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Planetary gear set constraints

13 REPLIES 13
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Message 1 of 14
kgill147
4596 Views, 13 Replies

Planetary gear set constraints

Hi guys,

 

I'll start by saying I am self taught so there is most likely something I am missing that I could have learned in a thousand dollar class.  However, since I see a bunch of plantetary gear issues, I know I'm not the only one.  Reason I am posting a new question on this topic is because I think my gear set is a little different than the ones I keep seeing.  Hope you can help!

 

I have attached the .iam assembly and the .ipt parts are to follow. Hard to just explain this with words. (If you cant open this assembly, please let me know what else you need from me to be able to.)

 

First off, I'm not very concerned with the teeth meshing properly at this stage. I just want to get the rotational constraints correct first.  There are two situations that I am trying to work out, and I think I took care of the first one. Its the second which causes the problem.

 

Situation 1: Blue carrier is grounded.

Input: Rotate purple sun gear.

Result: red planets turn the orange planets which turn the green sun(green sun to purple sun ratio = 1:1 but in the opposite direction)

 

Situation 2: Purple sun is grounded (Blue carrier is released)

Input: rotate the blue carrier

Result: I want the planets to still be able to rotate, and basically be driven by the purple sun which is being held. This should then drive the green sun to rotate in the same direction as the blue carrier gears.

 

The issue here is clearly that the red planets will not rotate since the purple sun is grounded.  What should the constraints be instead of a simple rotational motion constraint? In a perfect world, I would like to not have to ground the purple sun, and only have the purple sun rotate when I specifically rotate it. The main input to this system is rotating the blue carrier gear. The purple sun is simply a control/variant.

 

I know this is a lot, but its hard to explain everything I need this system to do.  Thank you for your time, and I would appreciate any help you can lend.  

13 REPLIES 13
Message 2 of 14
kgill147
in reply to: kgill147

more parts

Message 3 of 14
kgill147
in reply to: kgill147

more parts

Message 4 of 14
kgill147
in reply to: kgill147

last parts and a picture

Message 5 of 14
JDMather
in reply to: kgill147

Do  you have Inventor Professional with Dynamic Simulation?


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Message 6 of 14
JDMather
in reply to: kgill147

Did you give up on this?

Was this a school assignment?


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Message 7 of 14
kgill147
in reply to: kgill147

No, this is my job.  I dont know what dynamic simulation is. I dont believe I have it. It is not Inventor Professional. Is it possible to get this system to work properly?

Message 8 of 14
JDMather
in reply to: kgill147

I have done planetary gear systems before in Inventor with only the assembly Motion Constraints - but it is easier for me in Environments>Dynamic Simulation.

 

I will see what I can do in the next couple of days (hopefully this afternoon).

To get a question like this answered - you will have to be persistent - keep bumping it to the top.

If you disappear it could be you are a student with an assignment that is too late to turn in.


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Message 9 of 14
kgill147
in reply to: JDMather

I got ya. Thank you for your help.

Message 10 of 14
JDMather
in reply to: kgill147

I will have to deconstruct this thing step-by-step because there are basic errors in math.

incorrect dimensions.PNG

 

You should not use numbers like 1.333 - use 1 + 1/3 or better yet - use bolt pitch circle diameters.

 

You should not use numbers to center dimensions - use geometry and midpoint coincident or symmetry constraints.

(1.3333/2 is not equal to .66667)


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Message 11 of 14
kgill147
in reply to: JDMather

Ok thanks. Yea, I tried to explain that to my boss but he insisted that it did not matter.

Thanks,
Kevin Gill

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Message 12 of 14
356213
in reply to: kgill147

16 Teeth Sun gear 32 Teeth Planet gears 80 Teeth Ring gear 3 Planets can't mesh them

Message 13 of 14
JDMather
in reply to: 356213

@356213 

No files Attached?


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Message 14 of 14
JDMather
in reply to: 356213

@356213 


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