Turbomachine comprising a means of uncoupling a fan

Abstract

A turbojet engine includes a fan shaft driven by a turbine shaft via a device for reducing the speed of rotation. The engine includes an uncoupling device interposed between the reduction device and the turbine shaft. The uncoupling device is configured to uncouple the reduction device and the turbine shaft in response to the exceeding of a determined resistant torque exerted by the reduction device on the turbine shaft.

1 . A turbomachine comprises a fan shaft driven by a turbine shaft via a device for reducing the speed of rotation, wherein the turbomachine includes an uncoupling device interposed between the reduction device and the turbine shaft the uncoupling device being configured to uncouple the reduction device and the turbine shaft in response to the exceeding of a determined resistant torque called uncoupling torque exerted by the reduction device on the turbine shaft. 
     
     
         2 . The turbomachine according to  claim 1 , wherein the uncoupling device includes at least one fuse connecting element which is interposed between the reduction device and the turbine shaft and which is configured to be broken when subjected to the resistant uncoupling torque exerted by the speed reduction device on the turbine shaft. 
     
     
         3 . The turbomachine according to  claim 2 , wherein the fuse element comprises a segment of an input shaft of the reduction device bound to the shaft of the turbine, said segment being configured to be broken when subjected to a maximum torsional torque corresponding to the resistant uncoupling torque. 
     
     
         4 . The turbomachine according to  claim 2 , wherein an input shaft of the reduction device includes a tubular end segment which is coupled with a complementary tubular end segment of the turbine shaft via at least one radial fuse connecting element configured to be broken when subjected to a shear stress corresponding to the resistant uncoupling torque. 
     
     
         5 . The turbomachine according to  claim 4 , wherein the radial fuse connecting element includes a pin which is received in a radial orifice of the end segment of the input shaft and into an orifice facing the end segment of the turbine shaft. 
     
     
         6 . The turbomachine according to  claim 2 , wherein the reduction device is coupled to the turbine shaft via a coupling with trapezoidal teeth of the curvic type, including two toothed coupling plates meshing with one another and fastened to one another via axial fuse screws forming fuse connecting elements of the uncoupling device. 
     
     
         7 . The turbomachine according to  claim 1 , wherein the fuse connecting element is configured to be broken as soon as it is subject to a resistant uncoupling torque corresponding to a resistant torque exerted by the fan on the speed reduction device in the case of loss of at least one blade of a fan driven by said fan shaft. 
     
     
         8 . The turbomachine according to  claim 1 , wherein the fuse connecting element is configured to be broken as soon as it is subject to a resistant torque which is strictly greater than any torque corresponding to a resistant torque exerted by the fan on the speed reduction device in the case of ingestion of a bird without any blade loss by said fan. 
     
     
         9 . The turbomachine according to  claim 7 , wherein the fuse connecting element is associated with a fan including metal blades and is configured to be broken as soon as it is subject to a resistant uncoupling torque comprised between 120% and 140% of a normal torque under maximum speed conditions of the turbomachine. 
     
     
         10 . The turbomachine according to  claim 7 , wherein the fuse connecting element is associated with a fan including composite blades and is configured to be broken as soon as it is subject to a resistant uncoupling torque comprised between 130% and 170% of a normal torque under maximum speed conditions of the turbomachine. 
     
     
         11 . The turbomachine according to  claim 1 , wherein the turbomachine includes means for detecting uncoupling of the reduction device and of the turbine shaft able to control a reduction of speed of the turbine and/or a stopping of the turbomachine. 
     
     
         12 . The turbomachine according to  claim 1 , wherein the resistant uncoupling torque is greater than 50,000 N·m, and preferably comprised between 50,000 N·m and 400,000 N·m. 
     
     
         13 . The turbomachine according to  claim 1 , wherein the turbomachine includes an additional uncoupling device interposed between the reduction device and the shaft of the fan, which is configured to uncouple the reduction device and the fan shaft in response to exceeding a determined resistant torque, called uncoupling torque, exerted by the fan shaft on the reduction device. 
     
     
         14 . The turbomachine according to  claim 13 , wherein the uncoupling device includes at least one fuse connecting element which is interposed between the reduction device and the fan shaft and which is configured to be broken when it is subject to the resistant uncoupling torque exerted by fan shaft on the speed reduction device. 
     
     
         15 . The turbomachine according to  claim 14 , wherein the fuse element comprises a segment of an input shaft of the reduction device bound to the shaft of the fan, said segment being configured to be broken when it is subject to a maximum torsional torque corresponding to the resistant uncoupling torque. 
     
     
         16 . The turbomachine according to  claim 14 , wherein an output shaft of the reduction device includes a tubular end segment which is coupled with a complementary tubular end segment of the fan shaft via at least one fuse connecting radial element configured to be broken when subject to a shear stress corresponding to the resistant uncoupling torque. 
     
     
         17 . The turbomachine according to  claim 16 , wherein the radial fuse connecting element includes a pin which is received in a radial orifice of the end segment of the output shaft and in an orifice facing the end segment of the fan shaft. 
     
     
         18 . The turbomachine according to  claim 14 , wherein the reduction device is coupled to the fan shaft via a coupling with trapezoidal teeth of the curvic type, including two toothed coupling plates with trapezoidal axiafusel teeth meshing with one another and fastened to one another via axial fuse screws forming meltable connecting elements of the additional uncoupling device.