MDE Unit 1 Q3

Essential Components to Include:

A cross-section of a diesel engine piston should clearly depict the following components:

Piston Crown

• Shape: Typically flat or with a dish-like or dome-like shape to promote combustion.
• Combustion chamber indentations (if any): These can vary depending on the engine design.

Piston Rings

• Compression rings: These prevent combustion gases from escaping into the crankcase.
• Oil control rings: These prevent excess oil from entering the combustion chamber.
• Ring grooves: The channels where the piston rings sit.

Piston Skirt

• Shape: Usually elliptical or cylindrical.
• Oil return holes (if any): These allow oil to drain back to the oil sump.

Piston Pin

• Location: The hole where the connecting rod attaches.
• Securing clips or bushings (if any): These hold the piston pin in place.

Cooling Oil Galleries (if present):

• These channels circulate oil to cool the piston.

Piston Material:

• Indicate the material used for the piston (usually aluminum alloy or cast iron).

Additional Considerations:

• Clarity and Proportion: Ensure the drawing accurately represents the proportions of the piston components.
• Labeling: Clearly label each component for easy identification.
• Dimensions: Include relevant dimensions for technical accuracy (optional).
• Hatching: Use hatching to indicate different materials or sections.

Example:

Opens in a new windowwww.researchgate.net

crosssection of a diesel engine piston

Note: The specific details of the piston will vary depending on the engine type and size. It’s essential to refer to a specific engine manual or technical drawing for precise dimensions and features.

The force generated by the combustion of fuel within the cylinder of an internal combustion engine acts upon the piston crown. This force is then transmitted through a series of components to ultimately rotate the crankshaft.  

1. Internal combustion engine – Wikipedia

2. Internal Combustion Engine Basics | Department of Energy

The Process

1. Piston Crown: The force from the combustion pushes the piston downward.   1. How an Engine Piston Works – Ferber’s Tire & Auto Service ferberstireandauto.com
2. Connecting Rod: This component connects the piston to the crankshaft. As the piston moves downward, it exerts a force on the upper end of the connecting rod.   1. Connecting rod – Wikipedia en.wikipedia.org
3. Crankshaft Journal: The lower end of the connecting rod is connected to the crankshaft journal through a piston pin. The force exerted by the connecting rod on the piston pin creates a rotational force on the crankshaft journal.   1. Connecting rod – Wikipedia en.wikipedia.org
4. Crankshaft: The rotational force applied to the crankshaft journal causes the crankshaft to rotate. This rotational energy is then transmitted to the vehicle’s drivetrain.

Key Components and Their Role

• Piston: Converts combustion pressure into linear force.
• Connecting Rod: Converts linear force into rotational force.
• Crankshaft: Converts rotational force into torque, which drives the vehicle.

Visual Representation:

Opens in a new windowen.wikipedia.org

piston, connecting rod, and crankshaft

Important Considerations:

• Friction: To minimize energy loss, components are lubricated to reduce friction.
• Balancing: The crankshaft is balanced to counteract the forces generated during the combustion cycle.   1. Balancing Secondary Engine Forces: Ensuring Smooth Engine Operation – SchoolTube www.schooltube.com
• Engine Design: The specific design of the piston, connecting rod, and crankshaft will influence the efficiency of force transfer.

This is a simplified explanation of the process. In reality, there are additional factors and complexities involved in the operation of an internal combustion engine.