Power plants – Pressure fluid source and motor – Coaxial impeller and turbine unit
Reexamination Certificate
1999-01-28
2001-05-01
Look, Edward K. (Department: 3745)
Power plants
Pressure fluid source and motor
Coaxial impeller and turbine unit
Reexamination Certificate
active
06223528
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention is directed to a hydrodynamic torque converter with a converter circuit having an impeller wheel, a turbine wheel and a stator wheel, with each of the impeller wheel and the turbine wheel having an inner wall connecting the individual blades of the wheels and which forms an inner torus with the other inner wall and each inner wall having an extension extending toward the other wheel.
2. Description of the Related Art
A torque converter having inner walls with extensions is known, for example, from FIG. 4 of reference DE 41 21 586 A1. This prior art device has a converter circuit with an impeller wheel, a turbine wheel and a stator wheel, wherein the individual blades at the impeller wheel and at the turbine wheel are connected with one another in an identical manner at their free ends by an inner wall. The inner walls which together form an inner torus have, at their radial outer side and radial inner side, an extension located opposite to the blades, wherein the extension extends essentially axially toward the other respective wheel. The axial distance between the two extensions is smaller on the radial outer side of these walls than on the radial inner sides. The extensions on the radially inner side are arranged to be close in the radial direction to a cover ring connecting the free ends of the blades of the stator wheel with one another.
Because of the inflation or swelling of the converter during operation caused by centrifugal force, the axial distance between the extensions of the two walls must be large enough to prevent an unwanted grinding contact. However, experience shows that a disadvantage of a large axial distance of this kind includes a decrease in hydrodynamic characteristic value, since there is an interruption in the flow guidance which leads to separation and therefore to whirling in the flow. A poorer efficiency and a lower transmission ratio result. This problem may be reduced in the radial inner region by the cover ring, but this increases the quantity of structural component parts, the manufacturing effort and the weight of the torque converter; moreover, the flow cross section for the converter fluid is reduced.
SUMMARY OF THE INVENTION
It is the object of the invention to construct a hydrodynamic torque converter in such a way that minimum whirling of the current is ensured with a maximum flow cross section.
According to the invention, this object is met by lengthening one of the extensions of the front inner wall toward the other wheel so that the lengthened extension overlaps the corresponding extension at the other wheel. By constructing the extension of the front wall, considered in the direction of flow, of a wheel, such as the impeller wheel or turbine wheel, with a lengthening extending to the other wheel and overlapping the extension at the other wheel by a predetermined axial length with a predetermined radial offset in the direction of flow, the hydrodynamic torque converter can swell in its operating phase without causing a change in the flow conditions. The result is, rather, that the flow coming from the other respective wheel is conducted by the lengthening over the extension following in the flow direction, so that the flow immediately behind this extension accumulates at the outer side of the corresponding wall and can continue to flow at this location, as well as in the area of the lengthening and in the area of the wall previously receiving the flow, without separation or whirling. This results in a very high efficiency and large transmission ratio. This step may also be implemented at the radial outer sides of the walls of the impeller wheel and turbine wheel, wherein the lengthening is located at the extension of the wall of the impeller wheel and approaches the extension of the turbine wheel from the outside with a radial gap.b driving means for driving an elastic element of the torsional vibration damper. However, the effect is greater at the radial inner sides of the walls when the lengthening is provided at the extension of the turbine wheel and approaches the extension of the impeller wheel from the inside with a radial gap. The reason for this is that the requirement for a cover ring at the free ends of the blades of the stator wheel is eliminated because of the flow between the turbine wheel and impeller wheel which is optimized in this way, so that an unrestricted flow cross section is provided for the converter fluid without having to tolerate any disadvantages with respect to fluid mechanics. Further, less material is required due to the omission of the cover ring resulting in a considerable reduction in manufacturing effort and cost because, when a cover ring of this type is present, this same cover ring should be connected with each of the blades provided at the stator wheel.
A very good sealing of the hydrodynamic circuit relative to the inner torus is provided in that the lengthening approaches close to the associated extension of the other respective wheel with a radial gap. This, in turn, leads to a further improvement in dynamic transmission characteristics.
The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of the disclosure. For a better understanding of the invention, its operating advantages, and specific objects attained by its use, reference should be had to the drawing and descriptive matter in which there are illustrated and described preferred embodiments of the invention.
REFERENCES:
patent: 2660957 (1953-12-01), Koskinen
patent: 649974 (1962-10-01), None
patent: 41 21 586 (1993-01-01), None
Sasse Christoph
Weichel Detlev
Cohen & Pontani, Lieberman & Pavane
Lazo Thomas E.
Look Edward K.
Mannesmann Sachs AG
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