|
Navigation: Library > Iconic Diagrams > Mechanical > Rotation > Gears > transmission |
  
|
Iconic Diagrams\Mechanical\Rotation\Gears
Ideal
Lossy
Domains: Continuous. Size: 1-D. Kind: Iconic Diagrams (Rotation).
This models represents any type of gearbox with two shafts rotating in the same direction. The gear is ideal, i.e., it does not have inertia or friction. The gear has one fast moving shaft and one slow moving shaft. The gearbox has a reduction of i : 1 and thus a transmission ratio of 1/i.
The causality of this model is always mixed: one port has a torque out causality while the other has an angular velocity out causality:
p_in.T = 1/i * p_out.T
p_out.omega = 1/i * p_in.omega
or:
p_out.T = i * p_in.T
p_in.omega = i * p_out.omega
Ports |
Description |
p_in p_out |
Input port Output port |
Causality |
|
p_in not equal p_out |
|
Parameters |
|
i |
gearbox reduction, i > 1 |
This models represents any type of gearbox with two shafts rotating in the same direction. The gearbox has a reduction of i : 1 and thus a transmission ratio of 1/i.
p_in.omega = i * p_out.omega
Unlike the model of an ideal gearbox, this model includes power loss. The power loss is represented by the efficiency, where the efficiency is defined as the output power divided by the input power:
eff = Pout / Pin
The efficiency is a value between zero and one and given by the gearbox manufacturer. If you do no know the value, a good guess is a power loss of 3% per stage (eff = 0.97). If your gearbox for example contains three stages, you can set the efficiency as:
eff = 0.97*0.97*0.97 = 0.91
Ports |
Description |
p_in p_out |
Input port Output port |
Causality |
|
p_in not equal p_out |
|
Parameters |
|
i eff |
gearbox reduction [-], i > 1 gearbox efficiency [-] |
This models represents any type of gearbox with two shafts rotating in the same direction. The gearbox has a reduction of i : 1 and thus a transmission ratio of 1/i.
p_in.omega = i * p_out.omega
Unlike the model of an ideal gearbox, this model includes rotational inertia and power loss. The inertia is defined at the input axis. If the gearbox manufacturer gives the inertia at the output axis you can calculate the inertia at input axis as:
Jinput = Joutput/i^2
The power loss is represented by the efficiency, where the efficiency is defined as the output power divided by the input power:
eff = Pout / Pin
The efficiency is a value between zero and one and given by the gearbox manufacturer. If you do no know the value, a good guess is a power loss of 3% per stage (eff = 0.98). If your gearbox for example contains three stages, you can set the efficiency as:
eff = 0.97*0.97*0.97 = 0.91
Ports |
Description |
p_in p_out |
Input port Output port |
Causality |
|
preferred angular velocity out p_in preferred angular velocity out p_out |
|
Parameters |
|
i J eff |
gearbox reduction [-], i > 1 moment of inertia [kgm^2] gearbox efficiency [-] |