Planetary gear set of carrier, beveled planet, and sun wheels with adjustable gear ratio, assembly orientation, and friction losses
Simscape / Driveline / Gears / Planetary Subcomponents
The Sun-Planet Bevel gear block represents a set of carrier, planet, and sun gear wheels. The planet is connected to and rotates with respect to the carrier. The planet and sun corotate with a fixed gear ratio. You control the direction of rotation by setting the assembly orientation, left or right. A sun-planet and a ring-planet gear are basic elements of a planetary gear set. For model details, see Sun-Planet Bevel Gear Model.
You can model the effects of heat flow and temperature change through an optional thermal conserving port. By default, the thermal port is hidden. To expose the thermal port, right-click the block in your model and, from the context menu, select Simscape > Block choices. Select a variant that includes a thermal port. Specify the associated thermal parameters for the component.
Sun-Planet Bevel imposes one kinematic and one geometric constraint on the three connected axes.
rC is the radius of the carrier gear.
ωC is the angular velocity of the carrier gear.
rS is the radius of the sun gear.
ωS is the angular velocity of the sun gear.
rP is the radius of the planet gear.
ωP is the angular velocity of the planet gear.
The planet-sun gear ratio is defined as
gPS is the planet-sun gear ratio. As , .
NP is the number of teeth in the planet gear.
NS is the angular velocity of the sun gear.
In terms of this ratio, the key kinematic constraint is:
for a left-oriented bevel assembly
for a right-oriented bevel assembly
The three degrees of freedom reduce to two independent degrees of freedom. The gear pair is (1,2) = (S,P).
The planet-sun gear ratio, gPS, must be strictly greater than one.
The torque transfer is defined as
τloss is the torque loss.
τs is the torque for the sun gear.
τp is the torque for the planet gear.
For the ideal case, there is no torque loss, that is . Then the torque transfer equation is .
In the nonideal case, . See Model Gears with Losses.
Gear inertia is assumed negligible.
Gears are treated as rigid components.
Coulomb friction slows down simulation. See Adjust Model Fidelity.
|C||Rotational conserving port representing the gear carrier|
|P||Rotational conserving port representing the planet gear|
|S||Rotational conserving port representing the sun gear|
|H||Thermal conserving port for thermal modeling|
Ratio gPS of the planet gear
wheel radius to the sun gear wheel radius. This gear ratio must be
strictly greater than 1. The default value is
Relative orientation of sun and planet gears, controlling their corotation direction. Left or right orientation imply, respectively, that the gears corotate in the same or opposite direction.
The default is
Left — Sun and planet gears rotate in
Parameters for meshing and friction losses vary with the block variant chosen—one with a thermal port for thermal modeling and one without it.
Viscous friction coefficient
μS for the sun-carrier
gear motion. The default is
From the drop-down list, choose units. The default is
Thermal energy required to change the component temperature
by a single degree. The greater the thermal mass, the more resistant
the component is to temperature change. The default value is
Component temperature at the start of simulation. The initial
temperature alters the component efficiency according to an efficiency
vector that you specify, affecting the starting meshing or friction
losses. The default value is
For optimal simulation performance, use the Meshing Losses > Friction model parameter default setting,
No meshing losses - Suitable
for HIL simulation.