Presentation on theme: "Application of Four-Bar Mechanisms in Cars"— Presentation transcript:
1Application of Four-Bar Mechanisms in Cars Windshield WiperSoft Top MechanismGroup AChristopher BackJoseph Ashwin FranklinKwongvoon WongChen Lin
2Components of Soft Top Mechanism Cascading Four-bar MechanismsOpen Loop Four-bar ConfigurationUsed in Industrial robotsUsually requires multiple actuators to control motionPantograph LinkageOriginally used in scaled diagramsLinkages consist of Parallelograms
3Kinematic Diagram Open Loop Four-bar L= 4, J1= 3, J2= 0 DOF = M =3 Pantograph LinkageDOF = M = 1
9Dynamic Designer Convertible Animation Variation of designVelocity Analysis and Limit Position Analysiswith different R3 link length changing from 30 to unitsConclusionWith a constant input of theta2, the longer R3 is, the faster angle velocity of R4.That means the soft top can open faster in this condition.
10Dynamic Designer Convertible Animation The proceeding figures shows ,when the R3 is longer, it has a smaller rotation range of output link R4.That means :For wider rotation angle of R4,we select R3 a bit shorterTheta4 has the angle limit from 0 to Pi. It won’t work beyond this limit.For a faster speed of R4,we select R3 a bit longer
11Variations of the Crank-Rocker in Windshield Wipers Grashof ConditionS+L<P+QClass I case:Ground either link adjacent to the shortest and you get a crank-rockerThe shortest link will fully rotatethe other link pivoted at the ground will oscillate
12Tandem system Tandem system is widely used in the front windshield One Motor runs both wipersParallelogram linkage translates motion to wipers
13Most Common Type of Windshield Mechanism DOF= 3*(6-1)-2*7=1Four and Six-bar is a parallelogram linkage.Duplicate the rotary motion of the driver crank at the driven bar.
14Crank Rocker Input to Windshield Wiper The coupler of the parallelogram linkage is in curvilinear translationRemaining at the same angle while all points on it describe identical circular paths
15Two Vector Loop Closure equations In above case,R7=0;Design variable:t3,t4,t5,t6,t7
22ConclusionsThe Four-bar linkage mechanism will still be used in this wiper system for a long timeIt advantage includesUtilize one motor to drive two wiper bladeParametric changes gives different arcInput link can be place in various locationONE disadvantage commonly reported is Joint failure (joint dislocation)
23ReferencesHow Windshield Wipers Work. (2006) In: How Stuff Works Available: <http://auto.howstuffworks.com/wiper2.htm> [2007, October 12].Norton, R.L. Design of Machinery: An Introduction to the Synthesis and Analysis of Mechanisms and Machines. 3rd ed. New York, McGraw-Hill CoHow soft top convertible works. (2006) In: How Stuff Works Available: <http://auto.howstuffworks.com/wiper2.htm> [2007, October 12].Pantographs.(2006) In: Wikipedia The Free Encyclopedia:<http://en.wikipedia.org/wiki/Pantograph> [2007, October 12].