at the end of the cylinder through the throttling needle valve, most of the gas passes
through the one-way valve to supply air in a non-damped way (or under the
condition of very small damp) to drive the piston to complete the second stroke. In
fact, whether in pneumatic transmission or pneumatic servo technology, in addition
to the piston speed is very slow, usually a buffer cylinder is used.
8.2.1.1 Static Characteristics of Cylinders
The static characteristics of cylinder usually refer to the output thrust of cylinder
and the amount of compressed gas consumed by cylinder in unit stroke. The
following are described separately.
(1) Cylinder Output Thrust
Taking the single-side cylinder shown in Fig. 8.13 as an example, assuming that the
effective area of both sides of the piston is A 1 and A 2 , respectively, and the gas
supply and exhaust pressures are p 1 and p 2 , respectively, the theoretical thrust that
the piston can output is as follows:
F th ¼ A 1 p 1 À A 2 p 2
ð8:18Þ
Throttling needle valve
One-way valve
Buffer small piston
Inlet and exhaust holes
Piston
Piston rod
Fig. 8.12 Buffer schematic diagram
Fig. 8.13 Computation of
cylinder thrust
8.2 Structure and Characteristics of Actuators
15