Planetary gear transmission systems or components – With lubricaton – For differential planetary gearing
Patent
1991-08-26
1993-03-30
Wright, Dirk
Planetary gear transmission systems or components
With lubricaton
For differential planetary gearing
74606A, F16H 140
Patent
active
051979292
DESCRIPTION:
BRIEF SUMMARY
The invention concerns a drive shaft having an axle body at both ends of which are fastened gear heads and in which an axle housing surrounds a differential gear which is operatively connected with a drive pinion via a bevel wheel differential and axle bevel gears and axle half shafts with wheel hubs which define gear heads, a communicating connection for the exchange of coolant exists between said wheel hubs and said axle housing.
A drive shaft of the above kind has been disclosed in U.S. Pat. No. 4,391,351. Within each gear head of said drive shaft is situated a disc brake and a planetary gear. Each disc brake is cooled with oil which from the axle housing of the differential gear runs into the gear heads via suspension pipes which are penetrated by axle half shafts. The exchange of coolant in the interior of the axle body from the axle housing to the gear heads and vice versa is absolutely insufficient in the already known design. This is essentially to be attributed only to the fact that the oil in the interior of the axle body is kept moving by the rotation of the differential gear or the bevel wheel. A noticeable circulation of the oil cannot take place, since even though the predominant portion of the oil volume is intensively centrifuged and revolved by the bevel gear and the drive pinion, it remains here stationary in the axle housing of the differential gear. The consequences of this are high planch losses and an insufficient cooling of the disc brakes.
When the drive shaft is inclined, there is finally the danger that a gear head idles so that the cooling of the disc brakes is not all together ensured.
On the basis of a drive shaft of the kind mentioned above, the problem to be solved by the invention is to improve the cooling of the disc brakes by simple measures.
The invention solves the stated problem by collection and guide elements in the area of the bevel wheel whereby during rotation of the bevel wheel coolant from the axle housing is shifted into the gear heads by lowering the coolant level. By the proposed distribution of the coolant through collection and guide elements it is ensured that a relatively larger portion of the coolant volume be available in the gear heads, that is, in the places where excessive frictional heat accumulates and has to be eliminated. The claimed design of the drive shaft according to the invention in which the disc brakes and the planetary gear are situated within each gear head--surrounded by the wheel hub--provides the conditions for admitting the predominant portion of the volume of coolant. Very low speeds already lead to the filling of the gear heads. In addition the system is insensitive to foreign bodies. With the solution proposed it is possible to maintain a coolant circuit which is characterized by added essential advantages: The lowering of the coolant level in the axle housing reduces the planch power loss. Adequate collection and guide elements can be made available at reasonable cost so that the increase in price of the drive shaft is not worth mentioning. Since the exchange of the coolant also takes place in the interior of the axle, a large surface for heat removal is available. Together with the lifting of the coolant level in the gear heads, it is possible to control very favorably the time and steady-state behavior, that is, the course per time unit of the temperature rise until reaching an upper value. This specially applies to drive shafts of heavy utility vehicles in which the disc brakes are actuated at very short time intervals--with full engine power.
There are known already other drive shafts of different design in which the disc brakes are commodated in a separate housing spatially separated from the planetary gears (for instance, European patent application 00 76 387). The disc brakes here are in the coolant circuit of a pump. The continuously delivered flow of coolant is directly speed dependent. Accordingly, the pump must have large dimensions in order to convey sufficient coolant even at low speeds, which makes the drive shaft d
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Bier Waldemar
Kuhner Karl
Lommel Albrecht
Scheiber Friedrich
Sonnleitner Hermann
Wright Dirk
Zahnradfabrik Friedrichshafen AG
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