Actuating device for pipe-chamber feeders of hydraulic transport

Valves and valve actuation – Fluid actuated or retarded – Piston type expansible chamber reciprocating valve actuator

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Details

251 25, 91407, F16K 31122

Patent

active

048694606

DESCRIPTION:

BRIEF SUMMARY
FIELD OF INVENTION

The present invention relates to an improved actuating device for pipe-chamber feeders of hydraulic transporting and hoisting equipments adapted to convey solid materials such as coal or slag in the form of slurry. Such actuating devices generally contain valves and other closing appliances and the invention mainly relates to the speed-controlled actuation of closing elements of these appliances.


BACKGROUND OF THE INVENTION

The function of a pipe-chamber feeder consists of the periodical alternate filling of the chambers with slurry at low pressure, and emptying them at high pressure. While performing this function, the closing appliances, especially valves or sliding valves must be opened and closed by a suitable actuating device in a certain sequence and at short time periods, most advantageously in a manner as it is described in the Hungarian Patent Specification No. 160 526. However, the closing elements of the valves have to be moved slowly because a quick closing would cause disadvantageous pressure and velocity fluctuations, even heavy water impacts that are called water hammer in the art concerned.
Consequently, in prior art devices the change-over or switch-over steps i.e. the closing and opening of the valves are relatively slow and they result in a disadvantageous decrease of the performance of transport equipments having only two pipe chambers. In such equipments every change-over consists at least of two opening and closing steps, and during the change-over operations filling or emptying of the pipe chambers is not possible.
If three or more pipe-chambers are used there is no such decrease of the output. However, investment and operating costs of equipments having three or more pipe-chambers are much too high. In addition to this, a diminishing of the time necessary for the switch-over steps is still desirable even if the number of pipe-chambers is more than two.
The fact that the change-over steps in the known prior art hydraulic transport equipments are extremely time-consuming is specially disadvantageous with large-size equipments because the speed of actuation of the closing elements of big closing appliances is very slow, and also the pressure-changes in the large pipe-chambers take much time.


SUMMARY OF THE INVENTION

Main object of the invention is to greatly diminish the decrease of output caused by the slow actuation of the valves in known hydraulic transport equipments, especially in those, having two pipe-chamber feeders, and to attain that even if largest closing elements having a closing stroke as long as 300 to 600 mm are used, practically no loss in capacity or performance should occur by the change-over operations. Simultaneously, of course, water impacts should also be avoided.
These and other objects are attained by the present invention that results in that the closing element of the closing appliances especially closing elements of the main valves are quickly moved, say with a speed three or four times higher than up to now. Simultaneously with this, the closing appliances contain one or more means for significantly reducing the speed of said closing elements at the end phase of their closing stroke i.e. just before arriving at their closed position. It may be important that the speed reducing effect should be adjustable and if one speed reducing throttling device is used only, this is preferred to be adjustable manually. If two or more simultaneously functioning throttle devices are employed, it is important that at least in one of them the throttling effect should be adjustable.
The slowing down of the closing element can be continuous or stepped.


COMPARISON OF THE INVENTION WITH THE PRIOR ART

There are well known hydraulic stroke-end brakes called cataracts in which the speed of a quickly moving piston or other part is slowed down at the end of its stroke by a fluid caused to stream through a narrow opening. However, such hydraulic stroke-end brakes have never been employed in valves of hydraulic transport equipments. Thus the basic idea of t

REFERENCES:
patent: 1861742 (1932-06-01), Hand
patent: 2000297 (1935-05-01), Putnam
patent: 2211318 (1940-08-01), Lamerota
patent: 2694544 (1954-11-01), Hall

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