Four stroke engine project project( )

TEAM WORK 1 - احمد جمال منصور عبدالعزيز سكشن احمد السيد احمد حسن ابوالغيط سكشن احمد السيد محمد احمد سكشن احمد السيد محمد عبدالحميد سكشن احمد سعيد السعدني سكشن احمد عادل حسن سكشن احمد عبداللطيف عنتر فرحات سكشن 1

SUPERVISOR Prof.Dr/ Prof.Dr/

Four Stroke Engine

Basic 4 Cycle Theory Intake Stroke Intake Stroke Compression Stroke Compression Stroke Power Stroke Power Stroke Exhaust Stroke Exhaust Stroke

Intake Stroke Rotation of the crankshaft pulls the piston down. At this time, the intake valve is opened, allowing the piston to draw an air/fuel charge into the combustion chamber. As the piston nears the bottom of the stroke, the intake valve closes, sealing the charge in the combustion chamber. Rotation of the crankshaft pulls the piston down. At this time, the intake valve is opened, allowing the piston to draw an air/fuel charge into the combustion chamber. As the piston nears the bottom of the stroke, the intake valve closes, sealing the charge in the combustion chamber.

Compression Stroke As the crankshaft rotation continues, the piston is pushed up towards the top of the cylinder, compressing the air/fuel mixture. In modern engines the 'compression ratio' is about 8 to 1, meaning the entire contents of the combustion chamber is compressed into an area of about one eighth of its original size. The older stationary engines had compression ratios in the neighborhood of 4 or 5 to 1. Generally, the higher the compression ratio, the more power is obtained from the engine, that is until poor quality and/or low octane values of the fuel begins to have an adverse effect on the combustion. This usually causes the fuel to "diesel" or combust uncontrollably, sometimes called Detonation. As the crankshaft rotation continues, the piston is pushed up towards the top of the cylinder, compressing the air/fuel mixture. In modern engines the 'compression ratio' is about 8 to 1, meaning the entire contents of the combustion chamber is compressed into an area of about one eighth of its original size. The older stationary engines had compression ratios in the neighborhood of 4 or 5 to 1. Generally, the higher the compression ratio, the more power is obtained from the engine, that is until poor quality and/or low octane values of the fuel begins to have an adverse effect on the combustion. This usually causes the fuel to "diesel" or combust uncontrollably, sometimes called Detonation.

Power Stroke Typically, just before the piston reaches its top most position (Top Dead Center or TDC), the ignition system ignites the now compressed air/fuel charge. Though, in human terms, this burning of the fuel seems more like an instantaneous explosion, it is actually, in a properly running engine, a smooth, rapid flame front that moves from the source of the ignition (spark plug, ignitor, etc.) to all points within the combustion chamber. If the fuel is ignited from several different points due to deposits in the combustion chamber, poor quality fuel or engine problems, several flame fronts can be generated and will collide with each other making what is heard as the common "pinging" sound, sometimes called Preignition. The pressure inside the cylinder increases dramatically because of the combustion taking place and this pressure forces the piston down, which causes the crankshaft to rotate providing usable power output. Typically, just before the piston reaches its top most position (Top Dead Center or TDC), the ignition system ignites the now compressed air/fuel charge. Though, in human terms, this burning of the fuel seems more like an instantaneous explosion, it is actually, in a properly running engine, a smooth, rapid flame front that moves from the source of the ignition (spark plug, ignitor, etc.) to all points within the combustion chamber. If the fuel is ignited from several different points due to deposits in the combustion chamber, poor quality fuel or engine problems, several flame fronts can be generated and will collide with each other making what is heard as the common "pinging" sound, sometimes called Preignition. The pressure inside the cylinder increases dramatically because of the combustion taking place and this pressure forces the piston down, which causes the crankshaft to rotate providing usable power output.

Exhaust Stroke By the time the piston is forced most of the way down the cylinder, nearly all of the usable energy created from the burning fuel has been used. At this point, the exhaust valve begins to open and as the crankshaft rotation continues, the rising piston forces the spent gases out of the cylinder and into the exhaust system. Just prior to the piston reaching TDC, the exhaust valve closes and shortly thereafter, the intake valve reopens to start the process over. By the time the piston is forced most of the way down the cylinder, nearly all of the usable energy created from the burning fuel has been used. At this point, the exhaust valve begins to open and as the crankshaft rotation continues, the rising piston forces the spent gases out of the cylinder and into the exhaust system. Just prior to the piston reaching TDC, the exhaust valve closes and shortly thereafter, the intake valve reopens to start the process over.

OTTO CYCLE Otto cycle is the typical cycle for most of the cars internal combustion engines, that work using gasoline as a fuel. Otto cycle is exactly the same one that was described for the four- stroke engine. It consists of the same four major steps: Intake, compression, ignition and exhaust. Otto cycle is the typical cycle for most of the cars internal combustion engines, that work using gasoline as a fuel. Otto cycle is exactly the same one that was described for the four- stroke engine. It consists of the same four major steps: Intake, compression, ignition and exhaust.

PV diagram for Otto cycle PV diagram for Otto cycle

On the PV-diagram, 1-2 Isentropic Compression stroke. 2-3 Heat addition stroke. On the PV-diagram, 1-2 Isentropic Compression stroke. 2-3 Heat addition stroke. 3-4 Isentropic expansion process. 3-4 Isentropic expansion process. 4-1 Heat rejection. The distance between points 1-2 is the stroke of the engine. By dividing V1/V2, we get: r=v1/v2 4-1 Heat rejection. The distance between points 1-2 is the stroke of the engine. By dividing V1/V2, we get: r=v1/v2 where r is called the compression ratio of the engine. The efficiency is taken to be: where r is called the compression ratio of the engine. The efficiency is taken to be:

Components of 4-stroke engine

1-CYLINDER The core of the engine is the cylinder, with the piston moving up and down inside the cylinder. The engine described above has one cylinder. The core of the engine is the cylinder, with the piston moving up and down inside the cylinder. The engine described above has one cylinder. CYLINDER is made from gray cost iron. CYLINDER is made from gray cost iron.

CYLINDER ARRANGEMENT In line. In line. V. V. Flat. Flat. Radial. Radial.

(A) Inline -The cylinders are arranged in a line in a single bank

(B) V - The cylinders are arranged in two banks set at an angle to one another

. (C) Flat - The cylinders are arranged in two banks on opposite sides of the engine

(D) Radial

Valves -2 The intake and exhaust valves open at the proper time to let in air and fuel and to let out exhaust. Note that both valves are closed during compression and combustion so that the combustion chamber is sealed The intake and exhaust valves open at the proper time to let in air and fuel and to let out exhaust. Note that both valves are closed during compression and combustion so that the combustion chamber is sealed VALAE is made from alloy steel. VALAE is made from alloy steel.

ARRANGEMENT OF VALVES 1. L-HEAD. 2. I-HEAD. 3. F-HEAD. 4. T-HEAD.

L-HEAD The intake and the exhaust valves are both located on the same side of the piston and cylinder. The intake and the exhaust valves are both located on the same side of the piston and cylinder.

I-HEAD The intake and the exhaust valves are both mounted in a cylinder head directly above the cylinder. The intake and the exhaust valves are both mounted in a cylinder head directly above the cylinder.

F-HEAD The intake valves are normally in the head, while the exhaust valves are located in the engine block

T-HEAD The intake and the exhaust valves are located on opposite sides of the cylinder in the engine block, each requires their own camshaft. The intake and the exhaust valves are located on opposite sides of the cylinder in the engine block, each requires their own camshaft.

TIMING

Piston -3 A piston is a cylindrical piece of metal that moves up and down inside the cylinder. A piston is a cylindrical piece of metal that moves up and down inside the cylinder. The Piston is made from cost iron. The Piston is made from cost iron.

Piston rings -4 Piston rings provide a sliding seal between the outer edge of the piston and the inner edge of the cylinder. The rings serve two purposes: Piston rings provide a sliding seal between the outer edge of the piston and the inner edge of the cylinder. The rings serve two purposes: They prevent the fuel/air mixture and exhaust in the combustion chamber from leaking into the sump during compression and combustion. They prevent the fuel/air mixture and exhaust in the combustion chamber from leaking into the sump during compression and combustion. They keep oil in the sump from leaking into the combustion area, where it would be burned and lost. They keep oil in the sump from leaking into the combustion area, where it would be burned and lost.oil Most cars that "burn oil" and have to have a quart added every 1,000 miles are burning it because the engine is old and the rings no longer seal things properly. Most cars that "burn oil" and have to have a quart added every 1,000 miles are burning it because the engine is old and the rings no longer seal things properly.

(1)Compresssi on ring (plain section) (2)Compresssi on ring(taper faced) (3) Oil control ring steel rail multi piece

Connecting rod-4 The connecting rod connects the piston to the crankshaft. It can rotate at both ends so that its angle can change as the piston moves and the crankshaft rotates. The connecting rod is made from forged steel or aluminum. The connecting rod connects the piston to the crankshaft. It can rotate at both ends so that its angle can change as the piston moves and the crankshaft rotates. The connecting rod is made from forged steel or aluminum.

5-PISTON PIN It is used to connect the piston with the connecting rod. It is used to connect the piston with the connecting rod.

Spark plug 6- The spark plug supplies the spark that ignites the air/fuel mixture so that combustion can occur. The spark must happen at just the right moment for things to work properly The spark plug supplies the spark that ignites the air/fuel mixture so that combustion can occur. The spark must happen at just the right moment for things to work properlyspark plugspark plug

Crankshaft 7- The crankshaft turns the piston's up and down motion into circular motion just like a crank on a jack-in-the-box does. The crankshaft turns the piston's up and down motion into circular motion just like a crank on a jack-in-the-box does.

Bearing is a device supporting a mechanical element and providing its movement relatively to another element with minimum power loss. The rotating components of internal combustion engines are equipped with sleeve type sliding bearings. The reciprocating engines are characterized by cycling loading of their parts including bearings. Such character of the loads is a result of alternating pressure of combustion gases in the cylinders. Rolling bearings, in which a load is transmitted by rolls (balls) to a relatively small area of the ring surface, can not withstand under the loading conditions of internal combustion engines. Only sliding bearings providing a distribution of the applied load over a relatively wide area may work in internal combustion engines. Bearing is a device supporting a mechanical element and providing its movement relatively to another element with minimum power loss. The rotating components of internal combustion engines are equipped with sleeve type sliding bearings. The reciprocating engines are characterized by cycling loading of their parts including bearings. Such character of the loads is a result of alternating pressure of combustion gases in the cylinders. Rolling bearings, in which a load is transmitted by rolls (balls) to a relatively small area of the ring surface, can not withstand under the loading conditions of internal combustion engines. Only sliding bearings providing a distribution of the applied load over a relatively wide area may work in internal combustion engines.

The sliding bearings used in internal combustion engines: Main crankshaft bearings. Main crankshaft bearings. Connecting rod bearings. Connecting rod bearings. Small end bushes. Small end bushes. Camshaft bearings. Camshaft bearings.

1-Main crankshaft bearings. Main crankshaft bearings support crankshaft providing its rotation under inertia forces generated by the parts of the shaft and oscillating forces transmitted by the connecting rods. Main bearings are mounted in the crankcase. A main bearing consists of two parts: upper and lower. The upper part of a main bearing commonly has an oil groove on the inner surface. A main bearing has a hole for passing oil to the feed holes in the crankshaft. Some of main bearings may have thrust bearing elements supporting axial loads and preventing movements along the crankshaft axis. Main bearings of such type are called flange main bearings. Main crankshaft bearings support crankshaft providing its rotation under inertia forces generated by the parts of the shaft and oscillating forces transmitted by the connecting rods. Main bearings are mounted in the crankcase. A main bearing consists of two parts: upper and lower. The upper part of a main bearing commonly has an oil groove on the inner surface. A main bearing has a hole for passing oil to the feed holes in the crankshaft. Some of main bearings may have thrust bearing elements supporting axial loads and preventing movements along the crankshaft axis. Main bearings of such type are called flange main bearings.

2-Connecting rod bearings. Connecting rod bearings provide rotating motion of the crank pin within the connecting rod, which transmits cycling loads applied to the piston. Connecting rod bearings are mounted in the Big end of the connecting rod. A bearing consists of two parts (commonly interchangeable( Connecting rod bearings provide rotating motion of the crank pin within the connecting rod, which transmits cycling loads applied to the piston. Connecting rod bearings are mounted in the Big end of the connecting rod. A bearing consists of two parts (commonly interchangeable(

3-Small end bushes Small end bushes provide relative motion of the piston relatively to the connecting rod joined to the piston by the piston pin (gudgeon pin). End bushes are mounted in the Small end of the connecting rod. Small end bushes are cycling loaded by the piston pushed by the alternating pressure of the combustion gases. Small end bushes provide relative motion of the piston relatively to the connecting rod joined to the piston by the piston pin (gudgeon pin). End bushes are mounted in the Small end of the connecting rod. Small end bushes are cycling loaded by the piston pushed by the alternating pressure of the combustion gases.

Camshaft bearings.-4 Camshaft bearings support camshaft and provide its rotation Camshaft bearings support camshaft and provide its rotation

Team work