ME 450 – Fall 2005



ME 250 HW: Engine Assembly

Model the Engine-Assembly-II. Use the Piston, Connecting Rod, and the Piston Pin you modeled before. Add the Crank Shaft, Engine Block, and Block Head, Gasket, and the fasteners and washers. Modeling information is provided below. I’ll be brief on words. Place all the files including the fasteners in a folder called “Engine Assembly”. The assembly must animate properly without interference. You can make dimensional modifications as long as the proportions and alignments are correct and the model animates properly. You cannot simplify the parts or change their shapes.

Crank Shaft

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Add cosmetic thread on the 16 mm diameter portion.

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The width of the Keyways is 4 mm. The size of the End Hole is 8 mm and it is 30 mm deep. Create a reference plane 122 mm from the holed end of the shaft and create the Ring on the shaft as shown. Extrude the ring 5 mm away from the holed end. The ring size is 30 mm.

Create the profile of Counter Weight shape as shown. In the Counter Weight profile, the two circles are concentric with shaft center and the side lines are radial. The width of Top Form is 28 mm.

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Extrude it 14 mm deep

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Create 3 mm fillets on sharp edges of the Counter Weight.

Create a plane 25 mm from the face of the Counter Weight (the side opposite to the Ring), and create the other part of Counter Weight as shown.

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Delete the portion of the shaft between the pieces of Counter Weight. Now you have two bodies.

Create an offset shaft to join the pieces of the Counter Weight.

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Now Create the Top Form:

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Using the following sketching data:

Now use the Combine command (only if the parts are not joined by the extrude command) under features to rejoin the bodies into one body. Create the Top Form on the other part of the Counter Weight.

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Create 2-mm fillets on the edges of the Top Form. Also create a reference plane in the middle of the Offset Shaft parallel to one of the planes shown above. You need this to align the Crank Shaft and the Connecting Rod in assembly.

The Block Head

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This sketch will be provided to you. Download the part with the sketch and rename it.

Extrude the sketch 30 mm. Add a 10-mm plate to close one end (total thickness of 40 mm). Create a Cam Shaft Boss on the bottom surface

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The center of the boss is coincident with the center of the larger radius on the picture. The boss is extruded up to the top surface of the Block Head. Create the Cam Shaft hole that is 20 mm deep.

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Create the Crank Shaft Boss and Crank Shaft Hole.

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The line connecting the two centers is parallel to the bottom edge. The dimensions and the location of the Rib are up to you.

Create the lower round plate. The depth of the plate is 10 mm:

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Reopen the 22-mm Crank Shaft Hole which was closed by the plate. Leave the Cam Shaft hole as a blind hole. Use part-level Hole Wizard to model the fastener holes.

Engine Block

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Use the same sketch file and create a new model and extrude it 100 mm. Add a 5-mm thick plate at one end.

Create the Crank Shaft Boss and Hole to line up with the Block Head features. The Boss rises 25 mm above the surface.

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Do the same thing with the Cam Shaft Boss and Hole.

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Create the cylinder opening.

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The center of the Cylinder Bore is 5 mm from the edge point of the Crank Shaft Hole which is converted and made into a construction line. It is 45 mm from the very same converted edge.

The Cylinder Boss is 95-mm in height from its base. Its diameter is 10 mm more than the Cylinder Bore. The geometry of the first Fin is shown below:

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The Fin is placed on a plane 2mm from the top of he Cylinder Boss and its thickness is 1 mm as shown below:

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Another 8 fins are patterned in at 10 mm gaps. Finally there is a 10 mm fillet at the base of the Crank Shaft Boss:

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Gasket

The Gasket is 1 mm thick. Create this part in the assembly or cut and paste the sketch from the Block Head.

Fastener Holes

Create the fastener holes using assembly-level Hole Series.

Putting all the parts together

Place all the components in the assembly file (Piston Assembly) and mate them together as required. You must be able to spin the Crank Shaft without collisions. You can also set a motor on Crank Shaft and simulate the motion.

Adding the fasteners

The top part has a counter bore for an M6 size fastener. The last part has a blind threaded hole. Allow the defaults for the details of these features. Calculate (by you not Solid Works) the size of the fastener you need (in general, considering adequate space for any washers and nuts) or allow SW to pick the size. Insert the appropriate kind of fastener using toolbox parts or use Smart Fasteners to do it for you.

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Creating Exploded Views of an Assembly

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On the configuration tab for this assembly, Right Click on the assembly name and chooseNew Exploded View. On the Settings, choose all the hex bolts. In the Direction of Explode, click on a surface whose surface normal would be the direction of explosion. In this case the top surface of the Block Head is good. You can also use any edge in the direction of pull. Then Click on Apply. You can see that the bolts get pulled out by the default amount. Change the amount of pull to suit your need. Then, press Done. This makes the first step of the explosion. Now select the Block Head, the direction of pull, and click on Apply. To adjust the amount of pull, you can also grab the visible arrow and drag it. Again click on Done to form step two of the explode. Continue until the desired state. Note that each assembly configuration can have only one exploded view.

Model the third version of the engine assembly by adding valves, camshaft, follower (push rods), and a crankshaft gear. The Camshaft gear is an integral part of the camshaft. If you need to, alter part dimensions to make this work. The keyword here is “Make it work” – I would not check any dimensions as long as the engine “works”.

Add a Key Pin to the Crank Shaft:

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The height of the Key Pin in 2 mm measured at the center of the Crank Shaft.

Create the Camshaft Mating Gear. Add this “gear” to the engine assembly by fitting it into the Key Pin and sliding it to butt against the Support Shoulder of the Crank Shaft. Alternatively you can grab a gear model from the toolbox and adjust the bore and outside dimensions to approximately match the following gear-substitute.

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Create the Camshaft using the information in the Camshaft eDrawing on the web. Insert the Camshaft into the Camshaft Bore in the assembly. Align the thicknesses of the gears – only one face needs to be aligned.

Create a Valve:

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Make two configurations for the valve: Large, as shown above, and Small, with everything the same except the 24 mm is to be 23 mm.

Make a Cam Follower as shown:

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Modifications to the Engine Block

Move the Top Fin to the Top of the Cylinder (the 2 mm offset must be eliminated without changing the Fin thicknesses or their numbers). Then increase the size of the Fin as shown:

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Suppress the Fin Pattern so you can see things better. Create the Valve Chamber:

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Extrude the Valve Chamber 23 mm. Then, create an 8 mm diameter Valve Stem Jacket. Create the Valve Face Hole.

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And add a 2-mm 45-degree chamfer. Add a 6-mm Valve Stem Hole. Un-suppress the Fins and make sure everything looks right.

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Add the valves and cam followers to the assembly. The Cam centers and the Valve stems have an offset alignment which is OK. Create the gear mates (Camshaft rotates twice as fast as the Crankshaft) and define the cam mates. Define a simulation motor and animate the assembly. Good Luck.

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