MBD analysis of internal geneva mechanism using solid works.
Aim:
To model and analyse the motion of internal geneva mechanism using solid works at various speed parameters. To obtain the plot of contact force between driving and the driven wheel, angular Displacement of the driven wheel, and compare the above plots with and without the precise contact.
Geneva mechanism:
Geneva mechanism is a type of gear mechanism which transforms the continuous rotatory motion into intermediate motion of rotation. There are two types of geneva mechanisms. They are,
a) External geneva mechanism.
b) Internal geneva mechanism.
- External geneva mechanism:
The external geneva mechanism is a type of geneva mechanism in which the driver wheel and the driven wheel are connected externally.
b. Internal geneva mechanism:
The internal geneva mechanism is one in which the driver wheel is attached internally with the driven wheel by providing paths on the driven wheel.
Modelling internal geneva mechanism:
The modelling of internal geneva mechanism includes the modelling of driver wheel and the driven wheel. The driver wheel and the driven wheel are designed and modelled based on the following parameters.
The picture of the 3d model of driver wheel in the internal geneva mechanism using solid works is shown below.
Fig.1 Driver wheel
The image of 3D model of the driven wheel in internal geneva mechanism using solid works is placed below.
Fig.2 Driven wheel
These two 3D models are assembled in solid works to perform the motion analysis.
Fig.3 Assembly of driver and driven wheel
Motion analysis:
The motion analysis was done with various parameters. Initially, the parameters with 60 fps and 10 rpm is set. The angular displacement of the driven wheel and the angular velocity of the driver wheel at 10rpm is analysed. The contact force between driver and driven wheel is analysed with and without precise setting at 10rpm.
The precise setting with 60fps is shown below,
The plot that explains the contact force between driver and the driven wheel with and without precise contact is shown below.
At 10rpm and 60fps with precise contact,
At 10rpm and 60fps without precise contact,
The angular displacement of the driven wheel at 10rpm and 60fps is shown below,
The angular velocity of the driver wheel at 10rpm and 60fps is shown below,
The next set of analysis was done with 20rpm and at 120fps. The angular displacement of the driven wheel and the angular velocity of the driver wheel is analysed. The contact force between driver and the driven wheels with and without the precise contact was analysed.
The precise setting with 120fps is shown below,
The plot that explains the contact force between driver and the driven wheel with and without precise contact is shown below.
At 20rpm and 120fps with precise contact,
At 20rpm and 120fps without precise contact,
The angular displacement of the driven wheel at 20rpm and 120fps is shown below,
The angular velocity of the driver wheel at 20rpm and 120fps is shown below,
CAD models:
The CAD models used in the motion analysis of the internal geneva mechanism is changed into .zip file and attached in the following google drive link,
https://drive.google.com/
Motion mechanism:
The motion video of the internal geneva mechanism is provided by the following link,
Conclusion:
The various analysis can be done on the observed plots from the motion analysis of internal geneva mechanism.
- It was observed that the contact force of the mechanism reaches its peak when the driver wheel reaches the end of the slot.
- The angular displacement differ subsequently with increase in speed of the driver wheel.
- The angular velocity rises when it enter into the slot and it decreases when it reaches out of the slot in the driven wheel.