An intermittent air discharge apparatus has a main valve and a pilot valve, the main valve being switched between a discharge state and a discharge stop state. The pilot valve is switched between an air-supply state to supply air to a pilot chamber for air-discharge, and an air-supply stop state. When the pilot valve is switched to the air-supply state, an exhaust passage communicates with the pilot chamber for air-discharge. When the pilot valve is switched to the air-supply state, a supply or exhaust passage allows an air supply passage to communicate with the pilot chamber for air-discharge and a pilot chamber for stopping air-supply; when the pilot valve is switched to the air-supply stop state, communication with the air supply passage is blocked. A flow rate of air from the pilot chamber for air-discharge is set by the exhaust passage, and a flow rate of air from the pilot chamber for stopping air-supply is set by the supply or exhaust passage.

Control valves 100f, 100g, and 100h that reduce flow passage areas of parallel hydraulic fluid lines 41f, 41g, and 41h respectively when operating devices 34a, 34b for traveling are operated, are each disposed in the parallel hydraulic fluid line 41f, 41g, or 41h so that if saturation occurs during combined operations control likely to generate a significant difference in load pressure between any two actuators, the control valve prevents full closing of a pressure compensating valve lower in load pressure and thus prevents a slowdown and stop of the actuator undergoing the lower load pressure, and so that if saturation occurs during combined operations control likely to generate a particularly significant difference in load pressure between any two actuators, the control valve ensures a necessary supply of hydraulic fluid to the actuator higher in load pressure, thereby preventing a slowdown and stop of the actuator higher in load pressure.

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.

A control device controls movement of a valve body of a valve device and estimates a flow rate of the valve device; determines, on the basis of an input target flow rate value and the flow rate estimate, whether or not the flow of an operating fluid in the valve device is in a transient flow state; calculates an opening command on the basis of the target flow rate value and an upstream-downstream pressure difference of the valve device; and controls the movement of the valve body. When the control device determines that the flow is not in the transient flow state, it controls the movement of the valve body on the basis of the opening command, and when the control determines that the flow is in the transient flow state, it controls the movement of the valve body on the basis of the target flow rate value.

A fixed displacement hydraulic pump match flow demand control system that includes a spool valve, a plurality of fixed displacement pumps and a control valve is provided. The spool valve includes a spool. The spool is configured to shuttle within a chamber of a housing based at least in part on a pressure difference between a first end and the second end of the chamber. A fluid flow from each fixed displacement pump of the plurality of fixed displacement pumps is in fluid communication with an associated input port to the spool valve. At least one output port of the spool valve is in fluid communication with a hydraulically operated device and at least one of another output port is in fluid communication with a return. The control valve is configured to adjust the location of the spool in the chamber to regulate fluid flow to the hydraulically operated device.

To achieve improvement of operability and reduction of energy loss, when controlling so that an upper limit pressure of a discharge line becomes a pressure corresponding to an manipulation tool manipulation amount by controlling an increase or decrease of a bypass amount, in a hydraulic control circuit equipped with a bypass valve for controlling a bypass amount flowing from a hydraulic pump to an oil tank. By using a bypass valve control map representing a relationship between a manipulation tool manipulation amount and a spool stroke, the spool stroke of a bypass valve is controlled, and an upper limit pressure of the discharge line is set so that an opening area of the bypass valve is fully closed by a manipulation amount which is larger than a manipulation tool manipulation amount at which the maximum pressure of the discharge line is reached.

An object of the present invention is to provide a work machine that can increase the operation speed of an actuator by a regenerating function while ensuring accuracy of position control of the actuator. For this purpose, a controller computes a target actuator supply flow rate by subtracting a regeneration flow rate from a target actuator flow rate, computes a target flow control valve opening amount on the basis of the target actuator supply flow rate, computes a target pump flow rate equal to or more than the sum of a plurality of the target actuator supply flow rates, controls flow control valves according to the target flow control valve opening amount, and controls a hydraulic pump according to the target pump flow rate.

An amplifier is configured for use in a control valve. These configurations provide a pneumatic signal to an actuator that regulates flow through the device. The amplifier may include a variable orifice, or bleed valve, that moves in response to changes in actuating media around steady state. This bleed valve prevents bleed of actuating media at steady state. This feature reduces energy consumption or emissions from the control valve.

A cap with electromagnetic proportional valve, includes a pilot cap mounted on a valve housing and defining a pilot chamber, and an electromagnetic proportional valve mounted on the pilot cap and adapted to control a pressure of a working fluid supplied to the pilot chamber. The pilot cap includes a supply port into which a working fluid of a fluid pressure supply source is supplied, a discharge port from which the working fluid is discharged to the tank, a primary pressure passage which leads the working fluid at a primary pressure to the electromagnetic proportional valve from the supply port, a secondary pressure passage which leads the working fluid whose pressure is reduced to a secondary pressure by the electromagnetic proportional valve to the pilot chamber, and a drain passage which leads the working fluid discharged from the electromagnetic proportional valve to the discharge port.

A switching valve module which is part of a switching valve control system for use with reciprocating slat-type conveyors is disclosed herein. Disclosed herein is a switching valve module that includes an inner control valve and an outer control valve. A spool is positioned within the inner control valve and a spool positioned within the outer control valve. Movement of each the spool creates both a spool-type seal and a poppet-type seal between the spool and the respective control valve.