Pitch control ring for stator vanes of a turbomachine
A turbomachine including a variable-pitch stator vane stage is disclosed. A control ring that is coaxial around the casing includes two segments that are assembled together by side connection straps fastened on either side of the segments with mutual insetting and in the vicinity of the ends of the segments.
1. A turbomachine comprising:
a variable-pitch stator vane stage, arranged circumferentially in a casing, each vane having a control pivot that projects radially outside said casing and each pivot being connected by an arm to a common control ring that is disposed coaxially around said casing and that is mounted to turn on the outside thereof,
wherein said control ring comprises two ring segments that are assembled together by side connection straps fastened on an upstream side and a downstream side of said ring segments with mutual insetting, at least in the vicinity of circumferential end portions of the ring segments, the side connection straps being separable from said ring segments,
wherein two connection straps are fastened to the upstream side of each ring segment and two connection straps are fastened to the downstream side of each ring segment, and
wherein said side connection straps are bolted on upstream and downstream sides of adjacent circumferential end portions of said ring segments with at least one bolt arranged parallel to an axis of the turbomachine for each circumferential end portion.
2. A turbomachine according to claim 1 , wherein said ring segments include side recesses into which said side connection straps are set.
3. A turbomachine according to claim 2 , wherein each of said side connection straps is an annular segment that is chamfered to define frustoconical surfaces, and wherein said side recesses present a corresponding recessed profile.
4. A turbomachine according to claim 1 , wherein each of said side connection straps is an annular segment including a recess into which end portions of said ring segments are set.
5. A turbomachine according to claim 4 , wherein said ring segments are chamfered to define four frustoconical surfaces that are superposed coaxially in pairs, and wherein the recess in each side connection strap has two corresponding frustoconical facets co-operating respectively with such frustoconical surfaces that are coaxially superposed in pairs.
6. A turbomachine according to claim 1 , wherein the side connection straps are bolted to each circumferential end portion by two bolts.
7. A turbomachine according to claim 1 , wherein a bolt shank fits a hole in which the bolt shank is engaged in the ring segment circumferential end portion.
8. A turbomachine according to claim 1 , wherein an additional bolt is provided in the middle of two side connection straps.
9. A turbomachine according to claim 1 , wherein said ring includes at least one drive fork, said fork presenting a base fastened on one side of said ring with insetting.
10. A turbomachine according to claim 9 , wherein said base is formed integrally with one of said side connection straps.
11. A turbomachine according to claim 2 , wherein said side recesses extend over the entire circumference of said ring.
12. A turbomachine according to claim 1 , wherein said side connection straps abut said ring segments.
13. A turbomachine according to claim 1 , wherein a downstream face of a head of the bolt abuts an upstream face of the side connection strap fastened on the upstream side of the ring segments.