Internal Geneva Mechanism
The Geneva drive is a gear mechanism that translates a continuous rotation movement into intermittent rotary motion. The rotating drive wheel is usually equipped with a pin that reaches into a slot located in the otherwheel (driven wheel) that advances it by one step at a time. The angle by which the drive wheel has to rotate to effect one step rotation of the driven wheel is always smaller than 180° in an external Geneva drive and always greater than 180° in an internal one, where the switch time is therefore greater than the time the driven wheel stands still.
2D CAD drawings to create the 3D model of the internal Geneva mechanism
Create 3D models for driver and driven wheels
Assembled model
Performing motion analysis by rotating the driver wheel at 10rpm. We obtained the following plots.
Contact force (between driving and the driven wheel) as a function of time
Angular displacement of driven wheel.
Image for precise contact selection
60 Frames per second for 10 rpm
120 Frames per second for 20 Rpm
Observations
- Contact force is proportional to speed of driver it increases with increase in the speed.
- Contact force between driver and driven wheel is highest at the initial stage, when it enters the slot due to the movement of the driven wheel.
- Precise contact gives more accurate results as seen from the above plots.
- In angular velocity plot we see peak when it enters the slot and as the motion progresses there is reduction in the velocity.
- The displacement is intermitent in nature hence the angular displacement plot repeats itself at regular intervals.
- Here for one rotation of the driver wheel the driven wheel rotates by 90 degree.
- Hence for one complete rotation of driven wheel , 4 rotations of the driver wheel is required.
Note 》 i have attatched drawings in image format please check it.