A system including a pneumatic actuator having an actuator element, the system further including a compressed-air provision device which is configured to carry out a closed-loop position control of the actuator element by applying compressed air to the pneumatic actuator. The compressed-air provision device is further configured to carry out an assistance procedure in which the actuator element is set in an oscillation movement, pressure values and position values are detected, and, on the basis of the detected pressure values and the detected position values, friction information and/or mass information is determined and/or verified.

A drive control method of a hydraulic actuator of a construction machine includes: determining whether a rotation operation lever and a working device operation lever are operated; calculating the required pressure of a hydraulic cylinder fix a working device according to the operation amount of the rotation operation lever; calculating the required flow rates of a swing motor and the hydraulic cylinder for the working device, the required flow rates corresponding to the operation amounts of the working device operation lever and the rotation operation lever; calculating the opening areas of the first and second proportional solenoid valves of an inlet side and an outlet side by using the calculated required pressure and required flow rates of the hydraulic cylinder for the working device and the swing motor; and calculating current values to be inputted into the first and second proportional solenoid valves of the inlet side and the outlet side according to preset data values or a table in comparison with the calculated opening areas of the first and second proportional solenoid valves of the inlet side and the outlet side.

The present invention provides a controller for a hydraulic apparatus. The controller is configured to determine (410) that a mode change criteria has been met for the hydraulic apparatus. In response to the determination, the controller is configured to control (420) a valve arrangement to change a first actuator chamber of a hydraulic actuator between being fluidly connected to a hydraulic machine and fluidly isolated from a second chamber of the hydraulic actuator, and being fluidly connected to both the second actuator chamber and the hydraulic machine. Further in response to the determination, the controller is configured to control (430) the hydraulic machine to change a flow rate of hydraulic fluid flowing through the hydraulic machine to regulate a movement of the hydraulic actuator during the control of the valve arrangement.

An electro-pneumatic controller includes a base having a body, a top surface, and a bore formed within the body; a cover coupled to the base, the cover having an open end with a rim, the rim contacting the top surface of the base; a plurality of fluid flow paths formed within the base; and at least one flame arrestor disposed within one of the fluid flow paths.

A hydraulic system includes a first and a second rotating hydraulic machine, the first and second hydraulic machine being arranged to provide a torque via a common output shaft; a first valve arrangement for providing a differential hydraulic pressure level over the first hydraulic machine by using two sources of hydraulic fluid having different hydraulic pressure levels, a second valve arrangement for providing a differential hydraulic pressure level over the second hydraulic machine by using two sources of hydraulic fluid having different hydraulic pressure levels; and a control unit configured to control the first valve arrangement and the second valve arrangement such that different discrete levels of torque are provided via the output shaft of the hydraulic system. A hydraulic system for providing different discrete levels of torque using one hydraulic machine and a plurality of differential pressure levels, and a method for controlling a hydraulic system, are also provided.

The present invention aims at providing a new electro-hydraulic control terminal adopting modularized and configured cartridge valve RHCV. It has obvious advantages of hybrid combination and flexible customization when RHCV is applied in the independent control terminals based on “single loop resistance” to control hydraulic actuators including distributed cylinders and motors. It can follow the rules that functional diversities as many as possible can be achieved through technical diversities as few as possible, thus producing a new generation of electro-hydraulic product family and platform to meet the needs of customers.

A method for closed-loop controlling, in particular closed-loop pressure controlling, a piezo valve device, including the steps: calculating a control error integral signal representing a time integral of a control error of the closed-loop control of the piezo valve device, adjusting, based on the control error integral signal, at least one control opening voltage value defining within the closed-loop control an opening voltage value of a piezo valve of the piezo valve device, and using the adjusted at least one control opening voltage value, providing at least one drive voltage for driving the piezo valve within the closed-loop control.

The present invention relates to a hydraulic valve arrangement for controlling/regulating at least one hydraulic consumer of a mobile machine, with a summation interconnection of at least two hydraulic valves and at least one consumer interconnection of hydraulic valves, wherein the outputs of the summation interconnection are hydraulically connected with the inputs of the consumer interconnection, wherein at least one backflow valve is provided in the consumer interconnection. According to the invention, the at least one backflow valve for throttling a consumer return volume flow opens or closes in dependence on a consumer inflow pressure and comprises at least one main piston arranged in a bushing and at least two further pistons arranged in a lid separate from the bushing.

An independent metering valve circuit includes an actuator, a set of independent metering valves, an independent metering valve pre-compensator, an inverse resolver, and a signal conditioning element. The set of independent metering valves are fluidly coupled to the actuator and configured to independently control a flow of a hydraulic fluid to the actuator. The independent metering valve pre-compensator is configured to control the flow of the hydraulic fluid to the set of independent metering valves. The inverse resolver is configured to receive a first pressure signal from the independent metering valve circuit and a second pressure signal from a load-sense hydraulic system and output a third pressure signal. The signal conditioning element is configured to receive the third pressure signal and output a forth pressure signal configured to control a pump fluidly coupled to the load-sense hydraulic system and the independent metering valve circuit.

According to the present invention, a hydraulic system of construction equipment is implemented as a close center system, which converts an input signal of an electric or hydraulic joystick into a speed signal of a work apparatus, and controls a speed of the work apparatus regardless of an external load condition, thereby minimizing fatigue of a worker to improve work efficiency, improving a work apparatus operation ability of an unskilled person, and patterning standardized work to implement automation of construction equipment.