JP2001311471A - Sealing device for rotating shaft - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sealing device for a rotating shaft which the fitment accuracy is maintained at the high speed revolution in the hot environment and the deformation on the sealing surface is prevented while the sealing device is pressed onto the rotating shaft. SOLUTION: The sealing device comprises a cylindrical member represented by a sealing liner 32 having a bellows portion 34 forming deformable portion which a free end is pressed toward radial direction and contact with the outer periphery of the rotating shaft represented by outer shaft 7 or inner shaft 8 and is placed between a floating ring member 31 and the rotating shaft. It is characterized in that the sealing surface does not deform when pressing onto the rotating shaft and the deformable portion of the cylindrical member can be deformed by the centrifugal force and heat expansion while the rotating shaft is turning at high speed with high temperature.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotary shaft sealing device.

[0002]

2. Description of the Related Art Generally, lubricating oil is forcibly pumped by a pump for lubricating a bearing of a high-speed rotating shaft. In this case, in order to prevent leakage of the lubricating oil, it is customary to provide a seal member at a portion adjacent to the bearing. As this seal member, a floating ring seal in which a carbon ring slides on the outer peripheral surface of a rotating shaft is known.

When the floating ring seal is used, the outer peripheral surface of the shaft with which the carbon ring slides is extremely precisely adjusted in order to minimize and appropriately manage the gap between the carbon ring and the outer peripheral surface of the shaft. In addition to polishing, it is necessary to apply a wear-resistant coating such as spraying chromium carbide. When it is difficult or unfavorable to perform surface treatment on the shaft itself, a cylindrical member whose outer peripheral surface has been subjected to surface treatment may be pressed into the shaft.

[0004]

However, since this cylindrical member cannot avoid deformation in the radially expanding direction due to the action of centrifugal force at the time of high-speed rotation and thermal expansion, the cylindrical member with respect to the shaft is expected in consideration of this amount of deformation. The fitting tolerance of the shaped members must be determined. However, if the interference at the time of press-fitting is set to be large, the sliding surface of the seal may be deformed when the cylindrical member is press-fitted. Conversely, if the interference at the time of press-fitting is set to be small, at the time of hot high-speed rotation, There is a possibility that misalignment is caused by a decrease in fitting accuracy between the shaft and the cylindrical member, and leakage of seal air or lubricating oil is caused.

[0005] The present invention has the above problems of the prior art,
In other words, it was devised to improve the difficulty in setting an appropriate fitting tolerance between the shaft and the cylindrical member, and its main purpose was to ensure the fitting accuracy during hot high-speed rotation. Above,
An object of the present invention is to provide a rotary shaft sealing device that can prevent deformation of a sealing surface during press-fitting.

[0006]

In order to achieve the above object, according to the present invention, the rotating shaft (the outer shaft 7 or the inner shaft 8 in the embodiment) and the floating ring seal member (31) are used. A cylindrical member (the seal liner 32 in the embodiment) having a radially flexible portion (the bellows-like portion 34 in the embodiment) whose free end is pressed against the outer peripheral surface of the rotating shaft is interposed therebetween. I decided to make it.

[0007] In this case, since the flexible portion provided on the cylindrical member bends, deformation due to centrifugal force and thermal expansion is anticipated, and the seal surface is prevented from being deformed during press-fitting. it can.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the accompanying drawings.

FIG. 1 is a schematic view of a double-shaft bypass jet engine to which the present invention is applied. This engine 1
Each has a cylindrical outer casing 3 and an inner casing 4 which are connected to each other by a rectifying plate 2 and arranged coaxially. Also, the bearings 5f are composed of concentrically assembled hollow shafts, each of which is independent of each other.
It has an outer shaft 7 and an inner shaft 8 supported at the center of the casing with 5r, 6f, and 6r.

The outer shaft 7 is integrally provided with an impeller wheel 9 of a high-pressure centrifugal compressor HC on the front side and a turbine wheel 11 of a high-pressure turbine HT arranged adjacent to the nozzle N of the backflow combustion chamber 10 on the rear side. Is joined to.

The inner shaft 8 has a front fan 12 at the front end, a compressor wheel 13 constituting a moving blade of the low-pressure axial compressor LC behind the front fan 12, and a combustion gas injection duct 14 at the rear end. A pair of turbine wheels 15a and 15b, on which the moving blades of the low-pressure turbine LT are placed, are integrally connected to each other.

At the center of the front fan 12, a nose cone 16 is provided.
A stationary blade 17 having an outer end coupled to the inner peripheral surface of the outer casing 3 is disposed.

A stationary blade 18 of the low-pressure axial flow compressor LC is arranged on the inner periphery of the front end of the inner casing 4.
Behind it, a suction duct 19 for sucking in the front fan 12 and for feeding air pre-pressed by the low-pressure axial compressor LC to the high-pressure centrifugal compressor HC.
And an impeller casing 20 of the high-pressure centrifugal compressor HC which is continuous therewith. A bearing box 21 for bearings 5f and 6f supporting the front sides of the outer shaft 7 and the inner shaft 8 is connected to the inner peripheral side of the suction duct 19.

A part of the air sucked by the front fan 12 is sent to the high-pressure centrifugal compressor HC via the low-pressure axial compressor LC as described above. Then, the remaining relatively low-speed and large amount of air is injected rearward from a bypass duct 22 formed between the outer casing 3 and the inner casing 4, and becomes a main thrust in a low-speed range.

On the outer periphery of the high-pressure centrifugal compressor HC,
A diffuser 23 is connected to supply high-pressure air to the backflow combustion chamber 10 provided immediately after the diffuser 23.

In the backflow combustion chamber 10, the fuel injected from the fuel injection nozzle 24 provided on the rear end face and the high-pressure air sent from the diffuser 23 are mixed and burned. Then, a main thrust in a high-speed region is obtained by the combustion gas injected from the nozzle N facing backward through the injection duct 14 into the atmosphere.

A bearing box 25 for bearings 5r and 6r supporting the rear side of the outer shaft 3 and the inner shaft 4 is connected to the inner peripheral side of the injection duct 14.

The outer shaft 7 of the engine 1 has
The starter motor 26 is connected via a gear mechanism (not shown).
Output shafts are connected. When the starter motor 26 is driven, the impeller wheel 9 of the high-pressure centrifugal compressor HC is driven together with the outer shaft 7, and high-pressure air is sent into the backflow combustion chamber 10. When the high-pressure air and fuel are mixed and burned, the injection pressure of the combustion gas drives the turbine wheel 11 of the high-pressure turbine HT and the turbine wheels 15a and 15b of the low-pressure turbine LT. The rotating force of the high-pressure turbine wheel 11 drives the impeller wheel 9 of the high-pressure centrifugal compressor HC, and the rotating force of the low-pressure turbine wheels 15a and 15b drives the front fan 12 and the compressor wheel 13 of the low-pressure axial compressor LC. When the high-pressure turbine wheel 11 and the low-pressure turbine wheels 15a and 15b are driven by the injection pressure of the combustion gas, the engine 1 continues to rotate in a state determined according to a self-feedback balance between the fuel supply amount and the intake air amount. It will be.

As shown in FIG. 2, a portion adjacent to each bearing (represented by 5 as a representative code) supporting the outer shaft 7 and the inner shaft 8 is provided with the leakage of the lubricating oil supplied to each bearing 5. Floating ring seals 31 are provided for prevention. The inner peripheral portion of the floating ring seal 31 substantially slidably contacts the outer peripheral surface of the seal liner 32 that is press-fitted onto the outer peripheral surface of the outer shaft 7 or the inner shaft 8.

As shown in FIG. 3, the seal liner 32 has a sliding contact surface S of the floating ring seal 31.
A cylindrical part 33 having an outer peripheral surface coated with a wear-resistant coating made of, for example, chromium carbide spraying, and an end at an appropriate position on the inner peripheral surface of the cylindrical part 33, and a free end of which is formed on the outer shaft 7 or the inner shaft. 8 and a bellows-like portion 34 that is pressed against the outer peripheral surface.

The seal liner 32 is inevitably deformed in the radially expanding direction due to the action of centrifugal force during high-speed rotation and thermal expansion. In order to prevent a decrease in fitting accuracy between the shaft 7 (8) and the seal liner 32 at the time of hot high-speed rotation, the interference at the time of press-fitting the seal liner 32 to the shaft 7 (8) is increased in consideration of the deformation amount. In this case, the sliding surface S of the floating ring seal 31 may be deformed when the seal liner 32 is press-fitted.

Therefore, in the present invention, the seal liner 32 is provided with a bellows-like portion 34 which can be bent and deformed in the radially expanding direction at the time of press-fitting. As a result, even if the error due to the interference fit is maximized, the error is absorbed by the bending deformation of the bellows-like portion 34 (shown by the imaginary line in FIG. 3), so that the sliding contact surface of the floating ring seal 31 is formed. S does not need to be deformed. In addition, bellows-like part 3
By appropriately setting the shape and position of 4, the centrifugal deformation can be uniformly generated in the axial direction.

[0023]

As described above, according to the present invention, a cylindrical member having a radially flexible portion whose free end is pressed against the outer peripheral surface of the rotary shaft between the rotary shaft and the floating ring seal. Even if the interference during press-fitting is set large considering deformation due to centrifugal force and thermal expansion, the flexible portion provided on the cylindrical member bends during press-fitting. To prevent deformation. Therefore, according to the present invention, while eliminating the possibility that the fitting accuracy between the shaft and the sleeve is reduced at the time of hot high-speed rotation,
The gap size between the floating ring seal and the outer peripheral surface of the shaft can be minimized and appropriately controlled, and a great effect can be obtained in obtaining the desired sealing performance.

[Brief description of the drawings]

FIG. 1 is a schematic view of a jet engine to which the present invention is applied.

FIG. 2 is an enlarged vertical sectional view of an application site of the device of the present invention.

FIG. 3 is an explanatory view of the operation of the device of the present invention.

[Explanation of symbols]

 7 Outer shaft 8 Inner shaft 31 Floating ring seal 32 Seal liner 34 Bellows-like part

[Procedure amendment]

[Submission date] June 12, 2000 (2006.1.
2)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0017

[Correction method] Change

[Correction contents]

A bearing box 25 for bearings 5r and 6r supporting the rear ends of the outer shaft 7 and the inner shaft 8 is connected to the inner peripheral side of the injection duct 14.

[Procedure amendment 2]

[Document name to be amended] Drawing

[Correction target item name] Figure 2

[Correction method] Change

[Correction contents]

FIG. 2

Claims (1)

[Claims] 1. A cylindrical member having a radially flexible portion whose free end is pressed against the outer peripheral surface of the rotary shaft between the rotary shaft and the floating ring seal member. Rotating shaft sealing device.