Patent ID: 9140274
Filing Date: 2015-09-22
Classification: F15B,F16K,Y10T

Abstract:
1. A directional valve for controlling an actuator by means of pressurized medium, the directional valve comprising at least: a pressure port for pressurized medium; a first work port for supplying pressurized medium to the actuator; either a tank port for returning pressurized medium, or a second work port for receiving pressurized medium from the actuator, or both of them; a spool adapted to move axially inside the body of the directional valve, wherein; the spool comprises a first position, in which the spool tends to be set; the directional valve further comprises, in addition to the functions of a directional valve, a metering orifice placed in the pressure port or in the first work port or in the second work port or in the tank port, and across which a pressure difference is effective, which is dependent on the pressurized medium flowing through the metering orifice; the spool further comprises a second position, to which the spool can be moved by a pilot control force and in which the spool is fitted to open the flow of pressurized medium through the metering orifice; and the directional valve is, when the spool is in at least the second position, fitted to generate a compensating force proportional to said pressure difference, to move the spool to compensate for the flow; wherein: the pressure prevailing downstream of the metering orifice is guided to a first chamber in which said pressure generates a force effective on the spool; and the pressure prevailing upstream of the metering orifice is guided to a second chamber in which said pressure generates an opposite force effective on the spool; and wherein: the second chamber is fitted at the end of the spool, herein the pressure prevailing in the second chamber is effective directly on the spool; and the first work port is connected to the second chamber, wherein the flow of pressurized medium from the pressure port to the first work port takes place from the side of the spool to the inside of the spool and through the end of the spool to the second chamber.