design of connecting rod

8/18/2019 Design of Connecting Rod

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DESIGN OF I.C ENGINE CONNECTING ROD

ABSTACT

In a reciprocating piston engine, the connecting rod connects the piston to

the crank or crankshaft. Together with the crank, they form a simple mechanism

that converts reciprocating motion into rotating motion. As a connecting rod is

rigid, it may transmit either a push or a pull and so the rod may rotate the crank

through both halves of a revolution, i.e. piston pushing and piston pulling. Earlier

mechanisms, such as chains, could only pull. In a few two-stroke engines, the

connecting rod is only required to push. In this proect we are going to modelledconnecting rod by using creo cad tool available. Then with the use of !ATIA "#

$%&three-dimensional model of the connecting rod is obtained.


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'ITA$AT($E $I"IE) *+ !*E!TI $*

In a reciprocating piston engine, the connecting rod or conrod connects

the piston to the crank or crankshaft. Together with the crank, they form a simple

mechanism that converts reciprocating motion into rotating motion.

!onnecting rods may also convert rotating motion into reciprocating motion.

/istorically, before the development of engines, they were first used in this way.

As a connecting rod is rigid, it may transmit either a push or a pull and so

the rod may rotate the crank through both halves of a revolution, i.e. piston pushing

and piston pulling. Earlier mechanisms, such as chains, could only pull. In a few

two-stroke engines, the connecting rod is only required to push.

Today, connecting rods are best known through their use in internal

combustion piston engines, such as automotive engines. These are of a distinctly

different design from earlier forms of connecting rods, used in steam engines and

steam locomotives.

The earliest evidence for a connecting rod appears in the late 0rd century

A $oman /ierapolis sawmills. It also appears in two 1th century Eastern

$oman saw mills e2cavated at Ephesus and erasa. The crank and connecting rod

mechanism of these $oman watermills converted the rotary motion of the

waterwheel into the linear movement of the saw blades.

3ometime between 4456 and 4%&1, the Arab inventor and engineer Al-

7a8ari described a machine which incorporated the connecting rod with

a crankshaft to pump water as part of a water-raising machine, but the device was

http://en.wikipedia.org/wiki/Piston_enginehttp://en.wikipedia.org/wiki/Pistonhttp://en.wikipedia.org/wiki/Crank_(mechanism)http://en.wikipedia.org/wiki/Crankshafthttp://en.wikipedia.org/wiki/Automotive_enginehttp://en.wikipedia.org/wiki/Roman_Empirehttp://en.wikipedia.org/wiki/Hierapolis_sawmillhttp://en.wikipedia.org/wiki/Byzantine_Empirehttp://en.wikipedia.org/wiki/Byzantine_Empirehttp://en.wikipedia.org/wiki/Saw_millhttp://en.wikipedia.org/wiki/Ephesushttp://en.wikipedia.org/wiki/Gerasahttp://en.wikipedia.org/wiki/Crank_(mechanism)http://en.wikipedia.org/wiki/List_of_Roman_watermillshttp://en.wikipedia.org/wiki/Inventions_in_medieval_Islamhttp://en.wikipedia.org/wiki/Al-Jazarihttp://en.wikipedia.org/wiki/Al-Jazarihttp://en.wikipedia.org/wiki/Crankshafthttp://en.wikipedia.org/wiki/Pistonhttp://en.wikipedia.org/wiki/Crank_(mechanism)http://en.wikipedia.org/wiki/Crankshafthttp://en.wikipedia.org/wiki/Automotive_enginehttp://en.wikipedia.org/wiki/Roman_Empirehttp://en.wikipedia.org/wiki/Hierapolis_sawmillhttp://en.wikipedia.org/wiki/Byzantine_Empirehttp://en.wikipedia.org/wiki/Byzantine_Empirehttp://en.wikipedia.org/wiki/Saw_millhttp://en.wikipedia.org/wiki/Ephesushttp://en.wikipedia.org/wiki/Gerasahttp://en.wikipedia.org/wiki/Crank_(mechanism)http://en.wikipedia.org/wiki/List_of_Roman_watermillshttp://en.wikipedia.org/wiki/Inventions_in_medieval_Islamhttp://en.wikipedia.org/wiki/Al-Jazarihttp://en.wikipedia.org/wiki/Al-Jazarihttp://en.wikipedia.org/wiki/Crankshafthttp://en.wikipedia.org/wiki/Piston_engine


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unnecessarily comple2 indicating that he still did not fully understand the concept

of power conversion.

In $enaissance Italy, the earliest evidence of a 9 albeit mechanically

misunderstood 9 compound crank and connecting-rod is found in the sketch books

of Taccola. A sound understanding of the motion involved displays the

painter :isanello ;d. 46##< who showed a piston-pump driven by a water-wheel

and operated by two simple cranks and two connecting-rods.

=y the 41th century, evidence of cranks and connecting rods in the technological

treatises and artwork of $enaissance Europe becomes abundant> Agostino$amelli?s The iverse and Art factitious @achines of 4# alone depicts eighteen

e2amples, a number which rises in the Theorem Machinarum Novum by eorg

Andreas =Bckler to 6# different machines.

http://en.wikipedia.org/wiki/Renaissance_Italyhttp://en.wikipedia.org/wiki/Taccolahttp://en.wikipedia.org/wiki/Pisanellohttp://en.wikipedia.org/wiki/Renaissancehttp://en.wikipedia.org/wiki/Agostino_Ramellihttp://en.wikipedia.org/wiki/Agostino_Ramellihttp://en.wikipedia.org/wiki/Georg_Andreas_B%C3%B6cklerhttp://en.wikipedia.org/wiki/Georg_Andreas_B%C3%B6cklerhttp://en.wikipedia.org/wiki/Renaissance_Italyhttp://en.wikipedia.org/wiki/Taccolahttp://en.wikipedia.org/wiki/Pisanellohttp://en.wikipedia.org/wiki/Renaissancehttp://en.wikipedia.org/wiki/Agostino_Ramellihttp://en.wikipedia.org/wiki/Agostino_Ramellihttp://en.wikipedia.org/wiki/Georg_Andreas_B%C3%B6cklerhttp://en.wikipedia.org/wiki/Georg_Andreas_B%C3%B6ckler


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Engine wear and rod length:-

A maor source of engine wear is the sideways force e2erted on the piston through the

connecting rod by the crankshaft, which typically wears the cylinder into an oval cross-section

rather than circular, making it impossible for piston rings to correctly seal against the cylinder

walls. eometrically, it can be seen that longer connecting rods will reduce the amount of this

http://en.wikipedia.org/wiki/Crankshafthttp://en.wikipedia.org/wiki/Cylinder_(engine)http://en.wikipedia.org/wiki/Ovalhttp://en.wikipedia.org/wiki/Piston_ringhttp://en.wikipedia.org/wiki/Crankshafthttp://en.wikipedia.org/wiki/Cylinder_(engine)http://en.wikipedia.org/wiki/Ovalhttp://en.wikipedia.org/wiki/Piston_ring


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sideways force, and therefore lead to longer engine life. /owever, for a given engine block, the

sum of the length of the connecting rod plus the piston stroke is a fi2ed number, determined by

the fi2ed distance between the crankshaft a2is and the top of the cylinder block where

the cylinder head fastens> thus, for a given cylinder block longer stroke, giving greater engine

displacement and power, requires a shorter connecting rod ;or a piston with smaller compression

height it can result from fatigue near a physical defect in the rod,

lubrication failure in a bearing due to faulty maintenance, or from failure of the rod

bolts from a defect, improper tightening or over-revving of the engine. $e-use of

rod bolts is a common practice as long as the bolts meet manufacturer

specifications. espite their frequent occurrence on televised competitive

automobile events, such failures are quite rare on production cars during normal

daily driving. This is because production auto parts have a much larger factor of

safety, and often more systematic quality control.

High performance engines:-

)hen building a high performance engine, great attention is paid to the connecting rods,

eliminating stress risers by such techniques as grinding the edges of the rod to a smooth

radius, shot penning to induce compressive surface stresses ;to prevent crack initiation


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care is taken to torque the connecting rod bolts to the e2act value specified> often these bolts

must be replaced rather than reused. The big end of the rod is fabricated as a unit and cut or

cracked in two to establish precision fit around the big end bearing shell. Therefore, the big end

DcapsD are not interchangeable between connecting rods, and when rebuilding an engine, care

must be taken to ensure that the caps of the different connecting rods are not mi2ed up. =oth the

connecting rod and its bearing cap are usually embossed with the corresponding position number

in the engine block.

Powder metallurgy:-

$ecent engines such as the +ord 6.1 liter engine and the !hrysler %.& liter engine, have

connecting rods made using powder metallurgy, which allows more precise control of si8e and

weight with less machining and less e2cess mass to be machined off for balancing. The cap is

then separated from the rod by a fracturing process, which results in an uneven mating surface

due to the grain of the powdered metal. This ensures that upon reassembly, the cap will be

perfectly positioned with respect to the rod, compared to the minor misalignments which can

occur if the mating surfaces are both flat.

Compound rods:-

Articulated connecting rods

@any-cylinder multi-bank engines such as a "4% layout have little space available for

many connecting rod ournals on a limited length of crankshaft. This is a difficult compromise to

solve and its consequence has often led to engines being regarded as failures ;3unbeam

Arab, $olls-$oyce "ulture


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In certain engine types, masterCslave rods are used rather than the simple type shown in

the picture above. The master rod carries one or more ring pins to which are bolted the much

smaller big ends of slave rods on other cylinders. !ertain designs of " engines use a masterCslave

rod for each pair of opposite cylinders. A drawback of this is that the stroke of the subsidiary rod

is slightly shorter than the master, which increases vibration in a vee engine, catastrophically so

for the 3unbeam.

Fork and blade rods!

The usual solution for high-performance aero-engines is a DforkedD connecting rod. *ne

rod is split in two at the big end and the other is thinned to fit into this fork. The ournal is still

shared between cylinders. The $olls-$oyce @erlin used this Dfork-and-bladeD style. A common

arrangement for forked rods is for the fork rod to have a single wide bearing sleeve that spans the

whole width of the rod, including the central gap. The blade rod then runs, not directly on the

crankpin, but on the outside of this sleeve. The two rods do not rotate relative to each other,

merely oscillate back and forth, so this bearing is relatively lightly loaded and runs as a much

lower surface speed. /owever the bearing movement also becomes reciprocating rather than

continuously rotating, which is a more difficult problem for lubrication.

A likely candidate for an e2treme e2ample of compound articulated rod design could be

the comple2 erman %6-cylinder 7unkers 7umo %%% aviation engine, meant to have unlike

an F-engine layout with %6 cylinders, possessing si2 cylinders per bank only four cylinders

per bank, and six banks of cylinders, all liquid-cooled with five DslaveD rods pinned to one master

rod, for each DlayerD of cylinders in its design. After building nearly 0&& test e2amples in several

different displacements, the 7unkers firm?s comple2 7umo %%% engine turned out to be a

http://en.wikipedia.org/wiki/V_enginehttp://en.wikipedia.org/wiki/Rolls-Royce_Merlinhttp://en.wikipedia.org/wiki/Junkers_Jumo_222http://en.wikipedia.org/wiki/X_enginehttp://www.flugzeug-lorenz.de/index.php?eID=tx_cms_showpic&file=uploads%2Fpics%2FYY_169-1_Jumo222_Stirnschnitt.jpg&width=10000m&height=10000m&bodyTag=%3Cbody%20style%3D%22margin%3A0%3B%20background%3A%23fff%3B%22%3E&wrap=%3Ca%20href%3D%22javascript%3Aclose()%3B%22%3E%20%7C%20%3C%2Fa%3E&md5=3a4da1957d3bd583a511bb5044efc2d8http://www.flugzeug-lorenz.de/index.php?eID=tx_cms_showpic&file=uploads%2Fpics%2FYY_169-1_Jumo222_Stirnschnitt.jpg&width=10000m&height=10000m&bodyTag=%3Cbody%20style%3D%22margin%3A0%3B%20background%3A%23fff%3B%22%3E&wrap=%3Ca%20href%3D%22javascript%3Aclose()%3B%22%3E%20%7C%20%3C%2Fa%3E&md5=3a4da1957d3bd583a511bb5044efc2d8http://en.wikipedia.org/wiki/Junkershttp://en.wikipedia.org/wiki/V_enginehttp://en.wikipedia.org/wiki/Rolls-Royce_Merlinhttp://en.wikipedia.org/wiki/Junkers_Jumo_222http://en.wikipedia.org/wiki/X_enginehttp://www.flugzeug-lorenz.de/index.php?eID=tx_cms_showpic&file=uploads%2Fpics%2FYY_169-1_Jumo222_Stirnschnitt.jpg&width=10000m&height=10000m&bodyTag=%3Cbody%20style%3D%22margin%3A0%3B%20background%3A%23fff%3B%22%3E&wrap=%3Ca%20href%3D%22javascript%3Aclose()%3B%22%3E%20%7C%20%3C%2Fa%3E&md5=3a4da1957d3bd583a511bb5044efc2d8http://www.flugzeug-lorenz.de/index.php?eID=tx_cms_showpic&file=uploads%2Fpics%2FYY_169-1_Jumo222_Stirnschnitt.jpg&width=10000m&height=10000m&bodyTag=%3Cbody%20style%3D%22margin%3A0%3B%20background%3A%23fff%3B%22%3E&wrap=%3Ca%20href%3D%22javascript%3Aclose()%3B%22%3E%20%7C%20%3C%2Fa%3E&md5=3a4da1957d3bd583a511bb5044efc2d8http://en.wikipedia.org/wiki/Junkers


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production failure for the more advanced combat aircraft of the Third $eich?s 'uftwaffe which

required aviation power plants of over 4,#&& k) ;%,&&& :3< output apiece.

INTORD"CTION OF CATIA

!ATIA ;!omputer Aided Three-imensional Interactive Application< started

as an in-house development in 4G55 by +rench aircraft manufacturer Avions

Marcel Dassault, at that time customer of the CADCAM CAD software!"# to

http://en.wikipedia.org/wiki/Bomber_Bhttp://en.wikipedia.org/wiki/Luftwaffehttp://en.wikipedia.org/wiki/Dassault_Aviationhttp://en.wikipedia.org/wiki/Dassault_Aviationhttp://en.wikipedia.org/wiki/CAD/CAMhttp://en.wikipedia.org/wiki/CADhttp://en.wikipedia.org/wiki/CATIA#cite_note-1http://en.wikipedia.org/wiki/Bomber_Bhttp://en.wikipedia.org/wiki/Luftwaffehttp://en.wikipedia.org/wiki/Dassault_Aviationhttp://en.wikipedia.org/wiki/Dassault_Aviationhttp://en.wikipedia.org/wiki/CAD/CAMhttp://en.wikipedia.org/wiki/CADhttp://en.wikipedia.org/wiki/CATIA#cite_note-1


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develop assault?s Mirage fighter et. It was later adopted in the aerospace,

automotive, shipbuilding, and other industries.

#echanical engineeringH-

!ATIA enables the creation of 0 parts, from 0 sketches, sheet

metal, composites, and molded, forged or tooling parts up to the definition of

mechanical assemblies. The software provides advanced technologies for

mechanical surfacing =I). It provides tools to complete product definition,

including functional tolerances as well as kinematics definition. !ATIA provides a

wide range of applications for tooling design, for both generic tooling and mold

die.

Scope of application:-

!ommonly referred to as a 0 :roduct 'ifecycle @anagement software suite,

!ATIA supports multiple stages of product development ;!A2


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• *nce a design is completed. % and 0 views are readily obtainable.

• The ability to changes in late design process is possible.

• It provides a very accurate representation of model specifying all other

dimensions hidden geometry etc.

• It is user friendly both solid and surface modeling can be done.

• It provides clear 0 models, which are easy to visuali8e and understand.

• It provides a greater fle2ibility for change.

CATIA

There are different modules in !ATIA using which different tasks

can be performed. The main window and modules of !ATIA shown in

figure.


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+ig.o.6. !atia-v# Interface

The +ain +od,les are!

Sketcher

-art design


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Asse+bl

Dra%ting

/ire%ra+e and S,r%ace design

Sketcher!

3ketcher applications make it possible for designers to sketch precise and rapid %

profile.

3elect the sketcher icon and click the desired reference plane either in the geometry

area or in the specification tree, or select a planar surface. The creates a Jnon-

positionedK sketch ;i.e. a sketch for which you do not specify the origin and

orientation of the absolute a2is, which are not associative with the 0 geometry


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The &ersion ' 0art design application makes it possible to design precise 0

mechanical parts with an intuitive and fle2ible user interface, from sketching in an

assembly conte2t to interactive detailed design. &ersion ' 0art design application

will enable you to accommodate design requirements for parts of various

comple2ities, from simple to advance.

The application, which combines the power of feature-based design with the

fle2ibility of =oolean approaches, offers a highly productive and intuitive design

environment with multiple design methodologies, such as post-design and local 0

parameteri8ation.

3elect start-M @echanical esign -M:art esign from the menu bar

3elect one plane of the local a2is. / and " are aligned to the main a2es of this

selected plane. Associatively is kept between both the plane and the sketch.

Re%erence Ele+ent!

$eference elements are used as references for constructing the model. They are

not geometry features, but they aid in geometry construction the model. They are

not geometry features, but they aid in geometry construction by acting as reference

for sketching a feature, orientation the model, assembly, components, and so on.

=ecause of their versatility reference are frequently used.

1. Re%erence -lane

). Re%erence 2ine

3. Re%erence -oint


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Re%erence -lanes!

atum planes are used as reference to construct feature. atum planes areconsidered feature, but they are not considered model geometry. atum planes can

be created and used as a sketch plane where no e2ists.

Re%erence -lane o0tion ,sed are!

Thru plane, offset plane, offset coordinate system, =lend

section, thru a2is, thru pointCverte2, ormal to a2is, Tangent to cylinder, Angle to

the plane etc.

Re%erence 2ines!

$eference lines are used to create surface and other features, or as a sweep

traectories. (ser sketch reference line in the same manner as any other feature.

3ketched curves can consist of one or more sketched segment and of one or more

open or closed loop.

Re%erence lines o0tion ,sed are!

3ketch, Intersection surface, thru point, from file, !omposite, :roected, +ormed,

3plit, *ffset from surface, from curve, from boundary, *ffset curve, from equation

etc.

Re%erence -oints!

:oints are used to specify point loads for mesh generation, attach datum targets

and notes in drawing, and create coordinate system and pipe feature traectories.

(ser can also place a2is, planes, holes and shafts at a point.


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-oint o0tion ,sed is!

*n surface, *ffset surface, !urve coordinate surface, on verte2, offset coordinate

system, three surfaces, at center, on curves, on surface, *ffset point etc.

Dra%ting!

enerative rafting is new generation product that provides users with powerful

functionalities to generate drawings from 0 parts assembly definition.

The enerative rafting has been designed to how to generate drawings of

varying levels of comple2ity, as well as apply dimensions, annotations and dress-

up elements to these drawing. 3tart - @echanical esign N rafting.

&iews

Front &iew!

A front view is a proection view obtained by drawing perpendiculars from all points on the edges of the part to the plane of proection. The plane of proection

upon all points on the edges of the part to the proections.

-ro4ection $iew!

:roection views are conceived to be drawn or proected onto :lanes known as

proection planes. A transparent plane or pane of glass representing a proection

plane is located parallel to the front surface of the part.

Iso+etric &iew!

The Isometric "iew !ommand enables to create a %d view with any orientation,

this orientation being the same as the one in the 0d viewer. Among other results


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and depending on how the 0 viewer is oriented when created the view, can

obtained a regular F-O-P isometric view.

Di+ensioning!

Generate Di+ensions!

To generate dimensions in one shot from the constraints of a 0 part. *nly

the following constraints can be generatedH istance, 'ength, Angle, $adius and

iameter.

Di+ensions!

To create and modify dimensions. These dimensions will be associative to the

elements created from a part or an assembly. )hen created, these elements are

associative with a view.

Generati$e Balloons!

To generate balloons automatically to the components of an assembly which

are previously generated in assemblyQ

Asse+bl!

CATIA &' R)* assembly module allows part to be grouped into assembly or

subassemblies to model a complete part. Assembly esign allows the design of

assemblies with an intuitive and fle2ible user interface.

3tart N @echanical esign N Assembly design.


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T0es o% Asse+bl5s!

Botto+ ,0 Asse+bl!

:arts of Assembly are created in respective part files and Assembly inAssembly files. (sed for component having lesser parts.

To0 Down Asse+bl!

:arts are created in the Assembly file itself. (sed for components having

more parts.

Asse+bl 0roced,re!

To Assembly the already created components, selected product name in

specification tree- $ight click N select component N select e2isting components ;or<

To create parts in the assembly itself, select product name in specification tree

- $ight click N select component - 3elect new part or select ew !omponent or

ew product to create a sub Assembly.

Apply constraints to the components to assembly.

Constraint T0es!

!oincidence, !ontact, *ffset, Angle, +i2 Together, Ruick !onstraint =ill of

material S=*@H-


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The =ill of @aterial ;=*@< provides a listing of all parts and parameters in the

current assembly.

=*@ is a table to display the number and name of the components belonging to

the active component as well as the properties of these components.

Generate N,+bering! enerates numbers of these to all parts.

#ani0,lation!

Asse+bling co+0onents into a 0attern!

Assembly it to the leader of an e2isting components or feature pattern> then pattern using reuse pattern. A pattern must e2ist in order to use this option.

Catalog!

In catalog standard we can get standard nuts, bolts, keys, pins, screw, washers,

by selecting the required standard si8e and pitch by clicking ok we can get to

assembly and we can use it.


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DESIGN AND CA2AC"2ATIONS OF CONNECTING ROD

Theoretical calc,lation!

'ength of connecting rod ;4< U0%#mm

@ass ;m


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Assuming pU0.5 nCmm%

$adius of crank ;r< U 3tork lengthC%

U5.0C%

U60.1#mm

@a2imum force on the piston due to pressure

+4 U VC6W%Wp

U VC6W;4


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Connecting rod 0adding!


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Design the slots b ,sing 0ocket tool!

Gi$e the %illets b ,sing edge blend tool!


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Design the bolt slots!


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Connecting rod $iews!

design of connecting rod

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