Lesson Notes By Weeks and Term - Senior Secondary 2

Automobile: A petrol engine II

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TERM – 1ST TERM

WEEK TWO

Class: Senior Secondary School 2

Age: 16 years

Duration: 40 minutes of 5 periods each

Date:

Subject: AUTO MECHANICAL

Topic: AUTOMOBILE: A PETROL ENGINE II

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

I.) Describe a four-stroke cycle operation

II.) Discuss the working sequence of a four-stroke cycle operation

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 the four stroke cycle operation

Students listens attentively to the teacher                                                                          

STEP 2

EXPLANATION

Teacher discusses the working sequence of a four stroke cycle operation

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

AUTOMOBILE: A PETROL ENGINE II

The four stroke cycle operation

The four-stroke cycle operation, also known as the Otto cycle, is a type of internal combustion engine operation that completes the four strokes of intake, compression, power, and exhaust within four strokes of the piston.

The working sequence of a four-stroke cycle operation

  1. Intake Stroke:

   - The piston moves downward from the top of the cylinder, creating a vacuum in the combustion chamber.

   - The intake valve opens, allowing a mixture of air and fuel to enter the combustion chamber from the intake manifold.

   - As the piston reaches the bottom of the stroke, the intake valve closes.

  1. Compression Stroke:

   - With both the intake and exhaust valves closed, the piston moves upward, compressing the air-fuel mixture in the combustion chamber.

   - The compression raises the temperature and pressure of the mixture, preparing it for combustion.

  1. Power Stroke:

   - When the piston reaches the top of the compression stroke, the spark plug ignites the compressed air-fuel mixture.

   - The combustion rapidly expands the gases, generating high pressure that forces the piston downward.

   - As the piston descends, it transfers the energy of the expanding gases to the crankshaft via the connecting rod, producing useful work.

  1. Exhaust Stroke:

   - As the piston approaches the bottom of the power stroke, the exhaust valve opens, and the intake valve remains closed.

   - The piston moves upward, pushing the burned gases out of the combustion chamber and into the exhaust manifold.

   - Once the piston reaches the top of the exhaust stroke, the exhaust valve closes, and the intake valve begins to open, starting the next intake stroke.

EVALUATION: 1. What is a four stroke cycle operation?

  1. Briefly discuss the working sequence of a four stroke cycle engine

CLASSWORK: As in evaluation

CONCLUSION: The teacher commends the students positively