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GCE JAN 2010 : (A2 3) Systems and Control in Product Design

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ADVANCED General Certificate of Education January 2010 Technology and Design assessing Unit 6 Systems and Control in Product Design A2V31 Assessment Unit A2 3 [A2V31] WEDNESDAY 20 JANUARY, MORNING TIME 2 hours 30 minutes. INSTRUCTIONS TO CANDIDATES Write your Centre Number and Candidate Number on the Answer Booklet provided and on the A3 pro forma answer pages provided. Answer three questions. Answer the one question in Section A and either the two questions in Section B or the two questions in Section C. Answers to Questions 1(a)(v) or 1(b)(v), Questions 5(b)(i) and (ii) and 5(c) should be made on the A3 pro forma answer pages provided. INFORMATION FOR CANDIDATES The total mark for this paper is 80, including a maximum of 4 marks for quality of written communication. Figures in brackets printed down the right-hand side of pages indicate the marks awarded to each question or part question. At the conclusion of the examination, attach the A3 pro forma answer pages securely to the Answer Booklet with the treasury tag supplied. You are provided with an insert sheet for Question 1. Do not write your answers on this insert. A materials data sheet is provided. 5283 Section A This question is compulsory. You are advised to spend 1 hour and 15 minutes on this section. You are required to answer either 1(a) or 1(b). For candidates studying Electronic and Microelectronic control systems answer part (a) using the pro forma (answer 1(a)(v)) and an answer booklet. 1 (a) The car wash shown on the insert in Fig. 1(a) provides the user with a quick do it yourself service available with a range of programs. Inside the housing a prototype control system is to be designed to control the flow of water, shampoo and wax solution during a wash cycle. The control system is to provide the following sequence of flows to the lance after a token has been inserted by the operator: water for initial wash, on for 45 seconds, water and shampoo for washing, on for 90 seconds, break of 45 seconds to use hand sponge, water to rinse, on for 60 seconds, wax solution, on for 60 seconds, water to rinse, on for 60 seconds. (i) Determine if the sequence described above is that of an open-loop or closed-loop system. Give one main reason in support of your answer. [2] (ii) Outline two main safety points that the manufacturer would need to consider regarding the control circuitry. [2] (iii) The housing is formed from stainless steel sheets which are riveted to an internal box section frame. Briefly outline two main reasons why riveting would be used to join the steel to the frame. [2] (iv) With reference to Fig. 1(a) briefly outline two main physical properties and two main mechanical properties which make stainless steel suitable for the housing. [4] 5283 2 [Turn over (v) On the pro forma provided use electronic and microelectronic circuit diagrams with annotation to produce a viable solution that will fulfil each of the specified points stated below. (N.B. All brackets, housings, screws, nuts and bolts are not required.) Design a circuit that will detect the presence of a token and provide a 5 volt pulse for a duration of 50 milliseconds to start the car wash sequence. [5] Design a circuit that will allow the 24 volt water heater to be used to heat the water flow if a hot wash cycle is selected. As a safety feature the heater must not operate in the event of a failure in the flow of water. [6] 5283 The 24 volt solenoids are used to control the flow of water, shampoo and wax during the wash cycle. Assume a 5 volt 50 millisecond pulse is produced when a token is inserted. Design a PIC based circuit that will control the solenoids and associated indicator lamps, to provide the timing and sequence for a complete wash cycle. (Your answer must include a program.) [12] When the car wash is not in use the 12 volt indicator lamps are to flash in the repeating sequence: shampoo, rinse, wax. Design a circuit that will switch the indicator lamps in this sequence. [5] 3 [Turn over For candidates studying Pneumatic and Mechanical control systems answer part (b) using the pro forma (answer 1(b)(v)) and an answer booklet. (b) The car wash as shown on the insert in Fig. 1(b) provides the user with a quick do it yourself service available with a range of programs. Inside the housing a prototype control system is to be designed to control the flow of water, shampoo and wax solution during a wash cycle. Each wash cycle is registered by the mechanical counter, this helps calibrate the volume of shampoo and wax used against the number of washes. The control system is to provide the following sequence of flows to the lance after a token has been inserted by the operator: water for initial wash, on for 45 seconds, water and shampoo for washing, on for 90 seconds, break of 45 seconds to use hand sponge, water to rinse, on for 60 seconds, wax solution, on for 60 seconds, water to rinse, on for 60 seconds. (i) Determine if the sequence described above is that of an open-loop or closed-loop system. Give one main reason in support of your answer. [2] (ii) Outline two main safety points that the manufacturer would need to consider regarding the control circuitry. [2] (iii) The housing is formed from stainless steel sheets which are riveted to an internal box section frame. Briefly outline two main reasons why riveting would be used to join the steel to the frame. [2] (iv) With reference to Fig. 1(a), briefly outline two main physical properties and two main mechanical properties which make stainless steel suitable for the housing. [4] 5283 4 [Turn over (v) On the pro forma provided use Pneumatic and Mechanical circuit diagrams with annotation to produce a viable solution that will fulfil each of the specified points stated below. (N.B. All brackets, housings, screws, nuts and bolts are not required.) Design and sketch a suitable mechanism for the drive shaft that will operate each of the three valves to achieve the sequence of flows stated above. Include an annotated sketch to show how the mechanism is attached to the shaft. [12] Design a gearbox using shafts A, B, C and D so that the output shaft D which is connected to the drive shaft rotates once during one complete wash program. Assume that the motor rotates at 48 rpm and only gears between 20 and 160 teeth can be used (state clearly the number of teeth to be used on each gear). [6] 5283 Design a suitable bearing and housing arrangement for the hose support bracket that will allow it to rotate. [5] Design a suitable mechanism attached to the drive shaft that will turn the mechanical counter arm through 90 degrees to register one count after one complete rotation of the shaft. 5 [5] [Turn over Section B Electronic and Microelectronic Control Systems Answer both questions in this section. 2 Fig. 2 shows an incomplete counter circuit that has been designed to count the number of bottles from a production line to be packaged in a crate. Each crate holds six bottles. As the bottles pass and activate a microswitch, the number is displayed on an LED 7-segment display. 5V A a B 7-segment b C decoder c d D e f g Clk Microswitch Counter Reset R3 a b f g c e LED 7 Segment Display d R1 0V Fig. 2 (a) State the function of the resistor labelled R1 in Fig. 2. [1] (b) The counter in Fig. 2 operates when a falling edge trigger is received at the Clk input. Explain with the aid of a diagram what is meant by the term falling edge trigger. [2] (c) Explain with the aid of a diagram how the counter could be used to count the bottles in batches of six, resetting after each batch. [4] (d) During testing, it was found that the counter in Fig. 2 was sometimes adding 2 or 3 to the count even though only one bottle was passing the microswitch. Explain a likely cause of this problem and suggest a modification to the circuit that would overcome this problem. [4] (e) Draw a truth table for the 7-segment decoder showing the inputs A, B and C with the corresponding outputs a g to the LED 7 segment display for 0 through to 5. [6] 5283 6 [Turn over (f) It has been proposed that the LED 7-segment display in Fig. 2 be replaced by an LCD type. State one advantage and one disadvantage (excluding cost considerations) of LCD type displays compared to LED type displays. [2] 5283 7 [Turn over 3 (a) The designers of a children s electronic game require a low cost power supply. A block diagram for an unregulated low voltage DC power supply is shown in Fig. 3(a). AC Mains Transform Rectify Unregulated 12 volt DC o/p Smooth Fig. 3(a) (i) Briefly explain the function of the Transform, Rectify and Smooth blocks shown in Fig. 3(a). [3] (ii) Sketch and label the output waveform for each block of the power supply shown in Fig. 3(a). [4] (b) Fig. 3(b) shows a simple voltage regulator based on a Zener diode that is to be connected to the unregulated power supply shown in Fig. 3(a) in order to provide a constant 6 volt supply. Rs 20 mA 10 mA Unregulated voltage 12 V 2 V Zener diode 6V Fig. 3(b) (i) Explain how the output voltage supplied to the electronic game will remain constant despite fluctuations in the input voltage from the unregulated supply. [1] (ii) An output current of 20 mA is required to operate the electronic game. Calculate an appropriate value for the Resistor Rs in Fig. 3(b). [2] 5283 8 [Turn over (c) The children s electronic game is to include a microphone to detect sound. Fig. 3(c) shows a microphone and op amp. +9 V Op amp Microphone 9V Fig. 3(c) (i) With the aid of a diagram, briefly explain the operation of a ceramic type microphone. [3] (ii) A non-inverting amplifier is required to amplify the microphone voltage. Draw a suitable amplifier circuit based on the op amp shown in Fig. 3(c) and suggest suitable values for resistors R1 and Rf to achieve a gain of 100 given that [4] gain = 1 + Rf . (R1 and Rf are used to provide feedback.) R1 (iii) Briefly explain how a signal generator and an oscilloscope can be used to check the voltage gain of the amplifier in 3(c)(ii). [2] 5283 9 [Turn over Section C Pneumatic and Mechanical Systems Answer both questions in this section. 4 Fig. 4 shows part of a prototype drive system used to operate a conveyor belt in a mass production line. (i) Multigrade oil is often chosen to lubricate gears. Briefly outline its main characteristics. [2] (ii) Calculate the output torque on the auxiliary output shaft if the input torque on gear C is 150 N. [2] (iii) Using an annotated sketch, name and draw a mechanism used to transfer the rotary motion from the motor to gear C via shaft P at an even rate. [3] (iv) Calculate the overall velocity ratio from gear C to the wormwheel L. [4] (v) The bearings on the auxiliary output shaft experience both axial and radial loadings. Using an annotated sketch, outline a suitable bearing and housing arrangement to be used in the location indicated. [4] (vi) Calculate the power supplied by the motor to shaft P, rotating it at an angular speed of 240 rev/min with a torque of 200 Nm. [2] (vii)Block W on the conveyor belt has a mass of 5 kg. The conveyor belt is not horizontal and the block moves through a vertical height of 1 m over this distance. Assume g = 9.81 m/s2. Calculate the gain in potential energy. [2] 5283 10 [Turn over 5283 11 [Turn over Motor C 40 Teeth D 60 Teeth Shaft P Auxiliary output shaft E 40 Teeth H 50 Teeth G 50 Teeth Worm F 150 Teeth Fig. 4 Location of bearings Conveyor Belt J 160 Teeth K 80 Teeth Wormwheel L 60 Teeth Block W 5 Fig. 5(a) shows parts of a pneumatic based prototype box printing station. (a) (i) Briefly describe a pneumatic component which could be used on cylinder D to hold and release the boxes. [1] (ii) Briefly explain one advantage and one disadvantage associated with the use of interlocking in sequential circuits. 5283 12 [2] [Turn over 5283 13 [Turn over Cylinder B Cylinder A Air Bleed Fig. 5(a) Conveyor Belt 1 Cylinder C Departure Platform Cylinder D Conveyor Belt 2 (b) A box travels along to a further manufacturing stage which utilises the incomplete circuit shown in Fig. 5(b). The circuit when complete is expected to perform the following operation: S1 is pressed until cylinder X outstrokes, which in turn activates an outstroke of cylinder Y. After a short delay in time, cylinder Z outstrokes, pressing S2 which enables it to instroke again. (i) On the pro forma provided (Pro forma Answer No. 5(b)(i) + (ii)), complete the circuit to achieve the desired circuit operation. [2] (ii) As a safety feature on the pro forma provided (Pro forma Answer No. 5(b)(i) + (ii)), show how cylinder Z can be de-activated pneumatically. [2] With regard to Fig. 5(a). (c) The following sequence begins once a box is placed over the air bleed: Cylinder A outstrokes slowly to print a design on the box. Cylinder A instrokes. Cylinder B outstrokes slowly to push the box onto conveyor belt 1. Cylinder D outstrokes in order to lift the box. Cylinder C outstrokes to move cylinder D above conveyor belt 2 where it releases the box. Cylinder C instrokes. Cylinder B instrokes. Cylinder D instrokes. On the pro forma provided (Pro forma Answer No. 5(c), draw a suitable interlocking/ cascade sequential circuit to achieve the desired sequence. [7] (Your answer does not need to include details of how the box is held and released by cylinder D.) (d) Cylinder Y has a piston diameter of 40 mm and operates with an air pressure of 0.5 N/mm2. Cylinder Z has a piston radius of 25 mm and operates with an air pressure of 1 N/mm2. Calculate the piston rod diameter required for cylinder Z to instroke with three times the outstroke force of cylinder Y. Please assume = 3.14. [5] 5283 14 [Turn over X S1 2 4 14 12 5 3 1 Y 2 4 14 12 5 1 3 Z S2 Fig. 5(b) THIS IS THE END OF THE QUESTION PAPER 5283 15 1312-016-1 [Turn over 5283.02 Hose 24 volt water heater Lance Stainless steel housing Do not write your answers on this insert 24 volt solenoid valve 1 Water Water from Valve 1 Box section frame Rivet Stainless steel 24 volt solenoid valve 2 Shampoo Shampoo from Valve 2 Wax Rinse Shampoo Hose support bracket Wax from Valve 3 24 volt solenoid valve 3 Wax 12 volt indicator lamps Insert token For candidates studying Electronic and Microelectronic control systems. Fig. 1(a) Housing GCE Advanced Technology and Design Assessment Unit A2 3 January 2010 (for use with Question 1(a)) A2V31IN1 [Turn ove[Turn over 5283.02 BM1F1 Do not write your answers on this insert 2 Shaft B Shaft C Hose Gearbox Input Shaft A Output Shaft D Lance Water Valve 1 Water from Valve 1 Motor and gearbox Stainless steel housing Box section frame Rivet Stainless steel Drive shaft Valve 2 Shampoo Shampoo from Valve 2 Wax Rinse Shampoo Insert token Valve 3 Wax Wax from Valve 3 Mechanical counter Hose support bracket 123 Sectional view of the hose support bracket 90 For candidates studying Pneumatic and Mechanical control systems. Fig. 1(b) Housing Mechanical counter arm Drive shaft GCE Advanced Technology and Design Assessment Unit A2 3 January 2010 (for use with Question 1(b)) [Turn over 5283.03 Question No. 1(a)(v) or 1(b)(v) A2V31IN2 Pro forma answer page (answer number 1(a)(v) or 1(b)(v)) ADVANCED LEVEL TECHNOLOGY AND DESIGN Assessment Unit A2 3 Unit 6 January 2010 Candidate Number Candidate Number 71 71 Centre Number Centre Number 5283.03 Question No. 5(b)(i) and (ii) 12 12 5 4 5 4 S2 1 1 3 2 3 2 14 14 Z S1 Y A2V31IN5 Pro forma answer page (answer number 5(b)(i) and (ii)) X ADVANCED LEVEL TECHNOLOGY AND DESIGN Assessment Unit A2 3 Unit 6 January 2010 Candidate Number 71 Centre Number 5283.03 Question No. 5(c) 12 5 1 3 START 14 A 12 1 3 A2V31IN5 Pro forma answer page (answer number 5(c)) 5 14 B ADVANCED LEVEL TECHNOLOGY AND DESIGN Assessment Unit A2 3 Unit 6 January 2010 12 12 5 5 1 1 3 3 14 D 14 C Candidate Number 71 Centre Number

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Additional Info : Gce Technology and Design January 2010 Assessment Unit A2 3, Unit 6: Systems and Control in Product Design
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