Machine element or mechanism – Elements – Gear casings
Patent
1996-10-21
1998-06-23
Marmor, Charles A.
Machine element or mechanism
Elements
Gear casings
74467, 184 111, F16H 5704, F01M 906
Patent
active
057689547
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a gear case.
BACKGROUND OF THE INVENTION
Gear cases contain a lubricant sump. A pump conveys the lubricant from said sump to the places of the transmission to be lubricated. The volume of lubricant is here determined by the delivery of the pump and the number of places in the transmission to be lubricated. The lubricant level of the gear sump is set by two extremes: a lower level which ensures a reliable conveyance of the lubricant by the pump even at low temperatures; an upper level which is predetermined by the installation position of the rotating parts, such as shafts and clutches. It is known that when falling below the lower level suction noises and pressure drops result.
When exceeding the upper level, the rotating parts cause the lubricant to bubble which results in churning losses, discharge of lubricant from the vent and aging of the lubricant. Due to cramped conditions in the engine chamber, for example, in the case of a passenger car with front wheel drive and an engine installed across the travel direction, a reduction of the construction volume of the gear case altogether results. Besides, a small ground clearance of the vehicle causes the gear case to lose additional volume in the lower part, that is, in the area of the lubricant sump. A reduction of the construction volume together with a reduction of the lubricant volume means that the upper lubricant level approaches closer to the rotating parts.
ATZ Automobiltechnische Zeitschrift 84 (1982) 4 has disclosed a 3-gear automatic transmission. A lubricant sump and a second casing chamber are situated in a common gear case. The second casing chamber is above the lubricant sump. A temperature-controlled valve, in the form of a bimetal, is at the lowest point of the second casing chamber. At elevated temperatures of the lubricant the bimetal seals an aperture. At low temperatures of the lubricant the bimetal opens the aperture. During a cold operating state, the whole volume of the lubricant is thus in the lubricant sump. At elevated temperatures the additional volume of lubricant is held back in the second casing chamber. The high industrial expenditures and the functional safety are disadvantageous in this arrangement.
SUMMARY OF THE INVENTION
The problem on which the invention is based is to provide a gear case which ensures a safe filling state of the lubricant during all operating conditions.
According to the invention the problem is solved by the fact that, in a gear case of a vehicle, there are a first casing chamber with a lubricant sump from which the lubricant is conveyed by a pump to the places to be lubricated in the gear, a second casing chamber separated by a wall from the first casing chamber and a third casing chamber which is connected with the first by an aperture and is closed with respect to the second. The height of the wall between the first and second casing chambers sets an upper lubricant level so that an increase in volume of the lubricant resulting from an elevated temperature flows into the second casing chamber. Said lubricant volume is conveyed by a bucket wheel in the second casing chamber. A lower lubricant level is set by the lubricant volumes in the first and second casing chambers.
The solution, according to the invention, has the advantage that the lubricant volume is increased by using the installation space already existing in the gear case as an added casing chamber for the lubricant sump.
Another advantage of the solution, according to the invention, consists in that the upper lubricant level is set by the height of the wall, between the first and second casing chambers, so that an increase in volume of the lubricant flows into the second casing chamber and is conveyed from there by a bucket wheel. This ensures that the lubricant level does not reach the rotating parts during any state of operation.
In development of the invention it is proposed that the lubricant volume conveyed by the bucket wheel be transported to containers and that these have a discharge aperture. This a
REFERENCES:
patent: 1105773 (1914-08-01), Hans
patent: 1220811 (1917-03-01), Alquist
patent: 3618711 (1971-11-01), Vollmer
patent: 3800913 (1974-04-01), Schmitt
patent: 4217926 (1980-08-01), Van Gorder
patent: 5050447 (1991-09-01), Hayakawa et al.
patent: 5158152 (1992-10-01), Nemoto et al.
patent: 5161644 (1992-11-01), Swenskowski et al.
ATZ Automobiltechnische Zietzchrift; Herbert Oberhaus, Fritz Heckert and Hermann Heinrichs; The New Automatic Transmission THM; 1982; pp. 157-160.
Database WPI; Week 5944 28 May 1980; Derwent Publications Ltd., London, GB; AN 425300 & SU, A, 679 754 (Cons Road Equip Res), 18 Aug. 1979.
Grabherr Werner
Sellmair Helmut
Battista Mary Ann
Marmor Charles A.
ZF Friedrichshafen AG
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