Torque Converter

Torque Converter component

The Torque Converter component models a torque converter acting between the two connector ports (Pump and Turbine) as a function of the speed ratio.  Directionality is determined on which port is receiving power. Forward power flow means power flowing from pump to turbine. Reverse power flow means power flowing from turbine to pump.

A torque converter is a hydrodynamic connector between the engine and the rest of the driveline. It is comprised of a pump impeller on the driven side, a turbine on the transmission side and hydraulic fluid within a sealed case. When driven, the pump drives the fluid into the turbine, causing it to rotate, thus transmitting the power smoothly from the engine to the driveline. It also has the advantage of “multiplying” the torque to the driveline at low speeds, maximizing the torque to the wheels at start-up.

Due to the complex nature of the torque converter dynamics, tables of measured data are used. This component uses the following characteristics:

Torque Ratio $\frac{{\mathrm{\tau }}_{t}}{{\mathrm{\tau }}_{p}}$ vs Speed Ratio $\frac{{\mathrm{\omega }}_{t}}{{\mathrm{\omega }}_{p}}$

Load Capacity $C$ vs Speed Ratio $\frac{{\mathrm{\omega }}_{t}}{{\mathrm{\omega }}_{p}}$

Load capacity may be defined as:

or

Note:  It is possible for the power flow to be reversed. For example, during deceleration of the vehicle, inertial energy is transmitted back through the transmission to the engine. In this situation, the turbine is pumping and the pump is acting as a turbine. Since they were not designed to work optimally this way, the torque converter has very different characteristics. This is accommodated in the lookup table by providing torque ratio and capacity data for speed ratios , typically up to about 5.

Equations

Hydrodynamic Equations

,   $x$ ∈ $\left\{p,t\right\}$

Where ${\mathrm{ϕ}}_{\mathrm{fp}}$  and ${\mathrm{\varphi }}_{\mathrm{ft}}$  are the absolute rotation angles of the $\mathrm{pump}$ and $\mathrm{turbine}$ flanges, respectively, and

,

and

${\mathrm{K}}_{\mathrm{τ}}$



and

Torque Converter Equations

Power Loss:

The power loss (${P}_{\mathrm{loss}}$ ) is calculated as:

${\mathrm{\omega }}_{p}$



Connections

 Name Condition Description ID $\mathrm{pump}$ - Pump shaft pump $\mathrm{turbine}$ - Turbine shaft turbine support support $-$ Real output port for power loss lossPower data source = [input port] Conditional real input port for the torque ratio torque_ratio $\mathrm{Capacity}$ data source = [input port] Conditional real input port for the capacity capacity data source = [input port] Conditional real output port for the speed ratio speed_ratio

Parameters

Symbol

Condition

Default

Units

Description

ID

capacity unit

-

-

Defines the torque converter (TC) capacity unit. Two options are available:

or

TorqueConverterCapacityUnitMode

data source

-

GUI

-

Defines the source for the TC data:

 • entered via GUI [GUI]
 • by an attachment [attachment]
 • by an external file [file]
 • an input port [input port]

When [input port] option is chosen, two input ports (for torque ratio, ${K}_{\mathrm{\tau }}$, and capacity, C) are enabled. Also, an output port of speed ratio () is activated.

datasourcemode

${J}_{t}$

-

$0.1$

$\mathrm{kg}·{m}^{2}$

Turbine inertia

Iturbine

${J}_{p}$

-

$0.1$

$\mathrm{kg}·{m}^{2}$

Pump inertia

Ipump

$d$

-

$0$

Linear damping

DampingFactor

Use support

-

$\mathbf{false}$

-

Enables/disables the support flange

useSupport

$\mathrm{data}$

data source = GUI

$\left[0,1,1\right]$

or

Defines TC characteristics.

The columns are:

[${r}_{\mathrm{ω}}$    ${\mathrm{K}}_{\mathrm{τ}}$ (${r}_{\mathrm{ω}}$ )     $\mathrm{C}$ (${r}_{\mathrm{ω}}$ )]

Note: The rows of the array are ordered according to speed ratio, ${r}_{\mathrm{\omega }}$, with the first row having the smallest value |${r}_{\mathrm{\omega }}$|

tcdTable

data source = attachment

-

data

data source = file

-

fileName

columns

data source = attachment or file

$\left[2,3\right]$

-

Defines the corresponding data columns used for torque ratio, ${\mathrm{K}}_{\mathrm{\tau }}$, and capacity, C

columns

smoothness

-

Table points are linearly interpolated

-

Defines the smoothness of table interpolation. There are two options:

 • Table points are linearly interpolated
 • Table points are interpolated such that the first derivative is continuous

smoothness

Initial Conditions

 Symbol Condition Default Units Description ID ${\mathrm{ω}}_{\mathrm{pump}}$ - $-$ $\frac{\mathrm{rad}}{s}$ Initial angular velocity of the pump w_pump ${\mathrm{\omega }}_{\mathrm{turbine}}$ - $-$ $\frac{\mathrm{rad}}{s}$ Initial angular velocity of the turbine w_turbine

Note: The pump angular velocity, ${\mathrm{\omega }}_{P}$ , must be greater than zero.