CROSS-REFERENCES TO RELATED APPLICATIONS

This application claims the benefit of the French patent application No. 1903095 filed on Mar. 25, 2019, the entire disclosures of which are incorporated herein by way of reference.

FIELD OF THE INVENTION

The present invention relates to a turbofan engine which comprises a series of blades which are mounted to rotate to block the bypass air stream, and an aircraft comprising at least one such turbofan engine.

BACKGROUND OF THE INVENTION

An aircraft comprises a fuselage with a wing fixed on each side. Under each wing, there is suspended at least one turbofan engine. Each turbofan engine is fixed under the wing via a pylon which is fixed between the structure of the wing and the structure of the turbofan engine.

The turbofan engine comprises an engine and a nacelle which is fixed around the engine. The turbofan engine has, between the nacelle and the engine, a bypass stream in which bypass air circulates.

The nacelle comprises a plurality of thrust-reversing gates, each being rotationally mobile on the structure of the nacelle between a retracted position in which it is outside of the bypass stream and a deployed position in which it is positioned across the bypass stream in order to deflect the bypass air to a window which is in the wall of the nacelle and which is open between the bypass stream and the outside of the nacelle.

Thus, the bypass air is deflected outwards and, more specifically, towards the front of the turbine engine in order to produce a counter-thrust. In addition, the displacement of each thrust-reversing gate is produced using a connecting rod which crosses the bypass stream in retracted position and which therefore partially blocks the bypass stream.

Although the thrust-reversing gates give full satisfaction, it is desirable to find different mechanisms, in particular mechanisms that are less heavy and which offer no obstruction to the bypass air in retracted position.

SUMMARY OF THE INVENTION

One object of the present invention is to propose a turbofan engine which comprises a series of blades which are mounted to rotate to block the bypass air stream.

To this end, a turbofan engine is proposed that has a longitudinal axis and comprises an engine and a nacelle surrounding the engine which comprises a fan casing, in which a stream of bypass air is delimited between the nacelle and the engine and in which a flow of air circulates in a direction of flow, said nacelle comprising:a fixed structure fixed to the fan casing,a mobile assembly having a mobile cowl and a runner, the mobile cowl being fixed to the runner, the runner being translationally mobile on the fixed structure in a direction of translation between an advanced position in which the runner is positioned so that the mobile cowl is close to the fan casing and a back-off position in which the runner is positioned so that the mobile cowl is away from the fan casing to define between them an open window between the stream and the outside of the nacelle,a plurality of blades, each comprising a first end mounted to be rotationally mobile on the runner about an axis of rotation and in which the blades are angularly offset step-by-step about the longitudinal axis, in which each blade is mobile between a retracted position in which the blade is outside of the stream and a deployed position in which the blade is across the stream,a set of actuators ensuring the displacement of the runner between the advanced position and the back-off position, and vice versa, anda maneuvering system intended to displace each blade from the retracted position to the deployed position at the same time as the runner is displaced from the advanced position to the back-off position and vice versa, in which the maneuvering system comprises:for each blade, a shaft mounted to be rotationally mobile on the runner about an axis of rotation, and to which the blade is fixed,for each blade, a toothed segment fixed to the shaft and coaxial with the axis of rotation,a toothed arc coaxial with the longitudinal axis, mounted to be rotationally mobile on the runner about the longitudinal axis, in which the teeth of the toothed arc mesh with the teeth of each toothed segment,a slip mounted to be translationally mobile on the runner in a plane at right angles to the longitudinal axis between a first position corresponding to the retracted position and a second position corresponding to the deployed position,a connecting rod mounted articulated between the slip and the toothed arc,a rib integral to the fixed structure, anda guiding U integral to the slip and which straddles the rib, in which the rib has an appropriate form for displacing the guiding U and therefore the slip from the first position to the second position when the runner is displaced from the advanced position to the back-off position, and vice versa.

Such a turbine engine allows for a reduction of weight by replacing the thrust-reversing gates and their drive mechanisms with lighter pivoting blades with a simplified maneuvering system.

Advantageously, the turbofan engine comprises a radial guiding system which ensures a rotational guidance about the longitudinal axis of the toothed arc relative to the runner.

According to a particular embodiment, the radial guiding system comprises at least one window produced in a plane at right angles to the longitudinal axis through the toothed arc, and, for each window, at least two rollers, each being mounted to be rotationally mobile on the runner about an axis of rotation parallel to the longitudinal axis, in which each roller is mounted inside the window so that the outer edge of the window is bearing on one of the rollers and slips thereon and so that the inner edge of the window is bearing on the other roller and slips thereon.

According to a particular embodiment, the toothed arc takes the form of a crown ring, the radial guiding system comprises a plurality of outer rollers disposed along the outer edge of the crown ring and a plurality of inner rollers disposed along the inner edge of the crown ring, and each outer roller and each inner roller are mounted to be rotationally mobile on the runner, in which the outer edges of the crown ring are bearing on each outer roller and in which the inner edges of the crown ring are bearing on each inner roller and slip thereon.

According to a particular embodiment, the radial guiding system comprises at least one window produced in the runner in a plane at right angles to the longitudinal axis through a wall of the runner, and, for each window, at least two rollers, each being mounted to be rotationally mobile on the toothed arc about an axis of rotation parallel to the longitudinal axis, in which each roller is mounted inside the window so that the outer edge of the window is bearing on one of the rollers and slips thereon and so that the inner edge of the window is bearing on the other roller and slips thereon.

Advantageously, the turbofan engine comprises an axial positioning system which ensures a positioning parallel to the longitudinal axis between the toothed arc and the runner.

Advantageously, the axial positioning system comprises a plurality of front rollers disposed against a front face of the toothed arc and a plurality of rear rollers disposed against a rear face of the toothed arc, in which each front roller and each rear roller are mounted to be rotationally mobile on the runner about an axis of rotation extending radially relative to the longitudinal axis, and in which the front rollers and the rear rollers sandwich the toothed arc and roll on the respectively front and rear face of the toothed arc.

Advantageously, the axial positioning system comprises a window produced in a plane at right angles to the longitudinal axis through the toothed arc and bordered by an outer strip and an inner strip, at least one first pair of rollers which grip the inner strip and at least one second pair of rollers which grip the outer strip, in which each roller is mounted to be rotationally mobile on the runner about an axis of rotation extending radially relative to the longitudinal axis.

Advantageously, the axial positioning system comprises at least one first pair of rollers and at least one second pair of rollers, in which each roller is mounted to be rotationally mobile on the toothed arc about an axis of rotation extending radially relative to the longitudinal axis, an inner groove and an outer groove integral to the runner, each extending coaxially about the longitudinal axis, in which the opening of the inner groove is facing the opening of the outer groove, in which each groove thus comprises a front wall and a rear wall, in which the rollers are housed inside the grooves so that a first roller of the first pair is bearing on and rolls against the front wall of the inner groove, so that the second roller of the first pair is bearing on and rolls against the front wall of the outer groove, so that a first roller of the second pair is bearing on and rolls against the rear wall of the inner groove, and so that the second roller of the second pair is bearing on and rolls against the rear wall of the outer groove.

The invention also proposes an aircraft comprising at least one turbofan engine according to one of the preceding variants.

