Valves and valve actuation – Fluid actuated or retarded – Piston type expansible chamber reciprocating valve actuator
Patent
1996-10-04
1999-11-30
Chambers, A. Michael
Valves and valve actuation
Fluid actuated or retarded
Piston type expansible chamber reciprocating valve actuator
13756533, 251282, F16K 31122
Patent
active
059928190
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to an arrangement in a valve actuator operating on a valve stem provided with a piston so as to close or open the valve.
PRIOR ART
From NO 141.024 (Exxon) there is known a balanced, fail-safe, hydraulically operated valve system for regulating the fluidum flow in a subsea pipe. The valve comprises a valve housing in which a valve body can be displaced by means of a valve stem carrying a piston at the one end thereof. The piston can by supply of fluid displace the valve body to open position and at the same time compress a spring, the energy of the compressed spring being used when the valve body is returned to its close position.
In order to assist the spring power in displacing the valve body to closed position, it is according to NO 141.024 suggested to use a further cylinder communicating with a further valve stem which is not permanently connected with but can be brought to abutment with the valve body, said further cylinder and the main cylinder of the valve stem piston being connected to a pipe arrangement bringing surrounding fluid pressure in connection with said main and further cylinders in order to secure closing of the valve body when the surrounding pressure is larger than the internal pressure in the valve.
However, this publication NO 141.024 does not give any instructions for how such an arrangement can be used to minimize power consumption during normal operations of a valve.
Further, from CH 627.247 there is known a remotely controlled valve communicating with a command unit through a hydraulic channel, which is connected with a hydropneumatic accumulator which through a hydraulic relay communicates with the actuator of the valve. The valve arrangement also comprises a commutator which senses the pressure in the hydraulic channel for appropriate charging of the accumulator for thereby being able to affect a rapid closing of the valve in case of emergency.
OBJECTS OF THE INVENTION
An object of the present invention is to provide a valve actuator by which the associated valve can be opened and/or closed with an optimum power consumption.
Another object of the present invention is to provide a valve actuator which with its energy economy can preform a controlled and uniform displacement of the valve and the valve stem in question.
Still another object of the present invention is to provide a valve actuator having a fail-safe performance not only during normal operation but also in an emergency situation.
Yet another-object of the invention is to provide a valve actuator bringing forth the necessary optimum power required in the so-called crack region, i.e. in the stem range near a closed position.
An object of the present invention is also to provide a valve actuator which can be regarded and operated as a variable piston area actuator.
A further object of the inventor is to provide a valve actuator in which the pistons reflect control valves implementation.
Another object of the invention is to provide a valve actuator operating in a closed hydraulic system offering electric interface only, and offering also the possibility of topping up the hydraulic fluidum reservoir by ROV or other means in case of leakage.
SUMMARY OF THE INVENTION
The above objects are achieved in an arrangement as stated in the preamble, which according to the present invention is characterized in that in addition to the valve stem piston there is provided one or more supplemental pistons or pistons means.
In a specific embodiment said valve stem piston and said one or more supplemental pistons can be connected to individually controlled hydraulic supplies, so as to be controlled as a variable area type of hydraulic piston/cylinder.
The individually controlled stem piston and the supplemental piston or pistons can be controlled to be activated individually depending on the stroke position of the stem between and including open and closed position of the valve.
A preferred embodiment reflecting control valves implementation could involve that the valve stem
REFERENCES:
patent: 3656708 (1972-04-01), Hobbs
patent: 4145025 (1979-03-01), Bergeron
patent: 4795131 (1989-01-01), Scarano et al.
patent: 4934652 (1990-06-01), Golden
Asskildt Knut
Engdahl Goran
ABB Research Ltd.
Chambers A. Michael
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