Planetary gear transmission systems or components – Fluid drive or control of planetary gearing – Impeller-turbine type fluid circuit in series with planetary...
Reexamination Certificate
2000-11-02
2003-05-13
Lorence, Richard M. (Department: 3681)
Planetary gear transmission systems or components
Fluid drive or control of planetary gearing
Impeller-turbine type fluid circuit in series with planetary...
C475S282000, C475S311000, C475S317000
Reexamination Certificate
active
06561938
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention is relative to a hydrodynamic-mechanical multispeed compound transmission with at least four speeds for use in vehicles, especially in busses, and also to a method of developing a transmission line from a basic transmission in the form of a hydrodynamic-mechanical multispeed compound transmission with at least four theoretically possible gear steps for use in vehicles for differing requirements.
2. Description of the Related Art
Hydrodynamic-mechanical compound transmissions comprising a hydrodynamic speed-torque converter and a mechanical transmission part are known in many embodiments. Publication DE 36 04 393 C2 discloses a hydrodynamic compound transmission comprising a torque converter and a gearbox connected together in series. The gearbox comprises two planetary gear trains. The planet carriers of the two planetary gear trains are coupled to each other and form the output of the gearbox. The number of required planet gear webs or planetary gear trains can be kept low with such an arrangement and the transmission can therefore be built short and three gear steps can be realized given the appropriate assignment of shifting devices. The hydrodynamic speed-torque converter comprises an impeller, a turbine gear and two stators or reactors—a first stator and a second stator. Means are provided that make possible a coupling of the turbine gear as well as of the first stator to the mechanical transmission part in the form of the gearbox. Specifically, the entire transmission input shaft can be coupled either via the hydrodynamic speed-torque converter and thereby via the turbine gear to the sun gear of the one planetary gear train of the mechanical transmission part or directly via a so-called bridge coupling to the latter. The first stator is connected via a freewheel to the sun gear of the second planetary gear train of the mechanical transmission part. The characteristic properties of the speed-torque converter in each range of the translation ratio and the translation ratio of the mechanical transmission part are changed by shifting the transmission path of the moment emanating from the first stator shaft, namely, by the selective actuation of the coupling- and/or braking devices that either make possible a fixing of the first stator shaft or a coupling of the first stator shaft to the turbine gear shaft and therewith of the first sun gear of the first planetary gear train. The advantage of the three-speed transmission described in this publication consists unambiguously in its small size and its low weight. However, an appropriate design of this existing transmission as regards the main instance of use or an expensive modification of the same is necessary for optimizing certain parameters, e.g., the fuel consumption of a vehicle or for making possible higher final design speeds of the vehicle.
SUMMARY OF THE INVENTION
The invention solves the problem of further developing a hydrodynamic-mechanical compound transmission of the initially cited type in such a manner that it can meet the existing requirements of use in an even more optimal manner retaining the advantages of the low weight and the small size. Depending on the intended use (e.g., for the use in busses for city traffic (use with low final design speeds) or primarily for overland traffic (use with high final design speeds), the following should be striven for: An optimal, that is, as hyperbola-shaped as possible, graph of tractive force, low fuel consumption and a selective useable speed number (4- or 5- or 6-speed transmission), depending on the final design speed) as well as an overdrive that is simple to realize for the last-named possibility of use. The transmission should be able to be universally used, that is, e.g., for busses with a low weight and a rather large weight (bandwidth weight m
min
-m
max
) as well as with different final design speeds (bandwidth final design speed v
min
-v
max
) without significant additional modification of transmission components and should make possible different areas of application and therewith different modes of operation, especially the starting variants.
The hydrodynamic-mechanical multispeed compound transmission with a hydrodynamic transmission part and a mechanical transmission part, have hydrodynamic transmission part and mechanical transmission part connected in series, viewed in the direction of the power flow, with at least means being provided for circumventing the hydrodynamic transmission part during the transmission of power, are designed in accordance with the invention as regards the mechanical transmission part in such a manner regarding the translations that at least one gear step jump or progression phi is achieved between two speeds adjacent to one another between 1.1 and 1.45. The hydrodynamic transmission part comprises at least one hydrodynamic speed-torque converter. The mechanical transmission part comprises a mechanical speed-torque conversion device with at least two planetary gear trains. The hydrodynamic-mechanical multispeed compound transmission is preferably equipped with a rear-mounted train (i.e., after-shifting- or secondary switching set) so that theoretically 6 gear steps are conceivable. It is particular advantageous in this case to design the mechanical transmission part in such a manner that the following gear step jumps phi are achieved:
phi≦1.45 between the first and the second gear step and the second and the third gear step;
phi≦1.35 between two successive gear steps of the following speeds.
Phi can remain constant thereby or can be designed to fall in the direction of higher speeds.
The design of the transmission in accordance with the invention makes it possible to attain as hyperbola-shaped as possible graph of tractive force in the tractive force/speed diagram even at low speeds. Moreover, different operating concepts with an optimal result as concerns different design speeds can be realized by an appropriate control of the individual transmission elements on account of this basic speed graduation. For example, when the transmissions are used in busses both the lower speed range, that is particularly significant for city buses, and the upper speed range, that constitutes the main range of use in travel buses, are considered thereby. Therefore, the gear step jumps in the upper speeds that is, from an initial speed into the next higher speed, are preferably designed to be constant, which corresponds to the customary design criteria in the upper speeds, especially in the case of transmissions for use in travel buses. In the case of lower design speeds (greater axial translations), the first speed (speed with the greatest translation), can remain uncontrolled as a result. The speed jump between converter speed and 2
nd
speed remains below 1.8 therewith.
The mechanical transmission part is preferably designed in such a manner that the transmission elements in the first gear step that participate in the speed-torque conversion realize a translation in a range of 3<i<3.25 and in the last gear step a translation in a range of 0.7<i<0.9.
A plurality of control or drive variants can be realized on this basis with a basic transmission component without additional modification, which variants form the basis for the development of a series from a single basic transmission in the form of a hydrodynamic-mechanical multispeed compound transmission with at least four theoretically possible gear steps for use in vehicles for different requirements.
Specifically, the following can be achieved retaining the same basic transmission design by variation of the control of the transmission elements:
a) A plurality of transmission- and speed variants (4/5/6-speed),
b) A plurality of starting variants,
c) A plurality of drive variants by mixing the individual transmissions or speed variants with the individual start variants.
The individual speed variants are realized by omitting gear steps. The basic transmission concept is designed in such a manner that a plurali
Becke Martin
Körner Tillman
Nitsche Martin
Die Voith Turbo GmbH & Co KG
Ho Ha
Knuth Randall J.
Lorence Richard M.
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