Looking for a Gearmotor; How Much Torque to Close this door?

[Hes]

I'm trying to find a gearmotor that applies enough torque to close this door.

Door Mass = 136lbs
Door Dims = 40in width x 85in height
Time to close = 60sec
Door's rotation = 180 degrees

Any tips and advice would truly be appreciated.

 

[jedishrfu]

Do you have an actual door in mind?

Where is the door hinge axis?

If this is a real door you might simply measure the force needed to close it at the point where you plan to connect the lever arm.

 

[Asymptotic]

I can't see from the drawing how this could operate as a door closer. Is the gearmotor supposed to have a rotary output?
Is closure speed fixed? 180° open to closed in 60 seconds (2°/second) is rather slow over much of the closure range.
Take care to rescue the angel; crushing one in a door mechanism is considered poor engineering practice.

 

[tygerdawg]

Much more info needed for any kind of intelligent answer:

• This figure is plan (top) view, correct? If not, specify it so the community can determine the direction of the gravity vector. Gravity may add force requirements.
• Is the door hinged? If hinged, where is the hinge? Specify it.
• If no hinged, about what axis does the door pivot? Specify it.
• door mass ≠ lbs. You better figure that out first.
• Torque = (mass moment of inertia) x (angular acceleration)
• (mass moment of inertia) will likely be estimated from inertia primitive formulas and modified with parallel axis theorem. Look 'em both up.
• (angular accel) is estimated α ≅ Δ(angular velocity)/Δ(time to accelerate)
• Add a bunch of fudge factors for safety, friction, gravity effects, windage effects, robustness, etc., and that will give your peak torque. Size the gearmotor for that.

 

[Hes]

Much more info needed for any kind of intelligent answer:

• This figure is plan (top) view, correct? If not, specify it so the community can determine the direction of the gravity vector. Gravity may add force requirements. Yes this is top view
  
• Is the door hinged? If hinged, where is the hinge? Specify it. Yes on the right side.
  
• If no hinged, about what axis does the door pivot? Specify it.
• door mass ≠ lbs. You better figure that out first.
  
• Torque = (mass moment of inertia) x (angular acceleration)
• (mass moment of inertia) will likely be estimated from inertia primitive formulas and modified with parallel axis theorem. Look 'em both up.
• (angular accel) is estimated α ≅ Δ(angular velocity)/Δ(time to accelerate)
• Add a bunch of fudge factors for safety, friction, gravity effects, windage effects, robustness, etc., and that will give your peak torque. Size the gearmotor for that.

Thank you very much for your help. I kept struggling with finding the torque, using a different equation. That mass moment of inertia is going to help me a lot

 

[jedishrfu]

The moment of inertia won't anyone here wanting to help if we don’t know the axis of rotation for the door.

 

[Hes]

The moment of inertia won't anyone here wanting to help if we don’t know the axis of rotation for the door.

the axis of rotation is the end of the door on the right side