Fluid handling – Systems – Programmer or timer
Patent
1986-09-29
1989-01-31
Michalsky, Gerald A.
Fluid handling
Systems
Programmer or timer
13762413, F15B 2112
Patent
active
048009229
DESCRIPTION:
BRIEF SUMMARY
The invention concerns a hydraulically controlled valve of the type including a moveable valve body situated within a housing biased to a neutral position between two hydraulic pressure chambers.
In various systems it is desirable to remotely control an apparatus without the use of electrical signal wires. Such is the case with underwater valves for oil production and also in environments where there is a risk of explosion.
Cost and safety are two important factors in connection with oil activity at sea. This is especially true for underwater production systems. For small wells, remote-controlled valve trees mounted directly on the seabed have often proved to be expedient. These can be controlled from the surface, e.g. from a platform by hydraulic lines, and, perhaps by electric cables.
In earlier known control systems that consist of only hydraulic components, in other words where the control is hydraulic, long reaction time is a problem even when the distance of transmission is moderate. The main cause of this is that in existing hydraulic systems each valve activation requires a change in the pressure level in a signal wire. Change of pressure in a long narrow hose or even a long narrow pipe generally takes a lot of time because of compressible and viscous effects.
In order to reduce reaction time, the attempt has been made to use various forms of hydraulic control apparatuses. The control signal is, then, electrical, while the work operation is hydraulic. Such systems are practicable for large distances and when many valves are to be controlled.
However, such systems are comparatively complicated and costly. Another negative aspect is that the electrical lines must be connected under water. This can reduce reliability and increase cost.
The main purpose of the invention is, therefore, to create a hydraulically controlled valve that is especially suited for controlling other valves in underwater production systems, and that can be operated hydraulically in a more satisfactory manner than is the case with presently known devices. Primarily, it must be possible for the device to run with a shorter reaction time. In addition, it must be simple and reliable as all interuptions caused by failure will have major economic consequences, both directly an indirectly.
According to the invention this can be achieved by constructing the valve to include a moveable valve body situated within a housing and biased to a neutral position between hydraulic pressure chambers. A common conduit connects both pressure chambers to a source of a signal medium. A hydraulic accumulator means having a preselected natural frequency is connected one of the pressure chambers. A modulated signal is provided of a frequency related to the preselected natural frequency of the accumulator means so as to be reenforced thereby causing displacement of the valve body within the housing away from the neutral biased position.
Such a valve can be activated by sinus-formed pressure pulses with a specified frequency or specified frequency range. In addition to solving the control problem for a single valve, in an advantageously manner, the valve according to the invention makes it possible to create control systems with a plurality of units that are controlled through a single control line. The valves are constructed in a manner such as they give response to pressure pulses of different frequencies or within different frequency ranges. In other words, each valve in such a system is made sensitive to a pre-determined frequency interval. An operator on a platform, for example, can select which valve is to be operated by selecting and releasing pressure pulses with the signal frequency that the unit will respond to.
The mean pressure level in the signal wire can thus be kept constant, as only small, relatively rapid variations around the mean value are introduced. According to the invention, it is possible to construct the valve so that it is relatively sensitive allowing the size of these variations to be minimal.
The valve, according to the inventi
REFERENCES:
patent: 2945478 (1960-07-01), Hanna
patent: 4308884 (1982-01-01), Hoerger et al.
patent: 4687014 (1987-08-01), Godal
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