GB2147933A - Improvements in or relating to water level control - Google Patents

Abstract

A pivotable water level control gate set in a waterway is coupled to a rotatable float 10, partially immersed in a float chamber connected to the waterway. The float responds by motion about its rotational axis 14 to a change in water level and thereby operates the gate to adjust the water flow in accordance with the water level change. The float has a sealed buoyancy chamber 15, a constant mass part 16 which may be a chamber filled with a fixed volume of water, and optionally a third mass 17, again a water-filled chamber. The float construction ensures the metercentre close to the centre of mass so that small water level changes produce large control movements. The float may operate the gate via a pulley system or the gate is coupled to pivot with the float. <IMAGE>

Description

SPECIFICATION Improvements in or relating to water level control This invention relates to water level control.

It is an object of the present invention to provide means for water level control which will at least provide the public with a useful choice.

Accordingly in one aspect the invention consists in a float connectable to a water level control gate in a waterway for controlling the opening and closing thereof, said float having a first section sealed to provide a buoyancy force when said float is, in use, immersed in water; a second section constituting a constant mass; and means to rotatably mount said float, the construction and arrangement being such that when said float is in use and subjected to moments about the axis of rotation thereof arising from said first section, said second and said gate, the metacentre of said float is positioned with respect to the centre of gravity thereof so that as the level of water in which said float is immersed changes, the amount of movement imparted by said float to the control gate is greater than the change in water level.

In a further aspect the invention consists in apparatus for controlling the water level in a waterway, said apparatus comprising a gate displaceable between a position in which said gate prevents flow along said waterway and positions in which water may flow along said waterway; and a float which, in use, is rotatably mounted in a fixed position, at least partially immersed in water in said waterway, said float being connected to said gate so that rotation thereof displaces said gate toward and away from the closed position, said float having a first section sealed to provide a buoyancy force and a second section constituting a constant mass; the construction and arrangement being such that for a given water level the moments about the axis of rotation of said float arising from said first section, said second section and said gate are balanced but the metacentre of said float is positioned with respect to the centre of gravity thereof so that as the level of water in which said float is immersed changes, the amount of movement imparted by said float to said gate is greater than the change in water level.

To those skilled in the art to which the invention relates, many changes in construction and widely differing embodiments and applications of the invention will suggest themselves without departing from the scope of the invention as defined in the appended claims. The disclosures and the descriptions herein are purely illustrative and are not intended to be in any sense limiting.

Preferred forms of the invention will now be described with reference to the accompanying drawings in which: Figure 1 shows a perspective, schematic view of water level control apparatus according to the invention; Figure 2 shows a side elevation of water level control apparatus according to the invention with the gate in an open position; Figure 3 shows an end elevation view, from the downsteam side, of most of the operative parts of the apparatus shown in Fig. 2; Figure 4 shows a float for use in the apparatus depicted in Figs. 1 to 3 in an equilibrium position; Figure 5 shows the effect of increasing water level on the float depicted in Fig. 4; and Figures 6 and 7 show perspective views, partly in section, of alternative forms of water level control apparatus according to the invention.

Referring to the drawings and in particular to Figs. 1 to 5, according to the invention a float 10 is provided for controlling the movement of a water level control gate 11 in a waterway (not shown). The gate, in practice, will commonly be mounted in a control structure 1 2 (Figs. 2 and 3) constructed within the waterway. In the form shown the gate 11 is a radial gate mounted for pivotal movement about axis 1 3 and is biased under gravity towards the closed position.

As can be seen in Fig. 4, the float 10 is pivotally mounted at 14 so as to be partially immersed in water flowing along the waterway and includes a first section 1 5 which is sealed to provide a buoyancy force so that there is a force tending to rotate the float in a clockwise direction as shown in the drawings.

The float 10 further includes a second section 1 6 which, by itself or in combination with the mass of the float as a whole, provides a moment in opposition to the buoyancy due to the first section 1 5. The chamber may, as shown, include a third section 1 7 whereby mass may be added to the float to reinforce the moment due to the second section 1 6.

In addition to the moment due to the first section 15, the second section 1 6 and possibly the third section 17, the float is also subjected to tension T from the bias of the gate 11 and this force is indicated by the arrow in Fig. 4. In the embodiment shown a cable 1 8 supported by pulleys 1 9 connects the float 10 to the radial gate 11 which, as shown, is mounted in a position which is in a lower vertical plane than the float 10.

In the form shown the float 10, when viewed in side elevation, is substantially semicircular in form and the sections 1 5 and 1 6 are defined by adjacent segments of the semicircle. The pivot axis 14, as shown, lies at the common apex of the sectors defining the sections 1 5 and 16. In cross section the float 10 is substantially rectangular.

While the second section 1 6 may be provided by or include a fixed mass, the second section 1 6 is preferably a further chamber within the float 10 which, in use, is filled with water. A valve 20 may be provided in the wall of the float 10 to allow the section 16 to be emptied and a further aperture 21 communicating with the interior of the section 1 6 by means of tube 22 may be provided to allow the section 1 6 to be refilled after emptying.

The third section 1 7 is, in the form shown, merely a hollow chamber which may be filled with water through the aperture 23.

As can be seen from Figs. 1, 2 and 3 the float 10 is rotatably mounted in a float chamber 24 which is situated above but downstream of the gate 11. The chamber 24 serves to reduce buffeting of the float 10 by water flowing through the waterway and receives water throught inlet pipe 25 which branches off delivery pipe 26, the entrance to which is indicated by reference numeral 27.

An auxiliary chamber 28 is, as shown, preferably provided to one side of the float chamber 24 and communicates therewith via a slot 29.

A conduit 30 at the lower end of the auxiliary chamber 28 communicates the same with the main waterway, thus allowing the water level of the waterway to be transferred to the float chamber 24. A further emergency waterway connection is indicated by reference numeral 31.

The auxiliary chamber 28 preferably includes a buoyant weight 32 which is connected through suitable mechanism to the valve 20 on the second section 1 6 of the float 10 such that when the water level in the waterway and thus the auxiliary chamber 28 falls below a predetermined level, the weight falls thus opening the valve 20 and allowing water out of the section 1 6 of the float 10.

This causes the float to rotate in a clockwise direction as shown in the drawings which closes the gate 11.

After the gate 11 has been closed in this manner and it is wished to assume the normal operating mode once again, the valve 20 is closed and the chamber 1 6 filled through aperture 21 using pump 33 or by some other manual means.

It will be noted from the position of the slot 29 and the connection 31 that the float chamber 24 never empties and the slot 29 and connection 31 are positioned to ensure that sufficient buoyancy always remains to ensure closure of the gate 11 upon section 1 6 being drained.

In use apparatus as herein described is mounted in a waterway so that the float 10 communicates with the water either upstream or downstream of the gate 11 and can rotate subject to the changes in the water level. The effect of changing water level is shown in Fig.

5 wherein a rising water level is indicted in dotted outline by reference numeral 35. This rising water level creates an out-of-balance buoyancy force U which causes the float 10 to rotate through an angle 80. Upon rotation of the float 10 the centre of gravity G moves further away from the pivot axis 14 until balance is again restored.

The float has been designed specifically so that the metacentre thereof is close enough to the centre of gravity so that relatively small changes in water level cause the float to rotate through a relatively large angle.

In the embodiment depicted, the float has a radius of about 2.5m and a width of about 1.25m. Of the total float volume the section 1 5 preferably occupies in the order of 39.4% of the total volume while the chamber 1 6 preferably occupies on the order of 41.1% of the total volume. We have found that this configuration results in a rotation of about 40 for a water level variation of 150mm (i.e.

about 1/16th of the float radius) when connected to a gate of the type depicted.

It will be appreciated that some provision for adjustment of the connection between float and gate or in the manner of mounting the gate or some other alternative is desirable so that in any particular circumstances the fine adjustment of the balance of the system can be effected to ensure proper action.

The float chamber 24 and the float 10 are preferably enciosed in a shed to not only reduce the possibility of the water in the float chamber freezing in adverse weather conditions, but further prevent debris from falling into the chamber and fouling the movement of the float.

Referring now to Figs. 6 and 7 alternative.

more compact forms of the invention are provided for use in situations where the gate is mounted at much the same level as the float.

Accordingly as shown in Fig. 6, float 40 is provided which is rotatably mounted in chamber 41 in turn mounted in waterway 42. The float 40 controls the movement of a rotary gate 43 pivotally mounted at 44.

It will be noted that the mounting points 44 are provided on the outside of the chamber 41 and the float 40 is connected to the gate 43 by a cable 45 passing over pulleys 46.

The float 40 and the gate 46 are, for all intents and purposes. identical to the float 10 and gate 11 described above and operate in an identical manner.

The minimum level of water within chamber 41 is determined by the vertical position of slot 47 and this is set so that there is always sufficient water within the chamber 41 to ensure that there is buoyancy to close gate 43 upon the weight chamber being emptied.

A further alternative form of apparatus is shown in Fig. 7 in which float 50 is constructed, arranged and mounted so as to open and close gate 51.

The float 50 is once again mounted in a chamber 52, the chamber 52 being provided with a horizontal slot 53 to control the mini mum water level therein.

In this embodiment the float 50 and gate 51 are mounted to rotate about a common axis indicated by reference numeral 54 thus obviating the need for cables and pulleys. The float 50 and gate 51 are otherwise the same as the float 10 and gate 11 described above.

Claims (16)

1. A float connectable to a water level control gate in a waterway for controlling the opening and closing thereof, said float having a first section sealed to provide a buoyancy force when said float is, in use, immersed in water; a second section constituting a constant mass; and means to rotatably mount said float, the construction and arrangement being such that when said float is in use and subjected to moments about the axis of rotation thereof arising from said first section, said second and said gate, the metacentre of said float is positioned with respect to the centre of gravity thereof so that as the level of water in which said float is immersed changes, the amount of movement imparted by said float to the control gate is greater than the change in water level.

2. A float as claimed in claim 1 wherein said second section is a chamber constructed and arranged to receive and retain a fixed volume of water.

3. A float as claimed in claim 1 or claim 2 wherein said float is substantially semi-circular shaped when viewed in elevation.

4. A float as claimed in claim 3 when dependent on claim 2 wherein said first and second sections comprise adjacent sectors of said semi-circle when viewed in elevation.

5. A float as claimed in any one of the preceding claims wherein said float includes a third normally empty section whereby mass can be added to said float to increase the moment in opposition to said buoyancy force.

6. A float as claimed in claim 4 or claim 5 wherein said means to rotatably mount said float is located at the point of intersection of the sectors comprising said first and second sections.

7. A float when constructed arranged and operable substantially as hereinbefore described with reference to the accompanying drawings.

8. Apparatus for controlling the water level in a waterway, said apparatus comprising a gate displaceable between a position in which said gate prevents flow along said waterway and positions in which water may flow along said waterway; and a float which, in use, is rotatably mounted in a fixed position, at least partially immersed in water in said waterway, said float being connected to said gate so that rotation thereof displaces said gate toward and away from the closed position, said float having a first section sealed to provide a buoyancy force and a second section constituting a constant mass; the construction and arrangement being such that for a given water level the moments about the axis of rotation of said float arising from said first section, said second and said gate are balanced but the metacentre of said float is positioned with respect to the centre of gravity thereof so that as the level of water in which said float is immersed changes, the amount of movement imparted by said float to said gate is greater than the change in water level.

9. Apparatus as claimed in claim 8 wherein said float is rotatably mounted in a chamber formed or provided in said waterway, said chamber being constructed and arranged such that the water level therein changes in response to the change water level in said waterway.

10. Apparatus as claimed in claim 8 or claim 9 wherein said second section comprises a chamber arranged to receive and retain a fixed volume of water.

11. Apparatus as claimed in claim 10 further including a valve operable to release the water from said second section.

1 2. Apparatus as claimed in any one of claims 8 to 11 wherein said float further includes a third section whereby mass may be added to said float to increase the moment in opposition to said buoyancy force.

1 3. Apparatus as claimed in any one of claims 8 to 1 2 wherein said gate and said float are interconnected by means of a cable and pulley arrangement.

1 4. Apparatus as claimed in any one of claims 8 to 1 2 wherein said gate and said float are mounted for rotation about a common axis.

1 5. Apparatus as claimed in claim 8 wherein said float is as claimed in any one of claims 1 to 7.

16. Apparatus for controlling the water level in a waterway when constructed arranged and operable substantially as hereinbefore described with reference to the accompanying drawings.