Environmental Engineering Reference
In-Depth Information
M/G and T/C become a complete subassembly that would be delivered to the
transmission plant for assembly to the final product. Vehicle powertrain assembly
starts with the transmission, followed by integration with a fully dressed engine,
including all necessary electronic modules and wiring harnesses.
4.1.3.2 Wilson type
The Wilson stepped automatic transmission is simpler than the Simpson type
because there is no counter shaft. The 5-speed Wilson type, however, requires three
epicyclic gear sets, clutches and brakes along with an OWC.
Figure 4.5 is the schematic for a Wilson type automatic having an M/G for
hybrid functionality mounted to the torque converter impeller as was the case for
the Simpson type. The M/G with torque converter would again be a complete
assembly that is aligned and balanced at the manufacturing plant and delivered to
the transmission assembly plant.
Electrical
Stator
C1
B1 B2
B3
LUC
Rotor
OWC
C2
C3
Input
Output
Figure 4.5 Wilson type stepped automatic transmission
Both the Wilson type and the Simpson type rely on OWCs for their operation.
If it were possible to eliminate the OWCs, the transmission would have fewer
components and be simpler to build.
4.1.3.3 Lepelletier type
In 1990, a patent was filed by Lepelletier that described how to build a stepped ratio
automatic transmission without OWCs. To realize this, a single planetary gear set
and a compound or Ravigneaux planetary gear set are combined along with five
shift elements. In the process, a 6-speed transmission evolved.
The Lepelletier transmission with hybrid M/G is shown schematically in
Figure 4.6. Notice that, whereas the Simpson and Wilson type have the output shaft
taken from the carrier of the output planetary set, in the Lepelletier the output
shaft connects to the ring gear of the Ravigneaux set.
The key features of the Lepelletier transmission are input shaft to planetary
ring gear with its sun gear blocked to chassis. The input planetary runs in all gears
with the same ratio. The feature of the single input planetary is the splitting of
engine speed at the ring (true speed) and carrier (reduced engine speed). These two
power flow paths are then selected by either clutch C1 or C3 (1:1 into secondary
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