| 摘要 |
PURPOSE: To heighten the extent of axial rigidity as well as to make those of operating resistance and reaction so as to be extremely reducible by making a pressure regulating means consist of a nozzle discharging a gaseous body in a pressurizing chamber and a pressure adjuster for making the opening degree of a nozzle exhaust port variable. CONSTITUTION: When a piston 1 moves to the side of a pressurizing chamber 3 at one side far some factor or other, a signal is fed out of a detecting head and a different portion of a position counter comes to negative, and each of piezoelectric actuators 6c and 7a is driven so as to make pressure at the side of the pressurizing chamber 3 be heightrnrf, and consequently the piston 1 is made to operate in such a direction as putting back to the side of another pressuring chamber 4. When the piezoelectric actuator 6c is extended and a distance between the nozzle 6a and a pressure adjusting plate 6b is reduced, resistance to gas blowout grows larger after reducing the opening degree of the nozzle 6a, therefore pressure in the pressurizing chamber 3 is becomes heightened. A pressure differential is put to these two pressuring chambers 3 and 4, whereby the piston 1 and a table is shifted according to this pressure differential.
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