Implements or apparatus for applying pushing or pulling force – Fluid pressure – Vehicle attached
Reexamination Certificate
1998-12-21
2001-03-13
Watson, Robert C. (Department: 3723)
Implements or apparatus for applying pushing or pulling force
Fluid pressure
Vehicle attached
Reexamination Certificate
active
06199827
ABSTRACT:
Pneumatically inflatable, and hydraulically expandable lifting bags are known which bags include air or water inlet valves and/or air or water outlet valves for, for example, inflation or expansion of the bags, deflation or expansion of the bags, maintaining the bags in an inflated or expanded condition, and/or preventing the bags being subjected to excessive pressures.
DE-U-1,897,870 discloses an extendable or inflatable lifting device having a pressure release valve assembly; wherein the device comprises an enclosure having a first part movable relative to second part by applied fluid pressure; wherein the valve assembly is mounted on one of the parts and comprises a valve exposed to pressure inside the enclosure and is attached to and actuable by an actuating tether which is located in the enclosure and is attached to the other of said parts to cause the valve to open and release fluid from within the enclosure when the distance between the parts reaches a limit determined by the length of the tether.
Sometimes such valves fail to operate correctly, because of contamination, giving rise to operational problems. These problems are particularly prevalent in the case of outlet valves such as mechanically actuated outlet valves which can fail to close properly giving rise to unwanted fluid release, e.g. deflation of the bags, or preventing proper expansion or inflation of the bags.
In order to enable the risk of such problems arising the present invention generally provides an extendable or inflatable lifting device having a pressure release valve assembly; wherein the device comprises an enclosure having a first part movable relative to second part by applied fluid pressure; wherein the valve assembly is mounted on one of the parts and comprises a valve exposed to pressure inside the enclosure and is attached to and actuable by an actuating tether which is located in the enclosure and is attached to the other of said parts to cause the valve to open and release fluid from within the enclosure when the distance between the parts reaches a limit determined by the length of the tether; and characterised in that the valve which is actuated by the tether is a second valve of the assembly which second valve releases fluid into the valve assembly to actuate a first valve which first valve is arranged to open automatically only when the pressure within the valve assembly is greater than the pressure outside the enclosure.
In a particular embodiment the invention provides a pneumatically inflatable lifting device having an air release valve assembly; wherein the valve assembly further comprises a rigid mounting and a valve member is located in an opening in the mounting; wherein an annular part of the mounting around the opening provides a first valve seat on one side thereof and a second valve seat on the other side thereof; wherein the valve member comprises a first head joined to a second head by a neck which extends through the aperture; wherein the first head has a resilient flange which resiliently engages the first valve seat to form said first valve and the second head had a resilient flange which resiliently engages the second seat to form the second valve; and wherein the flange of the second head has an actuator formation thereon which is movable by the actuator to move at least part of this flange off the second seat whereby, in use, to allow fluid under pressure to flow past this flange into the opening for automatically lifting the flange of the first head off the first seat when the fluid pressure in the opening is greater than the fluid pressure at said one side of the mounting.
In many instances the enclosure will be a bag having flexible panels, but it could, for example, be a bellows having rigid panels.
The first valve, by opening only when the pressure inside the valve assembly is greater than the pressure outside the bag (hereinafter referred to as a “positive pressure differential”), ensures that contamination cannot enter the valve assembly from outside the device irrespective of the operational state of the expansion or inflation limiting second valve.
The valve assembly preferably also serves as an emergency or safety pressure release valve in the event of the second valve not functioning, e.g. due to the tether breaking, by allowing both valves to be opened forcibly by excessive pressure.
The valve assembly preferably comprises a valve member which is common to both valves and provides two independently movable parts, e.g. flanges, each of which form a part of one or other of the valves.
The valve member can preferably be expelled or partially expelled from the valve assembly by excessive differential pressure within the enclosure. Alternatively, the valve member includes a frangible diaphragm which ruptures when subjected to an excessive pressure differential.
The invention further provides a valve assembly comprising a rigid mounting and a valve member located in an opening in the mounting wherein an annular part of the mounting around the opening provides a first valve seat on one side thereof and a second valve seat on the other side; wherein the valve member comprises a first head joined to a second head by a neck which extends through the aperture; wherein the first head has a resilient flange which resiliently engages the first valve seat to form a first valve and the second head has a resilient flange which resiliently engages the second seat to form a second valve; and wherein the flange of the second head has an actuator formation thereon which is movable to move at least part of this flange off the second seat whereby, in use, to allow fluid under pressure to flow past this flange into the opening for automatically lifting the flange of the first head off the first seat when the fluid pressure in the opening is greater than the fluid pressure at said one side of the mounting.
The pressure exerted by the first head on the first seat is preferably substantial so that a considerable minimum positive pressure differential across the first valve is necessary before the valve will open, and so that when the differential falls to or below said minimum positive pressure differential said first valve closes automatically to retain pressure within the opening (i.e. between the valves) even when the second valve is open, whereby to maintain the inflated shape of the bag, and so that when a load is applied to the device, the amount of further inflation required is reduced.
REFERENCES:
patent: 4275869 (1981-06-01), Clements
patent: 5669086 (1997-09-01), Garman
patent: 655 368 (1938-01-01), None
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patent: 087 620 (1983-09-01), None
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patent: 2 599 110 (1987-11-01), None
patent: 2 286 430 (1995-08-01), None
Bek. gem. Jul. 30, 1964 Nr. 1 897 870, Dr. Walter andrejewski Patentanwalt, P.A. 328923*-8.5.64, pp. 1-8.
Fletcher Richard E
Rimington Richard M
Mangar International Limited
Pillsbury Madison & Sutro LLP
Watson Robert C.
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