GB Patent 1554640 - STORE EJECTOR RELEASE UNITS

Description

(54) IMPROVEMENTS IN OR RELATING TO STORE EJECTOR RELEASE

UNITS

(71) We, WESTLAND AIRCRAFT LIMITED, of Yeovil, in the County of Somerset, a

British Company, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the followingstatement:

This invention relates to store ejector release units(E.R.U.'s), that is to say the units that are used for carrying jettisonable stores on an aircraft, and particularly to such units that are known as crutchless E.R.U.'s.

By a crutchless E.R.U. we means an

E.R.U. that involves the use of so-called saddle lugs on the store. These lugs have a substantial lateral width and are adapted to be engaged by complementary hook systems and by laterally spaced-apart wedges on the E.R.U. and acting between the E.R.U.

body and the lugs so as to brace the saddle lugs against the co-operating hooks of the

E.R.U. in a manner to prevent lateral rocking of the lugs and consequent swaying motion of the store to which they are fitted.

Crutchless E.R.U.'s of this construction are for instance disclosed in U.K. Patent Specification Serial No. 1,092,828.

It has been proposed to interconnect the wedges in a crutchless E.R.U. with their associated suspension hook so that, when the E.R.U. is uncocked, the wedges are physically withdrawn from their wedging position to facilitate fitment of a store by providing a clearance between the wedges and the associated saddle lug on the store.

Since the hooks are arranged for movement through a limited arc, it follows that the wedging angle must be chosen so as to effect such a clearance within the allowable movement dictated by the limited hook movement, and it may be that the wedging angle has to be of such a magnitude as to preclude an efficient wedge action being achieved when the wedges are moved into contact with the saddle lugs.

Accordingly, the present invention provides an ejector release unit having a pivotally mounted hook for engagement during operation in a saddle lug attached to a store to be carried, and laterally spacedapart wedges slidably mounted in the unit so as to contact an upper surface of the saddle lug when said hook is engaged, wherein each wedge comprises at least two wedge parts arranged so that, in combination, said parts provide a first wedge angle determining the disengaged clearance (as herein defined), said parts being movable relative each other to provide an effective wedge angle, that is less than said first wedge angle, for sway bracing when the hook is engaged with a saddle lug.By "disengaged clearance" we means the clearance that exists between the underside of the wedges and the saddle lug of a store in position to be engaged by the associated hook of the E.R.U., when that hook is in its disengaged position and the wedges are withdrawn.

Preferably, each wedge comprises first and second wedge parts that co-operate to provide the first wedge angle, the first and second parts being slidable relative each other along an angled slide face defining the said effective wedg angle.

The first wedge part may have a generally convex downwardly facing surface for engagement, during operation, with the surface of the saddle lug.

Means may be provided which prevent separation of the wedge parts whilst permitting the relative movements therebetween.

In one embodiment the means comprise a longitudinally extending slot formed in the slide face of the first wedge part and a mating projection on the slide face of the second wedge part, a transverse slot being formed through the projection and at least one dowel located through the walls of the slot in the first part and through the transverse slot in the second part so as to prevent separation of the parts. Preferably, two spaced-apart dowels are provided, the spacing between the dowels being less than the length of the transverse slot so as to permit the relative sliding movement.

Means may be provided adjacent one end of said first wedge part for attachment to one end of a link, the other end of the link being connected to the hook in a manner so as to permit pivotal movement of the hook towards the first wedge part and to limit movement of the hook away from the first wedge part, so that movement of the hook away from the saddle lug effects withdrawal of the wedge. Conveniently, a compression spring is associated with the link and arranged so as to urge the first wedge part away from the hook and into engagement with the saddle lug.

Preferably, an adjustable abutment is provided on the hook and arranged to engage one end of the second wedge part to move the second wedge part into its operative position when the hook is moved so as to engage the saddle lug.

The abutment may comprise a threaded spindle screwed through a threaded boss on the hook, and locked by a locking nut.

A longitudinally extending projection may be provided along one side of the second wedge part for engagement with a mating solt in the structure of the ejector release unit so as to retain the wedge in an operative position when no store is attached.

The invention will now be described by way of example only and with reference to the accompanying drawings inwhich:

Figure 1 is a perspective exploded view of one end of an existing ejector release unit,

Figure 2 is a side elevation of a wedge for an ejector release unit and constructed in accordance with the invention

Figure 3 is a sectioned view taken alonglines A-A of Figure ktail view 2,

Figures 4 and 5 are detail views of parts of the wedge in the direction of arrow B of Figure 2,

Figure 6 is a side elevation of one of the parts of the wedge in the direction of arrow

C of Figure 5, and

Figure 7 is a part-sectioned fragmentary view of an ejector release unit according to the invention.

Referring now to Figure 1, a known ejector release unit (E.R.U.) comprises a body 10 provided with apertures 11 to facilitate attachment of the unit to an aircraft.

An outwardly facing double-pronged hook

12 is pivotally attached to the body 10 by a tubular pivot sleeve 13, the bore of which is also utilised for attachment purposes. A lug 14 formed on the hook 12 is pivotally attached to one end of a connecting lever (not shown), the other end of which is operatively associated with an actuating mechanism arranged to cause pivotal movement of the hook 12 between its engaged position in which it supports a store, and a disengaged position in which the store is released. The actuating mechanism is operated by gas pressure from an electrically fired cartridge in a manner well known in the art.

A downwardly extending spigot 15 is secured centrally in the end of the body 10 and, in operation, locates in a mating recess 16 in a saddle lug 17 secured to a surface of a store 18 to be carried by the E.R.U. The spigot 15 serves to locate the store 18, and to provide for the transmission of longitudinal (fore-and-aft) and yaw plane forces between the E.R.U. and the store 18.

The saddle lug 17 is provided with two laterally arranged slots 19 for engagement by the prongs of the hook 12 when in its engaged position thereby providing support for the store 18.

Two laterally spaced wedges 20 are slidably located in inclined slots 21 in the body 10 and are each retained by an inwardly extending longitudinal projection 22 located in a mating slot 23 in one surface of the inclined slots 21. Each wedge 20 is connected by a threaded pin 24 to a lug 25 provided on each side of the hook 12, and a spring 26, located on each pin 25, serves to urge the wedge 20 into its operational position in the slots 21 when the hook 12 is moved to its engaged position. A downwardly facing convex surface of the wedge 20 is thereby urged into contact with an upper surface of the saddle lug 17 to provide crutchless sway bracing of the store 18.

Movement of the hook 12 to a disengaged position causes automatic withdrawal of the wedges 20 up the inclined slots 21 in the body 10 and away from the upper surface of the saddle lug 17.

In the prior art construction shown in

Figure 1, each wedge 20 has a wedge angle that provides the vertical displacement necessary on withdrawal of the wedges 20 from the slots 21, by movement of the hook 12 from its engaged to its disengaged position, to provide adequate clearance between the withdrawn wedge and a newly offered-up store so as to provide unrestricted fitment of the store. This wedge angle, dictated by such considerations and the available movement of the hook 12, may not correspond to the smaller wedge angle that would provide optimum wedging action for sway bracing a store during operating. In practice, a compromise wedge angle may have to be adopted, providing both less than the desired clearance when the wedges are withdrawn, and less than optimum wedging action for sway bracing.

The wedge construction that characterises the E.R.U. of the present invention is shown in Figures 2 to 6 and from Figures 2 and 3 it will be seen that each wedge 28 comprises a first wedge part 29 and a second wedge part 30 mated along an angled slide face 31.

In combination, the first and second wedge parts, 29 and 30 respectively, together provide a first wedge anglela of approximately 11 degrees, chosen to provide a desired clearance when the wedges are withdrawn, the parts being slidable relative each other along the slide face 31 that is disposed at an angleg of approximately 5 degrees to the upper face of the second wedge part 30 and is so chosen that the first wedge part has an effective wedge angle that gives optimum sway bracing performance.

The first wedge part 29 has a downwardly facing generally convex surface 32, and is provided at one end with a drilled boss33.

A longitudinally extending slot 34 (Figureg is provided in the slide face 31a of the first wedge part 29, and a mating projection 35 (Figures 5 and 6) is formed on the slide face 31b of the second wedge part 30. A transverse slot 36 is provided through the projection 35 and is a clearance fit on two spaced-apart dowels 37 (Figures 2 and 3) located in mating holes through the walls of the slot 34 in the first wedge part 29. The length of the slot 36 is greater than the spacing of the dowels 37 so as to permit relative sliding movements of the first and second wedge parts 29 and 30 along the slide face 31, whilst preventing separation of the wedge parts 29 and 30.

A longitudinally extending projection 38 is provided on the second wedge part 30 adjacent a generally planar upper surface 39 thereof.

Figure 7 is a fragmentary part sectioned view of one end of an E.R.U. constructed in accordance with the invention. In this

Figure, parts similar to those previously described in relation to the arrangement shown in Figure 1 are identified by the same reference numerals.

Thus, the hook 12 is pivotally mounted to the body 10 about the pivot sleeve 13 for movement through an arc 40 between a store-engaged position (as illustrated) and a disengaged position.

One of a pair of laterally spaced wedges 28 is shown located between a wedge location face 41, fromed in the slot 21 of the body 10, and the upper surface of the saddle lug 17 attached to the store (not shown) so as to provide lateral sway bracing of the store in a manner hereinbefore described. The wedges 28 are retained in the slots 21 by the projections 38 (Figures 3 and 5) located in the slots 23, and the drilled boss 33 on the first wedge part 29 is attached to one end of the pin 24.

A threaded spindle 42 is screwed into a threaded boss 43 formed on the side of the hook 12, and is locked by a locking nut 44.

An inner end of the spindle 42 is arranged to abut an end surface of the second wedge part 30 so as to retain the second wedge part 30 in its operative position when the hook 12 is in the engaged position as illustrated.

Wedge location face 41 is located at an angle of approximately 11 degrees to the upper surface of the saddle lug 17 so as to correspond with anglela (Figure 2) that defines the first or total wedge angle of the co-operating first and second wedge parts 29 and 30 of wedge 28, and it will be clear that the angled sliding face 31 between the wedge parts 29 and 30 is located at an angle of 5 degrees from the wedge location face 41 to correspond with angle' (Figure 2). The difference (6 degrees), between these angles a and iS represents the effective wedge angle of the first wedge part 26 when providing sway bracing, as will be explained.

In operation of the E.R.U. according to the invention, as hook 12 is moved through the limited arc 40 to its disengaged position to release the saddle lug 17 and an associated store, the wedge 28 is withdrawn by the pin 24. This withdrawal movement of the wedge 28 takes place along the wedge location face 41, i.e. at an angle of approximately 11 degrees, that ensures a vertical displacement of the wedge to provide adequate clearance between the surface of the saddle lug 17 on a newly offered-up store and the convex surface 32, to facilitate fitment of the new store.

As the hook 12 is moved to engage the saddle lug 17 on the store, the threaded spindle 42 moves the second wedge part 30 of the wedge 28 into its operative position and, simultaneously, the first wedge part 29 is urged into position by the spring 26 on the pin 24. Because the second wedge part 30 is effectively locked in position by the spindle 42, the movement of the first wedge part to any slack between the store and the

E.R.U. under the thrust of the spring 26 takes place along the slide face 31 and with an effective wedge angle chosen to provide optimum wedging action for lateral sway bracing of the store.

In the embodiment described the effective wedge angle is 6 degrees, a value that has been found to provide very efficient wedge action with a small movement between the first and second wedge parts 29 and 30 of the wedge 28 in response to flight loads.

Thus the E.R.U. of the present invention combines the unrestricted fitment of stores with an efficient wedge action to provide the desired sway bracing characteristics This is achieved by a wedge construction that enables wedge angles having desired withdrawal and operational characteristics to be selected entirely independently so that optimum conditions can be achieved in any particular design.

Whilst a particular embodiment has been described and illustrated, it will be understood that modifications can be made with out departing from the scope of the invention as defined in the appended claims.

WHAT WE CLAIMIS:-

1. An ejector release unit having a pivotally mounted hook for engagement during operation in a saddle lugattached to a store to be carried, and laterally spacedapart wedges slidably mounted in the unit so as to contact an upper surface of the saddle lug when said hook is engaged, wherein each wedge comprises at least two wedge parts arranged so that, in combination, said parts provide a first wedge angle determining the disengaged clearance (as herein defined), said parts being movable relative each other to provide an effective wedge angle, that is less than said first wedge angle for sway bracing when the hook is engaged with a saddle lug.

2. An ejector release unit as claimed in

Claim 1, wherein each wedge comprises first and second wedge parts that cooperate to provide said first wedge angle, said first part being slidable relative said second part along an angled slide face defining said effective wedge angle,

3. An ejector release unit as claimed in

Claim 2, wherein said first part includes a generally convex downwardly facing surface for engagement during operation with the surface of a saddle lug on the store.

4. An ejector release unit as claimed in

Claim 2 or Claim 3, including means preventing separation of said first and second parts whilst permitting said relative sliding movements.

5. An ejector release unit as claimed in

Claim 4, wherein said means comprise a longitudinally extending slot formed in the slide face of said first part, a mating projection formed on the slide face of said second part, a transverse slot formed through the projection and at least one dowel located through the walls of the slot in said first part and the transverse slot in said second part.

6. An ejector release unit as claimed in

Claim 5, including two said dowels spacedapart by a distance less than the length of said transverse slot through the projection on the second part.

7. An ejector release unit as claimed in any one of Claims 2 to 6, including means adjacent one end of said first wedge part to attach said first part to one end of a link, the other end of said link being attached to said hook in a manner so as to permit movement of said hook towards said first wedge part and to limit movement of said hook away from said first wedge part.

8. An ejector release unit as claimed in

Claim 7, including a compression spring associated with each link and urging said first wedge part away from said hook.

9. An ejector release unit as claimed in any one of Claims 2 to 8, including means to urge the second wedge part into its operative position when said hook is moved so as to engage the saddle lug on a store.

10. An ejector release unit as claimed in

Claim 9, wherein said means comprise a threaded spindle screwed through a threaded boss on the hook and locked by a locking nut.

11. An ejector release unit as claimed in any one of Claims 2 to 10, including a longitudinally extending projection along one side of said second wedge part and engaged in a mating slot in said nut.

12. An ejector release unit as claimed in any preceding Claim, wherein said first wedge angle is approximately 11 degrees and said effective wedge angle is approximately 6 degrees.

13. An ejector release unit substantially as described with reference to and as shown in Figures 2 to 7 of the accompanying drawings.

**WARNING** end of DESC field may overlap start of CLMS **.