The Roots Type Supercharger, a positive displacement lobe pump, boosts engine performance by forcing more air into the cylinders. This article delves into the design, operating principles, and applications of this crucial automotive component.
Figure: Air inlet of a Roots-type supercharger. Air enters the housing through this inlet, which features cooling fins to mitigate temperature increases during compression.
How a Roots Type Supercharger Works
A roots type supercharger utilizes two or more counter-rotating rotors with lobes to compress air. These rotors are housed within a casing. As the rotors spin, air is drawn into the space between the lobes and the casing. The rotating lobes then trap this air and move it towards the outlet side. Since the outlet is smaller, the trapped air is compressed before being discharged into the engine intake manifold.
Figure: Roots type blower (supercharger). This illustration showcases the two rotors and the pathway of air through the supercharger.
This process differs from a centrifugal supercharger, which uses an impeller to accelerate air outwards and increase its pressure. The roots type supercharger’s positive displacement mechanism results in a consistent volume of air being delivered regardless of engine speed, leading to significant low-end torque gains. However, efficiency decreases at higher pressure ratios.
Design and Components
The rotors of a roots type supercharger are typically two, three, or four-lobed. They are meticulously designed using cycloidal curves to ensure a tight seal without actual contact. This precise geometry minimizes leakage and maximizes airflow.
Figure: Three-lobed vanes of a Roots-type supercharger. The lobes are precisely engineered using cycloidal curves to minimize leakage and maximize efficiency.
The rotors are driven by a belt connected to the engine’s crankshaft. A set of gears ensures precise synchronization of the two rotors, maintaining the necessary clearance to prevent contact and damage.
Figure: Driving pulley and helical gears of a Roots-type supercharger. The belt drive system connects to the engine crankshaft, while the gears ensure synchronized rotation of the rotors.
Applications and Advantages of Roots Type Superchargers
Predominantly found in automotive applications, the roots type supercharger provides substantial power gains, particularly at lower RPMs. This characteristic contributes to enhanced acceleration and overall driving experience. Its compact design allows for easier integration into existing engine bays.
Figure: Compressor for supercharging the air in combustion engines. This demonstrates the typical placement of a Roots-type supercharger in an automotive engine bay.
Beyond automotive applications, roots type blowers are also utilized in industrial settings for various tasks such as:
- Pneumatic conveying
- Vacuum applications
- Water treatment
Conclusion
The roots type supercharger provides a reliable and efficient method for increasing engine power. Its unique design and operating principles offer distinct advantages in specific applications. While less efficient at higher pressure ratios compared to centrifugal superchargers, its ability to deliver substantial low-end torque makes it a popular choice for enhancing performance in a variety of vehicles and industrial applications. Understanding its core functionality allows for better appreciation of its role in boosting engine capabilities.
