FUEL INJECTORS - How They Work | SCIENCE GARAGE

Summary

This video delves into the intricacies of fuel injectors, essential for optimizing an engine's fuel and air mixture. It contrasts fuel injection with carburetors, highlighting benefits like improved cold starts and fuel efficiency. The script explains three types of fuel injection: port, direct, and indirect, each with its mechanisms and advantages. It also touches on the historical shift from carburetors to fuel injection and the unique aspects of diesel engines. Sponsored by Squarespace, the video is part of a series exploring automotive technology.

Takeaways

• 🚗 Engines operate on a mix of fuel and air, with fuel injectors playing a critical role in delivering this mixture efficiently.
• ☕ The ideal fuel-to-air ratio for complete combustion in engines is 14.7:1, known as a stoichiometric air-fuel ratio.
• 📡 Fuel injectors are controlled by the car's computer, which times the fuel spray to work in concert with the spark plug for optimal combustion.
• 💧 There are three main types of fuel injection systems: port, direct, and indirect, each with its own method of delivering fuel to the engine.
• 🏭 Port fuel injection is cost-effective and self-cleaning for intake valves but is less efficient compared to other systems.
• 💉 Direct fuel injection offers better fuel economy and power but can lead to higher temperatures and carbon buildup in the cylinders.
• 🌀 Wall-guided and spray-guided are two subtypes of direct fuel injection, each using different methods to mix fuel with air within the cylinder.
• 🖱️ Indirect fuel injection, specific to diesel engines, uses a pre-ignition chamber to ignite a mixture of fuel and air before it enters the cylinder.
• 🌟 Mazda's SkyActiv-X HCCI engine combines the benefits of diesel and gasoline engines, achieving high fuel efficiency and reduced pollutants.
• 🛠️ The video also humorously touches on the challenges and maintenance aspects of different fuel injection systems, like carbon buildup and the need for glow plugs.

Q & A

What is the ideal fuel to air ratio for complete combustion in an engine?

The ideal fuel to air ratio for complete combustion in an engine is 14.7 to one, meaning for every one unit of fuel, 14.7 equivalent units of air at sea level are needed.

What are the benefits of fuel injection over carburetors?

Fuel injection offers benefits such as easier cold starts, better fuel efficiency, more consistent transient throttle response, and sometimes variability of fuel delivery depending on drive modes.

How does a fuel injector work?

A fuel injector is fed by the fuel rail and uses an electromagnetic coil to pull the plunger up, opening the pintle injector and spraying fuel out of the nozzle. The sprays happen multiple times every second, with each spray delivering an exact amount of fuel controlled by the car's computer.

What are the three types of fuel injections commonly seen in modern cars?

The three types of fuel injections commonly seen in modern cars are port injection, direct injection, and indirect injection.

How does port injection differ from direct injection?

In port injection, fuel is delivered via separate fuel injectors at the intake manifold, above the intake valve. In contrast, direct injection involves fuel being sprayed directly into the cylinder, either guided by the cylinder wall or spray pattern.

What is the purpose of the swirl cavity in wall guided fuel injection?

The swirl cavity in wall guided fuel injection is designed to create a vortex of air, which helps mix vaporized fuel with the air for efficient combustion when ignited by the spark.

How does indirect fuel injection work in diesel engines?

Indirect fuel injection in diesel engines uses a pre-ignition chamber where fuel and air are pre-ignited before being delivered to the cylinder. This process ensures complete mixing and efficient combustion.

What is the advantage of direct injection over port and indirect injection?

Direct injection allows for better fuel economy, more power, and doesn't require the intake valves to be open for it to function, which means the injectors are not dependent on the timing of the intake valves.

What are the potential issues with direct injection systems?

Direct injection systems can lead to higher temperatures and pressure, causing stress on the cylinders. They are also more costly to produce and are prone to carbon buildup around the intake valves.

What is Mazda's SkyActiv-X HCCI engine and how does it relate to fuel injection?

Mazda's SkyActiv-X HCCI engine combines the high compression and fuel efficiency of diesel engines with the reduced pollutants of gasoline engines. It utilizes techniques involving turbulence in direct fuel injection to achieve this.

Outlines

00:00

🚗 Introduction to Fuel Injectors

This paragraph introduces the topic of fuel injectors, explaining their importance in modern engines for delivering a precise fuel-air mixture. It discusses the evolution from carburetors to fuel injection systems, highlighting the benefits of fuel injectors such as easier cold starts, better fuel efficiency, and consistent throttle response. The paragraph also touches on the ideal fuel-to-air ratio for complete combustion and sets the stage for a deeper dive into the different types of fuel injection systems.

05:01

💧 How Fuel Injectors Work

This section delves into the mechanics of fuel injectors, describing how they are fed by the fuel rail and controlled by an electromagnetic coil. It explains the process of fuel injection in detail, from the fuel's entry into the injector, its storage in the reserve, to the precise spraying of fuel into the engine's cylinder. The paragraph also contrasts early mechanical fuel injection systems with modern electronically timed ones and introduces the three types of fuel injection systems commonly found in modern cars: port, direct, and indirect.

10:02

🌀 Types of Fuel Injection Systems

This paragraph explores the different types of fuel injection systems, starting with port injection, which is characterized by its simplicity and cost-effectiveness. It discusses the process of fuel delivery at the intake manifold and the creation of an air-fuel slurry. The paragraph then moves on to direct fuel injection, explaining the two subtypes for gasoline engines: wall guided and spray guided. It describes how direct injection works, including the use of a swirl cavity in wall-guided systems and the special nozzle in spray-guided systems. The paragraph also touches on the advantages and disadvantages of direct injection, such as better fuel economy and power but also the potential for higher temperatures and carbon buildup. Lastly, it briefly mentions the indirect fuel injection system, specific to diesel engines, and its use of a pre-ignition chamber.

📺 Sponsorship and Call to Action

The final paragraph of the script is dedicated to the sponsorship by Squarespace, which provides an all-in-one platform for building and managing online presence, including websites, online stores, and marketing tools. The script encourages viewers to take advantage of a free trial and offers a discount for first-time purchases through a specific link. It also includes a call to action for viewers to subscribe to the channel, follow on social media, and explore merchandise available at the shop.

Keywords

💡Fuel injectors

Fuel injectors are crucial components in modern internal combustion engines, responsible for delivering fuel directly into the engine's combustion chamber. They ensure a precise and efficient fuel-to-air mixture, which is vital for optimal engine performance and reduced emissions. In the script, the importance of fuel injectors is highlighted through their role in creating the necessary explosion for power generation while minimizing exhaust pollution.

💡Stoichiometric air-fuel ratio

The stoichiometric air-fuel ratio refers to the perfect mixture of fuel and air needed for complete combustion in an engine, which is 14.7:1 at sea level. This ratio is critical for maximizing engine efficiency and minimizing fuel waste and pollution. The script uses this concept to explain the ideal conditions for an engine to function optimally, comparing it to the right mix of ingredients in a recipe for cake.

💡Port injection

Port injection, also known as multipoint port fuel injection, is a type of fuel delivery system where fuel is injected into the intake manifold above the intake valves. This method is highlighted in the script for its cost-effectiveness and simplicity but noted for being less efficient compared to other fuel injection systems. The script uses a humorous analogy comparing port injection to store-bought cake, emphasizing its uniformity but lack of the finesse of more advanced systems.

💡Direct fuel injection

Direct fuel injection involves injecting fuel directly into the engine's combustion chamber. The script discusses two subtypes for gasoline engines: wall-guided and spray-guided. Wall-guided systems use the shape of the cylinder head to create a vortex for mixing fuel and air, while spray-guided systems use a special nozzle for vaporization and mixing. Direct injection offers advantages like better fuel economy and power but can lead to higher temperatures and carbon buildup.

💡Indirect fuel injection

Indirect fuel injection is specific to diesel engines and uses a pre-ignition chamber to ignite a mixture of fuel and air before it enters the main combustion chamber. This method allows for lower pressure requirements and can be more cost-effective, as mentioned in the script. It also enables the creation of smaller, higher-speed diesel engines but requires glow plugs for ignition, adding a layer of complexity.

💡Fuel rail

The fuel rail is a part of the fuel injection system that distributes fuel from the fuel pump to the individual fuel injectors. It sits atop the cylinder bay and is under pressure, ensuring that fuel is consistently supplied to the injectors. The script describes how the fuel rail feeds the injectors, emphasizing its role in maintaining a steady and precise fuel delivery.

💡Throttle body

The throttle body is a component that controls the amount of air entering the engine. It is mentioned in the script as part of the system that works in tandem with fuel injectors to regulate the air-fuel mixture. The script uses the throttle body as an example of how air intake is managed, which is essential for the proper functioning of fuel injection systems.

💡Cold starts

Cold starts refer to the ability of an engine to start efficiently in cold conditions. The script highlights that fuel injection systems, compared to carburetors, offer benefits such as easier cold starts due to their precise control over fuel delivery, which is crucial for engine performance in varying temperatures.

💡Transient throttle response

Transient throttle response describes the engine's ability to quickly and consistently respond to changes in throttle position. The script mentions that fuel injection systems provide better transient throttle response compared to carburetors, which is important for a smooth and responsive driving experience.

💡Carbon buildup

Carbon buildup refers to the accumulation of carbon deposits in the engine, particularly in the intake valves and combustion chamber. The script discusses how direct fuel injection can lead to carbon buildup due to the higher temperatures and pressures involved. This buildup can negatively affect engine performance and requires regular maintenance to mitigate.

💡Glow plugs

Glow plugs are heating elements used in diesel engines to aid in starting the engine, especially in cold conditions. The script mentions glow plugs in the context of indirect fuel injection systems, where they play a crucial role in the pre-ignition process. The need for glow plugs is contrasted with the more straightforward starting process of gasoline engines without them.

Highlights

Fuel injectors are essential for delivering the perfect fuel-air mix to the engine for efficient combustion.

The ideal fuel to air ratio for complete combustion is 14.7 to one, known as a stoichiometric air-fuel ratio.

Fuel injection systems have benefits over carburetors, such as easier cold starts and better fuel efficiency.

Fuel injectors ensure consistent fuel distribution across all cylinders for even power delivery.

There are three types of fuel injections: port, direct, and indirect, each with unique mechanisms.

Port injection delivers fuel via separate injectors at the intake manifold, creating an air-fuel slurry.

Direct injection can be wall-guided or spray-guided, with fuel injected directly into the cylinder for better mixing.

Indirect fuel injection, specific to diesel engines, uses a pre-ignition chamber to ignite the fuel-air mix before it enters the cylinder.

Direct injection offers advantages like better fuel economy and more power, but can lead to higher temperatures and carbon buildup.

Mazda's SkyActiv-X HCCI engine combines the benefits of diesel and gasoline engines for high efficiency and reduced pollutants.

Squarespace is an all-in-one platform for building a beautiful online presence and running a business.

Squarespace offers tools for website creation, domain management, online stores, and marketing.

With Squarespace, users can transfer existing websites and take advantage of their comprehensive platform.

Science Garage and other shows are part of Donut Media's lineup, offering a variety of automotive content.

Support for the channel comes through subscriptions, social media follows, and merchandise purchases.

Transcripts

- Fuel rails, fuel pumps, throttle body, multipoint, direct.

That's right, we're talking about fuel injectors.

Thanks to Squarespace for sponsoring this video.

From websites and online stores

to marketing tools and analytics,

Squarespace is the all-in-one platform

to build a beautiful online presence

and run your business, if you got one.

Squarespace.

If you don't know by now, engines run on fuel and air.

And there's a bunch of ways to get fuel-air mix

into the engine.

Sometimes, it's a carburetor,

but more often, it's fuel injection.

Somebody get me some coffee?

Just like the right mix of coffee and cake

can get me going in the morning,

an engine needs a perfect mix of fuel and oxygen

to function efficiently.

Fuel injectors are engineered to deliver this mix

to the cylinder to create an explosion

that produces the most power

and least amount of dirty, dirty exhaust as possible.

This ideal fuel to air ratio is 14.7 to one.

That means for every one unit of fuel,

14.7 equivalent units of air at sea level

are needed to achieve complete combustion.

This is referred to as a perfectly balanced

stoichiometric air-fuel ratio.

My ideal ratio is 36, 24, 36,

36 parts flour, 24 parts chocolate, and 36 parts sugar.

I love cake.

Engines didn't always have fuel injectors though.

Before fuel injections, engines needed carburetors.

Check out the episode on carburetors.

Fuel injection has a number of benefits over carburetors.

Benefits include easier cold starts,

better fuel efficiency,

and more consistent transient throttle response,

like quick throttle transitions.

And sometimes, even variability of fuel delivery,

depending on drive modes.

Fuel injectors also make sure

that the amount of fuel being sent to the engine

is consistent across all cylinders,

preventing inconsistent fuel distribution

and inconsistent power delivery.

Get it.

There are three types of fuel injections

that you're likely to see on modern cars.

Port, direct, and indirect.

But let's start with the injector itself.

Fuel injection is fed by the fuel rail,

which sits atop the cylinder bay.

Because of the pressure from the fuel pump,

fuel gets forced in the injector from the fuel rail

and through a small filter inside the injector.

Oh crap, I just said fuel five times in the same sentence.

If I don't say the counter-spell, the pig's gonna appear.

Nickelback, Nickelback, Nickelback.

Okay, alright.

Once inside the injector, the gas hangs out in the reserve,

says hi, grabs a drink, and maybe a small bite,

waiting for the moment to spray.

Then, when it comes time,

an electromagnetic coil pulls the plunger up,

opening the pintle injector,

spraying fuel out of the nozzle.

Sprays happen multiple times every second,

and every spray's an exact amount of fuel.

The timing's controlled by an electrical signal

from the car's computer,

and it works in concert with the spark plug

to create the sweetest music.

Early fuel injection systems worked much the same way

that a distributor cap fires at spark plugs.

It was mechanically timed.

So you're probably thinking, okay,

now I know how a fuel injector works,

but what are the different types of fuel injection, Nolan?

Well, I'm going to get to it, and my name's not Nolan.

Port injection,

sometimes referred to as multipoint port fuel injection,

means that fuel is delivered via separate fuel injectors

for each cylinder delivered with the fuel rail.

Port injection starts at the intake manifold,

where the injector's housed right above the intake valve

for the cylinder.

When the throttle body opens

and allows the air into the intake manifold,

the fuel injector sprays gasoline,

and a slurry is created.

No, I'm talking about Steph Slurry

of the Golden Slate Slurriers.

I'm talking about a mix of air and vaporized fuel.

During the intake stroke of the cylinder,

the intake valve opens,

allowing the air-fuel slurry into the chamber,

where it's then exploded.

Port injection has a number of upsides.

For one, it's cheaper to produce

than any other type of fuel injection

because you don't have to worry about protecting

the fuel injector from the pressure of the cylinder.

Additionally, the force of the slurry

being sucked into the cylinder through the intake valve

helps to clean the valve itself.

A downside to port injection is that it's not as efficient

as other fuel delivery systems.

If port injection was a type of cake,

it'd be store-bought yellow cake,

you know, like from a box.

It might not be homemade,

but you know the icing's gonna be evenly distributed,

and every bite you take's gonna be the perfect ratio

of cake to icing.

Cake Garage.

Another type of fuel injection is direct fuel injection.

This category's a little more broad,

and it's used in both gasoline and diesel engines.

There's two different types of direct fuel injection

for gasoline engines.

What are they?

Well, I'm glad you asked.

The two types are wall guided and spray guided.

In a wall guided fuel injection,

the fuel nozzle's not above the intake valve,

it's inside the cylinder.

After the air rushes in during the intake stroke,

gas shoots out from the side.

It hits a specially shaped cylinder head,

also called a swirl cavity,

and that mixes it with the air.

The angle of the cylinder head creates a vortex of air,

and this vortex helps mix vaporized fuel within the cylinder

so when the spark ignites the mix,

the explosion is (kiss) oh so beautiful.

Side note, my dentist keeps yelling at me

because the cake vortex in my mouth

is causing swirl cavities.

I might have a problem.

Spray guided fuel injections, similar to wall guided,

but it doesn't use a swirl cavity

to create the air-fuel mix.

Spray guided uses a special nozzle

that sprays perpendicular to the cylinder head,

so it can vaporize the fuel and mix with the air

before it gets ignited.

Alright, you might recognize this.

We're going to see what happens first

when we just put gas in without a vortex.

(explosion)

- Whoa.

- We've created this little mock up

to see if we can create a vortex

to ignite some gas.

Let's do this fellows.

Give me like eight squirts.

(explosion) Oh.

We got a pretty sweet explosion with the vortex,

so because we can, let's launch this cutie into space.

Gentlemen.

I think we're probably good.

(explosion)

- Oh. (laughs)

- I think we're probably good.

Direct injection also has a diesel cousin.

In fact, diesel engines have been fuel injected

long before traditional gasoline engines.

The biggest difference between the diesel and gas versions

of direct injection is the shape of the swirl cavity

and the pressure at which

the diesel's sprayed into the cylinder.

Because diesel's got a higher viscosity than gas,

a high pressure spray is vital to mix it with the air.

I can relate.

My cousin Jason's been putting pressure on me

to take his CrossFit class,

keeps spraying me with Muscle Milk

and telling me to trust the process.

CrossFit.

No thanks Jason.

I don't want to do 200 of anything.

Direct injection's got an advantage over port

and indirect injection because the intake valves

don't have to be open for it to function.

This translates to better fuel economy, more power,

and the injectors don't have to wait

for the timing of the intake valves.

After the initial blast of fuel

and the ignition of the air-fuel mixture,

some extra fuel can be released mid power stroke

to give a little more oomph.

You take your good with the bad though.

A direct injection isn't perfect.

All those extra gas squirts creates higher temperatures

and pressure, which can seriously stress out the cylinders.

In addition to being more costly to produce,

carbon buildup in the cylinder,

mainly around the intake valves,

really common in direct injection systems.

Carbon is a byproduct of combustion, you silly geese.

The third type of fuel injection is indirect,

which is specific to diesel.

Not all diesels use it, but only diesels do

because of how diesel fuel ignites.

Indirect fuel injection uses a pre-ignition chamber

located above and outside the cylinder.

Swirl chambers, aircell chambers, and pre-ignition chambers

are all different components,

but basically perform the same function

in indirect fuel injection systems.

In these chambers, gas and air are pre-ignited

before being delivered to the cylinder.

Fuel's released, air's pumped in from the piston,

compressing air in the cylinder,

and the device called a glow plug

completes the ignition of the mixture.

The shape of this chamber's designed to swirl the air

and make it as turbulent as possible,

ensuring that the fuel completely mixes

and has the added effect

of making the combustion more efficient.

The pre-ignition chamber in these indirect systems

means that pressure can be lower

than other diesel engines,

which, in turn, makes manufacturing them more simple

and less expensive.

Indirect injection also makes it possible

to make smaller diesel motors

that can produce higher engine speeds.

Pretty good.

The downside?

Glow plugs are needed to start these engines,

and those only grow on trees.

Mazda's doing some crazy things with their prototype

SkyActiv-X HCCI engine.

It takes the best of both worlds,

combining the high compression, very fuel efficient,

lean combustion of diesel engines

with the availability in reduced pollutants in gasoline.

It wouldn't be possible without some tricks

that they use involving turbulence in direct fuel injection.

You want to learn about the SkyActiv engine?

Well, get a time machine and travel to the future

because I haven't made that episode yet.

Fuel injectors.

Thanks to Squarespace for sponsoring this video.

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Squarespace is the all-in-one platform

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Don't tell my wife about my cake habit.