Vibration design for a Single linear engine

[Busa20]

hello,

we made a single linear engine(not a motorcycle engine), I just work for vibration design. but I find the Engine exciting force is too big and I don't know what kinds of monts can fits it.

anybody have the experience? Thanks!

 

[BrianPetersen]

Single cylinder engine?

Balancing the first-order vibration requires at least one balance shaft rotating at crankshaft speed but in the opposite direction, and preferably two such shafts spaced equally on either side of the crankshaft.

It can also be done the way the Ducati Supermono engine did it ... basically by making a "fake" second cylinder at 90 degrees (the Supermono used another connecting rod and a swinging mass) and arranging the inertia of that mechanism to match the piston and con-rod, and arranging the main counterweight on the crank to offset all of this.

A single cylinder engine without mechanical counterbalancing is always going to be rough.

 

[BrianPetersen]

Couple other small things. How big and what kind of RPM are we talking about. A small high-revving single is a different ball game from a big low-revving single because of the time between power strokes.

Lightest possible pistons and rods will minimize the vibration.

 

[Busa20]

thank you,BrianPetersen

yes ,it is a Single cylinder engine,15KW 1500Reciprocate per minute. our linear engine has not crankshaft, just a Reciprocating shaft.

Im sorry, my english is not very well, Im from china.

 

[GregLocock]

What mass is the engine? What mass are the reciprocating components? What do you want your engine mounts to actually do?



Cheers

Greg Locock

SIGlease see FAQ731-376 for tips on how to make the best use of Eng-Tips.

 

[Busa20]

thank you,BrianPetersen?GregLocock?

I attached a doc, Please take a look at it.

 

[GregLocock]

Is this homework? Are you a student?

Cheers

Greg Locock

SIGlease see FAQ731-376 for tips on how to make the best use of Eng-Tips.

 

[Busa20]

GregLocock,

I work at a test department, it is not homework,
just a real engine. do you think the Amplitude and Acceleration are ok? thanks

 

[BrianPetersen]

I cannot comment, because I can't read Chinese.

Also, what is "okay" depends on the application, which we know nothing about. If you are using this engine in a remote application with no people and no sensitive instruments anywhere in the area, then who cares how much vibration it makes. If you are using this engine to (say) reposition a telescope in an observatory, then even the tiniest vibration will make the image fuzzy. If you are using this engine in a luxury automobile, the amount of vibration that can be tolerated is very different from what can be tolerated in a fork-lift truck.

 

[Busa20]

thanks!BrianPetersen,

you are right. the engine is a prototype, we wanna use it at a series HEV as a power.

does anybody have this experience?

 

[EdDanzer]

Are you measuring this with engine mounted solidly or are there rubber isolators between the motor and the base? Is the engine a 2 cycle or 4 cycle, gas or diesel fueled and how are you converting the piston movement to work?

Ed Danzer

http://www.danzcoinc.com

http://www.dehyds.com