Securing arrangement

A securing arrangement 32 for securing an actuating lever 20 to a spindle 14, for example a spindle 14 of a variable inlet guide vane 10 in a gas turbine engine, comprises a fastening formation 38 rotatably co-operable, in use, with a corresponding fastening formation 30 on the spindle 14. The securing arrangement 32 is rotatable relative to the spindle 14 to a securing position in which the respective fastening formations 30, 38 co-operate so that the securing arrangement 32 secures the actuating lever 20 to the spindle 14. The securing arrangement 32 includes anti-rotation means 42, preferably in the form of anti-rotation tabs 44, for preventing rotation of the securing arrangement 32 from the securing position.

The present invention relates to a securing arrangement for securing an actuating lever to a spindle, and particularly but not exclusively to a securing arrangement for securing an actuating lever to a spindle in a rotary component of a gas turbine engine.

Gas turbine engines conventionally include variable inlet guide vanes to control airflow through the engine, and these generally include a spindle to which an inlet guide vane actuating lever is secured by a securing arrangement.

It would be desirable to provide a securing arrangement which maintains the actuating lever secured to the spindle during engine operation and which is of simple construction.

According to a first aspect of the present invention, there is provided a securing arrangement for securing an actuating lever to a spindle, the securing arrangement comprising a fastening formation rotatably co-operable, in use, with a corresponding fastening formation on the spindle, and being rotatable relative to the spindle to a securing position in which the respective fastening formations co-operate so that the securing arrangement secures the actuating lever to the spindle, wherein the securing arrangement includes anti-rotation means for preventing rotation of the securing arrangement from the securing position.

The anti-rotation means may be co-operable, in use, with the actuating lever to prevent rotation of the securing arrangement from the securing position. The anti-rotation means may be arranged to abut the actuating lever, in use, to prevent rotation of the securing arrangement from the securing position. The anti-rotation means may be arranged to abut a side face of the actuating lever, in use, to prevent rotation of the securing arrangement from the securing position.

The anti-rotation means may extend generally radially from the securing arrangement, and may be axially deflectable from the radially extending position to permit rotation of the securing arrangement, in use, relative to the spindle.

The anti-rotation means may extend generally circumferentially around the securing arrangement.

The anti-rotation means may comprise an anti-rotation tab, and may comprise a plurality of anti-rotation tabs, each anti-rotation tab preferably extending generally radially from the securing arrangement.

The plurality of anti-rotation tabs may be arranged generally circumferentially around the securing arrangement. Adjacent anti-rotation tabs may be arranged to be generally in abutment with each other.

The securing arrangement may include a circumferentially extending flange portion, the anti-rotation means preferably being defined by the flange portion. The securing arrangement may include a fastening portion extending from the flange portion, the fastening formation preferably being provided on the fastening portion. The fastening portion may extend from the flange portion, preferably generally perpendicular thereto.

The fastening formation may comprise a threaded formation which may be co-operable, in use, with a corresponding threaded formation on the spindle.

The securing arrangement is preferably adapted to secure an actuating lever to a spindle in a rotary component of a gas turbine engine.

According to a second aspect of the present invention, there is provided a gas turbine engine incorporating a securing arrangement according to the first aspect of the present invention for securing an actuating lever to a spindle in a rotary component of the gas turbine engine.

Referring toFIG. 1, there is shown generally a variable inlet guide vane10for use in a rotary component, for example a compressor, of a gas turbine engine. The guide vane10is rotatably mounted in a casing12of the engine and includes a spindle14extending from an upper end thereof.

The circumferential outer surface16of the spindle14defines a plurality of splines (not shown) which are co-operable with corresponding splines defined by a circumferential inner surface18of an actuating lever20, only part of which is illustrated in the drawings. The actuating lever20is operable, in use, to rotate the guide vane10to a desired position. A bush22is located between the casing12and a circumferential outer surface24of the actuating lever20and the actuating lever20is connected to an actuator ring (not shown), as is conventional in the art.

As best seen inFIG. 1, the spindle14is generally annular and defines a central passage26. At least part of the circumferential inner surface28of the passage26defines a fastening formation30which, according to a preferred embodiment of the invention, is a threaded formation.

In order to secure the actuating lever20to the spindle14and prevent detachment of the actuating lever20from the spindle14, for example during operation of the gas turbine engine, a securing arrangement32, according to the present invention, is employed. The securing arrangement32generally includes a circumferentially extending flange portion34and a fastening portion36which is generally annular and which extends from the flange portion34generally perpendicular thereto. The fastening portion36is locatable, in use, in the passage26of the spindle14and includes a fastening formation38, for example a threaded formation, which is rotatably co-operable with the fastening formation30on the spindle14.

As can be clearly seen inFIGS. 1 and 2, the flange portion34extends in use over an upper surface40of the actuating lever20such that when the securing arrangement32is rotated to a securing position in which the respective fastening formations30,38co-operate such that a lower surface of the flange portion34of the securing arrangement32is firmly engaged with an upper end of the spindle14, the securing arrangement32secures the actuating lever20to the spindle14and prevents unwanted or accidental release therefrom.

The securing arrangement32includes anti-rotation means, generally designated by the reference numeral42, for preventing rotation of the securing arrangement32from the securing position, and thereby preventing unwanted or accidental release of the actuating lever20from the spindle14.

In more detail, according to a preferred embodiment of invention, the anti-rotation means42comprises a plurality of anti-rotation tabs44(only some of which are shown inFIG. 2) arranged generally circumferentially around the securing arrangement32. Each of the anti-rotation tabs44extends generally radially from the securing arrangement32and is defined by the flange portion34. Each of the anti-rotation tabs44may slope gently downwardly in the direction of the fastening portion36, as best seen inFIGS. 1 and 3.

The anti-rotation tabs44are arranged so that adjacent tabs44are generally in abutment but such that a small gap46is defined between adjacent tabs44to allow individual tabs44to be deflected upwardly without causing deflection of adjacent tabs44. As best seen inFIG. 2, the size of the gap46is increased at the root of each of the anti-rotation tabs44to facilitate the deflection of individual tabs44and thereby prevent cracking and failure of the tabs44when deflected axially.

As best seen inFIG. 2, one side face47aof the actuating lever20includes a sloping or chamfered portion48which merges smoothly into the upper surface40of the actuating lever20. Accordingly, as the securing arrangement32is rotated in the direction of arrow A towards the securing position, the anti-rotation tabs44are deflected upwardly from their normal position so that they lie on the upper surface40of the actuating lever20. This deflected position is shown in broken lines inFIG. 3.

As rotation of the securing arrangement32continues, the individual anti-rotation tabs44which have passed over the upper surface40of the actuating lever20, and which are no longer in contact with the upper surface40, spring back to their original position due to the inherent resilience of the material from which the securing arrangement32is fabricated. This could for example be a resilient metallic material or any other suitable material having sufficient resilience to enable the tabs44to be deflected and subsequently spring back to their original position.

When the securing arrangement32is rotated so that it is in the securing position, as shown inFIG. 2, the anti-rotation tab44which is adjacent to a side face47bof the actuating lever20springs back to its original position and abuts the side face47b. Unlike the side face47a, the side face47bdoes not include a sloping portion48, and is instead a flat surface. This prevents the anti-rotation tabs44from being deflected upwardly towards the upper surface40of the actuating lever20if rotation of the securing arrangement32in the direction opposite to arrow A is attempted, and the abutment of the anti-rotation tab44adjacent to the side face47bof the actuating lever20with the side face47bthereby prevents rotation of the securing arrangement32from the securing position in the direction opposite to arrow A.

In the event of failure of the anti-rotation tab44which is in abutment with the side face47bwhen the securing arrangement32is in the securing position shown inFIG. 2, the securing arrangement32may rotate in the direction opposite to arrow A away from the securing position. However, only a small amount of rotation will occur since the next anti-rotation tab44which has not failed, for example adjacent to the failed anti-rotation tab44, will enter into abutment with the side face47band thereby prevent further rotation of the securing arrangement32. The securing arrangement32will accordingly still be in a securing position in which it is capable of securing the actuating lever20to the spindle14and preventing accidental or unwanted release of the actuating lever20from the spindle14.

When it is desired to intentionally release the actuating lever20from the spindle14, the anti-rotation tabs44can be bent upwardly or snapped off the flange portion34so that manual rotation of the securing arrangement32in the direction opposite to arrow A, away from the securing position, is possible. When the actuating lever20is subsequently secured again to the spindle14, it is envisaged that a new securing arrangement32would be used, the previous securing arrangement having been discarded.

In order to prevent the anti-rotation tabs44, which may present sharp edges, from causing damage to surrounding components in the engine, a circumferentially extending protective cap50, for example made of a rubber or plastics material, may optionally be located over the securing arrangement32, as illustrated inFIG. 3.

There is thus provided a securing arrangement32for securing an actuating lever20to a spindle14, for example a spindle14of a variable inlet guide vane10in a gas turbine engine, which prevents accidental and unwanted release of the actuating lever20from the spindle14.

Although embodiments of the invention have been described in the preceding paragraphs with reference to various examples, it should be appreciated that various modifications to the examples given may be made without departing from the scope of the present invention, as claimed. For example, the anti-rotation means42may be in a form other than anti-rotation tabs44. A single anti-rotation tab44may be provided. Fastening formations30,38other than threaded formations may be provided. The securing arrangement32may be adapted to secure an actuating lever20to a spindle14in a turbine, or in any other rotating component, of a gas turbine engine