RU2389642C1 - Packing facility of self-closing covers of aircraft hatches - Google Patents

Abstract

FIELD: machine building. ^ SUBSTANCE: invention refers to packing facilities for sealing automatically closing covers of aircraft hatches. The facility consists of a rubber packing element installed on cover 5 of the hatch. The packing element is made as thin ring 1 secured on cover 5 of the hatch with its cantilever-arranged internal part, while its external part designed to contact packed surface 22 of fringe 15 of the aircraft case is free. The internal part of the ring is clamped along whole perimetre of hatch cover 5 to ensure said cantilever attachment and simultaneously to give a conic shape to the packing element. Hold downs 3 and 4 have congruous conic surfaces contacting surfaces of ring 1 with their tops turned to the side of sealed volume. Hold down 4 is attached by glue to contact surface of the internal part of ring 1. Cover 5 of the hatch and fringe 15 of the aircraft case can be made with slit 21 between them and with pocket 2 along whole perimetre of the external part of the packing element; also pocket 2 communicates with environment through this slit. ^ EFFECT: invention facilitates pressure tightness of split joint of hatch covers operating under extreme sub and above zero temperatures avoiding application of heavy efforts for closing. ^ 3 cl, 4 dwg

Description

The invention relates to the field of space and aeronautical engineering, and more particularly, to sealing self-closing manhole covers operating in a wide range of plus and minus temperatures.

A device is known according to the author's certificate of the USSR No. 288554 (publ. 03.12.1970 [1]) for sealing aircraft hatches, comprising a cover reinforced with a power kit and interacting with the support profile of its shell with the edging profile of the hatch opening and a sealing element (harness). The sealing effect is achieved by compressing the sealing rope located inside the V-shaped support profile of the hatch, another V-shaped edging profile.

A device of this design has a large weight due to the presence of two shells and two V-shaped profiles. To close the lid, great efforts are required, since the sealing element (harness) has rigid characteristics, and considerable efforts are required to deform and overcome the frictional force between the V-shaped profiles at the moment of closing the lid.

There is also known a device according to USSR author's certificate No. 1744000 (publ. 30.06.1992 [2]) for sealing the hatch of an aircraft, containing a seal having a base and a flexible working part, including an inclined wall with a thickening in the form of a round head at the end contacting its edge with a manhole cover, and seal fastening elements on the manhole edging. The fastening elements contain a locking V-shaped thin metal profile into which a rubber seal is inserted and fixed.

In this device, under the action of forces caused by excessive external pressure and acting on the outer side of the side wall of the seal, depressurization (opening of the sealed joint) can occur, since the flexible side wall of the seal is thin enough and the force required to bend it from the contact surface is negligible. When the manhole cover is closed, the seal is compressed while its wall is pressed against the fixing thin-walled V-shaped profile having a sharp edge. As a result of this, the integrity (circumcision) of the side wall may be violated, which will lead to a violation of tightness.

In addition, great efforts are required to close the hatch at low temperatures, since with decreasing temperature the elastic modulus of the rubber increases significantly (the rubber hardens). This disadvantage is explained by the fact that in the free (not compressed) state, the wall of the seal forms an angle of about 70 ° with the surface of the contact surface of the cover (i.e., it is almost perpendicular), therefore, during compression, the wall of the seal not only bends, but also contracts, and this great effort. Corrugations are formed around the perimeter of the seal, and this leads to intermittent contact with the manhole cover and, as a consequence, to a violation of tightness.

Corrugations are inevitably formed, firstly, when a sealant closed around the perimeter is installed inside the fixing V-shaped element, since in the free state the wall of the sealant is deflected from the base to the outside of the sealant, and in the working state the fixing V-shaped element bends the side wall to the side base (to the inner side of the sealant having a closed perimeter), which requires a reduction in the perimeter of the thickened head, and since this is impossible, corrugations arise. Secondly, corrugations can occur when the lid is closed, the seal is crimped and the wall is bent into the section of the profile, which also requires a reduction in the perimeter of the thickened head and, since this is impossible, leads to the formation of corrugations.

The noted drawbacks of sealing devices known from copyright certificates [1], [2], lead to the impossibility of their use for self-closing manhole covers in a wide temperature range, because it follows from the foregoing that there are situations where the lid may simply not close.

To the proposed invention closest sealing device according to copyright certificate [2].

The present invention is aimed at obtaining a technical result, which consists in ensuring the sealing of a plug-in connection of automatically closing (without human intervention) manhole covers of aircraft operated both at high minus and plus temperatures, without the use of great effort to close. When disclosing the essence of the invention and describing an example of its implementation, other types of technical result achieved with which the aforementioned has a causal relationship will be named.

The proposed device, as well as the device closest to it according to the copyright certificate [2], contains a rubber sealing element mounted on the manhole cover with the possibility of creating a sealing effect when closing the lid by pressing the sealing element against the sealing surface of the aircraft frame.

To achieve the specified technical result in the proposed device, in contrast to the specified closest known rubber sealing element made in the form of a thin flat ring mounted on the manhole cover with its inner part cantilever, and its outer part, intended for contact with the sealing surface of the edging of the aircraft body is free. At the same time, for the indicated cantilever fastening, while at the same time giving the sealing element a conical shape, the inner part of the indicated ring is clamped around the entire perimeter of the manhole cover between two ring clamps mounted on the manhole cover from the side of the space to be sealed. These clamps have congruent conical surfaces in contact with the surfaces of the indicated part of the ring and facing their vertices to the side of the space to be sealed. In this case, the clip more distant from the surface of the hatch cover has an adhesive connection with the surface of the indicated part of the ring in contact with it.

In addition, the manhole cover and the edging of the aircraft body can be made with a gap between them and with the formation of a pocket in front of the sealing element from its outer side around the entire perimeter of the outer part of the ring. The pocket through this slot is connected to the environment.

Due to the above-described features of the implementation and installation of the sealing element, when closing the lid, only the cantilever part of the cross-section of the profile of the sealing element is deformed, and it only works on bending. There are no compressive deformations of the profile section, and therefore, the forces required to close the cover are small. At high negative temperatures, when the rubber seal loses its highly elastic properties (rubber hardens), the effort to close the lid remains small due to the fact that when the sealing element is cooled, not only linear, but also volume compression of its conical cantilever (not pinched) part occurs. In this case, the dimensions of the non-pinched part are reduced significantly more than that of the pinched part. Preliminary compression of the sealing element occurs before the cover is slammed, and therefore, the required amount of compression and the force of slam-shut of the cover are reduced.

In the particular case of the implementation of the proposed device, providing for the presence of the above-described slit and pocket, the overpressure in the latter caused by the oncoming flow of the environment provides uniform pressing of the sealing element to the sealing surface around the entire perimeter. This further increases the reliability of automatic slamming of the manhole cover over a wide temperature range and helps to ensure the required tightness.

It is advisable to perform the specified slit with a width of 1.0 ÷ 1.5 mm

In describing the specific implementation of the proposed device, the physical effects that determine the achievement of the inherent technical result of the invention will be discussed in more detail.

The invention is illustrated by drawings, which show:

- figure 1 is a General view of the sealing device for a round self-closing cover;

- figure 2 is a diagram of the sealing device, explaining the effect of preliminary compression;

- figure 3 - fragment "A" of figure 1 (the scheme of operation of the sealing device, explaining the effect of self-sealing);

- figure 4 - graphs of the dependence of the closing force of the cover on temperature.

The sealing device contains (see figure 1, 2) a thin flat elastic sealing element 1 in the form of a ring with an outer diameter of f ₁ and an inner diameter of f ₂ . Such a sealing element is similar to a conventional flat rubber gasket, easy to manufacture and does not require special molds. The sealing element 1 is mounted on the manhole cover 5 with two cone-shaped clamps 3 and 4. The clamps 3, 4 are located on the periphery of the inner surface of the cover 5, facing the side of the volume to be sealed. The clamp 4, more remote from the surface of the cover 5, is placed with a sealing element 1 on the glue. The conical surfaces of the clamps 3 and 4 facing each other are congruent, while these conical surfaces are oriented by the vertices of the corresponding cones in the direction of the volume to be sealed. Clips 3 and 4 are mounted on the cover 5 by means of bolted connections 24 (figure 2). The design of the hatch cover 5 together with the edging 15 of the aircraft body form an annular pocket 2 (Figs. 1, 3) around the entire perimeter of the outer part of the thin ring in the form of which the sealing element 1 is made. Into the pocket 2 through an annular gap 21 of width δ = 1 ÷ 1.5 mm of leaking gas (air) from the environment. The cover 5 (Fig. 1) is hung on the axis of rotation 9 and is automatically slammed by means of a spring drive 10, a cable 7 and a rocker 8. The drive 10 is mounted on a frame 11 with which the casing 12 of the aircraft body is fastened. In the closed position, the cover 5 is locked with a latch 14 of the lock lock. The sealing element 1 has a tight contact with the sealing surface 22 of the annular element 6 (see figure 3), belonging to the design of the edging 15 of the hatch.

The proposed device operates as follows. At positive ambient temperatures, cover 5 slams shut without any problems. The sealing element 1 has high elastic properties, and its cross section is easily crimped (deflected by an angle ω, see Figs. 1, 3), creating a sealing effect with a sealed surface 22 (see Fig. 3), which increases during flight from called self-sealing effect. When the device is operating in conditions of high negative temperatures, despite the fact that the material of the sealing element hardens and requires more compression forces during deformation, the proposed device provides reliable closing (closing) of the cover. This is achieved as follows.

1. Giving a thin flat elastic sealing element 1 conical shape with an angle α at the apex of the cone (see figure 2). Its installation on the manhole cover 5 is carried out using two conical metal clamps 3 and 4, which clamp one edge of the cone formed from a flat ring and the other remains free (the profile cross section looks like a cantilevered beam), and one of the clamps (4) is mounted on glue. This design solution allows you to reduce the force of closing (slamming) of the cover, since the deformation of the sealing element of the conical shape requires a compression force significantly less than the traditional compression of the profile section itself.

2. By reducing (compressing) the formed volume of the cone of the sealing element during cooling, the non-crimped part being compressed much more, and the pinched metal clamps 3, 4 and less adhesive. The diameter of the non-crimped part of the cone decreases from Ф ₁ to Ф ' ₁ (see Fig. 2), the free edge of the sealing element rotates (bends) by an angle φ, taking position 1'. In this case, a sharper cone is formed with an angle β at the apex smaller than the initial value α. A preliminary compression of the sealing element 1 takes place before the hatch cover 5 is slammed shut, and therefore, its compression is reduced upon closing. This effect (pre-compression effect) occurs due to the difference in the linear expansion coefficients (in rubber it is 15 times greater than in metal).

3. The creation of a pocket 2 in the design of the cover, connected to the environment through an annular gap 21 of width δ and having inside (during the flight) a zone of increased pressure P ₁ in front of the thin-walled elastic sealing element 1 (see figure 3). This design solution creates the effect of self-sealing, i.e. the sealing element is pressed against the sealing surface 22 of the annular element 6 by the very same pressure of the incoming flow of the environment, thereby creating an increased (additional) sealing effect. The excess pressure in the pocket 2 provides an additional uniform pressure of the sealing element to the sealing surface around the entire perimeter.

The proposed design of the sealing device allows you to use the described physical laws to reduce the compression forces of the sealing element, which increases the reliability of automatic closing of the manhole cover in a wide temperature range, both positive and large negative. This conclusion is confirmed by the graph of the dependence of the force F closing the cover on the temperature T (see figure 4). The temperature dependence of the linear force q of compression of the sealing element also has the same form. The linear load q of the additional pressing of the sealing element shown in figure 3 is determined from the expression:

q = (P ₁ -P ₂ ) · B,

Where:

P ₁ is the pressure of the oncoming flow of the environment;

P ₂ - pressure inside the aircraft;

In - shown in figure 3 the width of the non-clamped part of the sealing element 1,

and the total additional force F of pressing the sealing element from the self-sealing effect is

F = qL

where L is the length of the non-clamped part of the sealing element along the midline of the ring, which is this part.

The graph of figure 4 is obtained from the test results of hatches with a diameter of 346 mm It can be seen from the graph that with decreasing temperature from + 20 ° to 0 ° С, the force of hatching of the hatch cover increases, and with further cooling it falls (a “dip” appears) and only slightly increases after minus 30 °. The presence of "failure" is explained by the fact that when cooling below 0 ° C, the effect of preliminary compression of the sealing element is shown, which is described above and is explained using the operation scheme of the proposed sealing device (figure 2).

Thus, the technical solution according to the invention allows to create a device for sealing a detachable connection of automatically slamming hatches, operating in a wide temperature range.

Information sources

1. USSR Author's Certificate No. 288554, publ. 12/03/1970.

2. USSR Author's Certificate No. 1744000 A1, publ. 06/30/1992.

Claims (3)

1. A sealing device for sealing automatically slamming manhole covers of aircraft, containing a rubber sealing element mounted on the manhole cover with the possibility of creating a sealing effect when closing the lid and pressing the sealing element against the sealing surface of the aircraft body rim, characterized in that the sealing element is made in in the form of a thin ring, which is fixed on the manhole cover with its inner part cantilever, and its outer part, intended for cont activation with the sealing surface of the aircraft body rim is free, while for the indicated cantilever fixing while simultaneously giving the sealing element a conical shape, the inner part of the indicated thin ring is clamped around the entire perimeter of the manhole cover between two cone-shaped clamps mounted on the manhole cover from the side of the space to be sealed and having congruent conical surfaces in contact with the surfaces of the inner part of the specified thin ring and facing their tops toward the sealable space, the more distant from the manhole cover has a clamp adhesive connection with the surface in contact with it inside of said thin ring. 2. The device according to claim 1, characterized in that the manhole cover and the edging of the aircraft body are made with a gap between them and with the formation of a pocket connected to the environment through the specified slot around the entire perimeter of the outer part of the specified thin ring. 3. The device according to claim 1, characterized in that the width of the specified slit is in the range of 1.0 ÷ 1.5 mm

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