Turbine engine having a pair of propellers for an aircraft
An engine includes systems for changing the pitch of propeller blades, a system for an upstream propeller including a linear actuator and a transmission mechanism connecting the actuator to the blades to transform the sliding of the actuator into a rotation of the blades, the upstream propeller including a rotatable housing rigidly connected to a rotatable shaft supported in a static housing of the turbine engine by an upstream bearing and by a downstream bearing. The rotatable housing of the upstream propeller includes a support rigidly connected to the rotatable housing and surrounding the static housing. The actuator is annular and fixed outside to the support, the transfer mechanism includes connecting rods and rotatable radial arms traversing the gaseous flow path, and the downstream bearing is radially located between the static housing and the support.
1. A turbine engine having a pair of contrarotating upstream and downstream coaxial propellers for an aircraft, including respective systems for changing a pitch of blades of the propellers, the system for the upstream propeller including a linear hydraulic actuator, a sliding movable part of which is movable along an axis of the propeller, a transmission mechanism connecting the actuator to the blades in order to transform sliding of the actuator into a rotation of the blades about axes thereof, and a rotatable housing rigidly connected to a shaft for driving in rotation said rotatable housing being supported in a static housing of the turbine engine by a bearing upstream of the system, and by a bearing downstream of the system, wherein: the rotatable housing of the upstream propeller includes a support receiving the linear actuator and rigidly connected to said rotatable housing and surrounding a cylindrical end part of the static housing, the linear hydraulic actuator of the system for changing pitch is annular and comprises a fixed part directly mounted to the support of the rotatable housing so as to be joined axially and in rotation thereto, outside the support, and the sliding part being joined to the transmission mechanism, said actuator being fixed in rotation with the rotatable housing, a piston of the linear hydraulic actuator is rigidly connected to the fixed part, said transmission mechanism of the system comprising connecting rods connected at first ends by first bail joints to the sliding movable part and at second ends by second ball joints to rotatable radial arms radially traversing a gaseous flow path in order to control the pitch of the blades, and the downstream bearing is radially located between the static housing and the support.
2. The turbine engine according to claim 1 , wherein the downstream bearing, which is provided between the static housing and the support, is mounted inside the support.
3. The turbine engine according to claim 2 , wherein the support includes a cylindrical plate, of annular cross-section, attached to or rigidly connected to the rotatable housing of the upstream propeller and extending laterally from said rotatable housing and surrounding the cylindrical end part of the static housing in the direction of the downstream bearing.
4. The turbine engine according to claim 1 , wherein a pivot point of the blades is situated above the linear actuator.
5. The turbine engine according to claim 1 , wherein a fluid supply device of the actuator is provided between the static housing and the support of the upstream propeller, and wherein said support bears said actuator.
6. The turbine engine according to claim 5 , wherein the fluid supply device and the downstream bearing are arranged side by side between the static housing, and an interior of the support, the fluid supply device being vertically above the linear actuator, the downstream bearing being adjacent to the fluid supply device and being located between said actuator and the rotatable housing of the upstream propeller, the actuator being mounted by a fixed part thereof on an exterior of the support.
7. The turbine engine according to claim 5 , wherein the fluid supply device comprises an internal cylindrical part rigidly connected to the static housing, and an external cylindrical part arranged concentrically with the internal cylindrical part and rigidly connected to the support, two independent chambers being formed between the internal cylindrical part and the external cylindrical part by sealing means, said chambers being connected, for the internal cylindrical part, to fluid supply lines and, for the external cylindrical part, to respective chambers of the actuator.
8. The turbine engine according to claim 7 , wherein the fluid supply lines run along an interior of the static housing as far as the cylindrical end part thereof and communicate with the chambers of the fluid supply device.
9. The turbine engine according to claim 7 , wherein said internal and external cylindrical parts are in axial abutment against respective shoulders of the static housing and of the support, and axially immobilized by respective clamping nuts.
10. The turbine engine according to claim 7 , wherein the sealing means between the internal and external cylindrical parts delimiting the two chambers adjacent to the fluid supply device comprise composite double dynamic sealing joints.