Direct injection spark ignition with gasoline engine

In summary, the Diesel Cycle is more efficient than the Otto Cycle because the pressure rises while combustion and further energy can be extracted from the exhaust if it is not fully expanded to atmospheric pressure. Spark plugs are used in the Otto Cycle, but are not needed in the Diesel Cycle.
  • #1
sid_galt
502
1
If someday complete direct injection spark ignition with gasoline engine with Otto cycle is achieved so that very high pressure ratios are possible, what would be the impact on the automotive industry?
 
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  • #2
You can do that now, and you'd have a Diesel Cycle engine. That is the constraint that defines Diesel. The spark would simply be a redundancy.

KM
 
  • #3
But the diesel cycle engine runs on the brayton cycle. I am talking about the Otto cycle which is more efficient since the pressure rises while combustion and further energy can be extracted from the exhaust if it is not fully expanded to atmospheric pressure.
 
  • #4
sid_galt said:
But the diesel cycle engine runs on the brayton cycle. I am talking about the Otto cycle which is more efficient since the pressure rises while combustion and further energy can be extracted from the exhaust if it is not fully expanded to atmospheric pressure.

The Diesel engine runs on the Diesel Cycle. All you have to do is compare the P-V curves of the Otto and Diesel Cycles, and you will see the link. If you extend the 'compression' curve of the Otto cycle past the usual 'ignition point', you'll get exactly the curve of the Diesel Cycle. (Not quite that simple, to be sure.)

Both the Otto and the Diesel Cycles have the common characteristic of accomplishing the Intake, the Compression, the Combustion, the Expansion and the Exhaust in the Same place (Cylinder Chamber?). The Brayton Cycle (Which I personally prefer) Moves the air from place to place to accomplish these stages. To go from Otto to Diesel Cycle (as your suggestion does) only requires that fuel 'injection' be held off until you are ready for combustion, thus avoiding premature ignition (called Dieseling). The reason for spark plugs in an Otto Cycle, is just to get control over when combustion occurs, rather than having pre-ignition (Dieseling). The other way to control when combustion occurs, is to hold off fuel injection; exactly what a Diesel does, and this allows greater compression ratios. You described conversion from Otto to Diesel Cycle.

KM
 
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  • #5
Thanks for the help
 

1. What is direct injection spark ignition with gasoline engine?

Direct injection spark ignition with gasoline engine, also known as direct gasoline injection, is a type of fuel injection system for internal combustion engines. It involves injecting precise amounts of gasoline directly into the combustion chamber of the engine, rather than into the intake manifold or port.

2. How does direct injection spark ignition work?

In direct injection spark ignition, a high-pressure fuel pump injects gasoline directly into the combustion chamber at the exact moment it is needed for combustion. The fuel is atomized into small droplets, which are then ignited by a spark from the spark plug. This allows for better control of the fuel-air mixture and improves engine efficiency.

3. What are the benefits of direct injection spark ignition?

Direct injection spark ignition offers several benefits over traditional fuel injection systems. It can improve fuel efficiency, increase power output, and reduce emissions. It also allows for more precise control of the fuel-air mixture, resulting in smoother and more responsive engine performance.

4. Are there any downsides to direct injection spark ignition?

While direct injection spark ignition has many benefits, it also has some downsides. It can be more expensive to manufacture and maintain compared to traditional fuel injection systems. It also requires a higher level of precision in fuel delivery, which can make the engine more susceptible to damage if not properly maintained.

5. Is direct injection spark ignition the future of gasoline engines?

There is no definitive answer to this question as it ultimately depends on technological advancements and market demand. However, many automakers are increasingly incorporating direct injection spark ignition into their engine designs due to its potential for improved efficiency and reduced emissions. It is likely to continue being a significant technology in the automotive industry for years to come.

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