A supercharger is another invention in the piston type of internal combustion engine to increase its working efficiency. It is an air compressor that increases the pressure or density of air that enters an engine’s combustion chamber for excessive working.
As you know, from the combustion chamber using the fuel/air mixture, an automobile engine obtains its mechanical movement. So, the addition of a supercharger to increase the pressurize of air that enters the chamber also increases the amount of fuel mixed and burned, leading to the high performance of the engine.
In this article, you will get to know the definition, functions, types, working principles, and complete diagram of superchargers. You’ll also get introduced to the term twincharger and the similarities and differences between supercharging and turbocharging. So, let’s get down to the main reason why we’re here!
What is a Supercharger?
A supercharger is a mechanical-driven component that is used in piston engines to pump pressurized air into the intake manifold using an air compressor or blower. The high pressure increases the level of air entering the cylinder during the intake stroke. Superchargers let the engine burn more fuel and do more work as each intake circle of the engine gets more oxygen. These power components are mechanically driven by means of a gear, belt, shaft, or chain connected to the engine’s crankshaft.
This is where another component has more advantages than a supercharger, it is called a turbocharger. Although the part is known as a supercharger, it is named a turbosupercharger or turbo. It offers power using a turbine which is powered by exhaust gas obtained at the end stroke of the combustion. So, one of the differences between superchargers and turbochargers is their power source.
A supercharger is driven by the engine’s crankshaft, while, a turbocharger is powered by the wasted exhaust gas produced during the combustion process. Just like the other charging devices in engines, the primary function of a supercharger is to increase the air that enters the intake manifold. This lets the engine burn more fuel and do more work, hence increasing power.
Types of supercharger
Below are the various types of superchargers used to increase power in automobile engines:
Centrifugal superchargers: these superchargers are fairly easy to package in aftermarket retrofit installations. It uses a variable-ratio centrifugal supercharger, that contains a continuously variable pulley drive mounted to a conventional compressor.
Factory superchargers on vee-type engines are usually packed in the valley of the vee, which makes it favor longer, lower, narrower packaging.
Roots superchargers: the roots superchargers are the most popular type. In their setup, there are two counterrotating shafts that have lobes that force air down across the shafts. Generally, air enters the top of the unit and escapes through the bottom portion.
Twin-screw superchargers: these types force air from one end to the other end of the turbocharger.
Working Principle of Supercharger
I will be explaining how superchargers work with the three major types available which include centrifugal, roots, and twin-screw. Their difference is how they pressurize air into the intake manifold of the engine.
The centrifugal types of superchargers use an impeller that draws and sucks air, while the roots and twin-screw type uses different meshing lobes. They all obtain rotary power from the engine crankshaft. and they boost the engine at varying levels.
The roots supercharger is the oldest version, patented in 1860 by Philander and Francis Roots to ventilate mine shafts. The project was introduced to automobile engines in 1900 by Gottlieb Daimler.
In its working, the meshing lobes of the roots supercharger spin, making it trapped air in a pocket between the lobes. The air is contained between the fill side and the discharge side. large quantities of air move into the intake manifold and stack up to create positive pressure.
The roots supercharger is located at the top portion of an engine because of its largeness. It is the least efficient among the three types because they add more weight to the vehicle. Also, they move air in discrete bursts instead of in a smooth and continuous flow.
Watch the video to have more understanding of the working of roots superchargers:
Similarities and Differences Between Superchargers and Turbochargers
The similarities between turbo and superchargers are that they both increase the working power of the engine. They both have a compressor that exerts air into the engine intake manifold. So, the two components have the same purpose in automobile engines.
The difference between the two components is that superchargers use mechanical power to spin their compressor. This power is obtained from the crankshaft using gear, belt, or chain. In the case of turbochargers, the power is generated from the exhaust gas developed from the combustion cycle. The component is also a supercharger but the power source makes them different.
Now the question is, which of them is better, the turbo or the supercharger?
Both of these pieces of equipment can be used to economize fuel and increase power. And they both have their benefits and limitations. Turbochargers use free energy that will completely evaporate into the atmosphere, but instead, the gas is used to power the part. The driving turbine increases exhaust backpressure, which exerts some load on the engine. well, the load applied is less when compared with the supercharger.
The mechanical load superchargers exert on the vehicle is way higher due to the big and heavy blower they contain. These blowers consume 900 crankshaft horsepower in an engine rated at 7,500 total horsepower.
However, the benefit of a supercharger is that the engine is boosted almost instantly, unlike turbochargers that suffer some response lag. The engine waits for enough exhaust gas to be built for the turbocharger can pick up. This is why the supercharger is still used. Most manufacturing companies can’t squander precious horsepower on blowers, which is why they mostly use turbos.
Twincharging is a term given to the vehicle that incorporates both a belt-driven supercharger and an exhaust-driven turbocharger. In its design, there is a complex series of bypass valves in the induction and exhaust systems and also an electromagnetic clutch. With this, at low engine speeds, a boost will be obtained from the supercharger.
Boost is derived from both of the systems at the middle of the rev range. At the highest revs, the system is disconnected from the supercharger and isolated the associated ducting. The addition of both systems eliminates their disadvantages. Finally, let’s quickly look at the advantages and disadvantages of supercharges.
Advantages and Disadvantages of Superchargers
Below are the benefits of a supercharger in a piston engine:
- Great atomization of fuel
- Better air/fuel mixture
- Higher power output
- Better scavenging products
- Good torque characteristics over the whole range
- Smooth and complete combustion
- Fuel with poor ignition quality can be used
- Less exhaust smokes
- Mechanical efficiency is improved
- Improved cold starting
- Fast acceleration of the vehicle
- A quick reflection of a power boost.
Despite the advantages of a supercharging device some limitations still occur. Below are the disadvantages of a supercharger:
- Gas loading is increased
- Increased heat loss due to increased turbulence
- The cooling requirement of the engine is high
- Increased thermal stress
- High detonation tendency in SI engines.
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All for the day
In conclusion, the supercharger is another great device used in automobile engines to boost their working power. We defined superchargers as mechanical components which are used in piston engines to pump pressurized air into the intake manifold. We also saw its function, types, working, etc. I hope you find the article interesting if so, check more posts below to gain more knowledge. Please don’t forget to share this post with other technical students. Thanks!