Method for centering engine structures
AssigneePratt & Whitney Canada Corp.
InventorsEric DUROCHER, John PIETROBON, Nicolas GRIVAS
Life of this patent
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Abstract
A method for centering an engine structure such as a bearing housing is provided which may be used, for example, during assembly of a mid turbine frame or other engine case structure. In one aspect, the method includes using spacers with respective radial spokes which connect inner and outer portions of the case. In another aspect, centring may be provided by machining selected contacting surfaces of selected components.
Claims17
A method for positioning outer and inner cases of a gas turbine engine relative to one another, the outer and inner cases having a plurality of radial spokes extending between them when the outer and inner cases are assembled, the method comprising:
- (1) determining a variance between a present spoke length and a desired spoke length for each spoke based on a desired positioning of the cases;
- (2) modifying an effective length of each spoke according to the variance to meet the desired spoke length;
- and then
- (3) assembling the cases with the spokes to provide the desired positioning of the cases.
A method for centering a bearing housing during a mid turbine frame assembly procedure, the mid turbine frame to be assembled including at least an inner case co-axially supported in an outer case by a plurality of radial spokes, and the bearing housing attached to the inner case, each of the spokes having an inner end abutting and connected to one of axial surfaces of the inner case, the method comprising:
- a) selecting one of the inner end of each spoke and each said axial surface to be machined for concentric adjustment of the bearing housing within the outer case before the respective spokes are connected to the inner case;
- b) measuring a radial distance D1 between the respective axial surfaces of the inner case and an inner diameter surface of the bearing housing when the respective inner ends of the spokes are selected to be machined;
- c) measuring a radial distance D2 between respective inner ends of the spokes and an inner diameter surface of the outer case when the respective axial surfaces are selected to be machined;
- d) machining the inner end of the individual spokes to suit the respective measurements taken in step (b), thereby obtaining a predetermined radial distance D between the inner diameter surface of the outer case and the inner diameter surface of the bearing housing when the mid turbine frame is assembled;
- or
- e) machining the respective axial surfaces of the inner case to suit the respective measurements taken in step (c), thereby obtaining a predetermined radial distance D between the inner diameter surface of the outer case and the inner diameter surface of the bearing housing when the mid turbine frame is assembled;
- and
- f) connecting the inner ends of the spokes to the axial surfaces of the inner case, respectively after step (d) or (e).
A method for centering a bearing housing during an assembly procedure of a mid turbine frame, the mid turbine frame to be assembled including an inner case co-axially supported in an outer case by a plurality of spokes, and the bearing housing attached to the inner case, the method comprising:
- a) completing the assembly procedure of the mid turbine frame;
- b) holding the mid turbine frame on a fixture which provides a machining position of the mid turbine frame relative to an inner diameter surface of the bearing housing;
- and
- c) machining an inner diameter of the outer case held on the fixture.
Dependencies are inferred from the claim text.