Turbomachine fan rotor

1. A turbomachine fan rotor having an axis of rotation and comprising:

a disk carrying blades including roots that are engaged in substantially axial grooves in an outer periphery of the disk, each axial groove having a bottom;

a retaining cheekplate secured to the disk; and

spacers engaged between said bottom of the grooves in the disk and the blade roots, an upstream end of each spacer configured to bear against the retaining cheekplate, each spacer including a nib extending radially outwards relative to the axis of rotation and configured to retain an upstream end of the corresponding blade root,

wherein the nib of each spacer includes a downstream abutment face against which the upstream end of the blade root directly bears in a stress state induced by a violent force exerted on at least one of the blades, the downstream abutment face being oblique relative to the axis of rotation of the rotor.

2. A rotor according to claim 1 , wherein the downstream abutment face of the nib forms an angle lying in the range 10° to 80° approximately, relative to the axis of the rotor.

3. A rotor according to claim 2 , wherein the downstream abutment face of the nib forms the angle lying the range 20° to 70° approximately, relative to the axis of the rotor.

4. A rotor according to claim 1 , wherein each blade root includes an upstream face that extends obliquely relative to the axis of rotation of the rotor and which is situated facing the downstream abutment face of the nib.

5. A rotor according to claim 4 , wherein, in an unstressed state, the facing oblique faces of the nib and of the blade root are inclined relative to each other by an angle of less than 10°, the angle tending to disappear by elastic deformation of the nib in event of a violent force being applied to the blade.

6. A rotor according to claim 5 , wherein, in the unstressed state, the facing oblique faces of the nib and of the blade root are inclined relative to each other by the angle lying in the range 2° to 5° approximately.

7. A rotor according to claim 1 , wherein the oblique face of the nib is smooth.

8. A turbomachine, an airplane turboprop, or turbojet, comprising a fan rotor according to claim 1 .

9. A turbomachine fan rotor having an axis of rotation and comprising:

a disk carrying blades including roots that are engaged in substantially axial grooves in an outer periphery of the disk, each axial groove having a bottom;

a retaining cheekplate secured to the disk; and

spacers interposed between said bottoms of the grooves in the disk and the blade roots, an upstream end of each spacer configured to bear against the retaining cheekplate, each spacer including a nib extending radially outwards relative to the axis of rotation and configured to retain an upstream end of the corresponding blade root,

wherein the nib of each spacer includes a downstream abutment face against which the upstream end of the blade root bears in event of a violent force, the downstream abutment face being oblique relative to the axis of rotation of the rotor, and

wherein the nib includes, at a radially outer end, a downstream radial face for axially positioning the upstream end of the blade root.

10. A rotor according to claim 9 , wherein each blade root includes an upstream face that extends obliquely relative to the axis of rotation of the rotor and which is situated facing the downstream abutment face of the nib, and

wherein, in an unstressed state, the facing oblique faces of the nib and of the blade root are kept spaced apart from each other by the blade root bearing against the downstream radial face of the nib.

11. A rotor according to claim 9 , wherein the downstream radial face of the nib is connected to the oblique face of the nib via a transverse groove configured to facilitate elastic deformation of the radially outer portion of the nib in an upstream direction.

12. A rotor according to claim 11 , wherein the groove has a section of concave rounded shape.

13. A turbomachine fan rotor having an axis of rotation and comprising:

a disk carrying blades including roots that are engaged in substantially axial grooves in an outer periphery of the disk, each axial groove having a bottom;

a retaining cheekplate secured to the disk; and

spacers interposed between said bottom of the grooves in the disk and the blade roots, an upstream end of each spacer configured to bear against the retaining cheekplate, each spacer including a nib extending radially outwards relative to the axis of rotation and configured to retain an upstream end of the corresponding blade root,

wherein the nib of each spacer includes a downstream abutment face against which the upstream end of the blade root bears in event of a violent force, the downstream abutment face being oblique relative to the axis of rotation of the rotor, and

wherein grooves or teeth are formed on the oblique face of the nib.

14. A blade root spacer having an axis and extending around the axis, the spacer comprising at one end a nib including two faces for bearing against the blade root, which faces are respectively formed by a first face that is radial to the axis, for positioning the blade root, and by a second face that is oblique relative to the axis, for retaining the blade root.

15. A spacer according to claim 14 , wherein the radial and oblique faces are connected to each other via a transverse groove having a section of concave rounded shape.

16. A turbomachine fan rotor having an axis of rotation and comprising:

a disk carrying blades including roots having an upstream face and which are engaged in substantially axial grooves in an outer periphery of the disk, each groove having a bottom;

a retaining cheekplate secured to the disk; and

spacers interposed between said bottoms of the grooves in the disk and the blade roots, an upstream end of each spacer configured to bear against the retaining cheekplate, each spacer including a nib extending radially outwards relative to the axis of rotation and configured to retain the upstream end of the corresponding blade root,

wherein the nib of each spacer includes a downstream abutment oblique relative to the axis of rotation of the rotor,

wherein, in an unstressed situation, the respective upstream faces of the blade roots are spaced apart from the respective downstream abutment faces of the spacer nibs, and

wherein, in a situation in which at least one of said blades is subjected to an upstream substantially axial force, the upstream face of the corresponding at least one blade root is pressed against the downstream abutment face of the corresponding spacer nib.