Rotary kinetic fluid motors or pumps – Working fluid passage or distributing means associated with... – Casing having tangential inlet or outlet
Patent
1993-11-04
1994-10-11
Look, Edward K.
Rotary kinetic fluid motors or pumps
Working fluid passage or distributing means associated with...
Casing having tangential inlet or outlet
415204, 4152131, 60 3936, F01D 2524
Patent
active
053541731
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
This invention relates to a scroll for a radial inflow turbine.
BACKGROUND OF THE INVENTION
Radial inflow turbines, for instance those which are incorporated into small gas turbine engines or turbochargers, are usually associated with a structure commonly referred to as a scroll. The scroll is configured so as to direct hot gases exhausted from the combustion apparatus of the engine into the inlet of the radial inflow turbine. It is typically a hollow generally toroidal to component with provision for the tangential flow of hot combustion gases into its interior and the exhaustion of these gases through a suitable annular outlet into a radial inflow turbine situated at its center.
Such scrolls are, of course, exposed to very high operating temperatures and this gives rise to difficulties associated with the thermal expansion and contraction of its various regions. It has been found with traditional scroll designs that great difficulties are associated with the annular outlet of the scroll. Typically thermal expansion and contraction of the scroll can result in the axial distance across the outlet varying by as much as 10 to 12%. Such variation is highly undesirable in view of the overall effect which it has upon the efficiency of the turbine into which it directs combustion gases.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a scroll of novel configuration which is less prone to significant variation in the area of its outlet due to thermal effects than is the case with scrolls of conventional configuration.
According to the present invention, a scroll suitable for directing hot gas into a radial inflow turbine comprises an annular chamber defined by two coaxial confronting, axially spaced apart annular members interconnected at their radially outer extents, and means for directing hot gas into said chamber to flow therein in a generally circumferential direction, the radially inner extents of said members cooperating to define an annular exhaust outlet from said chamber to operationally direct said hot gases on to a radial inflow turbine, the major portions of said members converging in a generally radially inward direction towards said annular outlet and being so configured that both of said major portions of said members are of generally curved cross-sectional shape so as to be curved in the same generally axial direction whereby the major portion of one of said members is located inwardly of the other, annular support means coaxial with said members being provided to support said scroll, said support means being attached to said inward member intermediate its radially inward and outward extents and arranged at said attachment to be locally generally normal to said inward member.
BRIEF DESCRIPTION OF THE DRAWINGS
The present invention will now be described, by way of example, with reference to the accompanying drawings in which:
FIG. 1 is a sectioned side view of the upper half of a prior art scroll.
FIG. 2 is a sectioned side view of the upper half of a scroll in accordance with the present invention.
FIG. 3 is a view on arrow A of FIG. 2.
DETAILED DESCRIPTION OF THE INVENTION
Referring to FIG. 1, a known scroll 10 comprises two axially spaced apart angular walls 11 and 12 which converge in a radially inward direction to define a annular outlet 13 to a radial inflow turbine 14. The walls 11 and 12 are interconnected at their radially outward ends so that they define an annular volume 15. In operation hot gases are directed into the volume 15 in a tangential direction (by means not shown) so that the gases flow generally circumferentially through the volume 15 before being exhausted through the annular outlet 13.
A major drawback with scrolls of this type is that their thermal expansion characteristics result in an undesirably large variation in the cross-sectional area of the annular outlet 13. Moreover since the shroud 15a surrounding the radial inflow turbine 14 is conventionally attached to one of the walls 11, those thermal expansi
REFERENCES:
patent: 4122673 (1978-10-01), Leins
patent: 5094587 (1992-03-01), Woollenweber
Look Edward K.
Rolls-Royce Business Ventures Limited
Verdier Christopher
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