Planetary gear transmission systems or components – Fluid drive or control of planetary gearing – Control of differential planetary gearing
Patent
1996-08-02
1998-07-28
Ta, Khoi Q.
Planetary gear transmission systems or components
Fluid drive or control of planetary gearing
Control of differential planetary gearing
475221, 475 89, F16H 4820
Patent
active
057856222
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a differential drive apparatus having an input member and two output members.
It is known, especially in wheel driven vehicles, to introduce an unequal torque division between the output members of a differential drive apparatus by applying braking torque to one of the output members. Conventional limited slip differential drive apparatuses are of two types, namely those which are sensitive to differences in torque of the output members and those which are sensitive to differences in rotational speed of the output members. The torque transferred across conventional differential drive apparatuses is equal to that carried by the brake, and the braking energy is extracted from the system and wasted.
One object of the present invention is to provide a differential apparatus of the type transferring torque between the output members primarily as a function of their speed differential and wherein: the output members. For a given transfer of torque this leads to lighter and more responsive power handling by the brake; in speeds of the output members. This increases the sensitivity of the system with respect to differences in speed of the output members; and wherein and the amount of torque transferred is enabled without dismantling the apparatus.
These objects are achieved in a differential gear of the kind described in WO 87/07348 (EP-B1-0 267 953; U.S. Pat. No. 5,176,589) and comprising a differential gear housing driveable for rotation, a first output shaft operatively connected to a first gear element and a second output shaft output shaft operatively connected to a second gear element of a differential planet gear disposed within the differential gear housing, said differential planet gear having further gear elements attached to the differential gear housing, and a planet gear disposed within the differential gear housing and having a ring gear attached to the differential gear housing, at least one planet wheel operatively connected to the ring gear and a sun wheel operatively connected to the planet wheel, said sun wheel being connected to a hollow shaft having the second output shaft disposed therein, brake means being disposed between the differential gear housing and said hollow shaft for braking relative rotation between the differential gear housing and the hollow shaft. In the differential gear according to the present invention, the brake means is operable in response to a difference in rotational speeds between the first and the second output shaft. According to the present invention, the brake means includes a fluid pump having mutually rotatable members, one member rotating with the hollow shaft and one with the differential gear housing.
In a first embodiment of the present invention said means further includes a control brake mechanism operable by fluid pressure generated by the pump.
In a second embodiment of the present invention, said means comprises solely the pump. In this case, the braking effect of the pump depends on fluid counterpressure from the pump delivery modified by possible leakage and flow restrictions.
The present invention will now be described more in detail, reference being made to the accompanying drawings, wherein:
FIG. 1 is a schematic representation of a differential gear utilizing bevelled gears in its differential planet gear,
FIG. 2 is a schematic representation of a differential gear utilizing epicyclic gears in its differential planet gear,
FIG. 3 is an axial schematic view of gear train A' seen from the left in FIG. 2 but showing the gear elements thereof at another relative scale, and
FIG. 4 is an axial schematic view of gear train B' as seen from the right in FIG. 2.
In FIGS. 1 and 2, reference numeral 1 a differential gear having a housing, or, crown wheel casing 2. The housing 2 is driveable for rotation by means of a crown wheel 3 meshing with a drive pinion not shown.
The differential gear shown in FIG. 1 is one embodiment of the gear described in the above-mentioned patent and includes a differential planet gear train A and
REFERENCES:
patent: 2808739 (1957-10-01), Mueller
patent: 3015970 (1962-01-01), Mueller
patent: 3590954 (1971-07-01), Plantan
patent: 4012968 (1977-03-01), Kelbel
patent: 5176589 (1993-01-01), Borgudd
patent: 5655983 (1997-08-01), Dick
Slim Borgudd
Ta Khoi Q.
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