Clutch schedule for a seven-speed Lepelletier transmission
Simscape / Driveline / Transmissions
The 7–Speed Lepelletier block consists of one planetary gear set, one Ravigneaux gear set, and six disk friction clutches. The transmission base shaft connects to the ring gear of the planetary gear set. The follower shaft connects to the ring gear of the Ravigneaux gear set. Three of the clutches control the power-flow paths between the planetary and Ravigneaux gear sets. The other three clutches serve as brakes, grounding various gears of the Ravigneaux set to the transmission housing.
This diagram shows a seven-speed Lepelletier transmission. The labels for the gear components are superimposed on the input and output gears. The table lists the gear and clutch components that are labeled in the diagram.
|C||Planet gear carrier|
|SL||Large sun gear|
|SS||Small sun gear|
|A–C||Forward clutches that control the power-flow path|
|D–F||Forward, braking clutches|
Drive Ratios, Clutch Schedule, and Power Flow
The drive ratio between the transmission input and output shafts follows from the elementary gear ratios specified for the gear blocks. The elementary gear ratios are
NPR is the number of teeth in the planetary ring gear.
NPS is the number of teeth in the planetary sun gear.
NRR is the number of teeth in the Ravigneaux ring gear.
NRSL is the number of teeth in the Ravigneaux large sun gear.
NRSS is the number of teeth in the Ravigneaux small sun gear.
The table shows the clutch schedule, drive-ratio expressions, drive-ratio default values, and the power-flow diagrams for each gear of the 7-Speed Lepelletier block.
The letters in the clutch schedule columns denote the brakes and clutches. A value
1 denotes a locked state and a value of
an unlocked state. The clutch schedule generates these signals based on the Gear
port input signal. The signals are scaled through a Gain block and used as actuation
inputs in the clutch blocks.
The power-flow diagrams show the power-flow paths between input and output shafts for each gear setting. Power flow is shown in orange. Connections to the transmission housing (a mechanical ground) are shown in black.
|Gear||Clutch Schedule||Drive Ratio Equation||Default Ratio||Power Flow|
Gear — Numerical input for the gear
Specify -1 for reverse, 0 for neutral, and 1–7 for the forward gears.
B — Base interface
Conserving port associated with the base shaft.
F — Follower interface
Conserving port associated with the follower shaft.
Initial gear — Gear state at the beginning of simulation
Neutral (default) |
Sets the initial engagement or disengagement of the clutches using the clutch schedule. When the transmission is in neutral, there is no power flow from the base shaft to the follower shaft.