlet is provided for feeding the hydraulic fluid into the first cylinder and a second inlet is provided for feeding the hydraulic fluid into the second cylinder, wherein a first outlet is provided for draining the hydraulic fluid from the first cylinder and a second outlet is provided for draining the hydraulic fluid from the second cylinder wherein a first check valve is associated with the first cylinder and a second check valve is associated with the second cylinder.

A method for detecting and isolation a leak in a hydraulic system having a supply pump serving at least one control valve is disclosed. In one embodiment, the control valve has multiple work sections. In step of the method, the hydraulic system is activated. In another step, an actuation command for at least one of the work sections is received, for example from a human-to-machine interface. Subsequently, the method may include generating a flow demand for the work sections for which an actuation command has been received. The method also includes the step of implementing at least one of a first, second, third, and fourth leak detection and isolation protocol to detect and isolate a leak between the pump and the control valve assembly, a leak between the reservoir and the control valve assembly and a leak between the at least one work circuit and the control valve assembly.

To reduce the cost by reducing the number of parts and simplify the control of regeneration in the hydraulic actuator even though the meter-in control and the meter-out control can be performed separately while the supply and the discharge of hydraulic fluid is controlled. A meter-in valve that controls supply flow from a hydraulic pump into a hydraulic cylinder is provided, and meter-out switching valve that switches the direction of supply and discharge of the hydraulic oil into the hydraulic cylinder and controls the discharge flow from the hydraulic cylinder to the oil tank is installed on the down stream side of the meter-in valve, and further, a regeneration control valve is installed on the down stream side of the meter-out switching valve.

The present disclosure relates to the technical field of cranes, and in particular to a crane hydraulic control system and a crane. The crane hydraulic control system of the present disclosure includes a prime mover, an execution control mechanism, a hydraulic baking device, a running energy recycling device and an operation energy recycling device. By means of cooperation among the operation energy recycling device, the energy recovery device and the hydraulic energy conversion device, kinetic energy in a driving braking process of the crane and the potential energy in a load lowing process are respectively converted into hydraulic energy for recovery, storage and reuse, therefore, the present disclosure can achieve the recovery of the superstructure energy and the lower vehicle energy of the crane so as to effectively reduce the energy waste.

A hydraulic apparatus has a plurality of pump modules each of which is formed by a plurality of working chambers having a common high pressure manifold. A connecting circuit switchably connects pump modules to first and second hydraulic circuit portions to allocate capacity as first and second demands for hydraulic fluid vary. In an apparatus which may have two or more connecting circuit outputs, valves may be controlled or working chamber pumping cycles made inactive to facilitate the reallocation of a pump module from one output to another, and a control strategy addresses pump module allocation when the demands for hydraulic fluid exceed available capacity.

To avoid a large size of a direction change-over valve and enable accurate supply flow control when providing a flow control valve at an upstream side of the direction change-over valve to change the relationship between supply flow rate and discharge flow rate for a hydraulic actuator. The configuration is to control a supply flow rate to a stick cylinder based on an opening area of the stick's direction change-over valve and stick's flow control valve, calculate a target opening area of the stick's flow control valve based on a target supply flow rate from hydraulic pumps A, B to the stick cylinder, the opening area of the stick's direction change-over valve, and a target differential pressure between hydraulic pump A and a load pressure of stick cylinder, and control the stick's flow control valve so as to keep the target opening area calculated.

Systems and methods are provided for a hydraulic stabilizer trim actuator (HSTA). The HSTA may operate one or more movable control surfaces. The HSTA operate responsive to commands issued by the pilot and/or by a controller and may include hydraulic architecture that minimizes the probability of an un-commanded movement or movement in the opposite direction of such commands.

A hydraulic system for a machine includes a plurality of hydraulic component, wherein the hydraulic components include hydraulic actuators and hydraulic motors. The hydraulic system also includes a plurality of hydraulic circuits, and a plurality of hydraulic pumps for supplying hydraulic fluid to the plurality of hydraulic components via the hydraulic circuits. At least one hydraulic component receives hydraulic flow exclusively from a designated one of the hydraulic pumps and at least another, different hydraulic component receives shared hydraulic flow from a flow sharing set of the hydraulic pumps.