Planetary gear transmission systems or components – Fluid drive or control of planetary gearing – Fluid controlled mechanical clutch or brake
Reexamination Certificate
2001-10-30
2004-05-25
Pang, Roger (Department: 3681)
Planetary gear transmission systems or components
Fluid drive or control of planetary gearing
Fluid controlled mechanical clutch or brake
C137S565370
Reexamination Certificate
active
06739999
ABSTRACT:
The present invention relates to a fluid recovery system for an automatic transmission unit.
BACKGROUND OF THE INVENTION
Automatic transmission units for vehicles, in particular automobile vehicles, are known in which the clutch and the gear change of the vehicle are associated with actuators used respectively for the opening/closing of the clutch and/or the selection and engagement/disengagement of the gears.
The above-mentioned actuators are generally of hydraulic or electro-hydraulic type and are supplied by means of a hydraulic pump receiving an operating fluid (normally oil) from a hydraulic circuit which is coupled to the actuators and is adapted to provide these actuators with the pressurised operating fluid so that they can operate.
During the normal operation of automatic transmission units, there may be leakages of operating fluid from the actuators because the gaskets present in these actuators are not fully leak-tight; this lack of leak-tightness may in particular be caused by damage to or wear of the gaskets.
This situation may cause fluid to escape from the hydraulic circuit causing a possible malfunction of the automatic transmission unit and pollution of the external environment; when the quantity of operating fluid escaping from the circuit as a result of leakages is a substantial proportion, for instance 20-30%, of the volume of the operating fluid in the hydraulic circuit, operating anomalies may occur as a result, for instance, of the intake of air or other gases by the pump.
A known solution is to provide the hydraulic actuators with high quality gaskets so as to reduce fluid leakages to predetermined values.
This solution has the drawback that it is particularly costly and does not make it possible to recover the fluid that has leaked.
SUMMARY OF THE INVENTION
The object of the present invention is therefore to provide an operating fluid recovery system for a transmission unit which is free from the above-mentioned drawbacks.
The present invention relates to an operating fluid recovery system for a transmission unit as described in claim 1.
REFERENCES:
patent: 3003659 (1961-10-01), Miller
patent: 4010660 (1977-03-01), Ahlen
patent: 4782851 (1988-11-01), Malik
patent: 5105922 (1992-04-01), Yant
patent: 5882273 (1999-03-01), Jang
patent: 5901744 (1999-05-01), Richards
patent: 6332855 (2001-12-01), Murasugi
patent: 198 56 941 (2000-02-01), None
patent: 0 644 370 (1995-03-01), None
Patent Abstracts of Japan, vol. 2000, No. 12, Jan. 3, 2001 (JP 2000 257705, Sep. 19, 2000).
Patent Abstract of Japan, vol. 012, No. 064, Feb. 26, 1988 (JP 62 209268, Sep. 14, 1987).
Magneti Marelli Powertrain S.p.A.
Pang Roger
Price D. Douglas
Steptoe & Johnson LLP
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