Instrument Panel and Air Vent Integration

Vajira Jayasinghe

Marcus Obal

Alex Perez

A thesis submitted in partial fulfillment

of the requirements for the degree of

BACHELOR OF APPLIED SCIENCE

Supervisor: Professors W.L. Cleghorn and J.K. Mills

Industrial Partner: Mr. Thomas Gehring, International Automotive Components

And Mr. Felix Chang, International Automotive Components

Connections Program

Ontario Centres of Excellence

Center for Materials and Manufacturing Ontario

Department of Mechanical and Industrial Engineering

University of Toronto

March 2008

i

ABSTRACT

International Automotive Components (IAC) is seeking a reduction in material and assembly

costs through the development of an air vent product that can be easily implemented into their

current manufacturing process. The goal of this project is to integrate an injection molded plastic

center instrument panel (IP) with its associated air vents. Creating a single part mold would lead

to a reduction in manufacturing, assembly and shipping costs, which would be beneficial to IAC

when bidding for future contracts with automotive manufacturers.

The final design (shown in Figure 1) creates the only front loaded concept available on the

market that IAC is currently aware of. Typically vents are loaded from the rear and attached to

the IP using rivets, screws, or snap fits. The front loaded concept holds the vent components in

place using a retaining ring snapped into the IP itself. In making the assembly front loaded,

minor changes in other components, as well as new assembly considerations, snap fit

orientations, and part loading are encountered.

Figure 1 - Naming Convention for a Typical Air Vent

Vent

Housing

Instrument

Panel (IP) Vanes

Louvers

Retaining Ring

ii

ACKNOWLEDGEMENTS

The authors would like to thank the following individuals and organizations for their support:

Professor Cleghorn for his guidance, and for providing the opportunity to participate in this

program.

Mr. Thomas F. Gehring of International Automotive Components for providing the focus of this

project, and contributing considerable guidance and resources throughout the duration.

The Ontario Centres of Excellence for their generous financial contribution that made the project

possible.

iii

TABLE OF CONTENTS

ABSTRACT ........................................................................................................................................ i

ACKNOWLEDGEMENTS ..................................................................................................................... ii

TABLE OF CONTENTS ...................................................................................................................... iii

LIST OF FIGURES ............................................................................................................................. iv

LIST OF TABLES ............................................................................................................................... v

1 INTRODUCTION ........................................................................................................................ 1

1.1 MOTIVATION .................................................................................................................... 1

1.2 BACKGROUND .................................................................................................................. 1

1.3 OBJECTIVES ..................................................................................................................... 3

1.4 SPECIFICATIONS ............................................................................................................... 4

2 INDUSTRY PARTNERSHIP .......................................................................................................... 6

2.1 PROFESSIONAL GUIDANCE ............................................................................................... 6

2.2 INDUSTRY LESSONS LEARNED: ......................................................................................... 6

3 DESIGN PROCESS ..................................................................................................................... 9

3.1 BENCHMARKING .............................................................................................................. 9 3.1.1 JUNKYARD ............................................................................................................................................. 10 3.1.2 DEALERSHIPS ........................................................................................................................................ 13

3.2 CONCEPTS ...................................................................................................................... 16 3.2.1 HINGE MODEL ...................................................................................................................................... 16 3.2.2 CARTRIDGE MODELS ............................................................................................................................. 18 3.2.3 REAR-LOADING MODEL ......................................................................................................................... 21 3.2.4 RETAINING-RING MODEL ....................................................................................................................... 22

3.3 PROTOTYPING ................................................................................................................ 23 3.3.1 PROTOTYPE ONE ................................................................................................................................... 24 3.3.2 RETAINING RING BENEFITS .................................................................................................................... 26 3.3.3 REVISIONS TO PROJECT SCOPE............................................................................................................... 27 3.3.4 PROTOTYPE TWO ................................................................................................................................... 30

4 OPTIMIZATION ....................................................................................................................... 32

4.1 VANE SYSTEM OPTIMIZATION ....................................................................................... 32

4.2 LOUVER AND DAMPER SYSTEM OPTIMIZATION ............................................................. 37

5 MANUFACTURABILITY ........................................................................................................... 41

6 FUTURE WORK ....................................................................................................................... 45

6.1 REVISIONS TO PROTOTYPE TWO .................................................................................... 45

6.2 FLOW ANALYSIS ............................................................................................................ 46

6.3 SAFETY TESTING ............................................................................................................ 47

6.3 FORMAL DESIGN REVIEW .............................................................................................. 47

7 CONCLUSION .......................................................................................................................... 49

8 REFERENCES .......................................................................................................................... 50

APPENDIX A - ECONOMIC EVALUATION ........................................................................................ 51

APPENDIX B - DEFINITIONS ............................................................................................................ 52

iv

LIST OF FIGURES

Figure 1 - Naming Convention For a Typical Air Vent .................................................................. 1

Figure 2 - Diagram of a Typical Air Vent ...................................................................................... 3

Figure 3 - Barrel design vent (‟98 Plymouth Breeze) ................................................................... 11

Figure 4 - Front view of Driver‟s Vent (‟92 Honda Civic) Showing Variable Vane Profile ....... 11

Figure 5 - Side View of IAC Sample Vent ................................................................................... 12

Figure 6 - Instrument Panel (IP) vent of '92 Acura Integra .......................................................... 13

Figure 7 - Instrument Panel (IP) Vents ('06 Volkswagen Jetta) ................................................... 14

Figure 8 - Instrument Panel (IP) Vent („07 Volkswagen Passat).................................................. 14

Figure 9 - Instrument Panel ('07 Audi Q7) featuring Aluminum Trim ........................................ 15

Figure 10 - Hinge Model............................................................................................................... 17

Figure 11 - Hinge Concept Assembly ........................................................................................... 17

Figure 12 - Dual Cartridge Model ................................................................................................ 18

Figure 13 - Dual Cartridge Model ................................................................................................ 19

Figure 14 - Single Cartridge Model Featuring Pre-Loaded Cartridge .......................................... 20

Figure 15 - Single Cartridge vent concept .................................................................................... 20

Figure 16 - Rear loading vent concept .......................................................................................... 21

Figure 17 - Retaining Ring Model ................................................................................................ 22

Figure 18 - Detailed view of Retaining Ring Snap Fits ................................................................ 23

Figure 19 - Initial Prototype of retaining ring concept ................................................................. 25

Figure 20 - Various views of Prototype ........................................................................................ 25

Figure 21 - Aluminum Ring for Aesthetic Finish ......................................................................... 26

Figure 22 - Air Vent Featuring Krytox Lubricated Joints ............................................................ 27

Figure 23 - Retaining Ring Featuring Locking Pins and Discrete Snap Fits ................................ 28

Figure 24 - Vertical Thumbwheel Controlling Both Louvers and Damper .................................. 29

Figure 25 - Solvent Bonded ABS Prototype ................................................................................. 30

Figure 26 - Four Bar Linkage Vane System Coupled with Thumbwheel Control ....................... 33

Figure 27 - Cad Model of Vane Linkage and Thumbwheel Assembly ........................................ 34

Figure 28 - Vane Linkage And Thumbwheel Optimization Properties ........................................ 35

Figure 29 - CAD model of Thumbwheel driven Louvers Coupled to Rear Damper ................... 37

Figure 30 - Louver Linkage Attachment to Thumbwheel Cam and Vent Housing...................... 38

Figure 31 - Optimized Orientation of Damper Linkage ............................................................... 39

Figure 32 - Final CAD Model ....................................................................................................... 40

Figure 33 - Louver and Thumbwheel Control Featuring New Curved Linkage .......................... 46

v

LIST OF TABLES

Table 1 - Projected Tooling Costs & Savings for IAC ................................................................. 42

Table 2 - Projected Molding Costs & Savings for IAC ................................................................ 43

Table 3 - Projected Assembly Savings for IAC ............................................................................ 43

Table 4 - Piece Price Savings for IAC .......................................................................................... 51

Table 5 - Projected Savings for IAC ............................................................................................. 51

1 Introduction 1

1 INTRODUCTION

This section covers the factors under consideration when pursuing this project. In

particular, an explanation of the current air vent industry and their practices will aid in

understanding IAC‟s motivation for creating this project. Similarly, an in depth look at

the current industry will also help explain the objectives and specifications required in

creating an appropriate design.

1.1 MOTIVATION

Modern manufacturing has entered an extremely competitive era because of the rapid

growth in foreign markets. Automated manufacturing decisions which were largely

prevalent in the 70s-80s are being rethought in light of the addition of lower wage

workers. According to Mr. Gehring, manufacturers aggressively bid on projects by

undercutting their competitors. In order to continue profiting in such an environment,

new advancements must be made which lower existing prices. As a result, International

Automotive Components (IAC) is seeking a reduction in material and assembly costs.

The project is focused on the integration of an automobile‟s center instrument panel and

its associated air vents. This would lead to a cost reduction, which would be beneficial to

IAC when bidding for future contracts with automotive manufacturers.

1.2 BACKGROUND

Through benchmarking we were able to determine that approximately every five years,

the automotive industry changes the interior designs for all their vehicles. These updates

1 Introduction 2

are cyclical in nature and often incorporate past design elements with slight

improvements. The advent of new materials and technology allow for new possibilities

that were previously unattainable. Despite this, the automotive industry is very

conservative and often resistant to unproven changes. Because of the large scale of

automotive industry projects, even the smallest change must first be justified through

safety, cost, performance, and warranty requirements.

IAC is interested in developing the groundwork for a product that can be easily

implemented into their existing manufacturing process. It is important to note that recent

changes in the IAC corporate structure have led to manufacturing changes both in terms

of labor and design which are discussed in further detail in section 3.3.3.

One of the most important issues involved in communicating with industry professionals

is a good command of the product naming conventions involved.

Figure 2 outlines a simple model air vent with the technical names commonly used when

referring to the various components. These conventions are applied when describing

various elements of the design concepts, throughout the report.

1 Introduction 3

Figure 2 - Diagram of a Typical Air Vent

1.3 OBJECTIVES

This project targets the integration of an injection molded, plastic Instrument Panel (IP)

for an automobile and its associated air vent casings. This study is focused on the many

challenges that arise within the manufacturing process as a result of this integration. The

overall development of the final product follows a design cycle of: researching,

designing, prototyping, evaluating, and repeating. With these targets in mind, the

objectives are as follows:

To benchmark the existing designs for vent manufacture

To create models based on viable concepts from research

Retaining

Ring

Instrument

Panel (IP)

Louvers Vane Linkage

Vanes

Vent Housing Damper

Horizontal

Thumbwheel

Louver

Linkage

Vertical

Thumbwheel

1 Introduction 4

To develop a prototype of the selected model based on feedback from industry

contact

To evaluate the prototype against stringent manufacturability requirements

To create a rapid prototype (SLA) model addressing any concerns found in the

prototype

To validate the functionality of the model to allow for incorporation to future

IAC products

The final model is hard to conceptualize at this stage of the project. Ideally the initial

prototype will address all the concerns regarding this product. However, in practice the

design cycle is an iterative process; there are always further modifications and

improvements that can be made to any product. Therefore, if possible the only changes

needed to create a final rapid prototype should be optimizations (redesigned shapes for

better air flow/ease of mold etc.)

1.4 SPECIFICATIONS

In addition to these general guidelines, several specifications were also provided by IAC,

which are industry standards:

1.5mm gap required between louvers and vanes

Minimum 13mm deep louvers

Any vanes/louvers longer than 80mm will have to be switched from simple

plastic to glass-filled composite for rigidity

Vanes/louvers are allowed a maximum deflection of 1mm under loading

1 Introduction 5

All vent designs must meet a fixed layout for degrees of freedom (Ex. The left

shoulder, right shoulder, eyes, and hip of a mannequin must have air flow

successfully directed to them)

There are also numerous safety requirements which any design must meet, which often

require years of testing to provide proof of concept. This is another driving factor behind

the need for minimal impact on current designs and manufacturing standards.

2 Industry Partnership 6

2 INDUSTRY PARTNERSHIP

The secondary objective of this thesis was to foster a partnership between industry and

university students. This interaction can be described in two main components, in-kind

support, and lessons learned specific to this industry.

2.1 PROFESSIONAL GUIDANCE

International Automotive Components (IAC) generously provided in-kind contributions

during scheduled meetings. Mr. Gehring was able to provide current air vents that would

not otherwise be available to students. These models are currently in production and

even include new prototypes. Not only did this provide insight into upcoming trends of

the industry, but allowed us to take a systematic look at IAC design methodology.

More importantly, IAC provided extremely useful feedback when we came forward with

new designs. These industry professionals could quickly make informed decisions about

our designs after a simple examination. They possessed an impressive knowledge of past

concepts that had been attempted as well as their respective outcomes, and were able to

streamline our decision making. Through experience they could decide if clearances

were too large or small, if material choices were appropriate, and most importantly, if the

design would conform to industry standards.

2.2 INDUSTRY LESSONS LEARNED:

The connections program offers students the opportunity to work with industry

professionals who have years of experience in their field. This allows a thesis project to

2 Industry Partnership 7

progress very quickly in comparison to research based assignments. This interaction is

vital when a company expects tangible results in such a short time frame. These

professionals are able to efficiently guide the students toward the desired goal, thus

minimizing time lost re-working established standards.

One of the most important things involved in designing a new variant of the air vent is a

strong understanding of the current industry. This is because there are often several

designs present that can achieve the same result, while being subject to various trade-offs.

For example, designs that look more industrial may provide better air flow, however

consumers rarely evaluate air vent performance and may be convinced to purchase a

vehicle based on more aesthetically appealing vents. Several industry practices were

made clear from the beginning:

Aesthetics dictate how vents will be designed

Air vent mechanics are restructured approximately every 5 years in

accordance with industrial design trends

Materials the consumer can see are often selected independent of cost since

they contribute to perceived value

Materials the consumer cannot see are always selected to minimize cost

provided they do not impact product performance

Overall, aesthetics play a much larger role than functionality (For example, a

new vent design may not allow the louvers to seal when closed, thus to restrict

air flow an alternate method of sealing must be devised)

2 Industry Partnership 8

In addition to professional guidance, students in the connections program are exposed to

the rigours of professional life. The students are given an opportunity to appreciate the

demanding schedule involved in the corporate environment. Due to numerous deadlines

and various commitments, an industry contact may not be available at one‟s convenience.

Maintaining contact with a professional in a managerial position can be a relentless task

which is often time consuming and takes perseverance. It is important to remember that

while a student‟s project may be promising, the company will always have higher

priorities since the main focus of any business is the bottom line. As a student, one must

appreciate the nature of the business and work within its schedule.

3 Design Process 9

3 DESIGN PROCESS

Any design cycle typically involves a form of research, brainstorming, development and

evaluation. The process is cyclical in nature because evaluation often results in redesign.

When considering the requirements of the automotive industry, an all encompassing

factor that shapes the design cycle is manufacturability.

Manufacturability must be incorporated in all steps, and as such affects the standard

outline of a design cycle. Instead of research, competitors can be benchmarked for

current solutions. The gathered data can then be used for concept generation, and can be

selected from for prototyping. The presence of an industry professional provides a

unique opportunity to provide relevant feedback on prospective designs. They can

provide valuable commentary on the whether a given design falls within the framework

of a manufacturable end-product. Without a manufacturable product, any work

accomplished is of little or no value to the partnered company.

Each of the following sections outlines the detailed approach undertaken to complete a

specific stage of the design process.

3.1 BENCHMARKING

The following section outlines product or technical benchmarking that was carried out at

various locations to determine past and present design trends in the air vent industry. This

is an established concept in the automotive industry where competitors often evaluate one

another to determine user expectations.

3 Design Process 10

Based on the objectives discussed, data was obtained by pursuing two strategies within

product benchmarking. Older models were reverse engineered to find their strengths and

weaknesses whereas newer models were evaluated via non-destructive means. The

important thing to remember is that the designs of interest were ones that could be loaded

from the front or prevent loading from the back; to fit with the final requirements of our

industry partner.

3.1.1 JUNKYARD

The junkyards provided a unique opportunity to delve into the inner workings of the

mechanism and view the trends in industry over the generations of vehicles. The closest

available junkyard is Standard Auto Wreckers (located in Markham, Ontario). While the

bulk of the models available were from the 90s, it was useful to note several trends in

vent design over the model years regardless of company. In particular there was a large

concentration of barrel designed vents. Barrel design denotes a vent in which the entire

housing rotates on a horizontal axis to direct air up and down. An example of such a vent

can be seen in Figure 3 below. It seems that this design was the standard approximately

10 years ago based on the samples available. While the barrels are practical from a

manufacturing standpoint, the poor aesthetics and air flow provided were the driving

factors for change according to Mr. Gehring. As mentioned earlier these design changes

occur every few generations and are driven by industrial design, much like fashion

trends.

3 Design Process 11

Figure 3 - Barrel design vent (’98 Plymouth Breeze)

Another point of interest was the design trends from Japanese manufacturers. One design

from a 1992 Honda Civic bore a striking resemblance to modern designs, in terms of both

functionality and appearance.

Figure 4 - Front view of Driver’s Vent (’92 Honda Civic) Showing Variable Vane Profile

The Civic vent shows varying vane side profiles intended to control air flow when aiming

at the extremes with the vanes. This technique is an alternative to creating a blockage of

flow within the back of the housing through the use of an undercut, as seen in a sample

provided by IAC in Figure 5 below.

3 Design Process 12

Figure 5 - Side View of IAC Sample Vent

This provides an interesting commentary in design methodology. While both methods

achieve the same overall goal, a variable vane profile may have increased cost due to

added complexity in the manufacturing process. Another similarity to the sample is that

it was rear loaded with snap fits. There is also an interesting progression in thumbwheel

geometries over the years. This is an indication of positioning/size being optimized for

greater control of directions.

The vane loading process in the 1992 Acura Integra seen in Figure 6 below was not

unique but it provided a useful platform for one design concept. The snap fit along the

top of the vent housing is simply used to hold the vanes in position. However this design

can be modified, such that the vanes can be loaded with a combination of snaps to create

a top-loaded cartridge with pre-assembled vanes.

Undercut creates

Blockage of flow

3 Design Process 13

Figure 6 - Instrument Panel (IP) vent of '92 Acura Integra

Remarkably this summarizes the most of the variations of models encountered at the

junkyard. As mentioned earlier, the large majority of vehicles used the barrel concept

that IAC strongly indicated should not be pursued.

3.1.2 DEALERSHIPS

The dealerships allowed insight into the current trends between automakers as well as the

development of these designs over time. Each dealership displayed a particular design

philosophy that was prevalent in all their vehicles. A limited number of manufacturers

displayed the air vent features sought after by this project.

One design met the specified requirements while maintaining an aesthetic appeal through

simplicity. The 2006 Volkswagen (VW) Jetta featured in Figure 7 duplicates the vertical

motion and shut-off offered by the IAC sample model through a second thumbwheel.

While the design adds complexity to manufacturing, from a user standpoint it offers

better control.

Snap fit holder

3 Design Process 14

Figure 7 - Instrument Panel (IP) Vents ('06 Volkswagen Jetta)

Figure 8 - Instrument Panel (IP) Vent (‘07 Volkswagen Passat)

In the 2007 Volkswagen Passat seen in Figure 8 above, the centre console featured a

louver assembly sandwiched between two pieces of POM. This entire assembly could

potentially be front-loaded into the housing, and retaining face for the vent then snapped

in place.

The Audi Q7 when compared to the Volkswagen Passat shows an identical concept.

Although the geometry is different, the exact same component structure is used. Simply

changing the less expensive plastic trim for an aluminum one Audi creates a much more

Dual

Thumbwheels

3 Design Process 15

elegant look for a luxury vehicle as seen in Figure 9 below. The primary benefit of this

being a low level design change and no alteration of the assembly process resulting in

increased perceived value.

Figure 9 - Instrument Panel ('07 Audi Q7) featuring Aluminum Trim

In addition, the Audi vent in Figure 9 also featured a variation in the profile of each vane

similar to the previously mentioned Civic vent. It is important to note that even though a

variable vane profile has been displayed in use with two separate auto manufacturers, and

is independent of design change over time; it is not in holding with IAC‟s goal of cutting

costs, and thus must be eliminated from consideration for any prospective concepts.

Although several other dealerships were visited, designs similar to those above were

apparent in Japanese and North American variants. Ultimately the platform displayed by

Volkswagen and Audi provided the only viable front-loaded ideas in current production

models.

3 Design Process 16

3.2 CONCEPTS

The driving factor behind each design was to prevent any sort of impact to the front

aesthetic. In terms of creating molds for these parts, one can theorize that each of the

following designs will result in multiple parting lines in addition to further molding

challenges. Without input and advice from experienced designers, the viability of each

concept would have taken months to determine.

All concepts were completed in Solidworks since it is software supported by IAC and can

readily be converted into the code for a rapid-prototyping. The simplification of the vent

design with block shapes was made to aid in the evaluation of the prospective designs

without getting distracted with the aesthetics of the product.

3.2.1 HINGE MODEL

One method of avoiding any changes to the front aesthetic is to have the entire vent body

split into four separate pieces which snap together after molding. This can be

accomplished through the use of a living hinge similar to a pencil case. This idea would

still create a single rear extrusion, but the walls of the box would not be joined at the

point of molding. A space is left for the vanes and louvers to be loaded from the rear

encased in their respective POM sleeves. This design eliminates any clearance issues,

allowing the housing to lock into place once the walls were connected. A solid model of

the design is shown in Figure 10 below.

3 Design Process 17

Figure 10 - Hinge Model

From the images above, it is clear that the most promising feature of this concept is the

limitation on the number of snap fits. The interlocking of components relied on to hold

everything together would be challenging to implement both for molding and assembly.

The feasibility of the hinge design with respect to material properties and strength of

construct become the primary concerns.

Figure 11 - Hinge Concept Assembly

POM

sleeve

ABS

3 Design Process 18

3.2.2 CARTRIDGE MODELS

The cartridge concept allows a large degree of flexibility in terms of implementation.

The nature of the design allows a natural choice between having two cartridges (one for

each direction of vane) or one cartridge (with both vane sets loaded in together).

The dual cartridge model shown in Figure 12 below is a relatively simple concept. The

cartridges load from the side and bottom, complete with the louvers and vanes

respectively, already assembled. Each will be offset 1.5mm to allow a gap between the

horizontal and vertical cartridges.

Figure 12 - Dual Cartridge Model

The flexibility in the design comes from the fact that the cartridges themselves can be

loaded from any direction specified, and can be assembled separately from the vent,

being loaded into the housing on demand.

3 Design Process 19

However there are weaknesses into the overall housing of the air vent that are introduced

with this process. Additionally the attachment of the thumbwheel mechanisms to operate

the vanes must also be considered and will require innovative solutions.

Figure 13 - Dual Cartridge Model

The single cartridge variant seen in Figure 14 below allows us to have good control over

the spacing between the two sets of vanes, resulting in a smaller overall space taken up

by the mechanism. Furthermore, combining the vane assembly process into one cartridge

reduces the number of parts, and the number of workers involved on the assembly line.

The cartridge itself will have a higher complexity to assemble, but will pass through less

hands and there is less chance of being short shipped multiple components. The snap fits

represented here have not been optimized for single use. Consultation with experienced

designers is necessary to determine the strength of such a joint in implementation.

ABS

POM

3 Design Process 20

Figure 14 - Single Cartridge Model Featuring Pre-Loaded Cartridge

During benchmarking several different models were noted regarding the vane connection

to the vent housing. In Figure 13 above there is an oversized stub on the end of the vane

that is perpendicularly forced into the opening of the vent housing or in this case the

POM cartridge. In the single cartridge design of Figure 15 below, the vanes simply snap

into the opening horizontally. Both have benefits and drawbacks, but for demonstration

purposes, each is shown once.

Figure 15 - Single Cartridge vent concept

ABS

POM

3 Design Process 21

Additionally both cartridge designs introduce air leakage into the performance of the

vent, the final impact of which can only be determined through either simple prototyping

or computational fluid dynamics.

3.2.3 REAR-LOADING MODEL

The idea of rear loading is similar in thought to the hinge design. By finding a way to

load the louvers and vanes from the rear, the impact the front aesthetic is avoided but a

single piece design of the entire console is maintained. Since the vent and duct work are

controlled by IAC, there is more flexibility regarding the length of the rear extrusion.

Figure 16 - Rear loading vent concept

The principle of this design centres on maintaining a static outer dimension for the rear

extrusion, while the inner wall drafts outward from the center console face. This allows

the rear wall to thin and creates an opening large enough to slide the vanes in from the

rear. Ideally the rear extrusion can be truncated at a length such that this draft is not

prominent. Moreover the vanes will be attached to linkages (not included for

simplicity), with the grooves in the mold providing the offset distance between the

louvers and vanes.

3 Design Process 22

3.2.4 RETAINING-RING MODEL

This concept solves the problem of loading the vent assembly from the front, by creating

a space large enough for the assembly to be loaded. By snapping a „retaining ring‟ on

after the vent has been inserted, the vent can remain loaded, with no unsightly marks or

lines to indicate how it was assembled.

Figure 17 - Retaining Ring Model

A key feature of the retaining ring concept is that the material of the ring can be modified

to reflect a higher valued vehicle as mentioned in section 3.1.2. Simply by replacing the

plastic material with a metal such as aluminum, the aesthetic of the IP is enhanced and

thus the perceived value.

The idea for the retaining ring concept came about during the benchmarking process. It

was noted as a viable design which met all the requirements stipulated by IAC, except

that it altered the front aesthetic of the IP. While this change was perceived to be

minimal, the concept was not seriously considered as a design because of this violation.

3 Design Process 23

The retaining ring concept is essentially a variant of traditional vent design and as such

would work well with traditional snap fits for the louvers and vanes. Examples of such

snap fits can be seen in Figure 18 below.

Figure 18 - Detailed view of Retaining Ring Snap Fits

3.3 PROTOTYPING

IAC was approached and consulted about the various concepts early in November 2007.

Professional feedback was received from an experienced IAC design engineer and the

engineering manager who had assigned the project.

Regarding the hinge concept, the same concerns brought up about the strength of the part

and high complexity of the required mold were confirmed. The hinge design would

require far too much testing and redesign even for completion of the prototype.

3 Design Process 24

Assuming such a project was approved, implementation by the company would likely

never occur due to the large commitments in R&D that would be required.

A similar response was received when discussing the cartridge concept. Although

theoretically sound, the prototyping stage would be extremely complicated due to the

precise nature of the model.

The most positive reaction was to the rear loading and retaining ring concepts. This was

due to their inherent simplicity, which meant they posed the least impact to existing

manufacturing methods and the least complexity in creating a working model. However,

it was found that the rear loading model would be restrictive for further component

additions to the vent housing.

Based on the feedback received, the clear model to pursue with the initial prototyping

stage was the retaining ring concept.

3.3.1 PROTOTYPE ONE

The following figure outlines several views of a physical prototype constructed from

foam board and bamboo. This prototype was constructed as a learning model, to help

identify the various issues that would be encountered when pursuing this design. Often

the best way to understand interferences, manufacturability, and assembly complications

is through a physical model. It also allowed IAC to gain a greater understanding of the

model chosen, and provide helpful pointers for the next steps.

3 Design Process 25

Figure 19 - Initial Prototype of retaining ring concept

A particular challenge immediately encountered was in the design of a secure lock for the

retaining ring. The ring itself would require either a continuous or discrete set of snaps to

hold it in place. A discrete set of snaps was recommended for ease of adjustment in later

manufacturing steps (ex. The snaps could be added or removed and retested vs. a

continuous ring which would need to be tested after each change).

Figure 20 - Various views of Prototype

3 Design Process 26

3.3.2 RETAINING RING BENEFITS

As mentioned in previous sections, the retaining ring is dual purpose. The primary

function of this component of the air vent is to allow front loading of other parts thus

allowing for the integration of the vent housing and the IP. Additionally, as confirmed by

IAC, the retaining ring had the potential to address an aesthetic trend currently seen in

many vehicles.

Figure 21 - Aluminum Ring for Aesthetic Finish

The aluminum ring seen in Figure 21 is just one example of the many vehicles that apply

such a ring as an added cost as was previously mentioned. This ring usually attaches on

top of existing vents and serves no functional purpose. Such a design increases the

amount of snap fits used as well as the cost and complexity of the model.

The retaining ring concept addresses both functional and aesthetic requirements at the

same time thus potentially adding value to future IAC designs.

3 Design Process 27

3.3.3 REVISIONS TO PROJECT SCOPE

Upon presentation of the retaining ring model to IAC, the project scope was both

expanded and modified to reflect changes in IAC‟s business model. Under new

ownership, IAC‟s manufacturing operations were relocated from Ontario to Mexico.

Such changes had wide ranging impacts on manufacturing techniques, material selection,

and assembly processes. For example, it can be noted that all concepts mentioned in

section 3.2 incorporated two dissimilar plastics such as ABS and polyoxymethylene

(POM). Higher manufacturing wages in North America warranted an automated process

and thus the use of POM, a self lubricating plastic used in joints. The shift in

manufacturing site allows for all components to be made of ABS and utilizes a manually

applied product called Krytox grease in the joints for lubrication. A visual example of

Krytox can be seen in Figure 22 below as the white substance found on the joints of

mating components.

Figure 22 - Air Vent Featuring Krytox Lubricated Joints

3 Design Process 28

In addition to manufacturing considerations, IAC requested that further refinement of the

retaining ring itself be carried out. A further developed model that utilized discrete

snaps would be ideal for testing purposes and to make such a ring universal in design.

Figure 23 - Retaining Ring Featuring Locking Pins and Discrete Snap Fits

As shown in Figure 23, the updated retaining ring features a series of discrete snaps on

three of the four sides of the ring. Due to interference with the louvers, snaps could not

be used on the fourth side. A series of pegs that will lock into the vent housing were used

to overcome the interference while still guaranteeing a safe, interlocking design that will

not come loose, especially during airbag deployment.

At the same time, IAC widened the scope of this project by presenting the challenge of

incorporating a vertical thumbwheel into the retaining ring design. This thumbwheel

would control both louver motion and an added rear damper to completely shut off air

flow. Such a design can be seen in Figure 24 below. The motivation for the addition of a

3 Design Process 29

damper was mainly driven by industrial design since current trends in vent aesthetics

could compromise shut-off capability of louvers. This made the addition of a rear

damper essential, while keeping the user interface intuitive to the consumer.

Figure 24 - Vertical Thumbwheel Controlling Both Louvers and Damper

3 Design Process 30

3.3.4 PROTOTYPE TWO

The second and final prototype was hand crafted, solvent bonded ABS. This model

incorporated both the horizontal and vertical thumbwheels requested by IAC.

Furthermore, the vertical thumbwheel controlled both the louver and rear damper motion

utilizing optimized geometry discussed in Section 4. An image of the prototype can be

seen in Figure 25.

Figure 25 - Solvent Bonded ABS Prototype

While this prototype was created as the second prototype, with a rapid prototyped SLA

expected in the final stage, IAC determined that the design created was already ideal.

Any additional designs created would incorporate minor changes, and the SLA model

would not compare in practicality to the ABS used. The materials used for this prototype

3 Design Process 31

better simulate stiffness, wear, ease of assembly, and joint movement. In fact, with the

cooperation of IAC, Krytox grease was even applied to the moving components of the

vent as a final step.

4 Optimization 32

4 OPTIMIZATION

The following section will focus on the optimization of the two mechanical systems

found in the air vent that is the study of this thesis. The vertical thumbwheel system was

added to the project scope following presentation of the initial prototype to IAC and it

was pursued on a purely academic basis of optimization. It is useful to note that in

industry, designs are not typically optimized due to time constraints. Section 4.1 looks at

the optimization of the vane system while Section 4.2 focuses on the optimization of the

louver and damper system.

4.1 VANE SYSTEM OPTIMIZATION

The vane system of any vent can be broken down into a simple 4 bar mechanism as

displayed in the highlighted segments of Figure 26 below.

4 Optimization 33

Figure 26 - Four Bar Linkage Vane System Coupled with Thumbwheel Control

The fixed base length is a static value formed by the vent housing, which is determined

by the distance between the vane snap points. There are two pivot points at either end of

the fixed base length, about which the vanes themselves rotate. The vanes are joined by a

linkage which completes the four bar mechanism. A three dimensional model of this can

be seen in Figure 27 below.

Van

e

Vane linkage

Fixed base link length

Thumbwheel

Vane linkage coupler

arm

Vane linkage coupler

point

Fixed pivot for vane

4 Optimization 34

Figure 27 - Cad Model of Vane Linkage and Thumbwheel Assembly

The four bar mechanism of the vane system is typically driven at some point along the

vane linkage, which is in turn attached to a coupler arm. This coupler arm is driven at a

coupler point connected to the horizontal thumbwheel. Understanding this generic setup,

one can begin to optimize the geometry to achieve the following:

minimize the effort required from the user to manipulate the mechanism

must require provide enough resistance to maintain a static position

design a compact mechanism that will use the least amount of material

possible

provide the appropriate range of motion to the vane via the thumbwheel

Vanes

Horizontal

Thumbwheel

Vane Linkage

4 Optimization 35

ensuring the thumbwheel provides a large enough range on the input to select

specific angles

minimize forces on the joints to avoid fatigue, sticking, etc.

choose the coupler location so that it is out of sight and does not interfere with

the other mechanisms in the vent

After examining several geometry configurations, it was determined that the layout of

Figure 28 below was the optimized arrangement.

Figure 28 - Vane Linkage and Thumbwheel Optimization Properties

There are two important relations that are highlighted in yellow and red in Figure 28.

The first relation highlighted in red shows that the thumbwheel drives the coupler arm at

a radius equal to the distance between the fixed vane pivot and the vane linkage

4 Optimization 36

attachment. Based on this relation alone, it is clear that the thumbwheel radius must be

equal to or greater than the second highlighted portion in red. This ensures that the

thumbwheel and the vanes are tracing out arcs of equal radius, allowing the coupler arm

and vane linkage to transmit forces directly. This results in minimizing user effort and

reducing wear.

The second relation highlighted in yellow demonstrates that the distance from the

thumbwheel center to the base link of the 4 bar vane system must be equal to the length

of the coupler arm attached to the vane linkage. This relation is a direct by-product of the

first relation of equal arcs. In other words, if the coupler arm had a length of zero, the

thumbwheel would be centered along the fixed base link and would drive the vane

linkage directly without the aid of a coupler arm. Essentially, the thumbwheel would act

as an additional vane connected to the vane linkage.

This configuration which eliminates the coupler arm was chosen for the final model of

this thesis. It meets the criteria previously listed; of reduction in components, minimizing

moving parts, and minimizing material usage. Simultaneously, the optimized geometry

addresses the other concerns related to the forces encountered through user-interaction.

This results in a more cost effective product subject to less warranty claims.

Nevertheless, some designs will require the use of a coupler arm because of the compact

designs used in many air vents. Even so the coupler arm itself is of a variable length

4 Optimization 37

(including zero), as such the model derived in Figure 28 is parametric and can be

manipulated for any air vent configuration.

4.2 LOUVER AND DAMPER SYSTEM OPTIMIZATION

The vertical thumbwheel and louver system is identical in geometry to the horizontal

thumbwheel and vane system. The louver pivot points form fixed length base links

which are attached to the louvers. Similarly, the louvers are connected by a louver

linkage thus completing the four bar mechanism. The length of the coupler arm is

determined by the offset of the thumbwheel center from the louver pivot points. The

coupler point on the thumbwheel is driven about the center in a radius equal to the length

along the louver from the pivot point to the point of the louver linkage attachment.

Figure 29 - CAD model of Thumbwheel driven Louvers Coupled to Rear Damper

Inactive portion

of cam

Louver Coupler

point

Damper

Active portion of

cam

Louver Linkage

Damper

Linkage

4 Optimization 38

The damper and thumbwheel system required a different approach. Many variants

currently manufactured incorporate multiple links, complicated dual cam mechanisms,

and other components requiring intricate molding techniques. In continuation of the

goals of minimizing material usage, user effort, and number of components, the model

seen in Figure 29 above was generated.

The geometry of this system can be broken down into two stages defined as the active

portion of the thumbwheel cam and the inactive portion of the thumbwheel cam.

The primary components of this system are the damper, the damper linkage, and the

thumbwheel with a recessed cam profile containing the activated/deactivated stages.

Initially, the inactive portion of the cam is locked into the damper linkage through the use

of a peg. The other side of the damper linkage is locked into a horizontal slider that is a

recessed slot in the side of the vent housing as can be seen in Figure 30 below.

Figure 30 - Louver Linkage Attachment to Thumbwheel Cam and Vent Housing

4 Optimization 39

This horizontal slider prevents the linkage from sliding back up the cam as the

thumbwheel turns, but allows for a change in position of the linkage as the radius of the

cam changes during the active portion. The cam radius decreases about the center of the

thumbwheel, and as the thumbwheel turns the damper linkage is pulled forward,

simultaneously applying a torque to the damper. This torque causes the damper to

quickly close. By rotating the thumbwheel in the opposite direction, the process is

reversed.

Since the end of the damper linkage that is attached to the cam and slider has a fixed

vertical position, a pivot point is formed and the angle relative to the active cam profile

changes relative to the thumbwheel rotation. To minimize user effort, the damper linkage

orientation was chosen to be co-linear with the restrictive slider half way through active

20 degrees of the cam motion as seen in Figure 31 below. This ensures that for the active

cam portion, the damper linkage is as close to perpendicular as possible to the cam profile

thus minimizing the input force required.

Figure 31 - Optimized Orientation of Damper Linkage

10 degrees

Slot and

linkage

collinear

10 degrees

4 Optimization 40

Most importantly, the louvers and damper need to work in tandem. The louvers have a

range of motion of 100 degrees from open to close and correspondingly, the cam profile

on the thumbwheel also forms an angle of 100 degrees about the center of the

thumbwheel. The inactive portion of the cam comprises 80 degrees of motion while the

active portion of the cam makes up the remaining 20. This motion corresponds to the

final 20 degrees of movement of the louvers before closing. When shutting off air flow,

it is likely that in the last 20 degrees of motion the intent of the user will be to close the

louvers completely. Thus, it is intuitive that the damper closes in conjunction with the

louvers and not as an added input following the closing of the louvers. Furthermore, the

final 20 degrees of motion of the thumbwheel must also correspond to the damper

rotating roughly 60 degrees to shut off air flow. This relationship is proportional to the

length of the damper and the height of the vent housing. This quick motion was chosen

to minimize “whistling” noises as prescribed by IAC‟s experienced designers.

With consideration for the optimizations described above, the final CAD model of the

retaining ring air vent and IP integration can be seen in Figure 32.

Figure 32 - Final CAD Model

5 Manufacturability 41

5 MANUFACTURABILITY

As mentioned in previous sections, the manufacturability of this product is paramount to

it's usefulness to IAC. From the outset of the project scope, careful attention was paid to

the overall viability of the design. Any concept had to be evaluated with respect to the

feasibility of creating an effective mold, compensating for mold flow, assembly

considerations, and adhering to industry standards.

In order to truly appreciate the considerations that are present for manufacturability, one

must first understand the implications that these factors carry. An air vent design cannot

simply be created and then modified as necessary to become feasible for a company to

produce. Instead manufacturability must be considered at every stage of the design

process.

It is this single fact that is likely the largest departure which this thesis takes from an

ordinary research project. Concepts cannot be pursued for their creativity, or due to their

uniqueness. Instead to avoid increased testing and production costs, these ideas are

dismissed in favour of more established and reliable methods. An automotive

manufacturer such as IAC simply does not have the capital to invest in radical new

concepts with relatively low potential benefits.

Typically these types of analyses are accompanied with product design charts to justify

the design. However, these forms largely serve as a failsafe should the design not

succeed; they are to explain why design choices were made. Since this entire document

5 Manufacturability 42

serves as an explanation of the design considerations which went into the air vent

integration, such documents are meaningless. A more useful evaluation of the benefits of

the integration of an air vent with an IP can be found by examining IAC‟s bottom line.

There are three areas in which the benefits of this design can be categorized; Tooling,

Molding, and Assembly costs.

The integration of the air-vent housing with the IP directly results in the elimination of

the housing mold, and the assembly fixture required for the two separate pieces.

However it simultaneously requires a new mold to be created to meet the modified design

requirements, and an investment to cover the creation of a new set of parts, the retaining

rings. Despite the investments required, on a tooling basis alone the design results in a

net savings of $102,000 as shown in Table 1.

Table 1 - Projected Tooling Costs & Savings for IAC

Cost Center Savings Extra Cost

Tooling Housing mould eliminated $180,000 -

Assembly fixture $47,000 -

Housing integrated with bezel - $45,000

Additional retainer brackets - $80,000

Total $227,000 $125,000

Net $102,000 -

From a molding perspective, it is simpler to view the savings on a dollar per hour basis,

as a total cost basis would require sweeping assumptions of production numbers, factory

performance etc. Implementing the air vent integration immediately results in a

reduction of one 500 ton machine as well as one operator, to eliminate the separate

5 Manufacturability 43

molding process. In tandem with these savings, an increase to an 800 ton machine to

compensate for the larger mold would be required, as well as molding considerations for

the new retaining ring. The projected savings per hour of $138 dwarf the additional

costs, resulting in a net savings of $58 per hour. These results are displayed in Table 2

below.

Table 2 - Projected Molding Costs & Savings for IAC

Cost Center Savings Extra Cost

Molding 500 ton machine ($/hr) $120 -

Reduce one operator ($/hr) $18 -

Increase to 800 ton machine ($/hr) - $35

Mould additional retainer brackets ($/hr) - $45

Total ($/hr) $138 $80

Net ($/hr) $58 -

Moreover, an additional assembly operator at $18 per hour can be removed since the part

is now joined in the mold.

Table 3 - Projected Assembly Savings for IAC

Cost Center Savings Extra Cost

Assembly Reduce one operator ($/hr) $18 $0

Net ($/hr) $18 -

To put these projected savings into perspective the piece price savings as well as general

estimations are often tabulated in the automotive industry. This allows a simple scaling

5 Manufacturability 44

factor of production to be applied when dealing with large projects. For a detailed

breakdown of how these numbers were calculated see Appendix A.

Assuming one part is produced every 45 seconds during production, a piece price savings

of 95 cents can be determined from the savings per hour previously mentioned. Based on

industry projections there are approximately 17 million IPs produced in North America

every year. When considering that an industry-wide redesign occurs every 6 years, this

gives any vent mold a usability of 6 years before it must be replaced/redesigned.

IAC has approximately 25% of the total IP market, resulting in a total savings of

$24,225,000. When these savings are considered with the more qualitative aspects of the

design, a clear benefit for the company can be found. Furthermore, there is an added

aesthetic bonus provided by the retaining ring as mentioned previously, which could

allow IAC to match current Industrial Design standards at a much lower cost.

Additionally the reduced warranty issues since the entire IP is now joined with the vent

drive up the potential customer value of such a product.

6 Future work 45

6 FUTURE WORK

The following section will outline additional work that can be carried out to further

develop the retaining ring concept.

6.1 REVISIONS TO PROTOTYPE TWO

The ABS prototype fully met the requirements put forth by IAC; the only improvement

suggested for future revisions was a modification to the feel of moving the vertical

thumbwheel. Through experience, Mr. Gehring of IAC was able to recognize that the

cam mechanism incorporated into the vertical thumbwheel seen in Figure 25 would be

subject to asymmetric forces. This would result in the user applying a larger force than

typically required to move the louvers. Due to the geometry of the links and the cam

system, the linkage joining the damper to the cam would be subject to a pulling force

along one side of the cam during damper closing. However, it would also be subject to a

pushing motion along the inside track of the cam when the damper is to be opened.

Although this design is functional and does not pose a quantitative mechanical problem,

Mr. Gehring‟s years of knowledge in the automotive interior industry led him to

recommend the change based on a qualitative perspective, understanding that consumers

would not approve of the feel that this type of system would offer. A design to rectify

this problem was modeled using CAD software for rapid prototyping should IAC require

a sample in the future. The model can be seen in Figure 33 below where the cam profile

with changing radius was replaced with a constant radius cam. In addition, the static

length link was coupled with a bent link to provide a variable link length. This variable

link length would still be capable of providing the change in distance between the cam

6 Future work 46

and damper capable of closing the damper, while eliminating the push and pull motion

the previous cam design was subject to.

Figure 33 - Louver and Thumbwheel Control Featuring New Curved Linkage

6.2 FLOW ANALYSIS

Although the final design poses little impact to the overall manufacturing process and in

reality few changes to the final vent housing, it is not possible to simply assume that there

will be no effects to the current air flow requirements dictated by IAC policy. Due to the

complexity and cost involved in performing Computational Fluid Dynamics (CFD), the

use of such a method is outside the project scope of this thesis. However it would be

prudent, when implementing this design to take CFD into consideration to guarantee

customer satisfaction once full production was underway.

6 Future work 47

In particular, a mannequin layout provided from the client automotive company would

include the degrees of freedom required (i.e. angle to be obtained to Left shoulder, Right

shoulder, Eyes, Hip). This information is usually kept confidential, but if necessary, IAC

can complete all work in-house should the need arise.

6.3 SAFETY TESTING

As previously mentioned, significant effort goes into ensuring that all components in a

vehicle meet stringent safety requirements. Before large scale production can occur,

several scenarios must be met. For example; an IP must first be examined to ensure no

sharp points are sticking out if someone collides with centre console.

Since the method of attachment between the vents and IP has changed and the vent

mechanisms are now held in place solely by the retaining ring, reactions under all forces

must be closely examined. In particular, sudden impacts to the vehicle must be

scrutinized to simulate either an accident or airbag deployment. These events should not

cause pop-out of the vents and any of its associated components.

6.3 FORMAL DESIGN REVIEW

In order to validate the design for senior management and justify any investments, a

formal design process is typically enforced in most companies. Two standard documents

are a Design Failure Mode Effect Analysis (D-FMEA), and a Design Validation Plan and

Report (DVP&R).

6 Future work 48

DFMEA examines the potential failures that can occur from a given product and their

root causes. Several values are assigned to these failures, based on severity, occurrence,

and detection of the failure. These values are then used to assign a priority to determine

which matters are most pressing. Unfortunately, the scales used for the previously

mentioned values are confidential within the corporate structure of IAC. Any DFMEA

created would require a reliable resource in determining these scales to ensure an

accurate representation of the industry standards.

A DVP&R is essentially a set of tests specific to the product, normally provided by the

manufacturer. It is comprised of a listing of items with test procedures; each item

consisting of a specific physical test. The DVP&R provides the exact testing procedures,

and the specific passing criteria for each item. It also details how many samples must be

tested, how many times to perform the test, etc. The plan is determined statistically, and

designs must be modified until the all requirements are passed.

7 Conclusion 49

7 CONCLUSION

The original scope of the project put forward by IAC was to integrate an air vent housing

and instrument panel into a single mold. The primary for this was to reduce overall costs

for IAC. The retaining ring model developed not only satisfied the original project scope

outlined by IAC but surpassed their expectations by providing an additional aesthetic

benefit. The scope of the project was further expanded to include the control of a damper

system via the vertical thumbwheel. This system was optimized and added to the

retaining ring model, at which point the manufacturability was evaluated and

demonstrated a significant benefit to IAC.

There is potential to further evaluate this model. The future work associated would lie in

evaluating potential affects to air flow for user comfort, impacts to safety for industrial

implementation, and adherence to other various industry standards.

8 References 50

8 REFERENCES

Chang, Felix. Personal Interview. 2007.

Chang, Felix. Personal Interview. 2008.

Gehring, Thomas. Personal Interview. 2007.

Gehring, Thomas. Personal Interview. 2008.

Appendix A - Economic Evaluation 51

APPENDIX A - ECONOMIC EVALUATION

The following is an evaluation of the piece price savings derivation for the retaining ring

air vent design.

Table 4 - Piece Price Savings for IAC

Cost Center Net Savings

($/hr)

Manufacture

(s/part)

Piece Price

Savings

Molding $58 45 $0.73

Assembly $18 45 $0.23

Total Savings per

assembly $0.95

Table 5 - Projected Savings for IAC

Instrument

Panels produced

in North

America

No. parts / year Savings/Assembly Projected

Savings

17,000,000 $0.95 $16,150,000

Assuming that the typical design cycle span of 6 years (6 years of production) then the

projected savings for this time frame are:

$96,900,000

IAC has an IP market share of 25% resulting in a projected saving of:

$24,225,000

Appendix B - Definitions 52

APPENDIX B - DEFINITIONS

ABS - From the chemical name Acrylonitrile butadiene styrene, it is a common

thermoplastic used to make molded products. For air vents ABS is the

primary plastic used to make most or all of the components.

Damper - typically a rubberized molded part located at the rear of the vent housing

which allows air flow to be completely restricted.

IAC - International Automotive Components, the industrial sponsor of this thesis

Instrument

Panel (IP)

- typically a rubberized molded part located at the rear of the vent housing

which allows air flow to be completely restricted.

Krytox - a high performance synthetic lubricant (commonly referred to as a grease)

patented by DuPont. The grease is used as a substitute for POM in the vent

industry as opposed to switching plastics.

Linkage - A plastic molded part to which vanes (for the horizontal version) or louvers

(for the vertical version) are attached. Joins all vanes/louvers, allowing

them to move at once from a single control, typically a thumb-wheel.

Louvers - horizontal bar extending from left to right ends of a vent housing which

controls the flow of air up and down.

MDF - An acronym for Medium-density fiberboard, it is formed combining wood

fibres with wax and a resin binder, and then forming the material into

panels. It is commonly used in the air vent industry as a prototyping

material to create mock-ups of potential designs.

OCE - Ontario Centers of Excellence, the government sponsor of this thesis

POM - From the chemical name Polyoxymethylene (it is also sometimes referred to

under DuPont's brand Delrin) it is a lubricating plastic commonly used in

joints where repeatable motion is occurring. For air vents POM commonly

makes up the linkages which hold both vanes and louvers.

Retaining

Ring

- A rectangular shaped piece of molded plastic which snaps into the front of

the instrument panel holding the vent housing in place.

SLA - Stereo Lithography Apparatus, a device commonly used to produce three

dimensional models from computer aided design files. This is commonly

known in industry as rapid prototyping

Appendix B - Definitions 53

Thumb

Wheel

- A user-interface device commonly incorporated into vent design, it can be

used to direct air flow (when attached to louvers/vanes) or to control air

flow (when attached to a damper).

Vanes - vertical bar extending from top to bottom of a vent housing which controls

the flow of air left to right.

Vent Housing - A molded plastic part that contains all the mechanisms of the air vent.