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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 τtτp vs Speed Ratio ωtωp

Load Capacity C vs Speed Ratio ωtωp

Load capacity may be defined as:

C = τpωp2N · mrpm2                or             C = ωpτprads12N · m

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 > 1, typically up to about 5.

Equations

Hydrodynamic Equations

 

ϕx  =  ϕfx  ϕsupport      use Support = true0otherwise  ,   x ∈ p,t

 

Where ϕfp  and ϕft  are the absolute rotation angles of the pump and turbine flanges, respectively, and

ωp = ⅆⅆ t ϕp  =ϕ·p 

ωt = ⅆⅆ t ϕt  =ϕ·t 

rω  = ωtωp     , ωp >0

ω^P =  ωp  ωp  ωtωt  ωt  > ωp     and    ω^T  =  ωt  ωp  ωtωp  ωt  > ωp

 

τ^te + Kτrω  · τ^pe = 0

τ^pe =  ω^p2Crω 2  mode = mode 1[(2 π60)ω^p]2Crω   mode = mode 2

 

τpe =  τ^pe  ωp    ωtτ^te  ωt   >  ωp     and    τTe  =  τ^te  ωp    ωtτ^pe  ωt   > ωp

 

τte + τpe + τse = 0

 

Torque Converter Equations

Jt  · ω·t +12d · ωt  +  τte  + τt= 0

Jp  · ω·p +12d · ωp  +  τpe  + τp= 0

τsupport =  τte+τpe  +  12d · ωp  + 12d · ωt

Power Loss:

The power loss (Ploss ) is calculated as:

Ploss  =   τp · ωp+ τt · ωt 

Connections 

Name

Condition

Description

ID

pump

-

Pump shaft

pump

turbine

-

Turbine shaft

turbine

support

use support=true

Conditional Support Flange

support

Loss Power

Real output port for power loss

lossPower

Torque ratio

data source = [input port]

Conditional real input port for the torque ratio

torque_ratio

Capacity

data source = [input port]

Conditional real input port for the capacity

capacity

Speed ratio

data source = [input port]

Conditional real output port for the speed ratio

speed_ratio

 

Parameters

Symbol

Condition

Default

Units

Description

ID

capacity unit

-

radsN · m12

-

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

radsN · m12 

or

N · mrpm2

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, Kτ, and capacity, C) are enabled. Also, an output port of speed ratio (rω ) is activated. 

datasourcemode

Jt

-

0.1

kg·m2

Turbine inertia

Iturbine

Jp

-

0.1

kg·m2

Pump inertia

Ipump

d

-

0

N · mrads

Linear damping

DampingFactor

Use support        

-

false

-

Enables/disables the support flange        

useSupport

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

data

data source = GUI

  0,1,1 

 

 

 

 

 

 

 

 

 

rads,  N·m12

or

rads,  , N · mrpm2

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Defines TC characteristics.  

The columns are:

[rω    Kτ (rω )     C (rω )]

Note: The rows of the array are ordered according to speed ratio, rω, with the first row having the smallest value |rω|

tcdTable

data source = attachment

  -

data

data source = file

  -

fileName

columns

data source = attachment or file

  2,3

 

-

Defines the corresponding data columns used for torque ratio, Kτ, 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

ωpump

-

rads

Initial angular velocity of the pump

w_pump

ωturbine

-

rads

Initial angular velocity of the turbine

w_turbine

 

Note: The pump angular velocity, ωP , must be greater than zero.

 

See Also

MapleSim Driveline Library Overview

MapleSim Library Overview

1-D Mechanical Overview

CVT and Torque Converter

 

 

References

D. Hrovat and W.E. Tobler. “Bond graph modeling and computer simulation of automotive torque converters,” Journal of the Franklin Institute. Volume 319, Issues 1-2, January-February 1985, pp 93-114.


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