Abstract:
A control gate is adapted to be installed across a channel for liquids. The Control gate has a barrier member capable of vertical or tilting movement and it is either slidingly or pivotally mounted to a frame of the control gate. In one instance, the control gate has at least one side member attached to the barrier member. A drive member co-operates with the side member(s) to allow raising and lowering of the barrier member to regulate flow of liquid through the control gate. The drive member includes a spool and an engagement member that is secured under tension and winds around the spool. As the spool turns it causes, with the engagement member, movement of the barrier member. Also described is a method of measuring flow rate through a control gate.

Description:
REFERENCE TO PRIOR APPLICATIONS  
       [0001]     This application is a Continuation of U.S. application Ser. No. 10/362,081, filed Aug. 6, 2003, a 35 USC §371 national phase of PCT/AU01/01036 filed Aug. 21, 2001, which claims benefit from Australian Applications PQ9554 and PQ1217 filed Aug. 21, 2000 and Nov. 3, 2000, respectively. 
     
    
     FIELD OF THE INVENTION  
       [0002]     This invention relates to control gates for flow and level control of liquids and to lifting mechanisms for such gates.  
       BACKGROUND OF THE INVENTION  
       [0003]     Control gates are commonly known for regulating the flow and level of water in water channels especially for irrigation. Control gates are typically of the vertical slide type e.g., U.S. Pat. No. 4,726,709; the radial control type e.g., U.S. Pat. No. 5,516,230; or the swing down type e.g., U.S. Pat. No. 4,073,147. Such gates have proved popular but require large motors or complex actuating devices to lift the gates against the weigh of water, the flow of the water or the weight of the gate.  
       SUMMARY OF THE INVENTION  
       [0004]     It is an object of the present invention to provide a control gate which reduces the motor torque requirements to lift the control gate.  
         [0005]     A further object of another aspect of the invention is to provide a means of measuring the flow rate through the gate.  
         [0006]     A further object of a further aspect of the invention is to provide a control gate with associated lifting mechanism which can be assembled as a self contained unit that can be retrofitted to existing regulating structures.  
         [0007]     A further object of the invention is to provide a lifting mechanism for control gates which can be integrated into the construction of control gates or retrofitted to existing control gates.  
         [0008]     With these objects in view the present invention in a first aspect provides a control gate adapted to be installed across a channel for liquids, said control gate having a barrier member that is pivotally mounted at or adjacent the base of said flow channel and at least one side member or central member attached to said barrier member, a drive means co-operating with said at least one side member or central member to allow raising and lowering of said barrier member to regulate flow of liquid through said control gate.  
         [0009]     Preferably said at least one side member or central member has a circular arcuate section which co-operates with said drive means. In one embodiment said drive means includes a rack or chain on said circular arcuate section which co-operates with a driven pinion, worm or sprocket. In a preferred embodiment two side members are provided and said side members sealingly engage with a support frame within said flow channel. In a further embodiment said drive means includes a winding spool which co-operates with at least one cable along or parallel to said circular arcuate section whereby the winding onto or off said spool of said at least one cable will cause movement of said control gate. In a further embodiment said circular arcuate section may include a flange which projects into the flow of liquid to alter the flow characteristics through said control gate.  
         [0010]     In another aspect of the invention there is provided a lifting device for a control gate having a movable barrier member which controls flow of liquid through said control gate, said lifting device including at least one engagement member running the length of said barrier member and at least one driving member which co-operates with said at least one engagement member to cause lifting of said movable barrier on rotation of said at least one driving member.  
         [0011]     Preferably said at least one driving member includes a pinion gear, worm drive, sprocket, spool or pulley and said at least one engagement member includes a rack, chain or at least one cable under tension.  
         [0012]     In another aspect of the invention there is provided a moving device for controlling movement of a barrier member, said moving device including at least one engagement member running the length or a side of said barrier member and at least one driving member which co-operates with said at least one engagement member to cause movement of said barrier on rotation of said at least one driving member. Preferably said engagement member is a pair of opposing cables secured to said at least one driving member in the form of a spool member from which said cables wind off and on from said spool member. In a practical embodiment said spool member can also move axially during rotation to allow the cables to wind directly onto and off said spool member at a substantially constant position on said spool member.  
         [0013]     In yet a further aspect of the invention there is provided a flow stabilization device for flow control gate for the regulation of liquid flow along a channel, said flow stabilization device including a flow direction plate pivotally attached to said control gate, said flow direction plate adapted to allow liquid passing through said control gate to exit from said control gate substantially parallel with the floor of said channel.  
         [0014]     Preferably said flow direction plate is pivotally attached to a pivotable plate over which said liquid flows and said flow direction plate retains a substantially parallel disposition with respect to the floor of said channel. In a preferred embodiment said flow direction plate forms one side of a parallelogram with the opposing side being fixed in a position parallel to the floor of said channel.  
         [0015]     In yet a further aspect of the invention there is provided a method for measuring flow rate of a liquid through a gate in a channel, said method including the steps of measuring the pressure of the liquid at a first position upstream of said gate, measuring the pressure of the liquid at a second position downstream of said gate, measuring the position of opening of said gate and calculating said flow rate using an algorithm based on said measurements. It is preferred that the measurements take place adjacent to the gate. Preferably said algorithm is determined using a system identification method.  
         [0016]     In yet another aspect of the invention there is provided a device for measuring flow rate of a liquid through a gate in a channel, said device having a first pressure sensor for measuring the pressure of the liquid at a first position upstream of said gate, a second pressure sensor for measuring the pressure of the liquid at a second position downstream of said gate, an opening sensor for measuring the position of opening of said gate and computation means for calculating said flow rate using an algorithm based on said measurements.  
         [0017]     In a further preferred aspect there is provided a control gate adapted to be installed across a channel for liquids, said control gate having a first frame member adapted to be secured to said channel, a second frame member which slidingly co-operates with said first frame member, said second frame member including a gate for controlling flow of liquid therethrough, and sealing means on said second frame member to provide sealing between said gate and said second frame member.  
         [0018]     Preferably said sealing means is a continuous seal located on or within said second frame member. It is preferred that said continuous seal includes a plurality of parallel ribs which abut said gate to provide a positive sealing effect.  
         [0019]     In yet a further aspect of the invention there is provided a method for measuring flow rate of a liquid through a gate in a channel, said method including the steps of providing at least one sensor in or adjacent said gate, measuring the output from said at least one sensor, and calculating said flow rate through said gate using an algorithm based on said measurements. Preferably said algorithm is determined using a system identification method. Preferably said measurements may be made using pressure, magnetic inductive, sonar or other suitable types of sensors and/or a combination of different sensors. Preferably the position of opening of said gate is also measured and this measurement is also included in the determination of said algorithm. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0020]     In order that the invention may be more readily understood and put into practical effect, reference will now be made to the accompanying drawings, in which:— 
         [0021]      FIG. 1  is a perspective view of a control gate made in accordance with the invention;  
         [0022]      FIG. 2  is a part side view of the control gate shown in  FIG. 1 ;  
         [0023]      FIG. 3  is a part side view of the control gate shown in  FIG. 1  with a second embodiment of a control gate driving mechanism;  
         [0024]      FIG. 4  is a part side view of the control gate shown in  FIG. 1  with a third embodiment of a control gate driving mechanism;  
         [0025]      FIG. 5  is a plan view of the control gate shown in  FIG. 1  with a fourth embodiment of a control gate driving mechanism;  
         [0026]      FIG. 6  is a plan view of the control gate shown in  FIG. 1  with a fifth embodiment of a control gate driving mechanism;  
         [0027]      FIG. 7  is a plan view of the control gate shown in  FIG. 1  with a sixth embodiment of a control gate driving mechanism;  
         [0028]      FIG. 8  is a plan view and side view of the control gate shown in  FIG. 1  with a seventh embodiment of a control gate driving mechanism;  
         [0029]      FIG. 9  is a cross-sectional view along and in the direction of arrows  9 - 9  of  FIG. 8 ;  
         [0030]      FIG. 10  is a perspective view of a control gate having the control gate mechanism as shown in  FIG. 5 ;  
         [0031]      FIG. 11  is a perspective view of a second type of control gate having the control gate mechanism as shown in  FIG. 5 ;  
         [0032]      FIG. 12  is a perspective view of the control gate shown in  FIG. 1  having a flow stabilization device;  
         [0033]      FIG. 13  is a side view of the control gate shown in  FIG. 12  with the gate shown in a closed flow mode;  
         [0034]      FIG. 14  is a side view of the control gate shown in  FIG. 12  with the gate shown in an open flow mode;  
         [0035]     FIGS.  15  to  19  illustrate a variation of the control gate shown in  FIG. 1  showing the assembly sequence of the control gate;  
         [0036]      FIG. 15  is a perspective view showing the fitting of the sealing member to the support frame;  
         [0037]      FIG. 16  is a perspective view showing the outer frame receiving the support frame with barrier member pivotally attached thereto;  
         [0038]      FIG. 17  is a cross-sectional view along and in the direction of arrows  17 - 17  shown in  FIG. 16  but including the outer frame;  
         [0039]      FIG. 18  is a side view showing the sealing of the barrier member to the sealing member of the control gate shown in the direction of arrow  18 - 18  of  FIG. 16 ; and  
         [0040]      FIG. 19  is a similar view to that of  FIG. 1  showing a further embodiment of the invention. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0041]     Throughout the description and drawings the same reference numerals have been used for similar integers to avoid repetition of description. In  FIGS. 1 and 2  of the drawings there is shown a control gate  10  for controlling the flow of water through a channel  12 . Channel  12  can be a drain, irrigation channel or other water course where flow must be regulated. In this embodiment channel  12  has a pair of side walls  14 , 16  and a floor  17  in the form of a U-shaped channel. Although a U-shaped channel is shown the channel could be of any shape e.g. circular, trapezoidal or other shape. The channel  12  is preferably formed of concrete to provide ease of construction and a smooth flow of water. Preferably slots (not shown) are cut into opposing side, walls  14 , 16  for reception of a support frame  18  of control gate  10 . Support frame  18  is U-shaped and will slide into the slots for an easy installation. Support frame  18  interlocks with the slots or other frame to provide structural stability for the assembly. Barrier member  22  is pivotally mounted to support frame  18 . Barrier member  22  is formed from a bottom plate  24  and a pair of circular arcuate side plates  26 , 28 . Barrier member  22  can pivot to a fully closed position where bottom plate  24  is substantially vertical to a fully open position where bottom plate  24  is substantially horizontal.  
         [0042]     By positioning bottom plate  24  in a position between the fully open and close positions the rate of flow of water can be controlled. Side plates  26 , 28  have a right angular section with a circular arcuate section  30  along the hypotenuse. The right angular section can be substituted by more or less of an angle of 90°, if required. Bottom plate  24  is rectangular or square depending on the dimensions of channel  12 . Seals  32 , e.g., seal strips, run along the length of the support frame  18  to provide a water tight seal with barrier member  22  and prevent water bypassing flow through barrier member  22 . In a practical embodiment a continuous seal strip is provided on either side of the pivot for barrier member  22  and is fixed within support frame  18  and extend the full length of support frame  18 .  
         [0043]     In order to control the flow rate accurately a motor  34  is used to lift barrier member  22 . Motor  34  can be monitored by a circuit means (not shown) to determine the positioning of barrier member  22  or by a switch (not shown) for manual operation. Motor  34  is coupled to a reduction gear box  36  which has an output shaft  38  supported by bearings  40  on either side of channel  12 . Pinion gears  42  are secured to shaft  38  and mesh with a racks  44 , 46  on the outer periphery of respective side plates  26 , 28 . The pinion gears  42  are directly located above the pivot point for barrier member  22 . The arrangement of the racks  44 , 46  and pinion gears  42  provides a great mechanical advantage which allows smaller capacity motors  34  to be used in view of the lower torque requirement needed to lift barrier member  22 .  
         [0044]     In use, motor  34  is preferably monitored by a control panel (not shown) to which a plurality of control gates  10  may be connected. Motor  34  can be selected or deselected to control the angle of bottom plate  24  with respect to the floor  17  of channel  12 . By having pressure sensors (not shown) in the channel, the flow of water through control gate can be measured and varied by the lifting of bottom plate  24  by the rack and pinion action of racks  44 , 46  and pinion gears  42  with rotation of shaft  38  by motor  34  under monitoring from the control panel. It is preferred that a pair of pressure sensors are used and that they are mounted on the support frame  18  upstream and downstream, respectively. These sensors can be placed anywhere on the support frame but preferably adjacent the bottom thereof on the side of support frame  18 . With the measurements from the pair of pressure sensors together with the measurement of the gate opening, the flow rate can be calculated by a computational means within said control panel using the known technique of “system identification”. The expression “system identification” used in this specification refers to the known technique of deriving a system model from experimental data. It consists of suggesting a suitable mathematical representation for the model of the system of interest, followed by a tuning process in which the particular representation is optimized as to reproduce as closely as possible experimental timed observations from the system. The methodology provides a means of comparing different models and ranking them according to their ability of reproducing the system&#39;s behavior. System identification is a particular sub-topic in mathematical system theory and also in statistics. The technique of system identification will allow development of a specific relationship for each gate in a multiple gate system. Water will flow in the direction indicated by arrow  48  and flow over bottom plate  24  in the position shown in  FIG. 1 . When bottom plate  24  is vertical all flow will be stopped as bottom plate  24  will block all flow. Seals  32  will ensure that there is no seepage between support frame  18  and barrier member  22 .  
         [0045]      FIG. 3  shows a similar embodiment to that shown in  FIG. 2  but rack  50  is located to the side of the circular arcuate section  30  as part of a flange and pinion gear  42  is located below rack  50 .  
         [0046]      FIG. 4  shows a similar embodiment to that shown in  FIG. 2  except that rack  46  has been replaced by a chain  52  along the periphery of circular arcuate section  30  and pinion gear  42  has been replaced by a sprocket  53 . A worm drive could also replace pinion gear  42  and a worm track could replace rack  50 .  
         [0047]      FIG. 5  shows a similar embodiment to that of  FIG. 1  but pinion gear  42  has been replaced by a spool  54  and rack  50  has been replaced by cables  56 , 58 . Cable  56  is guided along the peripheral edge of circular arcuate section  30  and is secured at one end of barrier member  22  and at the other end  60  to spool  54 , after looping therearound. Similarly cable  58  is guided along the peripheral edge of circular arcuate section  30  and is secured at the opposite end of barrier member  22  and at the other end  62  to spool  54 , after looping therearound. The positioning of cables  56 , 58  could be by the use of a channel on circular arcuate section  30  or a flange thereon. Rotation of spool  54  by shaft  38  will cause lifting of barrier member  22  by either cable  56  being unwrapped from spool  54  whilst cable  58  is wrapped onto spool  54  or vice versa. Spool  54  is located very close to circular arcuate section  30  and under tension to ensure that cables  56 , 58  do not lift from their peripheral contact therewith and maximize the mechanical advantage obtained from this positioning.  
         [0048]      FIG. 6  shows a similar embodiment to that of  FIG. 5  but there is only one cable  64  which is secured at each end of circular arcuate section  30  and to spool  54 . Rotation of spool  54  will lengthen or shorten the opposing sides of cable  64  from spool  54  depending on the direction of rotation.  
         [0049]      FIG. 7  shows a similar embodiment to that of  FIG. 5  but there is only one cable  66  which is secured at each end of circular arcuate section  30 . Cable  66  is looped around spool  54  under tension for a couple of turns to provide sufficient frictional force to avoid slippage of cable  66  on spool  54 .  
         [0050]      FIG. 8  shows a similar embodiment to that of  FIG. 7  except that spool  54  is replaced by a pulley  68  which is driven by a continuous cable  70  which wraps around a central spool  72  under tension. Central spool  72  is driven by motor  34 . Central spool  72  also has a similar continuous cable  74  for coupling to opposing side plate  28 .  
         [0051]     In the embodiments shown in FIGS.  5  to  8  spools  54 , 72  may also be axially movable during rotation to allow the cables to be positioned on the spools at a substantially constant axial position along the spools. Such axial movement of spools  54 , 72  will provide a smooth laying on or laying off of the cables from the spools  54 , 72 .  
         [0052]      FIG. 10  illustrates how the lifting mechanisms shown in FIGS.  1  to  9  can also be used for a standard radial gate  76 . Radial gate  76  has a part cylindrical plate  78  which in its closed position will rest on the floor  17  of channel  12 . Side frames  80 , 82  are joined along opposing peripheries of plate  78  to complete radial gate  76 . Pivots  84 , 86  on side frames  80 , 82  co-operate with side walls  14 , 16  of channel  12  to allow radial gate  76  to pivot upwardly and allow water to flow thereunder. Seals (not shown) are provided on the lower edge of plate  78  and on both circular edges of plate  78  to ensure there is no seepage through the gate. This embodiment shows the use of the lifting mechanism shown in FIG.  5 . Cables  56 , 58  are secured at each end of plate  78  and extend along the outer surface of plate  78 .  
         [0053]      FIG. 11  illustrates how the lifting mechanisms shown in FIGS.  1  to  9  can also be used for a standard vertical slide gate  88 . Slide  90  can be moved up and down within U-shaped frame  92  which is affixed to the side walls  14 , 16  of channel  12 . Frame  92  extends above channel  12  to provide guidance for slide  90  when it is fully raised. Water can flow through the gap  94  formed between the bottom of frame  92  and the bottom of slide  90 . Seals (not shown) are provided within frame  92  to ensure there is no seepage through gate  88 .  
         [0054]     FIGS.  12  to  14  show the same embodiment shown in  FIGS. 1 and 2  but with the addition of a flow stabilization device  96 . In this embodiment the flow stabilization device  96  is a plate,  98  which extends the full width of the bottom plate  24 . Plate  98  is pivotally mounted to bottom plate  24  by hinge  100 . A pair of extension arms  102  (only one shown) extend parallel to the floor  17  of channel  12  and are the same width as the width of plate  98 . A pair of rods or links  104  are pivotally attached at either end to a respective extension arm  102  and the free edge  106  of plate  98 . Rods or links  104  will be the same length as the bottom plate  24 .  
         [0055]     Thus the side edge of bottom plate  24 , the plate  98 , a respective rod or link  104  and a respective extension arm  102  will form a movable parallelogram. As extension arms  102  are fixed in their parallel relationship with floor  17  of channel  12  then plate  98  will also be in a substantial parallel relationship with floor  17  when bottom plate  24  is lifted. Without plate  98  water will flow over bottom plate  24  and create turbulence where it leaves bottom plate  24  to exit the control gate. Plate  98  will maintain a horizontal flow path for the water as it exits the control gate.  FIGS. 13 and 14  show a closed flow rate and open flow rate respectively and it can be clearly seen that the horizontal flow path is maintained at any flow rate. Plate  98  will reduce the turbulence one would normally expect when water exits a flow control gate.  
         [0056]     In the embodiment shown in  FIGS. 15 and 16  the assembly of the control gate  10  is illustrated. An outer frame  110  replaces the slots in channel  12  for reception of support frame  18 . Outer frame  110  is a U-shaped structure with vertical sections  112 ,  114  and a bottom section  116 . Sections  112 ,  114 ,  116  have a U-shaped profile and are secured to the side walls  14 , 16  and bottom  17  of channel  12 . The securement can be by fasteners, adhesive or any other suitable means. Outer frame  110  is grouted, sealed by silicone type sealers or other waterproofing agents to prevent seepage between channel  12  and outer frame  110 . Support frame  18  as previously described has barrier member  22  pivotally attached thereto. Support frame  18  in this embodiment is formed as a hollow square or rectangular section and has side arms  118 ,  120  which join with bottom arm  122 . The shape of support frame  18  and outer frame  110  are not limited to the shapes shown in the preferred embodiments as they can vary to suit requirements.  
         [0057]     Interlocking extrusions, circular or triangular shapes may be used as examples. Seal  32  is mounted as a continuous strip to the inner facing surfaces of side arms  118 , 120  and bottom arm  122 . Seal  32  preferably extends over the opposing edges of support frame as seen at  124  ( FIG. 17 ). This overhang  124  will provide a seal between outer frame  110  and support frame  18  to prevent seepage therebetween. Seal  32  can be of any suitable profile but the preferred embodiment has a pair of parallel ribs  126 , 128  which provide a very effective seal with barrier member  22 . The double rib will provide an excellent double seal for the pivot point of barrier member  22  as shown in  FIG. 18  and for the side plates  26 , 28 .  
         [0058]     In use, support frame  18  with barrier member  22  fitted thereto, will be guided into position into vertical sections  112 , 114  and into sealing engagement with bottom section  116 . The overhangs  124  will ensure that there is no seepage between outer frame  110  and support frame  18 . Support frame  18  will then be interlocked to outer frame  110 . If barrier member  22  needs to be repaired, or a different type of barrier member fitted (e.g. a radial gate as shown in  FIG. 10  or vertical slide control gate as shown in  FIG. 11 ), it is any easy matter to withdraw support frame  18  with barrier member  22 .  
         [0059]     Pressure sensors  130 , 132  ( FIG. 15 ) are located upstream and downstream of control gate  10  and preferably on support frame  18 . In the preferred embodiment pressure sensors  130 , 132  are located at a point immediately upstream of seal  32  and a point immediately downstream of seal  32  i.e. either side of ribs  126 , 128 . The type of sensors used can vary to suit the nature of the flow rate to be measured and the invention is not limited to the type of sensor used, its position or the number of sensors used.  
         [0060]     The embodiment shown in  FIG. 19  is a variation of the embodiment shown in  FIG. 1 . The addition of a curved flange plate  134 , 136  on the circular arcuate section  30  of each side plate  26 , 28  will alter the flow characteristics of the liquid passing through the control gate. Curved flange plates  134 , 136  are mounted perpendicular to the plane of side plates  26 , 28  and extend inwardly therefrom. The change in flow characteristics has been found to increase the sensitivity of pressure measurements by the pressure sensors.  
         [0061]     Although the preferred embodiments have been described with reference to the flow of water it will be apparent that the invention can be used for many different liquids and slurries. The preferred embodiments show the use of a pair of pinion gears  42  or spools  54  the invention will work with one or more than two of such integers. The use of a pair of pinion gears or spools  54  provides a better balance for lifting the control gates. Side plates  26 , 28 ;  80 , 82  could be substituted by a centrally located plate. The flow measurement method has the pressure sensors on support frame  18  but they can be positioned to other suitable positions to suit computational requirements.  
         [0062]     Further embodiments of the invention will now be described with particular reference to  FIG. 16  but is not limited to that Example. The pressure sensors of  FIG. 16  can be omitted and a substitute system of flow rate determination can be used. Electromagnetic or sonar devices can be included in such a system. For the electromagnetic system the concept is that any conductive liquid passing through a magnetic field will induce a voltage which can be measured. This method is based on Faraday&#39;s law of induction. The amplitude of the induced voltage is related to the velocity of the liquid. The flow rate through the gate can be derived from these measurements using system identification techniques. Bottom plate  24  and side plates  26 , 28  can include suitable devices to induce a magnetic field and to measure the induced voltages. Sonar techniques may also be used using either the Doppler effect or the direct travel time method. In the Doppler effect method an acoustic signal is transmitted into the moving liquid and the change in the frequency of the signals reflected from the particles of the liquid is measured. The frequency distribution of the frequency shift of the reflected signals is related to the velocity of the liquid. In the direct travel time method pairs of transmit and receive acoustic sensors are located in opposite boundaries of the moving liquid. The sensors are oriented so that the direction of the acoustic path between them is aligned to transmit to the opposite sensor and to also receive a signal from the opposite sensor. The sensors are positioned such that the path between the sensors traverses the liquid flow direction at an angle other than perpendicular. The time of the signal to travel in either direction is measured. The difference in travel time is directly related to the velocity of the liquid between the two sensor points. Additional pairs of sensors may be used to build up a profile of the liquid velocities.  
         [0063]     The measurements made and the use of system identification methods will determine whether additional sensors are used. A number of different sensors of the same type or different type can be used in combination which has the potential of improving the flow rate measurement algorithm. One type of sensor may measure high flow rates better than low flow rates and the different sensors may be weighted when deriving the relationship under system identification. The pressure sensors of the embodiment shown in  FIG. 15  can also be integrated into such a system, if required.  
         [0064]     The invention will be understood to embrace many further modifications as will be readily apparent to persons skilled in the art and which will be deemed to reside within the broad scope and ambit of the invention, there having been set forth herein only the broad nature of the invention and certain specific embodiments by way of example.