One-way flow control valve
A one-way flow control valve is a valve that throttles a medium (liquid, gas) in one direction and allows it to flow through unthrottled in the other direction. The valve consists of two individual valves that are housed in a housing: On the one hand, a throttle, which reduces the line cross-section (in the symbol above), and a non-return valve (below). The symbol shown is an adjustable throttle, recognizable by the arrow that goes through the throttle symbol .
functionality
If the medium flows through the valve (based on the circuit symbol) from the left connection to the right connection, the check valve opens, the throttle is bypassed and therefore has no effect. In the opposite direction, the check valve closes and the pressure medium has to pass the throttle, which reduces the flow rate (here: depending on the setting).
application
One-way flow control valves are used in pneumatics and hydraulics . They can be used, for example, to determine the speed of movement of a piston.
For this purpose, with pneumatic cylinders, the outflowing compressed air is always throttled via the throttle function of the throttle check valve installed there, while the incoming compressed air flows unthrottled in the flow direction through the second throttle check valve installed in this line. The main counterforce that the inflowing air has to overcome is the counterpressure in front of the throttle for the outflowing air and not the sliding or static friction of the piston in the cylinder. Therefore, the piston movement is less at risk of stick-slip .
In the case of hydraulic cylinders, the speed of the piston can be set by throttling the inflowing or outflowing fluid, since the risk of stick-slip is significantly lower due to the practically incompressible hydraulic oil . The use of one-way flow control valves offers the advantage that the speeds can be set separately for both directions of movement.