Hydrodynamic mechanical compound transmission

Details Hydrodynamic mechanical compound transmission Hydrodynamic mechanical compound transmission

1999-12-30

2001-05-15

Wright, Dirk (Department: 3681)

Planetary gear transmission systems or components

Fluid drive or control of planetary gearing

Fluid resistance inhibits relative rotation

Reexamination Certificate

active

06231467

ABSTRACT:

The invention concerns a hydrodynamic-mechanical compound transmission, especially with the features from the preamble of claim
1
.
Hydrodynamic-mechanical compound transmissions, comprising a hydrodynamic speed/torque converter and a mechanical transmission part, are known in a number of versions. Document DE 36 04 393 C2 discloses a hydrodynamic compound transmission, comprising a torque converter and a gearbox connected to it in series. The gearbox has two planet wheel sets for this purpose, in which the planet carriers of the two planet wheel sets are coupled to each other and form the output of the gearbox. The number of required planet wheel arms or planet wheel sets (under some circumstances, a Ravigneaux set) can be kept low with this type of arrangement, and with appropriate arrangement of switching devices, at least three speeds can be implemented, during which the axial design length can be kept very short. The hydrodynamic speed/torque converter comprises a pump wheel, turbine wheel, as well as two guide wheels—a first guide wheel and a second guide wheel, means being provided that permit coupling of the turbine wheel and the first guide wheel to the mechanical transmission part in the form of a gearbox: in particular, the overall transmission input shaft can be connected either via the hydrodynamic speed/torque converter and then via the turbine wheel to the sun wheel of one planet wheel set of the mechanical transmission part, or directly via a so-called bypass clutch to it. The first guide wheel is connected via a freewheel to the sun wheel of the other second planet wheel set of the mechanical transmission part. The characteristic properties of the speed/torque converter in each range of transmission ratio and the transmission ratio of the mechanical transmission part are changed by switching the transfer path of the torque, starting from the first guide wheel shaft by alternating activation of coupling and/or braking devices that permit either stopping of the first guide wheel shaft or clutch of the first guide wheel shaft to the turbine wheel shaft and thus the first sun wheel of the first planet wheel set. The advantage of this 3-speed transmission consists of its limited design size. However, a corresponding layout of this existing transmission with respect to the main use or a costly modification of it is required in order to optimize certain parameters, like fuel consumption of the vehicle or to permit higher final design speeds of the vehicle.
The underlying task of the invention is to further develop a transmission of the type mentioned at the outset, so that this can fulfill the existing use requirements more optimally, in which the advantages of low weight and limited design size are also to be retained. Additional functions, like creation of a braking torque or driving of secondary units, as well as implementation of overdrive with the least possible expense, while retaining the advantages of limited design size, are to be implemented with limited design cost.
The task of the invention is characterized by the features of claim
1
. Advantageous embodiments are stated in the subclaims.
The hydrodynamic-mechanical compound transmission comprises a first hydrodynamic transmission part and an additional second mechanical transmission part. The first hydrodynamic transmission part comprises a hydrodynamic speed/torque converter. The mechanical transmission part comprises at least a mechanical speed/torque converter. Preferably, a mechanical speed/torque converter is used, having at least two planet wheel sets, whose planet carriers are connected to each other and form the output of the mechanical speed/torque converter. The transmission also has a hydrodynamic retarder, which is integrated in the housing and is arranged in spatial proximity to the hydrodynamic transmission element, the hydrodynamic retarder being coupled to the output of the mechanical speed/torque converter. Coupling then occurs preferably by connection of the rotor blade wheel to rotate in unison with the coupled transmission elements, preferably the planet carriers that simultaneously form the output of the mechanical speed/torque converter.
The arrangement of the hydrodynamic retarder according to the invention, which is characterized by integration in the transmission housing and spatial arrangement of the retarder referred to the power flow direction from the transmission input shaft to the transmission output shaft before the mechanical transmission part, in which the rotor blade wheel of the hydrodynamic retarder can be connected to the output shaft of the mechanical transmission part, i.e., arrangement of the hydrodynamic retarder in the immediate spatial vicinity of the hydrodynamic transmission element, makes it possible to integrate all hydraulic components of the operating medium supply system, like gear pump, starting converter, control unit and supply lines, spatially next to each other in the transmission, in which only short paths are required to guide, the operating medium, which has a significant effect on the method of operation of the transmission, for example, a reduction of the response times during start-up of hydrodynamically operating components, like the hydrodynamic speed/torque converter and hydrodynamic retarder, reduction of hydraulic resistance and increase in energy efficiency.
The first hydrodynamic transmission part and the mechanical speed/torque converter form a so-called basic transmission module or core transmission, which can be furnished as a complete assembly group. This is preferably expandable by a secondary set, which is arranged coaxial to the base transmission module and, viewed spatially in the power flow direction in traction operation, is arranged either in front of the mechanical speed/torque converter or behind it. The output of the mechanical speed/torque converter then simultaneously forms the input of the secondary stage. However, the hydrodynamic retarder according to the invention, viewed in the power flow direction in traction operation, is always arranged in front of the take-off or output of the secondary set. The following two possibilities are essentially obtained for additional arrangement possibilities with reference to the mechanical speed/torque converter of the mechanical transmission part:
1. Arrangement of the retarder, viewed in the power flow direction in traction operation spatially in front of the mechanical speed/torque converter.
2. Arrangement of the hydrodynamic retarder, viewed in the power flow direction in traction operation spatially behind the mechanical speed/torque converter.
In the first mentioned possibility of arranging the secondary set, viewed spatially in the power flow direction in traction operation spatially in front of the mechanical speed/torque converter, two possibilities are again obtained for integration of the hydrodynamic retarder, which are also combinable with the two possibilities just mentioned:
1. Arrangement of the hydrodynamic retarder between the secondary set and the mechanical speed/torque converter.
2. Arrangement of the hydrodynamic retarder, viewed in the force flow direction in traction operation spatially in front of the mechanical secondary stage.
By analogy, these assertions also apply to arrangement of the secondary set, viewed in the power flow direction in traction operation spatially behind the mechanical speed/torque converter.
The described basic variants permit the design of an overall transmission with integrated braking function with simultaneously limited design size and limited weight, in which additional speeds can be implemented by means of the secondary set and by corresponding layout of the individual transmission elements of the mechanical speed/torque converter in conjunction with the mechanical secondary stage, an essentially uniform traction force trend is achieved over the entire operating range.
Design integration of a hydrodynamic retarder and its central arrangement in the overall transmission, especially in front of the mechanical speed/torque con

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