At present, a drive device and a valve including the drive device, such as actuator and adjusting valve comprise a sealing chamber; when the working medium is charged in the chamber, the air in the working medium can enter the chamber; it always exists the state of mixing the air and the working medium is in the chamber; if the working medium is the liquid, the compressed air and uncompressed liquid exit in the drive device together. Although the drive device can work, it is not stable.
Specifically, with reference to FIG. 1, a valve 1 includes a drive device 10 and a sensing chamber 13 formed by the shell 11 and the membrane 12 of the drive device. The membrane 12 is connected with a drive shaft 14. The membrane 12 can sense the pressure in the chamber and drive the drive shaft 14; the drive shaft 14 further drives the valve core component 15 to control the working medium. When the air in the working medium enters the valve, the working medium can enter the sealed chamber of the drive device so that the air in the chamber cannot be discharged; it is always the mixed state of air and working medium in the chamber: the greater of the volume of the chamber, the more of the air, which means that the chamber has less and less of the working medium held in the chamber. As the capacity of the working medium in the chamber is small, the pressure of working medium sensed by the membrane is not accurate, which results in an unstable valve.