PACE TERM PROJECT

Alex Furse and Mike Milewski

As Design Engineers we were responsible for the design of a deck lid (trunk) of a new automobile. The design criteria required was that the motion of the deck lid was constrained to move along a predetermined path. Three positions of the Deck lid were specified: 1) closed, 2) midpoint and 3) open.

The assignment was to design a mechanism using Unigraphics NX-3 Motion that will move the deck lid along a path through the three positions. It was assumed that the deck lid and linkage was two-dimensional and of negligible mass. The Deck lid cross section CAD geometry was provided in IGES format. Only the driver ground pivot was fixed.

P A C E

Project Objectives

Alex Furse and Mike Milewski

P A C E

Project Constraints

Alex Furse and Mike Milewski

Driver Ground Pivot

Figure 1a. Initial Position

P A C E

P A C E

Project Constraints

Alex Furse and Mike Milewski

Figure 1b. Middle Position Figure 1c. Open Position

P A C E P A C E

P A C E

Method of Approach

Alex Furse and Mike Milewski

• Brainstorming

• Researching existing hinge designs

P A C E

Research and Planning

Alex Furse and Mike Milewski

Figure 1a. BMW hinge.

Figure 1c. Plymouth hinge.Figure 1b. Alfa hinge.

• Sketching

• Alternative designs

- Roller / track system

P A C E

Concepts

Alex Furse and Mike Milewski

Figure 2. Roller Model

• Trial and Error

- Physical Paper Linkages

- Working Model 2D

- Solid Works

- Graphical Sketching

P A C E

Motion Analysis

Alex Furse and Mike Milewski

Figure 3c. Graphical Sketching

Figure 3a. Physical Paper Linkages

Figure 3b. Working Model

• Analytical

- Synthesis of Mechanism:

Analytical Design of a Four-Bar Mechanism for Three-position

Rigid-body Guidance

Equation (11.7-4)

xB1(A13nC1n + A23nS1n – xO2C1n – yO2S1n + xO2)

+ y B1(A23nC1n – A13nS1n + xO2S1n – yO2C1n + yO2)

= A13nxO2 + A23nyO2 – ½(A13n2 + A23n

2)

 

Using Equation (11.7-4) with the assistance of Matlab and Excel we were able

to find the various link lengths and positions.

P A C E

Motion Analysis

Alex Furse and Mike Milewski

P A C E

Results

Alex Furse and Mike Milewski

Figure 4. Perspective

P A C E

Results

Alex Furse and Mike Milewski

Figure 5a. Initial Position

P A C E

Results

Alex Furse and Mike Milewski

Figure 5b. Mid Position

P A C E

Results

Alex Furse and Mike Milewski

Figure 5c. Open Position

P A C E

Results

Alex Furse and Mike Milewski

Video 1. Open to Close Motion

• Designed to minimize the effect of pinching

- bend- spacers

• toleranceslink hole: + 1 thoupin: - 1 thoucenter to center: + 10 thoubends: +/- 1 degree

P A C E

Optimization

Alex Furse and Mike Milewski

Figure 6a. link bend

Figure 6b. spacer

• Trunk lid gas piston

- damping

- easy use: little force

required to open trunk lid

- multiple locations but placed

so its following the shortest

distance

P A C E

Optimization

Alex Furse and Mike Milewski

Figure 7. Piston and Truck Lid

• Designed links so that they can be easily manufactured.

• material: mild steel

• 2 stage process - sheet metal pieces cut out

with dye - stamped into shaped

• cheap process

• interchangeable: links and coupler link can be used for both sides

P A C E

Manufacturing

Alex Furse and Mike Milewski

Figure 8. Coupler flat

• reduce sheet metal thickness

achieved by press fitting a bushing

in the link bosses to maintain

contact area of pins and links and

reduce wear

• Rubber Sock

- decreases wear and contact

stress

- damps closure position

P A C E

Improvements

Alex Furse and Mike Milewski

Figure 9b. link sock

Figure 9a. Bushings

P A C EPACE Goals

Alex Furse and Mike Milewski