Lepelletier 6-Speed

Model six-speed Lepelletier transmission based on planetary gear and Ravigneaux gear

Library

Transmission Templates

Description

The Lepelletier 6-Speed transmission block is a subsystem that models a standard automotive transmission having six selectable forward gear ratios and a single reverse gear ratio. The Lepelletier gearbox is constructed by connecting a planetary gear to a Ravigneaux gear. The sun of the planetary gear is connected to the housing and cannot rotate. The carrier of the planetary gear is connected, by clutches (A and C), to the large and small sun wheels of the Ravigneaux gear, respectively. The input, or driver, shaft is always connected to the ring of the planetary gear and can simultaneously be connected to the carrier of the Ravigneaux gear using a separate clutch (B). The output, or driven, shaft is connected to the ring of the Ravigneaux gear. The five transmission clutches A, B, C, D, and E are modeled with Controllable Friction Clutch blocks. You connect the transmission along a driveline axis, with the In and Out connector ports representing the input and output shafts, respectively.

This transmission subsystem has two independent internal degrees of freedom and therefore requires that two clutches be locked at any instant in order to achieve a unique drive ratio from the input shaft to the output shaft. The clutch schedule and the corresponding drive ratios are provided in the block subsystem's clutch schedule table. You disengage this transmission by unlocking all its clutches simultaneously.

Using Transmission Template Subsystems

A Transmission Template block is not library-linked. Once you make a copy in your model, you can use it as is. You can also open and customize it as a subsystem by reconfiguring the properties of the individual Gear, Controllable Friction Clutch, and Inertia blocks.

You must provide a five-component Simulink® vector signal of the normalized pressures applied to each clutch. The order of the pressure signals is ABCDE.

Default Inertia, Gear, and Clutch Settings

All the Controllable Friction Clutch blocks in this Transmission subsystem have their default settings. The Gear ratios are reset to nondefault values.

To prevent dynamical singularities, some of the gear wheels have attached Inertia blocks with small default inertias in the 10–2 kg-m2 (kilogram-meters2) range.

Subsystem Parameters

The gear ratio is the ratio of gear wheel radii r, gear wheel teeth N, or torque transferred τ. The gear ratio is the reciprocal of the ratio of the angular velocities ω transferred. The drive ratio is the effective gear ratio, output to input, of the entire transmission.

The basic Lepelletier 6-speed transmission gear ratios are

gRS = Planetary ring/sun gear ratio = rpR/rpS = NpR/NpS

gRSl = Ravigneaux ring/large sun gear ratio = rR/rSl = NR/NSl

gRSs = Ravigneaux ring/small sun gear ratio = rR/rSs = NR/NSs

This table specifies the locked (L) and free (F) clutches A, B, C, D, and E for each gear setting. A free clutch is completely disengaged.

Lepelletier 6-Speed Clutch Schedule

Gear SettingDrive RatioABCDE
Reverse-gRSl·(1+gRS)/gRSLFFLF
1gRSs·(1+gRS)/gRSFFLLF
2(1+gRS)(gRSs+gRSl)/[gRS·(1+gRSl)]FFLFL
3(1 + gRS)/gRSLFLFF
4gRSs·(1 + gRS)/[gRSs·(1 + gRS) - 1]FLLFF
5gRSl/[gRSl + 1/(1 + gRS)]LLFFF
6gRSl/(1 + gRSl)FLFFL

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