CVT

Continuously Variable Transmission component

The CVT component models the Continuously Variable Transmission.  The CVT is a type of transmission that allows changes in gear ratio without the “bumps” experienced with discrete gear changes. Mechanically, a CVT has two conical pulleys, connected by a belt drive. Changes in ratio are effected by adjusting the gap between the two sides of the pulleys, thus changing the relative diameters of the pulley and hence the gear ratio.

Kinematic Equation

Ideal Case

${\mathrm{\varphi }}_b \= r·{\mathrm{\ϕ}}_a$ 

$r · {\mathrm{\τ}}_b\= -{\mathrm{\τ}}_a$

Non-Ideal Case

${\mathrm{\varphi }}_b \= r_{ }·\mathrm{\κ} · {\mathrm{\ϕ}}_a$ 

$r · {\mathrm{\τ}}_b \= -\left({\mathrm{\tau }}_a-{\mathrm{\tau }}_{\mathrm{loss}}\right)$

Where

$\mathrm{\&kappa;}\&equals;\left\{\begin{array}{cc}1-S_r& {\mathrm{\&omega;}}_a·{\mathrm{\tau }}_a\ge 0 \\ 1-\frac{1}{S_r} & {\mathrm{\omega }}_a·{\mathrm{\tau }}_a<0\end{array}\right.$

and $S_r$ is the slip number (user input), also the torque loss is defined as

${\mathrm{\tau }}_{\mathrm{loss}}\&equals;\left\{\begin{array}{cc}\&lpar;1-{\mathrm{\&eta;}}_{}\&rpar; · {\mathrm{\&tau;}}_a& {\mathrm{\omega }}_a·{\mathrm{\tau }}_a\ge 0 \\ \&lpar;1-\frac{1}{\mathrm{\&eta;}}\&rpar;·{\mathrm{\&tau;}}_a& {\mathrm{\omega }}_a·{\mathrm{\tau }}_a<0\end{array}\right.$

where $\mathrm{\eta }$ is the torque efficiency (user input). Also

${\mathrm{\omega }}_a$ = $\frac{\&DifferentialD;}{\&DifferentialD; t} {\mathrm{\varphi }}_a \&equals;{\stackrel{·}{\mathrm{\&varphi;}}}_a$

Connections 

Parameters

See Also

Driveline Library Overview

MapleSim Library Overview

1-D Mechanical Overview

CVT and Torque Converter