Hydraulic and earth engineering – Fluid control – treatment – or containment – Flow control
Reexamination Certificate
1998-11-03
2001-01-09
Lillis, Eileen D. (Department: 3673)
Hydraulic and earth engineering
Fluid control, treatment, or containment
Flow control
C405S087000, C405S092000, C405S093000, C405S099000, C405S100000
Reexamination Certificate
active
06171023
ABSTRACT:
BACKGROUND TO THE INVENTION
This invention relates to a water control gate assembly, and in particular to a self-actuating automatic top-hung gate for controlling the flow and/or water level in a waterway.
In water supply schemes, and in particular irrigation schemes relying on the upstream control of water, various types of water control gates are currently in use. These extend from simple manually operated sluice gates to highly complicated automatic control gates for operating electronically or mechanically operated hydraulic equipment in response to various electronic water level and flow sensors. Most water control gates require human intervention, which add significantly to their operating costs. Further, many water control gates only tend to operate effectively under normal flow conditions, and not flood conditions. More sophisticated gates which are hydraulically or mechanically operated are prone to failure, and require regular maintenance, as well as access to a power source.
SUMMARY OF THE INVENTION
According to the invention there is provided a water control gate assembly comprising a self-actuating top-hung gate for controlling the flow and/or level of water in a waterway, a pivot arrangement located above and upstream of the gate for allowing the gate to pivot between a closed position and an open position in which water flows beneath the gate, the gate including a ballast tank having an upstream inlet for charging the ballast tank so as to increase the closing moment of the gate and a downstream outlet for discharging the ballast tank so as to decrease the closing moment of the gate.
Preferably, the upstream inlet is arranged to start charging the ballast tank with water in the event of the upstream water level reaching a first lower level, and the downstream outlet is arranged to start discharging the ballast tank in the event of the upstream water level reaching a second upper level. with the ingress of water into the ballast tank between the first and second levels progressively increasing the closing moment of the gate and maintaining it closed against the progressively increasing opening moment of upstream water pressure against the gate.
Conveniently, the gate is arranged to start opening when the water level approaches the second upper level, the downstream outlet being configured to progressively discharge water from the ballast as the gate tilts progressively upwards.
The upstream inlet, the downstream outlet and the ballast tank are arranged to operate in the opposite manner on closure of the gate, with the upstream inlet progressively filling the tank and the downstream outlet no longer being capable of discharging water as the gate pivots downwards.
Conveniently, the ballast tank occupies an upper portion of the gate, and a lower portion of the tank comprises a buoyancy chamber or tank which is separated from the ballast tank by means of a wall which slopes downwardly from the upstream to the downstream side of the gate.
Typically, the water control gate assembly comprises a pair of supports, such as piers, located on opposite sides of the gate, the pivot arrangement including pivot shaft assemblies pivotably connecting each pier to the top-hung gate via upwardly and rearwardly extending arms.
The gate may be formed with side and bottom seal arrangements for sealing the respective sides and base of the gate against the respective inner side walls of the supports and the bed of the waterway.
In one form of the invention, in which the water control gate assembly is in the form of a spillway crest gate, the gate is formed with a spillway outlet above the ballast tank for discharging water over the gate without opening it. A baffle plate may be located above the spillway outlet so as to limit the depth of free discharge before the gate starts opening.
Conveniently, the gate is formed with an emergency discharge valve which is arranged to void the ballast tank in the event of the gate failing to open after it has reached a third flood level which is higher than the second upper level.
In another form of the invention, in which the water control gate assembly is in the form of a weir scour gate, the downstream outlet may comprise a syphon arrangement which allows for almost complete discharging of the ballast tank after priming of the syphon arrangement so as to cause rapid opening of the gate.
In another form of the invention, a level control canal gate, the downstream outlet is provided with valve means responsive to close the outlet in the event of the downstream water level reaching a predetermined upper level, thereby allowing the ballast tank to fill and to increase the closing moment of the gate. The valve means is further arranged to open the outlet in the event of the downstream water level falling below a predetermined lower level, thereby to increase the opening moment of the gate.
In yet another form of the invention, an estuarine control gate, the gate is arranged to open in response to the downstream water level exceeding the upstream water level.
In a still further form of the invention, a tidal control gate, the gate is arranged to close in the event of the downstream water level exceeding the upstream level by a predetermined increase in downstream or seaward level of water.
REFERENCES:
patent: 2984986 (1961-05-01), Hill
patent: 4836711 (1989-06-01), Sala et al.
patent: 4877352 (1989-10-01), Tuttle et al.
patent: 5372456 (1994-12-01), Langemann
patent: 5516230 (1996-05-01), Bargeron et al.
patent: 5577863 (1996-11-01), Nottle
patent: 2501747 (1982-09-01), None
patent: 0670674 (1979-06-01), None
Blakely & Sokoloff, Taylor & Zafman
Lillis Eileen D.
Pechhold Alexandra K.
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