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Spring Examinations 2010/ 2011
Exam Code(s) 3BM, 3BG Exam(s) 3 rd^ Mechanical Engineering 3 rd^ Biomedical Engineering Module Code(s) ME 312 Module(s) Automated Systems Paper No. 1 Repeat Paper External Examiner(s) Prof. Noel O’Dowd Internal Examiner(s) Dr. Padraig Molloy, Prof. Sean Leen Instructions: Answer three questions, all questions will be marked equally.
Duration 2 hours
No. of Pages 3 Department(s) Mechanical & Biomedical Engineering Course Co-ordinator(s) Dr. Padraig Molloy Requirements: MCQ Handout Statistical/ Log Tables Cambridge Tables Graph Paper Yes Log Graph Paper Other Materials Release to Library: Yes
Question 1 (a) Explain how compressed air quality is classified. What is the importance of removing atmospheric moisture and solid contaminants from compressed air? Describe how the following systems dry compressed air: aftercooling; refrigeration drying; adsorption drying. [ 10 ] (b) Design a dominant-reset electro-pneumatic memory circuit controlling a single-solenoid 5/ way valve. The circuit is activated by means of a normally open electric switch which causes a double-acting cylinder to extend and remain in that position until the reset switch is pressed. Détente or latching type switches may not be used. Show pneumatic and electrical circuits. [ 10 ] Question 2 (a) Design an electro-pneumatic circuit that will control a single-acting cylinder. When the circuit is actuated the piston will have continuously reciprocating extension and retraction motion. The length of forward stroke and the speed of forward motion should be adjustable. [ 14 ] (b) Redesign your circuit incorporating non-contact sensing using three-wire inductive sensors. [ 6 ] Question 3 As shown in Figure Q3 boxes arriving on the lower roller conveyor are lifted by Cylinder A. Cylinder B then pushes the boxes onto the upper roller conveyor. Cylinder A must remain extended until Cylinder B is fully extended. Cylinder A retracts fully before Cylinder B is allowed to return. Design an electro-pneumatic circuit using appropriate non-contact sensors to indirectly control this operation. [ 20 ] Figure Q 3
