NOVEL COMBINED VALVE

A combined valve, which comprises a first spool (1), a second spool (2) and a third spool (3). The second spool (2) and the third spool (3) are coaxial with the first spool (1), the first spool (1) is nested on the third spool (3), and the second spool (2) is further nested on the first spool (1), thereby forming a control state in which the second spool (2) is opened and closed according to a lifting action of the first spool (1). When the amount of lift of the first spool (1) for small flow control is less than a specified amount, a pilot passage (46) is closed by the second spool (2), and a third valve port (3A) is closed by the third spool (3). When the lift of the first spool (1) exceeds the specified amount, the second spool (2) rises with the rise of the first spool (1) and opens the pilot passage (46), and the third spool (3) opens a third valve port (3A) to forming a large flow control state. The combined valve may cater for the high-precision adjustment of a small flow area, and the low pressure los