Question 22 QMED03 - Oiler

The Correct Answer is C ### Why Option C is Correct: Fuel injection systems are fundamentally designed to perform three main functions in precise control: 1. **Meter Fuel:** Measure and deliver the exact amount of fuel required by the engine (based on load, speed, and other variables). 2. **Atomize Fuel:** Break the liquid fuel into a fine mist of droplets to ensure rapid and complete mixing with air. 3. **Inject Fuel at the Proper Time:** Deliver the fuel into the cylinder or intake runner at the precise moment dictated by the engine's operational cycle (e.g., during the intake stroke for port injection or near the end of the compression stroke for direct injection in a diesel engine). Timing is critical for engine efficiency, power, and emissions control. Therefore, "inject fuel at the proper time" is the third core design mandate of a fuel injection system. ### Why Other Options Are Incorrect: **A) create turbulence in the combustion chamber:** While turbulence (or swirl) is crucial for good air-fuel mixing, it is primarily a function of the intake port and piston crown design, not the fuel injector itself. The injector's role is to atomize and direct the spray, relying on the pre-existing airflow motion. **B) aid in completing cylinder scavenging:** Scavenging is the process of pushing exhaust gases out of the cylinder using fresh air (especially critical in two-stroke engines). This is achieved through port design and intake/exhaust timing, not by the action of the fuel injector. **D) minimize fuel penetration into the cylinder:** Injector design optimizes **fuel spray penetration**—how far the fuel stream reaches—to match the shape and temperature of the combustion chamber. Minimizing penetration completely would result in poor mixing and potentially fuel pooling near the injector tip. The goal is precise, optimized penetration, not minimization.