The electronic control coupling realizes the highly reliable 4WD system with lighter weight
and simpler construction.
CONSTRUCTION
The electronic control coupling is comprised of the front housing, main clutch, main cam,
ball, pilot cam, armature, pilot clutch, rear housing, magnetic coil, and shaft.
The front housing is joined to the propeller shaft and rotates along with
the shaft.
The main clutch and pilot clutch are assembled to the front housing on the outer
side and to the shaft on the inner side (The pilot clutch is installed via the pilot cam).
The shaft is engaged via serrations with the drive pinion of the rear differential.
OPERATION
Coupling stops (2WD: Magnetic coil de-energized.)
The drive force from the transfer is transmitted to the front housing connected to the
propeller shaft. The drive force is also transferred to the pilot clutch and the outer side
of the main clutch assembled to the front housing. Because the pilot clutch and the main clutch
are not engaged with the magnetic coil de-energized, the drive force is not transferred to the shaft
and the drive pinion of the rear differential.
Coupling operates (4WD: Magnetic coil energized.)
The drive force from the transfer is transmitted to the front housing connected
to the propeller shaft. The drive force is also transferred to the pilot clutch and the outer
side of the main clutch assembled to the front housing. When the magnetic coil is energized,
the magnetic field is generated among the rear housing, pilot clutch, and armature. The magnetic
field induces the pilot clutch and armature to engage the pilot clutch. When the pilot clutch
is engaged, the drive force is transferred to the pilot cam. When there is a difference in rotation
speed between the front and rear wheels (i.e. rotation speed of the propeller shaft is different
from that of the drive pinion), the rotation speed of the pilot cam applied with the drive force
and that of the main cam not applied with the drive force become different. The ball slides
along the curved space between the pilot cam and main cam by the rotational speed difference
and pushes the pilot cam and main cam. Then, the main clutch is pushed toward the main cam to
engage. When the main clutch is engaged, the drive force is transferred to the rear wheels via
the shaft and the drive pinion of the rear differential.
By controlling the current applied to the magnetic coil, the amount of the drive
force transferred to the rear wheels can be controlled within the range of 0 to 100%.
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