Fluid flow machine

A fluid flow machine of the radial type of construction with adjustable guide blades in a radially extending annular channel of the fluid flow housing. The bearing support of the guide blades takes place in a guide blade carrier that represents a one-piece bearing cage with lateral flow surfaces for the guide blades. The guide blade carrier is composed of two bearing rings which are combined into one structural unit by way of fixed connecting webs disposed in the flow path. In this structural unit, the space for the guide blades can be machined very accurately in its axial width to maintain the tolerances which means small gap losses and correspondingly favorable efficiencies. Since the guide blade carrier is so arranged in the housing that expansions of the housing by reason of heat or pressure warping are not transmitted, the gap tolerances can be selected correspondingly still smaller, and the efficiency can be still further improved. It is also significant that the fluid flow machine and its components can be constructed particularly simple from a constructive point of view and particularly reliable in operation by means of the housing-independent bearing support of the guide blades in the guide blade carrier.

The present invention relates to a fluid flow machine with a radial rotor 
arranged in the fluid flow housing as well as with adjustable guide blades 
arranged in a radially extending annular channel of the fluid flow housing 
which are rotatably supported by means of bearing pins in bearing bores of 
the housing parts forming the annular channel as disclosed, for example, 
in the U.S. Pat. No. 3,945,762. 
An exhaust gas turbocharger with a radial compressor and a radial turbine 
is disclosed in the aforementioned publication. Adjustable guide blades 
are arranged in an annular channel of the turbine housing, through which 
the fluid medium flows in the radial direction. The guide blades are 
provided at their narrow sides with bearing pins which are rotatably 
supported in bearing bores provided in the annular channel wall adjoining 
the bearing housing. Actuating levers engage at the bearing pins which 
cooperate with an adjusting ring. Gaps result between the annular channel 
walls and the narrow sides of the guide blades which influence the 
efficiency of the fluid flow machine. The gap width is particularly 
unfavorable in the disclosed construction in which the tolerance of 
housing parts attached at one another determine the annular channel width. 
For the dimensioned accuracy of a structural component composed of 
different parts as represents, for example, the compressor housing and the 
turbine housing--whereby the latter may not be constructed in one piece, 
contrary to the drawing, if the rotor and guide blades are to be 
attached--is dependent on the predetermined constructive tolerances which 
can still be realized with economically acceptable expenditures. A 
subsequent machining or finishing of the determinative housing walls is no 
longer possible in the assembled condition. The distance between the 
annular channel walls may correspondingly vary between a minimum and 
maximum value. The blade widths must therefore be selected smaller than 
the minimum width of the annular channel. Also, the influence of the 
warping of the housing parts by reason of the threaded connection and of 
the pressure and heat stresses of the housing must be taken into 
consideration in the selection of the blade width. This leads, as already 
mentioned, to undesirably large gaps and corresponding influencing of the 
efficiency. 
The present invention is concerned with the task to constitute the fluid 
flow machine constructively as simple as possible and operationally as 
reliable as possible as regards the bearing support of the guide blades 
and to thereby improve the efficiency by a reduction of the gap losses. 
The underlying problems are solved according to the present invention in 
that mutually opposite bearing rings are embedded in the housing parts 
forming the annular channel, which are rigidly coupled at one another by 
means of connecting webs into a one-piece structural part--the guide blade 
carrier--, which bearing rings contain the bearing bores for a bearing 
support of the guide blades on both sides, and whose surfaces form lateral 
flow surfaces within the area of the guide blades. 
The guide blade carrier, consisting of two bearing rings which are rigidly 
and nondetachably connected with each other by connecting webs, forms a 
separate component or structural part which represents a one-piece bearing 
cage with lateral flow surfaces for the guide blades. On this 
constructively simple structural part, the space for the guide blades can 
be machined very accurately in its axial width to maintain the dimensional 
accuracy which means small gap widths and correspondingly improved 
efficiency. In one embodiment of the present invention, the guide blade 
carrier is supported in the housing on one side in such a manner that 
warpings of the bearing- and fluid-flow-housings as a result of heat and 
pressure loads are not transmitted to the guide blade carrier and such 
influences therefore need not be taken into consideration in the 
determination of the gap widths. 
Furthermore, it is advantageous that the fluid housing having a fluid 
medium inlet and outlet can be rotated with respect to the bearing housing 
into any desired positions without changing the guide blade positions 
because they are supported in the guide blade carrier completely 
independently.

Referring now to the drawing wherein like reference numerals are used 
throughout the various views to designate like parts, and more 
particularly to FIG. 1, this figure is a longitudinal cross-sectional view 
through the turbine generally designated by reference numeral 1 of an 
exhaust gas turbocharger. The associated compressor connected with the 
turbine 1 by way of a common shaft 2 is not illustrated. The fluid flow 
housing 5 is axially clamped against the bearing housing 3 by way of a 
clamping ring 4 threadably secured at the fluid flow housing 5. The shaft 
2 is supported in the bearing housing 3. Adjustable guide blades 7 are 
arranged in an annular channel which extends radially and which is 
traversed by the fluid medium from the outside toward the inside. The 
guide blades 7 are rotatably supported in a guide blade carrier 8 on 
bearing pins 9 which engage in bearing bores 10 of an outer lateral 
bearing ring--on the fluid medium outled side--and of an inner lateral 
bearing ring--on the bearing housing side--of the guide blade carrier 8. 
The bearing rings are joined to the guide blade carrier 8 by way of some 
connecting webs 26 which are located within the flow path. The connecting 
webs 26 rigidly connect with each other the bearing rings. They are, for 
example, welded together with the bearing rings or nondetachably connected 
with the bearing rings in any other suitable manner. 
Within the area of the guide blades 7, the inner surfaces of the bearing 
rings form at least partially the boundary or flow surfaces for the fluid 
medium flowing through the annular channel 6. On the bearing housing side, 
the flow surface is also partially formed within the area of the guide 
blades by the adjusting ring 12 provided with cams 11 (FIG. 2) preferably 
projecting into the fluid-flow channel. In order that no flow-impeding 
component edges occur, the adjusting ring 12 represents the lateral flow 
surface also within the area of the guide blades. Furthermore, an annular 
flange 13, which is formed-on at the guide blade carrier 8, is supported 
with its end face 14 at the bearing housing 3 and at the same time is 
clamped fast at an outer shoulder against the fluid flow housing 5 
supported at the bearing housing 3. Axially fixed in this manner, an axial 
expansion gap 16 may be provided between the outer bearing ring and the 
housing aperture into which it is embedded, which permits an axial 
expansion of the guide blade carrier 8. However, any warping occurring as 
a result of heat or pressure expansions of the housing part is not 
transmitted with this unilateral clamping arrangement of the guide blade 
carrier 8 at the annular flange 13. Furthermore, a section of a heat 
shield 17 is clamped-in between the end face 14 of the ring flange 13, 
formed-on at the guide blade carrier 8, and the bearing housing 3, which 
intercepts excessive heat flow to the bearing housing 3 and represents the 
flow wall within the area of the rotor 18. An axially extending section of 
the adjusting ring 12 is axially, but rotatably fixed between an inner 
shoulder of the annular flange 13 and the heat shield 17 supported at the 
bearing housing 3. For the adjustment of the adjusting ring 12, an 
adjusting shaft 19 is arranged in the bearing housing 3 whose rotations 
are transmitted onto an actuating lever 20 which engages with an axial pin 
21 in a lug 22 which is connected with the adjusting ring 12. In the 
passage of the adjusting shaft 19 through the heat shield 17, the 
adjusting shaft 19 is preferably supported in a heat-insulating ceramic 
bushing 23. In order to attain a gas-tightness, the adjusting shaft 19 may 
be axially stressed against the ceramic bushing 23 by means of a spring 
(not shown). 
FIG. 2 illustrates a cross-sectional view of the turbine 1 along the 
cross-sectional line II--II indicated in FIG. 1. In the upper half of the 
cross-sectional view, the pin 21 of the adjusting shaft 19 is shown which 
engages in the lug 22 that is operatively connected by way of a pin 24 
with the radially drawn-in edge of the adjusting ring 12. The pin 24 
engages in an elongated aperture (not shown) of the heat shield 17 which 
extends in the circumferential direction, as a result of which the 
adjusting path is limited. Another non-illustrated possibility to limit 
the adjusting path 5 should be mentioned at this place. A radially 
outwardly directed limit pin connected with the adjusting ring engages in 
a limited aperture of the annular flange of the guide blade carrier. The 
improved heat shielding with respect to the hot gas space is of advantage 
in this case, for an aperture for the passage of the limit pin can be 
dispensed with. 
In the lower half of the cross-sectional view of FIG. 2, the adjusting ring 
12 with its cam-shaped raised portions is illustrated which cooperate 
within the area of the guide blade ends with the guide blades 7 for their 
positional change for different operating conditions of the exhaust gas 
turbocharger. The cam-shape is constructed streamlined, preferably in the 
form of blade profiles. 
FIGS. 3 to 5 illustrate the bearing support of a guide blade 7 in different 
views. 
FIG. 3 illustrates a cross section within the area of the bearing support 
through the bearing ring of the guide blade carrier 8 on the side of the 
bearing housing transversely to the bearing pin 9. It can be seen from 
this figure that the bearing bore 10 possesses within the area of the 
bearing pin connection a radial access 27 of the width of the blade 
profile. It can also be recognized that the diameter of the bearing pin 9 
is considerably larger than the blade width so that notwithstanding the 
radial aperture of the bearing bore, a safe canting-free guidance of the 
bearing pin 9 is assured. The bearing pins 9 may have different diameters 
or may also be of different length. As a result thereof, an incorrect 
installation position is precluded during the insertion into the guide 
blade carrier 8. 
FIG. 4 illustrates the view of the bearing support along line IV--IV of 
FIG. 3. 
FIG. 5 shows the view of the bearing support along the cross-sectional line 
V--V of FIG. 4. It can be seen from FIGS. 4 and 5 that the bearing bore 10 
is axially accessible only in the outer bearing ring. The insertion of the 
guide blades 7 which are provided with rigidly connected bearing pins 9, 
takes place in a radial movement and in a subsequent axial movement in 
which the bearing pins 9 are inserted into the bearing bores 10. Upon 
completion of the radial movement, a profile section of the blades is 
disposed in the slot of the one bearing bore. However, it is also possible 
to construct both bearing bores nonslotted. However, the bearing pins in 
that case cannot be constructed in one piece with the guide blades, but 
must be constructed attachable at the guide blades. 
A structural unit as is represented by the guide blade carrier can be 
machined in its axial width to very accurate dimensions of the space for 
the guide blades prior to the insertion of the guide blades. This means 
that the gap losses are kept correspondingly small and therewith 
efficiencies are attainable which are more favorable than with 
corresponding bearing support of the guide blades between the housing 
walls or bearing rings connected with the housing walls but not rigidly 
coupled at one another. Since further the guide blade carrier can be so 
arranged in the housing that any warping of the housing as a result of 
pressure and thermal stresses are not transmitted to the guide blade 
carrier, the gap tolerances can be selected correspondingly still more 
narrowly, and the efficiency can be further improved. It is also 
significant with these achieved improvements that the housing-independent 
bearing support of the guide blades within a guide blade carrier of the 
illustrated type of construction permits a constructively simple design of 
the fluid flow machine. The assembly of the different parts is thus 
possible practically without tools and in relatively short assembly 
periods of time. Threaded connections in thermally highly stressed areas 
are not required which is of great importance for the operating 
reliability of the fluid flow machine. 
It is further advantageous that the turbine housing can be screwed onto the 
bearing housing in every rotational position without changing thereby the 
guide blade position. This is of significance in the attachment of the 
exhaust gas turbocharger to different engines. 
While we have shown and described only one embodiment in accordance with 
the present invention, it is understood that the same is not limited 
thereto but is susceptible of numerous changes and modifications as known 
to those skilled in the art, and we therefore do not wish to be limited to 
the details shown and described herein but intend to cover all such 
changes and modifications as are encompassed by the scope of the appended 
claims.