RELEASE DEVICE

Abstract: A release device is responsive to hydrostatic pressure so that it can be used to connect lifesaving equipment to a ship and release it automatically if the ship sinks. The device has a housing (11) divided into two chambers (20, 22) by a membrane (13). A first chamber (20) is in communication with the exterior so that pressure variation acts on and deforms the membrane (13). A fastening element (40, 41, 42) extends into the first chamber (20) where it has a recess (45) that partly houses projecting balls (46). The balls (46) are maintained in the recess by a cup member (52) associated with the membrane (13). They prevent withdrawal of the element by contacting an abutment (48). Increased pressure deforms the membrane (13), carrying the cup member (52) away from the balls (46). These can thus leave the recess (45), and the element (40) (which may be coupled to equipment) is released from the housing (11) (which may be fast with the ship).

Description: RELEASE DEVICE This invention relates to a release device responsive to hydrostatic pressure, e.g. as may be used on ships for automatically releasing life saving equipment if the vessel sinks. Patent GB2051212 discloses a device such that pressure ( ue to submersion to a predetermined depth) displaces a membrane, leading to movement of a pivoted lever structure for releasing a detachable attachment member . In this arrangement , the engagement/disengagement mechanism is rather complicated and hence expensive. It will be appreciated that .it is of the greatest importance that such devices should function reliably and consistently, and this imposes severe design constraints. The release device of the present invention comprises a housing which is divided into a first and a second chamber by a flexible diaphragm, the first chamber having an inlet for the entry of water and the second chamber being essentially sealed against the entry of water; so that variation of pressure in the first chamber tends to cause movement of the diaphragm. A detachable attachment member has an outer end which projects out of the housing for securing equipment to the device, and an inner end which extends into the first chamber. A holding member extends in the first chamber and is movable with the diaphragm. At least one rollable element is rotatably engaged with an engagement structure formed at the inner end of the attachment member and retainable therein by engagement with the holding member when this is in a holding position; and there are abutment means engageable with a rollable element when this is in the engagement structure to resist withdrawal of the attachment member from the first chamber. The arrangement is such that the movement of the diaphragm produced by the entry of water above a predetermined pressure into the first chamber causes movement of the holding member away from the holding position to permit disengage enr of the rollable element therefrom so that the attachment member can be released. There may be biasing means urging the diaphragm to retain the holding member in the holding position, e.g. spring means acting on the diaphragm. One embodiment of the present invention will now be described with reference to the accompanying drawing which is a cross-sectional side view of the device. The figure shows a release device 10 suitable for the automatic release of liferafts. The release device 10 has a housing 11 formed of two cup-shaped housing parts Ha, lib having peripheral flanges 12 by means of which they are bolted together and retain a flexible diaphragm 13, which thus divides the interior into two chambers 20, 22. The first chamber 20 has a water inlet 21 for the entry of water or communication of pressure, when the release device is submerged. The second chamber 22 is essentially sealed against the entry of waτer. However, the second chamber 22 may have an inlet 14 closed by a slightly air-permeable but water-impermeable disc 15 so that air can leak through the disc 15 to keep chamber 22 at atmospheric pressure prior to submersion. A compression spring 24 is located inside the chamber 22 between a location cavity 26 in the base and the diaphragm 13 to bias the diaphragm 13 towards the first chamber 20. A detachable attachment member 40 has an outer end 41 adapted for securing the release device 10 to life- saving equipment. (The second housing part lib also has a securing portion 30). A shank portion 42 of the detachable member 40 extends into the first chamber 20, passing slidably through an aperture 43 in the first housing part 11a. Adjacent its end, the shank 42 has an engagement structure, here constituted by an annular groove 45. A holding member 50 has a cup-shaped upper portion 52 and a depending shank 54 that passes sealingly through the diaphragm 13 and is fast with it. The end portion of the shank 54 is embraced by the spring 24. In the holding configuration shown in the drawing, the diaphragm is planar and the cup portion 52 surrounds the end portion of the shank 42 of the detachable member 40, and is spaced from it. The spacing is sufficient to accommodate a plurality of ball bearings 46 which are partly located in the groove 45 and retained therein by engagement with the cup portion 52. Withdrawal of the detachable member 40 from the housing is prevented by engagement of the ball bearings with an abutment surface associated with the housing and provided in this example by an annular abutment member 48 mounted in the first housing part 11a concentric with the aperture 42. When the release device 10 is submerged in water to a predetermined depth, the pressure of the water coming into the first chamber 20 via the water inlet 21 will press the diaphragm 13 downwardly towards the second chamber 30, and the holding member 50 will be moved downwardly as well. The downward movement of the holding member 50 will release the rollable elements or balls 60. (The depth of the groove 45 is preferable less than half their diameter so they will tend to drop out when no longer held in). Thus the shank 42 of the attachment member 40 is disengaged, and can be pulled free of the housing very easily. (It will be appreciated that terms such as 'downwardly' generally refer merely to the orientation of the figure in the drawing and do not have absolute significance unless the context requires it. ) The present invention provides a very simple and highly reliable engagemen /disengagement mechanism in a release device. It has few parts and all the parts may be easy to machine. Thus the device can be much cheaper than the prior art device and still be very reliable. It can also be extremely strong. Thus an actual embodiment has withstood a tensile strain of 20kN for a substantial time. The strength and reliability are very desirable for marine applications.

Claims: Claims 1. A release device (10) comprising a housing (11) divided into a first space (20) and a second space (22) by a displaceable member (13), the arrangement being such that the pressure inside the first space is subject to pressure change outside the housing so that a pressure outside the housing will increase the pressure inside the first space and tend to move the displaceable member (13) towards the second space; a detachable attachment member (40) having an outer end (41) projecting out of the housing for securing equipment to the device, and an inner end located inside the housing and having a laterally projecting portion (46); engagement means (48) within the housing for engaging the projecting portion to resist withdrawal of the attachment member; release means (50) movable with the displaceable member (13) so as to actuate release of the engagement to permit said withdrawal; characterised in that said laterally projecting portion is provided by a rollable element (46) releasably partly received in a recess in the inner end of the attachment member and wherein in a first configuration the release means (50) acts to keep the rollable element engaged in the recess, while predetermined movement of the displaceable member 13 will cause the release member to release the engagement between the rollable element and the recess so as to release the attachment member from the housing. 2. A release device according to claim 1 wherein the release means (50) comprises an annular wall portion (52) which, in the first configuration, surrounds the inner end of the attachment member so as to act to keep the rollable element (46) in the recess.

Inventors: READ MARK EDWARD ADRIAN, READ, MARK, EDWARD, ADRIAN
Applicants: READ GROUP LIMITED
Application year: 1991
Main classification: B63C9
IPC codes: B63C9