DIAPHRAGM HOLDER FOR AN OLEO-PNEUMATIC-TYPE SHOCK ABSORBER

Abstract

A diaphragm holder for an oleo-pneumatic-type shock absorber includes a tubular body made of thermoplastic material, having one end arranged to hold a diaphragm and an opposite end defining an arched bottom for withstanding pressure forces. An insert is housed in the bottom of the tubular body and is arranged to mechanically reinforce the bottom and to distribute the pressure forces evenly.

Claims

1. A diaphragm holder for an oleo-pneumatic-type shock absorber, the diaphragm holder comprising a tubular body made of thermoplastic material having an end arranged to hold a diaphragm and an opposite end defining an arched bottom to hold pressure forces, and an insert housed in the arched bottom of the tubular body to mechanically reinforce said arched bottom and to distribute the pressure forces evenly.

2. The diaphragm holder according to claim 1, wherein the insert is made of metal or composite.

3. The diaphragm holder according to claim 1, wherein the insert is a cylindrical bush.

4. The diaphragm holder according to claim 3, wherein the sleeve is press-fitted on an injection gate of the tubular body.

5. The diaphragm holder according to claim 4, wherein an outer surface of the sleeve engages with an inner surface of a cylindrical stiffener of the arched bottom of the tubular body.

6. The diaphragm holder according to claim 5, wherein a network of radial ridges extends from the cylindrical stiffener in the direction of the arched bottom of the tubular body.

7. An oleo-pneumatic-type shock absorber comprising a diaphragm held by the diaphragm holder according to claim 1.

8. The oleo-pneumatic-type shock absorber according to claim 7, wherein the diaphragm is provided with flow restriction orifices and separates an inner volume of the shock absorber into two chambers.

9. An aircraft lander comprising the oleo-pneumatic-type shock absorber according to claim 7.

10. An aircraft comprising the aircraft lander according to claim 9.

11. The diaphragm holder according to claim 2, wherein the insert is made of metal, and the metal comprises steel or aluminium.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The invention will be best understood in the light of the following description, which is purely illustrative and non-limiting, and must be read regarding the appended drawings, among which:

[0018] FIG. 1 is a schematic cross-sectional view of an aircraft lander comprising a shock absorber known per se;

[0019] FIG. 2A is a perspective view of a diaphragm holder known per se;

[0020] FIG. 2B is an axial cross-sectional view of the diaphragm holder illustrated in FIG. 2A;

[0021] FIG. 3A is a perspective view of a diaphragm holder according to a particular embodiment of the invention;

[0022] FIG. 3B is an axial cross-sectional view of the diaphragm holder illustrated in FIG. 3A;

[0023] FIG. 3C is a detailed view of an end of the diaphragm holder illustrated in FIG. 3B.

DETAILED DESCRIPTION OF THE INVENTION

[0024] FIG. 1 represents an aircraft lander comprising an oleo-pneumatic-type shock absorber. In a manner known per se, the lander comprises a box 1 in which a rod 2 is mounted to slide along a vertical axis X. A lower end of the rod 2 is arranged to receive an axle or a bogie holding one or more wheels.

[0025] A diaphragm 3 separates the inside of the box 1 into a first chamber C1 filled with a hydraulic fluid F and a pressurised gas G and a second chamber C2 filled with hydraulic fluid F. The diaphragm 3 is held by a lower end of a diaphragm holder 4 extending along the axis X, while an upper end of the diaphragm holder 4 is directly added on a ceiling of the box 1.

[0026] The second chamber C2 is moreover delimited by a bottom 5 added in the rod 2. Under the bottom 5 extends a third chamber C3 filled with hydraulic fluid F and a fourth chamber C4 filled with pressurised gas G. The third chamber C3 and the fourth chamber C4 are separated by a separating piston 6.

[0027] The diaphragm 3 and the bottom 5 are provided with calibrated orifices allowing the hydraulic fluid F to as respectively from the second chamber C2 to the first chamber C1 and from the second chamber C2 to the third chamber C3. All this is well-known, and is only reminded of as an illustration.

[0028] FIGS. 2A and 2B illustrate a diaphragm holder 14 made of thermoplastic material well-known from the prior art. The diaphragm holder 14 is similar to that presented in FIG. 1, except its upper end comprises a cylindrical seat 11 arranged to be able to be adjusted in a homologous cylindrical seat arranged in the box 1, and bear against a step of said box 1. The cylindrical seat 11 comprises a groove arranged to receive a seal (not represented).

[0029] Moreover, the diaphragm holder 14 comprises a substantially tubular running part 12 comprising here longitudinal stiffeners 13 which run along the running part 12 parallel to the axis X and radially projecting outwards. The stiffeners 13 are regularly distributed around the running part 12.

[0030] The lower end of the diaphragm holder 14 comprises a cylindrical seat 15 adapted to slide in the rod 2 and an end part 16 on which the diaphragm 3 is added. Similarly to the cylindrical seat 11, the cylindrical seat 15 comprises a groove arranged to receive a sliding block (not represented).

[0031] The upper end of the diaphragm holder 14 has a bottom forming an arch 17, axisymmetrical with convexity oriented towards the diaphragm 3, which is integral with the running part 12. The arch 17 is consolidated inside by a dual stiffening system comprising, on the one hand, a pair of rings 19 centred on the axis X (namely an inner ring and an intermediate ring between the inner ring and the arch 17) and, on the other hand, a network of radial ridges 18 converging towards the central axis X of the diaphragm holder 14 by extending from the arch 17 to the most inner of the rings 19. In this way, the arch 17 is stabilised and can resist significant pressure forces, while having an optimal arrangement of material contributing to a lightening in mass of the diaphragm holder 14.

[0032] FIGS. 3A, 3B and 3C illustrate a diaphragm holder 24 according to a particular embodiment of the invention. The diaphragm holder 24 differs from the diaphragm holder 14 in that the arch stiffening system only comprises one single intermediate ring 29 extending along the central axis X of the diaphragm holder 24 and from which extends a network of radial ridges 28 in the direction of the arch 27. The intermediate ring 29 comprises an inner surface and an outer surface which are substantially truncated, allowing to facilitate the demoulding of the diaphragm holder 24.

[0033] The arch stiffening system 27 moreover comprises a sleeve 20 housed inside an inner volume delimited by the intermediate ring 29. The sleeve 20 comprises an inner tube 20.1 and an outer tube 20.2 which are coaxial to one another and which are connected together by a wall 20.3 extending transversally to the axis X. An outer surface of the outer tube 20.2 of the sleeve 20 is shaped to engage with the substantially truncated inner surface of the intermediate ring 29, while an inner surface of the inner tube 20.1 of the sleeve 20 is shaped to engage with a substantially truncated outer surface of an injection gate 21 of the diaphragm holder 24. The injection gate 21 extends along the axis X and forms a centring pin on which the sleeve 20 is press-fitted. The sleeve 20 is fixed on the injection gate 21 via a nut 22 screwed on the free end of said injection gate 21 to bear on an end of the inner tube 20.1 of the sleeve 20.

[0034] The sleeve 20 is here made of metal, preferably steel or aluminium.

[0035] The sleeve 20 forms an insert added into the arch 27 of the diaphragm holder 24 and allows a better distribution and transfer of forces exerted by the hydraulic fluid F and the gas G on the upper end of the diaphragm holder 24, in particular during the compression of the shock absorber. The sleeve 20 thus allows to improve the technical performances of the diaphragm holder 14 made totally of thermoplastic material.

[0036] Of course, the invention is not limited to the embodiments described, but comprises any variant entering into the field of the invention such as defined by the claims.

[0037] Although the sleeve is here made of metal, it can be made of any other material having a mechanical resistance greater than that of the thermoplastic material constituting the diaphragm holder. In particular, the sleeve can be made of any material guaranteeing isotropic characteristics to the sleeve, allowing an axisymmetrical deformation of the diaphragm holder during the compression of the shock absorber. The sleeve can, for example, be made of composite material.

[0038] The geometry and the dimensions of the sleeve can be different from those illustrated. The insert can, for example, pass through the arch.

[0039] Although the presence of the gate is particularly advantageous for facilitating the positioning of the insert, it is possible to remove the gate before placing the insert in the arch.

[0040] The insert can be fixed by any means in the arch, whether through press fitting, gluing, screwing, clipping, etc.

[0041] Although the diaphragm 3 separates here the inner volume of the shock absorber into two chambers C1 and C2, it can also delimit one single chamber and have no flow orifices.