Page 233 - Servo Motors and Industrial Control Theory -

Appendix C 231

F

ER Ruid

0V V+
The Gap
Inner Piston

4. A different method of designing ER fluid based clutch is to design it in radial
form as shown below. Assume that the gap between the inner disk and outer
cylinder is 0.5 mm. The radius of the disk is 60 mm. Assume that the ER fluid
maximum shear stress when a voltage 2 KV is applied across the gap a maximum
2
shear stress of 2 KN/m is developed. Similar to the previous problems in the vis-
2
cosity of ER fluid there is no voltage is 5 × 10 (m /s). Determine the maximum
−5
torque that is transmitted through the clutch when the applied voltage is zero.
Then, calculate the maximum torque that can be transmitted when the maximum
possible voltage of 2 KV is applied. Note that in this design there are two sur-
faces so the transmitted torque will be twice than when there is one surface.
Note that most problems set in this section a gap of 0.5 mm is used because the
author has been involved in practical experimentations mostly around this gap.
Repeat the problem when the gap is 1 mm and 4 KV is applied to achieve the
same maximum shear stress.
Assume that the rotating speed of input shaft is 1500 rpm.

ER Ruid

Input Torque Output
and velocity Torque
0V
V+

C.6 Selection of a Servo Motor for Particular Applications

In this section a couple of problems for selecting a servo motor for applications
where the performance requirements are specified, are set. For solving these prob-
lems you should refer to Chap. 9 of the book.