Rolling seal sluice gate
BACKGROUND TO THE INVENTION 
     This invention relates to sluice gates for isolating the flow of liquids through sluice openings. In a conventionally designed sluice gate a sliding gate or plate is arranged to cover or uncover the sluice opening. When the opening is closed the pressure of the liquid being isolated is active on the area of the gate covering the opening and causes friction in opposition to opening or closing movement between the gate and the frame against which it seals. In a rigid gate assembly it is also necessary for the gate and the frame against which it seals to be accurately machined to preclude leakage. Because the opening and closing movement is a sliding movement and also because the gate has to be strong enough to withstand the differential pressure on closure it is not easy to incorporate resilient sealing faces. 
     SUMMARY OF THE INVENTION 
     An object of the present invention is to provide a sluice gate in which the above disadvantages are overcome to a large degree and to provide a means of reinforcing a flexible gate so that it will withstand the differential pressure on closure and yet provide a completely open unobstructed passage in the open position. A further object is to provide means to reduce the forces necessary to operate the gate and to eliminate friction. A still further object is to provide a means to service the gate without having to drain the liquid in which it is submerged or to carry out the service in the liquid. 
     According to this invention, there is provided a sluice gate closure member, having a flexible liquid-impervious sheet with approximately horizontally spaced reinforcing members, and being adapted to be suspended from an upper edge thereof across the upstream side of a sluice opening to close it, and to receive control means for drawing the lower end of the closure member upwardly and away from the opening to progressively open it to allow the closure member to return progressively to a closure position, characterised in that reinforcing members are located on the upstream side of the closure member, at least some of which reinforcing members have lengths which extend beyond the edges of a sluice opening to be controlled by the closure member, and in that reinforcing members are also located on the downstream side, and paired opposite those on the upstream side of a length enabling them to pass into the sluice opening which is to be controlled and in which each pair are secured together with the flexible sheet between them. 
     The invention also provides a sluice gate having a closure member in which the flexible sheet has its upper end secured to a rigid cross-member adapted to be located adjacent the upper wall of the sluice opening and forming part of an assembly adapted to be adjustably secured to the sluice structure above the liquid level at the sluice opening. 
     Further features of this invention provide for the cross-member and its assembly to be removable with the closure member from the sluice structure for service or repair of the latter. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     These and other features of this invention will become apparent from the following description of preferred embodiments of the invention wherein reference is made to the accompanying drawings in which 
     FIG. 1 is an elevation of one form of a sluice gate; 
     FIG. 2 is a sectional side elevation of FIG. 1; 
     FIG. 3 is an elevation of an alternative form of sluice; 
     FIG. 4 a sectional side elevation of FIG. 3; 
     FIG. 5 a similar view to FIG. 4 but with the sluice gate partially open. 
     FIG. 6 a cross section through the closure member of the sluice gate; and, 
     FIG. 7 is a sectional side elevation showing a sluice gate suitable to isolate flow in both directions through the sluice opening. 
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENT OF THE INVENTION 
     Referring firstly to the embodiment of the invention illustrated in FIGS. 1 and 2 the sluice gate assembly 1 is mounted to control the flow of liquid through a sluice opening 2 in a concrete chanel 3. 
     The sluice opening is provided with a metal seating frame 4 secured to the wall around the opening 2 and against which the closure member 5 is to seat. The closure member 5 consists of a flexible sheet 6 of fabric reinforced resistant polymeric material such as rubber, neoprene or other similar suitable material. The fabric re-enforcement prevents the closure member from stretching while not interfering with the resilient seating surface or the flexibility of the member. 
     A cross-member 7 is provided by means of which the upper end of the closure member is bolted or otherwise suitably secured to the frame 4. 
     To support the closure member 5 against the differential pressure to which it is subjected during use to close the sluice opening 2 horizontal reinforcing members are provided. These members are provided in pairs with those 8 on the upstream side of the sheet 6 extending across substantially the full width of the sheet. The full width is adequate to provide sealing faces down each side of the sluice opening 2 and the sheet is also of a length that extends below the bottom edge of the opening 2. The reinforcing members 9 on the downstream side of the sheet 6 are of a length that will enable them to enter into the sluice opening 2 with their ends in close proximity to the adjacent sides of the sluice opening That is most clearly illustrated in FIG. 6 of the drawings. 
     The pairs of members 8 and 9 are bolted or otherwise secured together with the sheet 6 firmly retained between them. The pairs of members 8 and 9 are vertically spaced apart at the height of the closure member and the spacing is such that there remains sufficient flexibility to enable the sheet 6 to be frequently rolled or peeled away from the sluice opening from the bottom to the top. 
     The bottom end of the sheet 6 is clamped between a pair of cross-members 10 the upstream one of which is provided with a centrally located eyelet 11 or other suitable means whereby a cable 12 can be secured to the cross-member. It will be understood that &#34;cable&#34; is to be interpreted in this specification to include ropes or chains or rods or other elongate members which can extend between the eyelet 11 and a control means for operating the sluice gate. 
     Conveniently the control means can be a winch 13 and the cable is, in the embodiment illustrated passed around a guide pully 14 up through a opening to the winch drum. The winch 13 is firmly secured to the upper wall of the chanel. 
     The winch 13 may be power operated if necessary and other control means such as hydraulic of pneumatic piston and cylinder assemblies can be used if desired. 
     In use the liquid pressure acts on the closure member 5 to hold it against the resting frame 4 and seal off the opening 2. 
     To open the gate the winch 13 is operated and the bottom of the closure is lifted off the seating frame 4 and progressively rolled or peeled upwardly until the opening 2 is fully open. When it is desired to close the gate the winch 13 is released and the closure member restores progressively until the influence of gravity and the liquid flow into the closed portion. The differential pressure exerted on the flexible sheet 5 is resisted by the downstream reinforcing member 9 which transmit this load back to the member 8 and to the walls of the chanel around the opening 2. 
     The method of operation avoids frictional forces on the closure member 5 and the progressive opening requires relatively little effort to bring about full opening of the gate. 
     FIGS. 3, 4, and 5 illustrate an alternative embodiment of the invention which include other advantages in the assembly than those related to closure member described above. 
     The embodiment components described above have been allotted the same reference numerals as in the earlier description and not described again. 
     The closure member 5 is not attached to a seating frame and no such frame need be provided. The member 5 is clasped to a cross-member 15 attached to the end of a depending arm 16 of a bracket assembly 17. The assembly is secured to the upper wall of the chanel above the level of the liquid therein. The bracket assembly is shown bolted to the concrete structure and the bolting arrangement is such that adjustment of the depending arm 16 and consequently the portion of closed member 5 relative to the sluice opening 2 can be affected. The upper cross-member 15 is inclined downwardly towards the sluice opening so that the top of the closure member is biased towards the wall above the opening 2. 
     In FIGS. 4 and 5 the flexible sheet 6 is shown not in tight engagement with the wall around the opening. It will of course be appreciated that the sheet will firmly abut the wall when the gate is in use. 
     The lower end of the closure member 5 is secured to a cross-member 18 which is downwardly inclined away from the sluice opening 2. This also biases the closure member towards the wall around the opening. 
     Projecting from the cross-member 18 at right angles to the wall is a rigid arm 19 to the free end of which is attached the control cable 12 for the gate. The length of the arm is such that sufficient leverage is provided to enable the control cable to exert substantially vertically while still enabling a simple control mechanism such as the winch 13 to be used to operate the gate. The winch 13 will preferably be mounted on the bracket assembly and may be removable therewith from the chanel structure. 
     This embodiment operates generally in the same manner as that previously described but it also enables the closure member to be repaired or replaced without draining of the chanel or work being done beneath the surface of the of the liquid. The bracket assembly can be released and removed from the chanel while repair or replacement work is undertaken. 
     Further the closure member will seat directly against the concrete around the source opening 2 and the expense of installing a metal frame 4 around the opening is avoided. 
     Yet a further embodiment of the invention is illustrated in FIG. 7 of the drawings. This embodiment may be used when it is necessary or desirable to provide a sluice gate assembly which can isolate flow in both directions through the sluice opening. 
     The gate assembly is substantally a double closure assembly as described with reference to FIGS. 3, 4, and 5 but utilising a single winch mechanism. One closure member is associated with each end of the sluice opening 2 through the sluice wall and the two control cables 12 are secured to the ends of a bifurcated lever 20 for correction to the winch cable 21. This cable passes over a guide pully 22 to the winch drive. The pully rig, where loads on the gate assembly allow be dispensed with and the cable taken directly to the winch drive located directly above the sluice wall. 
     Many modifications and variations to the embodiment above described are to be made without departing from the scope of this invention. In particular other operating mechanisms can be used to progressively open and close the gate in the manner set forth and locking means will preferably be included to enable the gate to be secured at any stage of opening.