JP2000018096A - Jet engine tail cone supporting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the load to be burdened on a turbine frame by a tail cone at the rupture of a fan blade. SOLUTION: A cylindrical tail cone receiver 8a centering on a turbine shaft is installed in the rear end of a turbine frame constituting a turbine 4. A mounting part 7a at the front end side of a tail cone 7 is fitted in a peripheral surface part of the tail cone receiver 8a, and then the circumferential, required interval position of a fitting part is clamped by a bolt 14. Strength in the mounting part 7a of the tail cone 7 is so designed that the mounting part 7a is made so as to be damaged when load in a direction of separating the tail cone 7 from the turbine frame 8 has acted as going beyond the setting value.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tail cone support device for a jet engine used as a propulsion engine for a commercial aircraft.

[0002]

2. Description of the Related Art As shown in FIG. 4, a high bypass turbofan engine, which is one of jet engines, has a fan 1, a compressor 2, a combustor 3, and a turbine 4 in order from a tip end. In the direction (indicated by the axis O), the rotation of the fan 1 driven by the turbine 4 takes in air from the air inlet 5, and most of the air is blown out from the bypass duct 6 to generate propulsion force, and the remaining A part is compressed by the compressor 2 driven by the turbine 4, the fuel is burned in the combustor 3 by the compressed air, and the turbine 4 is driven by the high-speed combustion air flow.

[0003] In the high bypass turbofan engine, a cone is attached to the rear end to guide the air flow. However, the mounting structure of the tail cone 7 as the rear end cone has an excessive load. It must be strong enough so that it will not be damaged by action.

Therefore, conventionally, as shown in FIG. 5, a flange 9 is provided at the rear end of a turbine frame 8 as a strength member constituting the turbine 4 so as to be perpendicular to the turbine shaft. A flange 10 is extended from the front end of the tail cone 7 so as to correspond to 9, and the flanges 9 and 10 are fastened with bolts 11.

[0005]

However, since the turbine frame 8 is a strength member, for example, when a fan blade is broken, a load generated in each part of the engine is applied to the turbine frame 8. In particular, the load W generated on the tail cone 7 acts in a direction in which the tail cone 7 is separated from the engine in the mounting structure, and at this time, the tail cone 7
Is firmly attached to the turbine frame 8 by a flange joint, so that the turbine frame 8
May exceed the allowable value.

Accordingly, an object of the present invention is to provide a tail cone support device for a jet engine capable of reducing a load applied to a turbine frame.

[0007]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a cylindrical tail cone receiving portion centered on a turbine shaft at a rear end of a turbine frame constituting a turbine of a jet engine. Provided, the tail cone front end side mounting portion is fitted to the outer peripheral surface of the tail cone receiving portion,
A required circumferential position of the fitting portion between the tail cone mounting portion and the tail cone receiving portion is fastened by a bolt, and the strength of the tail cone mounting portion is weaker than the strength of the tail cone receiving portion. Use the designed configuration.

When a load is applied to the tail cone in a direction of separating from the engine, and the load exceeds a set value, the bolt fastening portion of the mounting portion of the tail cone is damaged by shearing force with the bolt, and the load energy is damaged while being damaged. Can reduce the load transmitted to the turbine frame.

In addition, on the outer peripheral surface of the tail cone mounting portion,
A reinforcing sleeve is fitted to fix the rear end to the tail cone, and a front end of the reinforcing sleeve is provided with a long hole along the turbine axis direction, and the tail cone mounting portion and the tail of the turbine frame are provided in the long hole. With the configuration in which the bolt for fastening to the cone receiving portion is inserted, damage to the tail cone is suppressed in the range of the elongated hole of the reinforcing sleeve, so that the tail cone can be prevented from falling off.

[0010] Further, a step is formed on the outer peripheral surface of the tail cone receiving portion of the turbine frame so as to have a small diameter, and the tail cone mounting portion is bent inward so that the front end portion follows the step. By adopting a configuration in which the reinforcing sleeve extends along the outside, the load energy can be absorbed even in the drawn shape portion of the tail cone, so that it is possible to allow a margin in the strength design of the mounting portion of the tail cone. Become like

[0011]

Embodiments of the present invention will be described below with reference to the drawings.

FIGS. 1 and 2 (a) and (b) show an embodiment of the present invention. In a high bypass turbofan engine as a jet engine having a configuration similar to that shown in FIG. 8, the strength of the attachment portion 7a of the tail cone 7 to the tail cone receiving portion 8a
The structure is designed to be weaker than the strength of the tail cone receiving portion 8a.

More specifically, at the rear end of a turbine frame 8 as a strength member constituting the turbine 4 of the engine,
Cylindrical tail cone receiver 8a centered on the turbine shaft
And an annular step 8b is formed on the outer peripheral surface of the tail cone receiving portion 8a so as to have a small diameter.
At the mounting portion 7a on the front end side of the tail cone 7, a narrowed portion 7b bent inward along the step 8b having a small diameter of the tail cone receiving portion 8a is formed, and the mounting portion 7a of the tail cone 7 is formed. The tail-shaped portion 7b is connected to the tail cone receiving portion 8 described above.
a from the outside, and the tail cone mounting portion 7a and the tail cone receiving portion 8
a, bolt holes 12 and 13 which communicate with each other are provided at predetermined intervals in the circumferential direction of the fitting portion with the fitting portion a, and the bolt holes 14 are used to fasten the mounting portion 7 a of the tail cone 7 to the tail cone 7.
The bolt hole 12 is designed to have a strength such that the bolt hole 12 is damaged when the load W in the direction of separating the bolt from the engine exceeds a set value.

A reinforcing sleeve 15 for preventing the tail cone 7 from falling off the turbine frame 8 is fitted on the outer peripheral surface of the mounting portion 7a of the tail cone 7,
The rear end is fixed to the body of the tail cone 7 with rivets 17, and the front end of the reinforcing sleeve 15 is bolted to the mounting portion 7 a of the tail cone 7 and the tail cone receiving portion 8 a of the turbine frame 8. A long hole 16 extending in parallel with the turbine axis direction is provided in accordance with the shape of the hole, and a recess 15 a is formed around the long hole 16 in accordance with the outer diameter of the throttle-shaped portion 7 b of the tail cone 7. The bolts 14 are inserted and fastened.

In the engine, for example, when a fan blade is broken, the load W generated at that time acts on the mounting portion 7a of the tail cone 7 in a direction to separate the tail cone 7 from the engine. However, since the drawn shape portion 7b formed on the attachment portion 7a of the tail cone 7 is deformed so as to be elongated, the energy of the load W can be absorbed.

Also, a throttle-shaped portion 7b of the tail cone 7 is provided.
When a large load W is applied that cannot be absorbed simply by stretching the tail cone 7, the tail cone 7 is attached to the bolt fastening portion between the attachment portion 7 a of the tail cone 7 and the tail cone receiving portion 8 a of the turbine frame 8. A large shearing force acts between the bolt hole 12 and the bolt 14 formed in the portion 7a. At this time, the mounting portion 7a of the tail cone 7 is damaged so that it exceeds a set load. Since the strength is designed, when the load W becomes larger than the set value, the bolt holes 12 are damaged as shown in FIG. 3, and the load energy can be absorbed while being damaged. Note that the load W when the fan blade breaks occurs instantaneously and disappears while energy is being absorbed. Therefore, the load W does not directly act on the turbine frame 8 and the load transmitted to the turbine frame 8 can be reduced, and the resultant stress value can be prevented from exceeding the allowable value. it can.

In the above, the mounting portion 7 of the tail cone 7
When the damage of the bolt hole 12 part of a is infinitely developed,
Although the tail cone 7 falls off from the engine, a reinforcing sleeve 15 having an elongated hole 16 through which a bolt 14 is inserted is provided on the outer periphery of the mounting portion 7a of the tail cone 7, so that When the tail cone 7 and the reinforcing sleeve 15 move rearward integrally, the elongated hole 16 is formed.
When the bolt 14 abuts on the end of the bolt, the progress of damage to the bolt hole 12 at that time is suppressed, and the tail cone 7 is prevented from falling off.

The present invention is not limited to the above-described embodiment. The small-diameter step 8b of the tail cone receiving portion 8a of the turbine frame 8, the drawing portion 7b of the mounting portion 7a of the tail cone 7, and the reinforcement Recess 15 in sleeve 15
It is needless to say that a may be unnecessary, may be applied to a jet engine other than the high bypass turbofan engine, and may be variously modified without departing from the gist of the present invention.

[0019]

As described above, according to the tail cone support device for a jet engine of the present invention, the following excellent effects are exhibited. (1) At the rear end of a turbine frame constituting a turbine of a jet engine, a cylindrical tail cone receiver centering on a turbine axis is provided, and the tail cone front end is mounted on an outer peripheral surface of the tail cone receiver. The tail cone mounting portion and the tail cone receiving portion are fastened with bolts at circumferentially required intervals of the fitting portion between the tail cone receiving portion and the strength of the tail cone receiving portion. The structure is designed to be weaker than the strength, so if a large load acts in the direction of pulling the tail cone away from the engine, the tail cone mounting part will be damaged while absorbing the load energy, and the load on the turbine frame will be reduced. The applied load can be reduced. (2) On the outer peripheral surface of the mounting portion of the tail cone, a reinforcing sleeve is fitted and the rear end is fixed to the tail cone, and a long hole along the turbine axial direction is provided at the front end of the reinforcing sleeve.
By adopting a configuration in which a bolt for fastening the tail cone mounting portion and the tail cone receiving portion of the turbine frame is inserted through the long hole, it is possible to prevent damage to the tail cone mounting portion from developing indefinitely. It is possible to prevent the tail cone from falling off. (3) A step is formed on the outer peripheral surface portion of the tail cone receiving portion of the turbine frame so as to have a small diameter, and the tail cone mounting portion is formed into a drawing shape in which the front end portion is bent inward so as to follow the step. By adopting a configuration in which the reinforcing sleeve extends along the outer side, the load energy can be absorbed by the drawn shape portion of the tail cone, so that the strength design of the mounting portion can be given a margin.

[Brief description of the drawings]

FIG. 1 is a schematic view showing one embodiment of a tail cone support device for a jet engine of the present invention.

FIG. 2 shows details of a tail cone support device for a jet engine according to the present invention, wherein (A) is an enlarged view of a portion A in FIG. 1,
(B) is a partially cut plan view of (A).

FIG. 3 is a partial plan view of a tail cone showing a state in which a bolt hole is damaged from the state of FIG.

FIG. 4 is a schematic diagram of a high bypass turbofan engine showing an example of a jet engine.

FIG. 5 is a schematic view showing an example of a conventional tail cone mounting structure.

[Explanation of symbols]

 Reference Signs List 4 Turbine 7 Tail cone 7a Attachment portion 7b Restricted shape portion 8 Turbine frame 8a Tail cone receiving portion 8b Small diameter step 12, 13 Bolt hole 14 Bolt 15 Reinforcement sleeve 15a Recess 16 Long hole

Claims (3)

[Claims] 1. A cylindrical tail cone receiver centered on a turbine shaft is provided at a rear end of a turbine frame constituting a turbine of a jet engine, and an outer peripheral surface of the tail cone receiver has a tail cone front end side. Fitting part of
A required circumferential position of the fitting portion between the tail cone mounting portion and the tail cone receiving portion is fastened by a bolt, and the strength of the tail cone mounting portion is weaker than the strength of the tail cone receiving portion. A tail cone support device for a jet engine, having a designed configuration. 2. A tail sleeve is fitted to an outer peripheral surface of a mounting portion of the tail cone, and a rear end portion is fixed to the tail cone.
2. A bolt according to claim 1, wherein an elongated hole is provided along the turbine axial direction at a front end of the reinforcing sleeve, and a bolt for fastening a tail cone mounting portion and a tail cone receiving portion of the turbine frame is inserted into the elongated hole. Jet engine tail cone support device. 3. A throttle shape in which a step is formed on the outer peripheral surface of a tail cone receiving portion of a turbine frame so as to have a small diameter, and a tail cone mounting portion is bent inward so that a front end portion follows the step. 3. A tail cone support device for a jet engine according to claim 2, wherein a reinforcing sleeve extends along the outside of the tail cone supporting device.