Lesson Notes By Weeks and Term - Senior Secondary 2

Carburetor and air cleaner or filter

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TERM – 3RD TERM

WEEK ONE

Class: Senior Secondary School 2

Age: 16 years

Duration: 40 minutes of 5 periods each

Date:

Subject: AUTO MECHANICAL

Topic: CARBURETOR AND AIR CLEANER OR FILTER

SPECIFIC OBJECTIVES: At the end of the lesson, pupils should be able to

I.) Define a carburetor

II.) Identify the types of carburetor

III.) Describe the operation of a carburetor

IV.) Identify the functions of a carburetor

INSTRUCTIONAL TECHNIQUES: Identification, explanation, questions and answers, demonstration, videos from source

INSTRUCTIONAL MATERIALS: Videos, loud speaker, textbook, pictures,

INSTRUCTIONAL PROCEDURES

PERIOD 1-2

PRESENTATION

TEACHER’S ACTIVITY

STUDENT’S

ACTIVITY

STEP 1

INTRODUCTION

The teacher explains the meaning of a carburetor and identify its types

Students listens attentively to the teacher                                                                          

STEP 2

EXPLANATION

Teacher discusses the operations and functions of a carburetor

Students exhibit attentiveness and active engagement

STEP 3

NOTE TAKING

The teacher writes a summarized

note on the board

The students

copy the note in

their books

 

NOTE

CARBURETOR AND AIR CLEANER OR FILTER

A carburetor is a mechanical device found in older vehicles that is responsible for mixing air and fuel in the correct proportions for combustion in the engine. It functions by utilizing the vacuum created by the engine's intake stroke to draw air into the carburetor's venturi, where it mixes with fuel from the carburetor's fuel bowl.

Types of Carburetors

1. Float Carburetor: The most common type, it uses a float to maintain a constant fuel level in the carburetor bowl. As fuel is used, the float drops, opening a valve to allow more fuel to enter.

2. Venturi or Constant Vacuum Carburetor: This type utilizes the Venturi effect, where air flowing through a narrow throat creates a low-pressure area, drawing fuel from a jet into the air stream.

3. Diaphragm Carburetor: Often found in small engines like lawnmowers, it uses a flexible diaphragm to meter fuel flow based on engine demands.

Operation of a Carburetor

  1. Air Intake: Air enters the carburetor through an intake manifold.
  2. Fuel Mixing: Fuel is drawn from the fuel tank and mixed with the incoming air. The amount of fuel is regulated by various components like jets, needles, and valves.
  3. Venturi Effect: In Venturi or Constant Vacuum carburetors, the narrowing of the air passage causes a decrease in pressure, which draws fuel from the carburetor's fuel bowl into the air stream.
  4. Mixture Formation: The air-fuel mixture travels into the engine's combustion chamber, where it is ignited by a spark plug.
  5. Adjustment: Carburetors often have adjustment screws or needles to fine-tune the air-fuel mixture ratio for optimal engine performance.

Functions of a carburator

The following are some of the functions of a carburetor:

  1. Mixing: It mixes air and fuel together in the right proportions for the engine to use.
  2. Regulating Fuel Flow: It controls how much fuel gets into the engine based on how fast you're driving or how hard you're pressing the gas pedal.
  3. Atomizing Fuel: It breaks the fuel into tiny droplets, making it easier for the engine to burn efficiently.
  4. Starting Aid: It provides extra fuel to help start a cold engine smoothly.
  5. Idling: It maintains a steady supply of fuel for the engine to run smoothly when the car is at a standstill.

EVALUATION: 1. What is a carburetor?

  1. Mention the 3 types of carburetor
  2. Identify 5 functions of the carburetor

CLASSWORK: As in evaluation

CONCLUSION: The teacher commends the students positively