Internal Geneva Mechanism
AIM:-
- To create 3D models for Driver and Driven Wheels
- To create assemble the driver an driven wheel in order to show Internal Geneva Mechanism
- To do motion Study of internal geneva mechanism ( with and without Precise Contact)
- To make a plot of the driven wheel's angular displacement and discuss the results in different cases
- To make a plot of the driver wheel's angular velocity and discuss the results
INTRODUCTION:-
The Geneva drive or Maltese cross is a gear mechanism that translates a continuous rotation movement into intermittent rotary motion.The Geneva Mechanism translates a continuous rotation into an intermittent rotary motion. The rotating Drive wheel has a pin that reaches into a slot of the driven wheel . The drive wheel akso has a raised circular blocking disc that locks the driven wheel also has a raised circular blocking disc that locks the driven wheel in position between steps.
There are three basic types of Geneva Mechanism namely external, internal and spherical . The spherical Geneva Mechanism is very rarely used . In the simplest form , the driven wheel has four slots and hence for each rotation of the drive wheel it advances by one step of 90 °. If the driven wheel has n shots, it advances by 360°/n per full rotation of the drive wheel.
In an inetrnal Geneva Drive the axis of the drive wheel of the internal drive is supported on only one side. 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 is always greater than 180° in an internal one. The external form is the more common, as it can be built smaller and can withstand higher mechanical stresses.
MODELING AND ASSEMBLY:-
First the part are individually created and then they are assembled using the appropriate mates.
Images of the parts and assembly is given below
Internal Geneva Driver Wheel
Internal Geneva Driven Wheel
Assembly
RESULTS:
Case1:
10rpm with Precise contact (60fps)
Contact Force between Driver and Driven wheel
Angular Velcoity Of Driver Wheel
Angular Displacement Of Driven Wheel
Case2:
10rpm without Precise Contact(60fps)
Contact Force between Driver and Driven wheel
Angular Velcoity Of Driver Wheel
Angular Displacement Of Driven Wheel
Case3:
20rpm with Precise Contact(120fps)
Contact Force between Driver and Driven wheel
Angular Velocity Of Driver Wheel
Angular Displacement Of Driven Wheel
Case4:
20rpm without Precise Contact(120fps)
Contact Force between Driver and Driven wheel
Angular Velcoity Of Driver Wheel
Angular Displacement Of Driven Wheel
YOUTUBE LINK OF ANIMATION VIDEO:-
Drive Link:-
https://drive.google.com/file/d/1VnU5VZwLXfj-1GmBLaI0lWa7GLeAMHR9/view?usp=sharing
CONCLUSIONS:
- The Precise Contact gives a more accurate result as we can see that the curves in the plot becomes less fluctuating and smooth. Moreover the values obtained from the precise contact plot are more flexible and true.
- When the driver tries to enter in the slot of the driven wheel it faces a jerk as the entry is not smooth therefore , we can see also from the plot that at the entry to the slot gives rise to a sudden increase in the contact force which decreases as the driver's spindle enters into the slot.
- Contact Force Increases with increase in rpm