Chapter 1: Introduction
This chapter describes about the background of an overview of ventilated car seat, function analysis, problem statements, objective, research methodology, methodology and benefits for the project.
According to a press release issued by market research agency Nielsen in the year of 2014 (Nielsen, 2014) Malaysia placing third in the world with 93 percent car ownership, and the country also has the highest incidence of multiple car ownership globally with 54 percent of households having more than one car, thus car seat is the most important integral part of automobile. From the time begin when there existed simple benches until today with massaging chairs, where automobile seats have changed immensely over time.
However, hinder the heat and moisture transport from the human back to the environment bringing thermal discomfort for a seated person. A seated person exposed to air flow while the bottom and the back are well surrounded with the seat structure material. In fact, a seated person dissipates heat from the back and bottom leads to raise in temperature of the seats and adversely rises the temperature of the back (Hatoum et al., 2017). Thus, moisture accumulation at the back affecting thermal comfort.
Ventilated car seat is a feature to cool down seat for improving thermal comfort. This feature has been most commonly offered for the front seats. In recent times, with the implementation of modern three-point seatbelt along with airbags it made drivers safer. Besides, Heating and cooling features has turn car seats into ambient zones on-the-go thus our modification mainly improved thermal comfort and quick vary in temperature. Conclusively, the excessive of features and functions on present car seats turned them into an extremely complex system like automated ventilation car seats.
In order to manufacture our Ventilated Car Seat, fabrication is using low cost material to upgrade existing car seats to ventilated car seats with cooling and heating effects thus applicable to hot and cold weather. Furthermore, for design drawing SOLIDWORK 2017 was used and decision matrix method was used for selection. Besides, Arduino, Powertrain Control Module (PCM), wiring diagram, Matlab and programming maybe needed.
Our targeted customer are car owners and automobiles manufacturer where their goal is to drag attention of the market and provide comfortable car seats to people. Moreover, ventilated car seats could provide people with pleasant journey.
1.3 Function Analysis
Before solving the problem, building a functional model allow us to analyze the interactions between various components and focus into the problem. Table 1 shows the system, subsystem, and supersystem components of the car seats.
System Subsystem Supersystem
Car Seats Seat track Seat cushion wire User
Headrest Cushion Headrest metal structure Car
Backrest Cushion Seat backrest metal structure Moisture
Seat base Cushion Seat base metal structure Sunlight
Seatbelt Height adjuster components Heat
Seat back inclination adjustment
Table 1: System of Car seats.
Note: Headrest Cushion, Backrest Cushion and Seat base Cushion are named as Cushion.
Figure 1: Function analysis of car seats problems
Based on Figure 1, factor that causes raise in temperature is sunlight and user contact with cushion thus high temperature is harmful to user. Therefore, cushion heat is the problem that make user discomfort since sunlight is unavoidable circumstances.?
1.4 Problem Statements
Scant knowledge in the field, and limited research, has led to very few advancements in regards to ventilation car seat. The system has not much significantly differences over the timespan, their Main parameter value is to cool the occupant more effectively, but constraint is less changes to the current seat structure as possible to maintain comfortability. Besides, observed through multiple scientific articles, the complex biology of the humans combined with the uniqueness of body leads to a challenge in creating a universal ventilated car seats.
When driving long journey sitting on the seat will causes raise in temperature, since the heat are unable to dissipated, hence leads to hips and back feels hot from cushion and uncomfortable, besides it could easily lead to various diseases. Due back and hips without ventilation, the driver can easily get acne, eczema and other health problems on hips. Furthermore, drivers got sweat on hips and back cause driver feels sticky and uncomfortable then driver lost concentration causes traffic safety problems might happens. (Shenzhen car life Technology Co., Ltd., 2016) However, nowadays cars are equipped with air-conditioning, but the cold air are unable to reach driver and passenger hips and back. Although there are some cushion designed to be inflated or filled with water, this type of cushion unable to reduce temperature significantly and when user sitting on it have swing feel, as it’s extremely unsafe.
Besides that, the other reason car seats is hot due to the sunlight coming through the car’s windows. The car acts as a greenhouse, and heats up objects in the car as the car seats, dashboard, and other object can reach up to 40-50 degrees Celsius in direct sunlight (Staff, 2014). Those objects mentioned give off energy, and that is what heats up the air inside the car thereby when user open the car door, user feels the hot air inside the car and the car seats is hot causes user unlike to sit immediately exceptional case will be the user is in a rush yet have no choice but to sit on it. Moreover, the constantly changing driving conditions, and a weather system differing from place to place has put up extreme challenges towards the development of seat ventilation.
Ventilation car seat is a modified car seat to allow users to sit comfortably. This phenomena in turn lead to many problems including the user need to waste time on waiting the car seat to be cold, or by placing something on the car seat.
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1.5.1 The objective of the capstone project are to design a Ventilated Car seat that provides additional cooling ability to the user is the priorities in this modification so that user can have pleasant driving experiences.
1.5.2 To design a ventilated car seats allow users can choose not only cooling effects but also introducing heating effects for chilly late night.
1.5.3 To fabricate the ventilated car seat that can speed up the cooling effects on the car seats.
1.6 Research Methodology
Research methodology need to be done before beginning the project. To collect useful information for the aim of the capstone project objectives this is important process to go through. Thence, the information collected can be used to develop the project and to achieve the objectives. There are several ways of methodology to be used for research and to run the project. Hence, the information research from articles, journal, patent, book, internet, and survey from people were used in this project.
Information research is a key to develop a ventilated car seats, the history, type, components, materials selection for ventilated car seats, the related information has to be studied and determined. By doing so, the problem statement for the existing car seats can be determined thus improvement can be made to build a comfortable ventilated car seats.
Moreover, survey form is conducted in this project. This survey form is to research on what customers need and ask for their ideas on improvement. Nowadays google survey form is common used to gather opinions from society and environmentally friendly. Therefore, to achieve and improve the project will be more liable.
Furthermore, SOLIDWORK 2017 will be used for design purpose. This is a powerful tools to draw 3D design, SOLIDWORKS is well known 3D CAD software tool. Besides, it consists of simulation allow us to test the designs and make the decisions to improve quality. Moreover, enables us to determine product mechanical resistance, product durability, natural frequencies, and test heat transfer.
In addition, the software Mindview 7 can be used in drawing the Gantt chart for the milestone and the timeline of the project. Ensure the project was complete on time, perform this is to arrange the time wisely and accurately.
(Excellent product design methods/routes are described in detail, and practicable. Clear process flow and various modern tools are utilised to solve all anticipate problems.)
1.8 Benefits of the project
An innovative ventilated car seats will improve customer satisfaction, safety and health benefits. Moreover, able to drag the attention of market in automobiles owners and manufacturer.
On the other hand, the benefits of the project will be the opportunity to demonstrate the skills and knowledge we have learned. Besides, allow us to build skills in problem analysis, market research, problem analysis, product development, business case preparation, presentation and public speaking. In addition, enhance project management, teamwork and problem solving skills. Furthermore, develop expertise in car seats problem area while understanding circumstance and constraints, for example social, legal, economic, cultural conditions and etc.?
Chapter 2: Literature Review
This chapter describes about the history of a ventilated car seat, type of car seat, component of ventilated car seat and material used and type of material duct for ventilated car seat.
Car was invented before modern car seat is created. The origin of the idea of the automobile came from Europe. Inventors began to test automobiles with engines operate using steam during the eighteenth century. Nicolas Cugnot from France had designed, constructed and operated a tractor that powered by a steam engine back in 1769. Unfortunately, the funding for Cugnot’s road vehicle trails presumably ended with one of Cugnot’s supporter deceased after a series of automobile accident. During the early 1800s, Richard Trevithick from England constructed a steam-powered carriage which leads to various other British engineers creating and commercially operated steam vehicles which can carry passengers. However, the limitation of uses of such vehicles on the public roads hindered their efforts of constructing steam operated vehicles. Innovation of railroads was made when they were forced to turn their attention to conducting trains or carriages on private rails. During 1860, a French engineer named Etienne Lenoir invented an internal combustion engine that used illuminating gas as the fuel and ignition with electric sparks. This engine was used to drive machinery and rapidly became the first commercial gas engine. In 1866, Otto and Langen from Germany developed the four-stroke cycle which is widely known today when they tried to improve the gas engine which is previously made by Etienne Lenoir. A German named Daimler used the Otto cycle in a gas vapor engine and the following year he applied his petrol engine to a motor car in 1885. The very first car or automobile was built and sold in 1892 by the Daimler Motoren Gesellschaft. Daimler’s engine was used in France by Emile Levassor who then designed a vehicle which set the basic mechanical pattern for modern automobiles (Nyamwange et al., 2014).
Many modifications and changes had been made on automobile since then to improve the safety of those who drive or ride on a motorized vehicle. The first car seat appeared in the 1930s. Since the main purpose of the car seat is to keep the children in place when car was moving, there was no any safety consideration on it. A company named Bunny Bear Company produced a seat which is basically a booster seat that hooks onto the back of an actual car seat in 1933. The main purpose of this seat is for the parents to keep an eye on their children. In the 1940s, another type of car seat which has a metal frame attached to it. This type of car seat allows children to get a better view out from the window but it was not designed for safety but more to convenience. Safety of car seat was not prioritized until 1960s. Briton Jean Ames and Leonard Rivkin took child safety in their mind while creating car seat which include seat belts on it. Briton Jean Ames designed a rear-facing seat that featured a Y-strap which is similar to the modern seat while Leonard Rivkin created a seat that had a metal frame surrounded by a buckle like a high chair. But their idea was not well received by people since the public were not educated on the benefits of safety in a moving vehicle. After that, Ford developed the Tot-Guard in 1968 which is a plastic chair that contains padded area in front of the child’s face. Shortly after that, General Motors (GM) also released ‘Love Seats’ that came in two versions, one for children and one for infants. Seat belts were meant to keep children in place. Then there came the Bobby Mac convertible seat. Several laws and regulations were then adopted to improve the safety of car seats. Seat belt is one of the most common and important feature of modern car seat. The use of seat belts on car seat enhances the safety of vehicle by a lot. Vehicles are now produced which have a significant safety content for occupant restraint, crash-worthiness and crash avoidance. The major developments in restraint systems during the early 1980s were focused to improve their comfort in order to increase the likelihood of the seat belt being worn. From the mid-1980s onwards, enhancement of the occupant safety has been emphasised. Seat belts help to link the occupant directly to the passenger compartment or the car seat which then allow the occupant to ride down the crash as the vehicle’s front-end crushes. Later product introductions aim to control occupant trajectories in accidents which prevent the driver to get thrown out of the car due to inertia and limit the effects of contact with vehicle interior to prevent additional injuries. Usage of seat belt on car seat had significantly improves the effectiveness of the total occupant protection system of car seat. (King et al,. 1996)
2.3 Type of car seat
2.3.1 Side-Slip Seat
Side-slip seat is a relatively new type of seat founded in 2007 by Molon Labe, LLC (company). This type of seat was introduced because of its potential to reduce the aircraft boarding time under operational conditions. Side-slip seat is a seat where the middle seat is fixed and the 2 seat beside can be move.
(a) (b) (c)
Figure 2.1: Side-slip seat
With the innovative technology of the Side-Slip Seat, the available infrastructure could be dynamically changed to support the boarding process by providing a wider aisle that allow two passengers to pass each other in a convenient way. During boarding phase, the aisle seat or the outer seat is hand-pushed half over the middle seat, which is in a staggered position like shown in figure 2.1(c). The passenger or stewardess can simply grabs the seat at the side and pull out into a locked position to unfold the seat to normal position. Before the aircraft takes off, all seats have to be in the normal position and locked which need the passenger or crew to press a mechanical button on the side which lock the seat and prevent it from being pushed or pulled during the flight.
Figure 2.2: Example of Side-slip seat
The developed boarding model is adapted to allow the parallel movement of two passengers along the aisle. Furthermore, the dynamic status of the seat row (folded/unfolded) is implemented to enable or disable the parallel movement. If both sides of the aisle are in the initial folded condition, a second passenger can pass without reducing the walking speed. If only one side is folded, the walking speed is reduced to 50%. If both sides are used by passengers and the Side-Slip Seats are unfolded, only one passenger is allowed to move in the aisle (Schultz, 2017).
2.3.2 Infant Car Seat
The rear-facing Infant Car Seat (ICS) was designed to meet the federal and state legal requirements for transporting children which is less than 1 year old. Infant Car Seat is a type of seat which main purpose is to protect an infant in the event of a crash or car accident. However, since they are used for child which is 1 year old when they could not move effectively on their own, they also often serve as a form of transport for infant over short distances since the infant car seat is portable and convenient. Most of the modern ICSs can be attached to a stroller to create a so called “travel system” so that it can be carried around easily. To remove ICS from a car, we need to rotate the carrying handle from a locked position to carrying position, then unlock ICS from the secure base, lift and place it in a stroller. A review of ICSs available in the market (from large retailers) revealed that the weight of ICS is approximately 4.5kg and it can hold infant with maximum weight of 13.6kg.
Figure 2.3: Infant car seat (ICS).
There is also a problem where it is difficult and potentially dangerous task to lift the infant car seat because of the awkwardness of the posture combined with the weight of baby and the ICS itself (Clamann et al, 2012).
2.3.3 Ergonomics Seat
Ergonomics or human factors engineering can simply be defined as the science of designing for people. Knowledge about human characteristics and capabilities were being applied to the design of car seat. Gathering knowledge about people involves multiple approaches with emphasis on anthropometry, biomechanics, psychology, statistic and so forth. Every discipline has an important role in the car seat development process. Ergonomic chair or seat is a critical step in preventing health problems in people who is in a sitting position for a long period of time. With the ergonomics approach, sitting is viewed as a specific, specialized activity which is influenced by the way that a person who is sitting interacts with his environment. Car seat is just one of the features contributing to automotive ergonomics. Automotive ergonomics used formula to optimize the car environment like the positioning of the driver, height of the waistline of the car relative to the driver’s hips and eyes, form of the bonnet and etc (Gkikas, 2013).
2.3.4 Folding Seat
Folding seat is a type of seat where one can fold it down. This type of seat is usually used by big cars.
Figure 2.4: Folding seat
Some of the rear right seats are foldable to enhance movement of passengers during boarding and alighting as shown in the figure above (Tetteh et al, 2017).
2.3.5 Bench Seat
The bench seat was the traditional seat installed in most of the American or Australian automobiles. Bench seats are usually supported by metallic frames and upholstered. A bench seat usually only reaches up to about the shoulder level of an adult sitting on it. Bench seats are only being used in the second row of seating in most of the common cars or the third row of SUVs and minivans (Tetteh et al, 2017).
Figure 2.5: Bench seat.
2.3.6 Bucket Seat
A bucket seat is a type of seat found in motorized vehicles that is intended for a single person and is usually defined in contrast to a bench seat where bench seat is intended for more than 1 person. Bucket seat has head and neck support compare to bench seat. It also often equipped with a head rest. Bucket seat is the most common kind of driver’s seat for common cars but this is not the case for driver’s seats in trucks. Many trucks are designed with a bench seat in the front.
Figure 2.6: Bucket Seat
Summarize of all type of car seat:
Type of seat Safety Comfort Convenience Health Cost
Side-slip seat – – + – –
Infant car seat + + – – –
Ergonomics seat + + – + –
Folding seat – – + – +
Bench seat – – – – +
Bucket seat – + – – +
Table 2.1: Overall view for type of seats
From Table 2.1, pros from each seat were chosen and integrated into the design. From side-slip seat, no feature could be taken into the design because this type of seat is designed for airplane and allow passenger to board with ease. Seat belt is a must for safety purpose, so seat belt feature from the type of seat above was taken and put into the design. For folding seat, the folding feature which allows driver or passenger to fold the car seat is good and was taken into consideration of our design. For bucket seat, we use this type of seat as the basic model of our design as this is the most commonly seen type of car seat on the market now.
2.4 Component of ventilated car seat
The main purpose of seat ventilation is to prevent perspiring occupants from feeling uncomfortable by sticking to leather-covered seats, for example. At the same time, thermal regulation creates an agreeable microclimate that keeps the driver comfortable longer. The processes that take place where the seat and occupant are in contact are vitally important for efficient moisture removal. The surface of the seat receives no direct airflow, only ventilation from behind. In order to allow the airflow here to run parallel to the seat surface, the structure below the seat cover must also be sufficiently permeable. For example like the picture below shows a configuration with eight fans on the Mercedes SL driver’s seat, where the fans draw in air from below or, in the case of the seat back, from behind and blow it out over the two exposed seat surfaces. A reverse flow of direction can also be achieved without any major difference in the resulting flow volume.
2.4.1 Car seat backrest
Figure 2.4.1 upholstery of a backrest.
A plastic front seat backrest is shown in Figure 2.4.1 are made of high-strength composite material, enabling design freedom on seat backrest for new premium interior styling. For example, The combined first-row composite seatbacks like Weigh almost 20% less than conventional seatbacks, reducing CO2 emissions over the life of the vehicle by an estimated 100 kilograms and Are 15% thinner than the industry’s thinnest seats, leading to 10 litters of additional interior cabin volume. The lighter weight can yield improved fuel performance for internal combustion, hybrid and all-electric vehicles; and less fuel consumption means fewer emissions of greenhouse gases. At the same time, the significantly thinner seatbacks allow designers either to provide more leg room to the second-row occupants or to shorten the overall length of the vehicle, thereby further reducing its total weight. The seatback is a technically mature system that has been fully validated for reliability, safety and comfort. Designers now have entirely new opportunities to customize and adapt seatbacks in vehicles. Since they are created with injection molding systems, the composite seatbacks allow for novel shapes and accessories to be added for the comfort of front seat occupants and the convenience of second-row passengers (Vinod, 2016).
2.4.2 Thermoelectric device
A thermoelectric device as shown in Figure 2.4.2 was used to control the temperature of the car-seat surface: the warm temperature in the summer and cold temperature in the winter. The characteristics of the thermoelectric device for the car-seat were analysed in relation to the input voltage and output temperature of the device (Bell. 2013).
Figure 2.4.2 thermoelectric cooling system
2.4.3 Compact centrifugal fan or radial fan for car seat ventilation
A fan device is show in Figure 2.4.3 which is built into a vehicle chair, and is arrange to ventilate away air that is drawn through the covering and filling of the vehicle chair, which has an electrically driven fan of radial type attached at the bottom of the chair. The fan wheel extends from the driving cover of the motoer, which extends up into the inlet of the fan. The fan is attached to a carrying means in the chair which is located on the underside of the filling and has passages for the ventilating air adjacent to the fan inlet.
Figure 2.4.3 radial fan device
2.4.4 SPA Seat Cushion
Figure 2.4.4 Backrest of an SPA seat Figure 2.4.5 Ventilated cushion of an SPA seat
Ventilated backrest from an SPA seat without massage function. The bigger cluster of holes is in the upper back area, while the lower back area has only four small holes. Another typical feature is grooves around various holes. These help to guide the flow in a desired direction.
When removing the foams from the frame, the only attachment is a rubber duct for seat ventilation. These two parts, like the upholstery, can be quickly assembled and disassembled without any special tools. The frame contains the attachment for the foams. The backrest is mounted to a plastic plate, where valves for the bolsters and massage bladders are.
2.4.5 Flexible Aluminium Foil Air Ducting
Figure 2.4.6 Flexible ducting Figure 2.4.7 Flexible Aluminium Ducting Ventilation Vent Tube
To optimize the airflow through the system, a significant factor is to understand the design of the ductwork is shown in Figure 2.4.7 and Figure 2.4.8 Even though the B-side is not strictly pipes, it can be assumed to be so, for engineering purposes. Crucial parts are the outlets, inlets and areas where the flow separates. Most literature focuses on fans with as pushing system. Throughout the system, it is not relevant if the fluid is pushed or pulled through the pipe (Cory, 2005). Included in performance enhancements, one factor is to reduce the noise. This increases the performance without compromising airflow. The noise is not the most essential part for this project, but it cannot be increased. If the noise reaches a lower level the comfort increases. An essential factor is that the noise is directly coupled with duct design. This means that a good duct can improve both airflow, and reduce the noise (Tsai, 1982).
2.4.6 Pneumatic Systems (Pneumatic Seat Control)
Figure 2.4.9 Pneumatic Seat Systems for Maximum Driving Comfort
Pneumatic Seat Systems with many added functions are especially comfortable and offer clear technical advantages. The multi-contour seat function allows vehicle occupants to adapt the contour of the seat to their individual requirements. Via air cells integrated into the backrest and seat cushion the seat adjusts to fit the body. The optional massage function further enhances comfort for vehicle occupants on long journeys by means of alternate inflation and deflation of the air cells. The drive dynamic function automatically adapts the side bolsters of the seat to the current driving situation, ensuring optimum stability for occupants at all times, even when cornering. The advantages of a comfort seat are thus combined with those of a sports car seat (Tsai, 1982).
2.4.7 Seat Foam
The angle of the seat surface is about 17° from the horizontal with an extra slightly softer area to resist forward slipping of the seat bones. The area behind the seat bones has been carefully designed to provide an upward force on the buttock behind the seat bones to provide extra pelvis support, i.e. to resist backward rolling of the pelvis. The example show in Figure 2.4.10.
Figure 2.4.10 Seat foam sectioned down the centre line
Figure 2.4.12 Arduino Uno
2.4.8 Ambient Temperature sensor
The ambient air temperature sensor is located behind the bumper or grill of many vehicles and monitors the air temperature outside of the vehicle. The ambient (ATC) or outside air temperature sensor is an (NTC) negative temperature coefficient sensor that informs the semiautomatic/automatic temperature control system of outside air temperature. The NTC sensor’s resistance decreases as the outside air temperature increases. The computer uses this input, along with other in-car temperature sensors to control temperature and blower speed. When there’s a problem with this sensor, performance will suffer and the compressor’s clutch may not engage.
Ambient air temperature sensor symptoms, like an inoperative clutch or input problems are diagnosed with a scan tool and a multi meter. Use a multi meter and verify manufacturer’s specifications, (~ 220-240 ohms at 70°-80° F), to test this sensor for proper resistance. So, the sensor when it reads 80°F (27°C) or higher, it will allow the operation of the ventilated seats during a remote start. When it reads 50°F (10°C) or lower, the system will allow operation of the heated seat during a remote start (Rosh 2013).
2.5 Type of car seat material
To fabricate a ventilated car seat Nylon Fabric, Faux Vinyl, PCV, Vinyl, Faux Leather, Suede and Brushed Nylon is the common material used. Each material is described briefly in section 2.5.1 to 2.5.7.
2.5.1 Nylon Fabric
Nylon can come of many colour because it has a durable, hard-wearing upholstery fabric. fabrics can also be drawn into most shapes and are readily dyed to colour key with other parts of vehicle interior. Because nylon is weaved, it is harder to tear than some fabrics. It is also very stain resistant, providing you can wash out any spills before the dry. It is also the most popular form of fabric found in most automobiles. It is available in many colours and is the least expensive form of trim for your vehicle (Willis, 2014).
2.5.2 Faux Vinyl
This is actually a vinyl which takes on the characteristics of leather or suede or other types of material. It is hard-wearing and can have the appearance and shine of soft leather or the dullness of fabric trim. Faux vinyl is a mock vinyl which emulates the real article at a fraction of the cost (Willis, 2014).
2.5.3 PCV Leather
Commonly known as soft plastic, this is a vinyl style-material that is pliable and easy to form. It stretches well and is used in lower-end models of cars and vans. It can be coloured or made in black and white, but it is notorious for being sticky to sit on during the summer. Heat has a tendency to make the upholstery sweat and the driver of the vehicle is best advised not to wear shorts in the summer if their vehicle is lined with PVC (Willis, 2014).
Easy to wipe clean, durable and hard wearing, vinyl is another coonly used material in the making of automobile upholstery. It has similar properties to PVC but vinyl can soft, hard, pliable or firm. You might be aware that old LP records were made from vinyl but, because it is used in a different capacity for upholstery, it can be as soft as velvet although it will still make the skin sweat during hot periods of weather (Willis, 2014).
2.5.5 Faux Leather
Faux leather is a very versatile material that can be made to appear like almost anything. People have covered their car seats in fake crocodile skin, fake snake’s skin and even dinosaur prints. It behaves like leather and is easy to wipe clean. Spillages can be quickly dealt with so faux leather doesn’t stain easily and is very durable (Willis, 2014).
Cloth-based suede fabrics are a nice choice for an automobile interior. Suede is soft to the touch and feels like brushed cotton. This automobile fabric is not used as often because it stains easily and it not as durable for many types of automobile use (Willis, 2014).
2.5.7 Brushed Nylon
Brushed nylon is soft and warm and ideal for an interior seat cover or door trim. It is a thick fabric that is usually just under a ¼ thick when used in vehicles. It seems well and is a firm, durable material which is quite hard to tear (Willis, 2014).
2.6 Type of material duct
Ducts are conduits or passages used in heating, ventilation, and air conditioning (HVAC) to deliver and remove air. The needed airflows include, for example, supply air, return air, and exhaust air. Ducts commonly also deliver ventilation air as part of the supply air. As such, air ducts are one method of ensuring acceptable indoor air quality as well as thermal comfort. Each material is show in section 2.51 to 2.5.4.we decided the flexible duct with aluminium is our material use to connect the airflow to the car seat.
2.6.1 Fabric Hose
This is actually an air distribution device and is not intended as a conduit for conditioned air. The term fabric duct is therefore somehow misleading; fabric air dispersion system would be the more definitive name. However, as it often replaces hard ductwork, it is easy to perceive it simply as a duct. Usually made of polyester material, fabric ducts can provide a more even distribution and blending of the conditioned air in a given space than a conventional duct system. They may also be manufactured with vents or orifices. Fabric duct offers also many benefits such as low cost, lightweight and easy installation, a uniform distribution of air, and a wide spectrum of available colours and sizes.
2.6.2 Metal ducts
Such ducts are made from sheet metal (galvanized or stainless steel, copper, aluminium), cut and shaped to the required geometry for the air distribution system. Since metal is a good thermal conductor, such ducts require thermal insulation, the commonest material for which is glass wool, usually in roll form (known as ‘wraps’ or ‘wrapped insulation’), wrapped around the outer duct wall. Wraps incorporate an aluminium foil facing that acts as a vapour barrier. Insulation can also be installed on the inner wall of the duct (‘duct liners’), as glass wool duct wraps or duct slabs faced with a glass matting or mesh providing acoustic insulation and strengthening the inner face of the duct.
2.6.3 Flexible duct
Flexible ducts these usually consist of two aluminium and polyester concentric tubes. A glass wool layer is inserted between the two tubes as thermal insulation. Their use is generally limited to short lengths, due to high pressure drop-off and the acoustic. The ducts can be deployed in hardly accessible places of the building and when it is difficult to plan how to connect boxes to the suspended ceiling. With 10-metre sections you can save time, as you do not have to work with short sections, and 120cm large cartons make their handling and storage quite easy. With its 25mm thick mineral wool insulation and a perforated tube inside, the duct also serves as a silencer.
2.6.4 Plastic ducts
This category includes ducts made from plastic or foam boards, shaped by cutting and folded to produce the required cross-sectional geometry. Boards are faced usually with an aluminium coating both internally and external. The main drawback of this type of ducting is their fire classification. Even if they comply with local standards, when exposed to fire they often exhibit poor performance in terms of the production of both smoke and flaming droplets.
2.7 Decision Matrix for duct
Decision matrix was used to make decision for conceptual design later, a few criteria was included in our decision matrix. These criteria included are insulation, safety, cost, weight, heat resistance, appearance.
Criteria % Fabric hose Flexible duct( aluminium) Plastic duct Metal duct
Insulation 20 2 3 2 1
Safety 20 2 2 3 1
Heat resistance 20 2 3 2 1
Cost 20 2 2 3 1
Weight 10 2 2 3 1
Appearance 10 3 3 1 2
Total 100 13 15 14 10
Table 2.2 Decision Matrix for duct table
1=bad/ high cost /high weight, 2=median, 3= good/low cost/ low weight
Based on the decision matrix table, we can conclude that the aluminium flexible duct has the highest total value among all the material of duct. Fabric hose has a scored 13 while metal duct only scored 10 and the plastic scored 14. Conclusion, the flexible aluminium duct will be choosen in design.?
Chapter 3: Conceptual Design
This chapter comprises of considering factors on conceptual design such as compliance with standard, environmental and sustainability, and ethical consideration. Also, the detailed conceptual for different designs and the decision matrix to select the best conceptual design for our project.
3.2 Compliance with Standard
A ventilated car seat able to impact the society by increasing comfort on passengers. The car seat is commonly used during day-to-day driving, hence it is an influential factor on drivers and passengers. Individuals mostly spend long periods of time sitting on the seat in the same position. In addition, the car seat will trapped the hot air while exposing long time under sunlight and thus causing discomfort on users. Besides, the material of car seat does not often meet the thermal comfort needs of users. The main purpose of ventilation car seat is to provide comfortable seat while driving.
In Malaysia, once the driver get into the vehicle after a car parked at outdoors, they will experience thermal discomfort. Temperatue in a closed car after exposed under the sun will increases more than 20°C above the ambient temperature. Therefore, with our product of ventilated car seat, the user could experience thermal comfort. Thermal comfort is defined as the state of mind is expressing satisfaction and comfortable with the surrounding environment (Eduard, 2016).
Individuals can be easily visualize the temperature of the car seat on their smart devices. As the development of wireless technology is improving, the integration of connected cars from impossible become possible. Recently, Apple has launched the car platform as named as “CarPlay”. The driver able to get directions, listen to music, make calls or even send and receive messages that directly shows on car’s built in display (Jihoon, 2016). Thus, the performance of ventilated car seat are enhanced and improve the design and also its features by cooling the temperature of seat that requested from outside the car. With this features, ventilated car seat enable individual to remain comfortable over different range of ambient temperatures of the car seat.
In addition, ventilated car seat able to remove the heat absorption effectively and remain at desired temperature. It allows the user to control the thermal seat with the smart devices and alter the temperature of car seat immediately from outside the car without affecting the thermal environment. Thus, this ventilated car seat able to increase the level of comfort in the most efficient way.
Furthermore, the drivers or passengers able sit on the car seat at comfort temperature without opening the windows when they feel uncomfortably hot while sitting on the seat. As they sit on the car seat after some period, the energy dissipation from the under thighs and lower back will cause the temperature of car seat to increase. With the ventilated car seat, it able to maintain the temperature between the individual and the seat until it reaches thermal equilibrium. Hence, driver and passenger are ensured to be comfort during the distance travelled.
As a conclusion, ventilated car seat will enable the user to have a comfort seat during driving. It able to view and control the temperature of seat from outside the car by just connecting with the smart devices. Not only that, it able to maintain the seat at desired temperature no matter how long the user sit on it. Thus, it will increase and improve the level of comfort easily and effectively (Aniket et al, 2016).
The others impact of ventilated car seat on society such as health issues. It may increase the seated person’s overall thermal comfort and reduce the transfer of heat to the back of driver. The hot air that trap inside the car might affect the health of user and performance of driving. Thus the ventilated car seat is very important and bring a lot of benefits to the vehicle user.
First of all, the car that parked outdoor mostly would absorb the solar radiation from sun and eventually increases the inlet vehicle temperature. Besides, the temperature of pelvis and the back of driver and car passenger also rises once they sit on the car seat that has absorbed the heat trap from surrounding. When the body temperature rises more than the body optimal temperature, it may causes thermal discomfort to an individual. However, if the body temperature continue rises more than 37°C, the individual might experience heat exhaustion and heat stroke and are a part of continuum. Heat exhaustion on individual when his or her temperature reaches in the range of 37°C to 40°C will experience headache, dizziness, malaise, thirsty and weakness. Meanwhile, the core temperature in heat stroke is greater than 40°C and it is a life-threatening illness. When a victim sitting inside a vehicle at high core temperature, the victim will trigger neurological dysfunction, delirium, nausea and coma (Chan, 2015). Hence, with the ventilated car seat, the heat would dissipates faster and would not trap on the car seat. The user would not experience body temperature rises, sweating in order to dissipated heat out from body, increase in heart rate as organ works in order to cool down and lowering core body temperature. At the same time, the performance in driving long journey is not affected and thus bringing thermal comfort for a seated person. Obviously, ventilated car seat would not causing the user to experience heat related illness.
Moreover, the design of the prototype enable to cool the back which are well in contact surface with the seat. In fact, when the user sitting on the seat in the same position more than half an hour in a journey, the seated person might dissipates heat from the back of body to the car seat and thus causing the temperature of the car seat also increases. If the heat does not escape from the car seat, the temperature of the seated person adversely increases and causes thermal discomfort. However, the concept of ventilated car seat may solve this problem of heat flow from the back of the seated person. It able to transfer the heat and cooling the human back at desired temperature. Hence, ventilated car seat able to achieve the concept of body cooling and enhance the thermal comfort in body health.
Furthermore, prolonged periods of sitting may causes postural problems and damage to the potential skin tissue. In order to improve the posture performance, ventilated car seat are designed in a contoured shape which are matching to our shape of vertebra. Good position of sitting would enhanced the postural problems and the comfort of seating is improved. Thus, the pressure that developed from sitting in a long period and the risk of skin damage are reduced. The contoured surface of the ventilated car seat are allowed the air from air conditioning are draws and flow along the contoured shape in order to cool the back of seated person. Thus, heat is no longer trap at the contact surface with the user (Liu, 2017).
As a result, the ventilated car seat interface temperature has played a vital role in the evaluation of comfort perceived by the user. It can enhance thermal comfort, dissipates heat loss, reduce the heat trap on the car seat and reduce overall heat related illness.
3.3 Environmental and Sustainability
Environmental requirements also consider as one of the impact on society. Citizen in Malaysia normally experience thermal discomfort in car due to Malaysia experiences summer in four seasons. Eduard demonstrated that in order to cool the inlet car which is parked under the sun in prolonged period, the driver might turned on the air conditioning in high speed of cool air flow. Apparently, fuel consumption of the car increases and eventually increases the emissions of carbon dioxide to the surrounding and causes pollution in environment (Eduard, 2016).
Meanwhile, the components of the prototype ventilated car seat are selected as material that friendly use and eco-friendly. The ventilated car seat able to cool down the seated person and thus reduce further emissions of carbon dioxide to the environment. Therefore, all the part of ventilated car seat are considering this criterion and further enhanced the performance.
Besides, the consideration for the components of the prototype such as material are selected wisely. This is to ensure that the materials of PU foam, seat cushion and others are well absorb heat from the seated person in order to achieve the thermal comfort. In addition, the material selected for the prototype would not causes toxic to the user and polluted to the environment. The seat cover’s material can be reusable which can be used on other car seat instead of throwing away or dispose straightly. Consequently, it can continues to be a useful and valuable item that able to reduce heat absorption on the car seat when in use. Hence, it can fully utilize the product and reduce amount of waste to the landfills.
Furthermore, the material selected for the prototype is high standard and good quality. The strength of material for the prototype could withstand the stress from any possible occurrence and beyond the elastic limit. This is to ensure our product is durable and reliable. Thus, the product can be used at a certain long lasting period. In consequence, maintenance and extra material used to repair the product can be reduced further, thus reduce harmful effect on the environment.
In conclusion, environmental factor encourage the proper design of ventilated car seat and material are ensured to be selected wisely. This is to achieve the environmental requirement and reduce further pollution to our living.
3.4 Ethical Consideration
The consideration of ethics is concerned and forms the major element in the research. According to Shuriye (2011), ethics is refer to the systematic study of values, standard of conduct, evaluate moral concept and identify between the right and wrong. With the ethics, engineers able to critically understand and reflect the moral issues in engineering practices.
One of the ethical consideration is the research information should be authentic and any misleading information is avoided. The data collection from the resources or participants is accurate and any insufficient data or information is not included in the research. The research is done carefully to ensure the information provided is reliable and any careless errors that may lead to research misconduct. All the information of the research is done with transparency and honesty.
Moreover, the research respondents or research participants are voluntary and had not been subject to any coercion for participation in the research through online surveying method. They are ensured not subjected to any harmful threat when they not willing to participate in surveying. Also, the respondents or participants have the right to withdraw from the research process at any time. Their recorded data will automatically been removed from the analysis once they withdraw from involving in the research.
Furthermore, all the respondents are ensured to be fully informed and understand the implication of their participation in the research. The interpretations of the research that presented should be done honestly and transparency. The research finding are communicated in nontechnical language and in compact narration when face to face interview or through online surveying form. Any possible conflicts of interest in the research have to declare to prevent any possible risk happens on respondents that may affect the study result in the research.
Besides that, the privacy of the respondents or research participants is protected. The responses obtained from the participants without permission will not be disclosed to others publicly. The researcher has the responsibility to protect the respondents and avoid causing any discomfort on them due to their involvement in the research process. Thus, the trustworthy relationship between the respondents and the researcher is built.
Generally, ethical considerations should be aware and concerned when the research is carried out by the researcher. When the ethics is considered, the respondents or participants in the research project is protected. Thus, the research able to be done smoothly and any mistake or misrepresentation of the research is avoided.
3.6 Explanation design how ventilated car seats work
Based the all design sketches in Figure 3.5 it shows 3 different design types of ventilated car seats thereby will further elaborate more on these individual design about working principles, pros and cons, and comparison.
3.6.1 Design A
Design A is shown in Figure 3.5.1(a) to 3.5.1(c). This design come with radial fan and thermoelectric device (TED) as it placed on centre of backrest cushion and bottom seats cushion. The extra components used on normal car seats are radial fan, TED, wiring harness, exhaust tube, exhaust tube bezel, bottle of water, power supply and control switch. The working principles to achieve ventilated car seats is to rely radial fan blow air to the TED, then TED produce cold air to vent tube and flow to cushion as it reduces the temperature of cushion. When engine ignite, the power supply generate electricity to Arduino, radial fan, TED, and control switch as it connected to Arduino by programming code and wiring.
Furthermore, in order to allow the car seats to cool efficiently several hole was drilled on the seat cushion to reduce temperature effectively since the air flow is easier to transfer from bottom to top surface. On the other hand, TED will produce cool and hot air at different exhaust port but our intention is to retain cold air and eliminate ambient hot air by using vent tube to exhaust hot air to bottom of the car seats then enter bottle of water to reject hot air and bezel was installed to get nice looking. While backrest cushion will be similar to bottom seats cushion.
Overall, this design has great reduction in temperature due to TED was used with radial fan thus it has greater air flow than axial fan since a radial fan typically has a fan characteristic with a steeper pressure curve. Cons of the air system, for example by heavy user or dirty air ducts resulting in reduced fan performance. Since the radial fan is located in the foot well of a passenger sitting behind the seat, it can be damaged accidentally if its construction is not sufficiently sturdy. This is largely prevented by the robust design and the anchoring to the seat frame.
3.6.2 Design B
Design B is show in Figure 3.5.2(a) to 3.5.2(c) emphasis on modification of material and axial fan. This design is to change material to coconut fibre due to the ability of heat dissipated is great and recyclable material. Besides, axial fan was used while it was bind on centre of seats cushion with the common size of 100mm*100mm and using duct tube to allow air flow to cushion easily. Small hole was drilled on cushion to let the air flow pass through and reduce upper surface of car seats temperature effectively. Furthermore, fan, switch, power supply, and Arduino were connected similar to design A.
For the backrest cushion two axial fan were used yet it placed at above and below of the centre as reference due to the size of backrest cushion is definitely larger than the bottom cushion since axial fan performance is low. Besides that, everything is similar to bottom seats. Benefits of coconut fibre is weak heat absorption and great heat dissipated but it cost more than normal material. Cons of the design B is similar to design A.
3.6.3 Design C
Design C is show in Figure 3.5.3(a) to 3.5.3(d). This design concept is able to generate two states which is heating and cooling effect as the air flow is from automobiles air conditioning system since the air flowing through dashboard compartment and to the foot compartment are commonly known thus a flexible aluminium duct tube was connected between air conditioning system to lower surface of backrest, and bottom seats cushion. Since air conditioning will produce small amount of water vapour due to sudden vary in temperatures, it will bring harmful effects to cushion thus a sponge was used to absorb water and prevent it damaged the cushion. Since user sit on cushion will apply pressure to sponge leads to water eject from sponge before it dry, so at the lower surface centre part of cushion need to remove it to some thickness in order for sponge to be fitted in.
Furthermore, since using flexible aluminium duct tube hence no worry about the position of duct tube as it can be placed side or middle then meet to centre part of cushion. Moreover, cushion have few small hole (d?15mm) to let the air flow from duct tube to pass through cushion and hit on the seats cover surface then temperature will vary significantly.
The design can be used as automated or manual, if automated ventilated car seats are made, a temperature sensors is required to put into the seat cushion to detect the desired temperature range from user setting through radio system screen as it will send to Powertrain Control Module (PCM) acts as the brains of the car system thus the air conditioning system will flow air to car seats. Moreover, it can be controlled wirelessly by using smartphone with the apps Carplay and before entering the car all it needs is to take out smartphones then the car seats temperature is control at desired temperature. On the other hand, if manual ventilated car seats are made, basically just turn the switch to foot compartment or maybe new compartment as car seats on dashboard then the air conditioning system will flow air to car seats. Therefore, automated and manual is suitable for modern and former automobiles.
Overall, this design is applicable to all country whether you live in hot weather states or cold weather states, heated and cooled seats (or ventilated seats) are perfect for a hot day or a chilly late night. Safety, cheaper, better and comfortable has achieved in this design.
3.7 Decision Matrix
Decision matrix was used to make decision from the 3 conceptual ideas previously, a few criteria are include in our decision matrix. These criteria are comfort, safety, cost, weight, ventilation effect, appearance. Comfort, safety, ventilation effect are given priorities compare to the other criteria.
Criteria % Design A Design B Design C
Comfort 20 3 60 3 60 4 80
Safety 20 2 40 2 40 4 80
Ventilation 20 4 80 3 60 4 80
Cost 20 2 40 3 60 3 60
Weight 10 4 80 4 80 4 80
Appearance 10 4 80 3 60 2 40
Total 380 360 420
Table 3.7 Decision Matrix Table
Based on the decision matrix table, we can conclude that design C has the highest total value among all the designs. Design A scored 380 while Design B only scored 360. In conclusion, Design C was chosen.
Chapter 4: Final Design
This chapter involves the detailed of
4.2 Final Design (SolidWorks)
Figure 4.2(a): Front view of the design.
Figure 4.2(b): Side view of the design.
Figure 4.2(c): Top view of the design.
Figure 4.2 (d): side view of the inside
Figure 4.2 (e): overview of the final design
In the Sitting Position (Low), four of the rear wheels and two of the front wheels touch the surface of the ground. The seat is sitting………………………………………………….
Chapter 5: Analysis and Discussion
5.2 Calculation and Results