Valve control unit of tank lorry

A valve control apparatus for a tank lorry, which is adapted to open and close an oil feed valve (60) mounted on the bottom surface of a storage tank (100) by controlling air pressure of a compressed air tank (T) mounted on the tank lorry, the valve control apparatus comprising:

• a first control valve (10) serving as a direction conversion valve actuated by air pressure transferred to a pilot port (13) so as to open and close the oil feed valve (60) by supplying compressed air to the oil feed valve (60) or discharging the supplied compressed air to the outside;
• a shuttle valve (40) adapted to discharge the compressed air introduced from one of inlets (41;
• 42) to the pilot port (13) of the first control valve (10) through a single outlet (43);
• a second control valve (20) serving as a direction conversion valve for actuating the first control valve (10) by supplying the compressed air to one inlet (41) of the shuttle valve (40) or discharging the supplied compressed air to the outside;
• a third control valve (30) serving as a direction conversion valve for supplying the compressed air to the automatic closing valve (50) mounted on the upper portion of the storage tank (100) or discharging the supplied compressed air to the outside;
• the automatic closing valve (50) adapted to discharge the compressed air introduced from the third control valve (30) to the other inlet (42) of the shuttle valve (40) according to an actuation of an air tank (59) having buoyancy against a load to thereby actuate the first control valve (10);
• and an oil feed valve (60) having a pair of ports (65a;
• 65b), the oil feed valve (60) being opened when the compressed air is supplied from the first control valve (10) to the port (65a), the oil feed valve (60) being closed by an actuation of the compression spring (69) and keeping the closed state by introducing the compressed air to the other port (65b) when the supplied compressed air is discharged.