Patent Publication Number: US-8992121-B2

Title: Leaf for a mitre gate and mitre gate including such a leaf

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a U.S. National Phase of International Application No. PCT/FR2010/052913, filed Dec. 24, 2010, designating the U.S., and published in French as WO 2010/077064 on Jun. 30, 2011 which claims the benefit of French Patent Application No. 09 59591 filed Dec. 24, 2009. 
     FIELD OF THE INVENTION 
     The present invention relates to a leaf for a mitre gate. The present invention also relates to a mitre gate having two leaves according to the invention. Such a mitre gate can be used as a lock gate in a stream of water. “Mitre gate” refers to a structure capable of retaining an open-surfaced liquid. When it is in use, a mitre gate separates a downstream pool from an upstream pool in which the liquid to be retained is located. This liquid subjects the mitre gate to a distributed pressure that varies as a function of time and of the distance from the bottom of the gate. A mitre gate therefore works in fatigue because it undergoes cyclic stresses. 
     BACKGROUND OF THE INVENTION 
     Each leaf of a mitre gate has a side for hinging with the lock wall and a side where the junction is done with the other leaf of the mitre gate in the middle of the stream of water. A leaf for a mitre gate of the prior art comprises a generally flat skin plate and two uprights respectively located on the hinge side and the junction side of the skin plate. The skin plate is intended to bear pressure exerted by the liquid situated upstream of the mitre gate, which causes two forms of mechanical stress. The lateral ends of the leaf, the hinge side and the junction side, transmit compression forces. Between these two lateral ends, the leaf works in flexion and compression, the flexion work being predominant in the central part of the leaf. Between these two lateral ends, the skin plate works in flexion. The structure of the leaf consists of horizontal beams and vertical and horizontal stiffeners, which are made up of thin plates secured to one another. 
     However, in a leaf for a mitre gate of the prior art, the compression forces to which the skin plate is subjected are transmitted from one end of the leaf to the other along lines of force that alternatingly pass through said horizontal plates and vertical plates. This alternation causes relatively high stress concentrations between these components, in particular the horizontal beams and the two uprights on the one hand, and the vertical stiffeners on the other hand. However, such stress concentrations decrease the fatigue life, and therefore the useful life, of the leaf. 
     SUMMARY OF THE INVENTION 
     The present invention aims in particular to resolve these drawbacks by proposing a leaf whereof the structures causes relatively low stress concentrations. 
     To that end, the invention relates to a leaf for a mitre gate, the leaf having:
         a skin plate intended for withstanding a pressure exerted by a liquid, and   at least two uprights respectively located on either side of the skin plate, the uprights being secured to the skin plate.       

     The skin plate is in the overall shape of a cylinder portion, the longitudinal axis of the cylinder being essentially parallel to the uprights. Each upright extends overall according to a generatrix of the cylinder. Each upright includes at least one bearing element, arranged to project relative to the skin plate, and each bearing element includes a bearing surface, for supporting the bearing element against a lock wall or against another leaf of the mitre gate. The bearing surface of each bearing element is aligned with a plane that is tangential to the skin plate. 
     In a leaf according to the invention, the cylindrical shape of the skin plate makes it possible to distribute the forces on each side of the leaf. Furthermore, the position of the uprights in the extension of the skin plate therefore allows the two uprights to directly react the compression forces transmitted by the skin plate, which prevents generating stress concentrations. Furthermore, since the bearing surface of each bearing element is aligned with a plane that is tangential to the skin plate, the compression forces are transmitted to the skin plate optimally, which favors the mechanical strength of the leaf. 
     According to other advantageous, but optional features of the invention, considered alone or according to any technically allowable combination:
         the bearing surface of at least one bearing element is perpendicular to a middle plane that is parallel to the plane tangential to the skin plate and that extends a middle fiber of the skin plate, on the bearing element side;   the bearing surface is centered on the middle plane;   the bearing surface of at least one bearing element is planar;   the bearing surface of at least one bearing element is in the shape of a cylinder portion whereof the longitudinal axis is parallel to the longitudinal axis of the cylinder that defines the shape of the skin plate;   each bearing element is made up of a profile;   the cylinder has an elliptical base;   the cylinder has a circular base;   the cylinder has a parabolic base;   a first ratio that has:
           as numerator, the curve radius of the cylinder, and   as denominator, the width of the skin plate, measured between the two uprights, is between 0.6 and 13;   
           the leaf also includes thin, flat cores, each core having, in a plane transverse to the skin plate, a curve coinciding with the skin plate, each core widening toward the middle thereof and narrowing toward its ends, each core being secured to the skin plate;   each core is pierced with at least one recess and in that the leaf includes at least one generally rectilinear stiffener extending through the recesses respectively belonging to several cores;   at least one stiffener is tubular;   the or each stiffener is fastened to several cores using welds made in a plane perpendicular to an axis of the cylinder;   the leaf also includes means for fastening a member for actuating the leaf, the fastening means being connected to one end of a stiffener.       

     Furthermore, the present invention relates to a mitre gate having two leaves as previously described. A second ratio that has:
         as numerator: the width of the mitre gate, measured between the two uprights that are the furthest apart, and   as denominator: the curve radius of the cylinder
 
is between 0.6 and 1.8.
       

    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       The invention will be well understood, and the advantages thereof will appear, in light of the following description, provided solely as a non-limiting example and done in reference to the appended drawings, in which: 
         FIG. 1  is a perspective view, with a partial tear-away and from the downstream direction, of a leaf according to the invention; 
         FIG. 2  is a perspective view, from the upstream direction, of the leaf of  FIG. 1 ; 
         FIG. 3  is a cross-sectional view, along plane III of  FIG. 1 , of the leaf of  FIG. 1 ; 
         FIG. 4  is a top view, along arrow IV of  FIG. 1 , of the leaf of  FIG. 1 ; 
         FIG. 5  is a horizontal cross-sectional view of a mitre gate according to the invention and including the leaf of  FIGS. 1 to 4 ; 
         FIG. 6  is an enlarged view of detail VI of  FIG. 5 ; 
         FIG. 7  is an enlarged view of detail VII of  FIG. 5 ; 
         FIG. 8  is an enlarged view of detail VIII of  FIG. 6 ; and 
         FIG. 9  is a view, similar to  FIG. 8 , of a lateral end of a leaf according to another embodiment of the invention. 
     
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
       FIG. 1  illustrates a leaf  1  that has a skin plate  2  and two uprights  4  and  6 . The skin plate  2  extends over nearly all of the upstream surface of the leaf  1 . The outer surface of the skin plate  2 , oriented toward the back of  FIG. 1 , is intended to be turned toward an upstream pool. 
     When the leaf  1  is mounted in a mitre gate that is in use, the retained water subjects the leaf  1  to a pressure P distributed over the skin plate  2 . In  FIG. 1 , the pressure P is shown in the form of a vector field, while  FIGS. 3 and 5  illustrate the result of the pressure P. 
     In this application, the terms “upstream” and “downstream” are preferably used in reference to the general flow direction of the water when the mitre gate is in the open position. 
     The skin plate  2  has a central region and two lateral or side regions  24  and  26 . The uprights  4  and  6  are respectively situated on either side  24  and  26  of the skin plate  2 . The uprights  4  and  6  extend parallel to a direction Z that is substantially vertical when the leaf is in the in-use position, as illustrated in  FIG. 5 . Each upright  4  or  6  extends over the entire height of the leaf  1  in direction Z. 
     As shown in  FIGS. 1 to 5 , the skin plate  2  is generally in the shape of a cylinder portion C 2 . As shown more particularly in  FIGS. 4 and 5 , the cylinder C 2  constitutes the cylindrical enclosure in which the skin plate  2  fits. The longitudinal axis Z 2  of the cylinder C 2  is essentially parallel to the uprights  4  and  6 . In other words, the axis Z 2  is vertical overall when the leaf  1  is in the in-use position, as illustrated in  FIG. 5 . 
     As shown more particularly in  FIG. 8 , the skin plate  2  is delimited by an upstream surface  22  and a downstream surface  28 . During use, the upstream  22  and downstream  28  surfaces are respectively intended to be turned toward the upstream and downstream pool side. The cylinder portion C 2  that defines the shape of the skin plate  2  coincides with the upstream surface  22  of the skin plate  2 . 
     In the case at hand, the cylinder C 2  has a circular base with curve radius R 2 . In other words, the cylinder C 2  is a cylinder of revolution around the single axis Z 2  and with radius R 2 . The cylinder C 2  has a relatively large curve radius R 2  in relation to a width L 2  of the skin plate. 
     In the example of  FIGS. 1 to 7 , the curve radius R 2  is equal to approximately 13.1 m. The width L 2  is equal to approximately 7.5 m. More specifically, a first ratio has:
         as numerator: the curve radius R 2  of the cylinder C 2 , and   as denominator: the width L 2  of the skin plate  2 , measured between the uprights  4  and  6  in a plane perpendicular to the axis Z 2 , such as the plane of  FIG. 4  or  5 . This first ratio is equal to approximately 1.7.       

     By design, the curve radius R 2  can be between 2 m and 40 m, while the width L 2  can be between 3 m and 19 m. The first ratio can be between 0.6 and 13. In other words, the curve radius of the cylinder varies in particular with the width of the leaf, which is equal to the width L 2 . A first ratio makes it possible to produce a skin plate  2  optimally distributing the compression forces and the flexion forces resulting from the pressure P. 
     Each upright  4  or  6  extends generally along a respective generatrix Z 24  or Z 26  of the cylinder C 2 . In other words, the upright  4  extends generally along the generatrix Z 24  and the upright  6  extends generally along the generatrix Z 26 . The uprights  4  and  6  are therefore parallel to one another. In other words, each post  4  or  6  fits on the cylinder C 2  in the extension of the skin plate  2 . The uprights  4  and  6  are thereby respectively adjacent to the sides  24  and  26 . 
     The uprights  4  and  6  are connected to the skin plate  2 . In this way, the uprights  4  and  6  can react the compression forces transmitted by the skin plate  2 . These compression forces are symbolized by arrows F 4  and F 6 , respectively, in  FIGS. 6 and 7 . The connection between the uprights  4  and  6  and the skin plate  2  can be made using welds or other equivalent securing means. 
     In a plane perpendicular to the axis Z 2 , such as the plane of  FIG. 3 ,  4 ,  5 ,  6  or  8 , the forces F 4  and F 6  have a component that is supported by a direction that is locally substantially tangential to the skin plate  2  respectively on each side  24  or  26 . Such a component of the forces F 4  or F 6  therefore extends substantially in a respective plane P 4  or P 6  that is tangential to the upstream surface  22  of the skin plate  2  or the cylinder C 2 , at each respective side  24  or  26 . The planes P 4  and P 6  are visible in  FIGS. 3 and 5 . 
     More specifically, and as shown in  FIG. 8 , the force F 4  extends in a middle plane P 40  that extends, on the side  24 , a middle fiber M of the skin plate  2 , situated equidistant from the upstream surface  22  and the downstream surface  28  of the skin plate  2 . Given the imprecisions introduced in practice, the force F 4  does not extend exactly in the middle plane P 40 , but extends substantially in the middle plane P 40 . Similarly, the force F 6  extends substantially in a middle plane P 60 , not shown, that extends the middle fiber M of the side  26 . 
     Each upright  4  or  6  includes a respective bearing element  40  or  60  that is arranged projecting from the skin sheet  2  so as to transmit the respective forces F 4  or F 6 . The bearing element  40  bears against an oblique surface of a lock wall  5 , in particular when the leaf  1  is in the closed position, as illustrated in  FIGS. 5 ,  6 ,  7  and  8 . 
     The upright  4  also includes a flat beam  41 , as well as a crossbeam  43 . The flat beam  41 , the crossbeam  43  and the bearing element  40  extend over the majority of the height of the leaf  1  in direction Z. The bearing element  40  here is formed by a profile in the form of a rectilinear rail. On the side of the skin plate  2 , the bearing element  40  has a base that is fastened on the crossbeam  43 . The crossbeam  43  is in turn fastened on the flat beam  41 . The assembly formed by the flat beam  41 , the crossbeam  43  and the bearing element  40  is approximately symmetrical relative to the plane P 4 . More specifically, the bearing element  40  is symmetrical relative to the middle plane P 40 . 
     As a result, the bearing element  40  is centered on the middle plane P 40 ; in other words, the bearing element extends at least partially along the middle plane P 40 . As a result, the bearing element  40  is locally tangential to the skin plate  2 , at the side  24  of the skin plate  2 . 
     The flat beam  41  is secured to the structure of the leaf  1 , as described hereinafter. 
     On the side opposite the skin plate  2 , the bearing element  40  has a flat bearing surface  42 , provided for bearing of the leaf  1  against the lock wall  5 . The bearing surface  42  is locally perpendicular to the curve defining a base of the cylinder C 2  in a plane perpendicular to the axis Z 2 . Furthermore, the bearing surface  42  is perpendicular to the middle plane P 40  and is centered on the middle plane P 40 . Furthermore, the bearing surface  42  is generally aligned with the plane P 4 , on the side  24 . In other words, the bearing surface  42  is located aligned with the plane P 4  and is intersected by the plane P 4 , since it is perpendicular to the plane P 4 . Inasmuch as the upright  4  extends generally along and around the generatrix Z 24 , the forces F 4  are transmitted directly from the skin plate  2  to the lock wall  5 , without causing significant stress concentrations. 
     As shown in  FIGS. 1 to 4 , the leaf  1  also includes several cores  31 . 0 ,  31 . 1 ,  31 . 2 ,  31 . 3 ,  31 . 4 ,  31 . 5 ,  31 . 6 ,  31 . 7 ,  31 . 8 ,  31 . 9 ,  31 . 10  and  31 . 11  that are thin and flat. Each core  31 . 0  to  31 . 11  has, in a plane transverse to the skin plate such as the plane P 31 . 2  or III in  FIG. 1 , a curve coinciding with the skin plate  2 . In other words, each core  31 . 11  has a cylindrical curve on the upstream side. Each core  31 . 0  to  31 . 11  widens toward the middle thereof and narrows toward its ends, i.e. toward the sides  24  and  26  of the skin plate. 
     Furthermore, each core  31 . 0  to  31 . 11  is pierced with two recesses in the form of circular through holes. Thus, the core  31 . 2  is pierced with two recesses  32 . 21  and  32 . 22  that are situated in the central region of the core  31 . 2  at approximately symmetrical locations relative to the middle plane of the leaf  1 . 
     Furthermore, the leaf  1  includes two stiffeners  33 . 1  and  33 . 2  that are generally rectilinear and that extend through the recesses  32 . 21 ,  32 . 22  and equivalent, respectively belonging to several cores  31 . 0  to  31 . 11 . In the case at hand, each stiffener  32 . 21  and  32 . 22  is tubular. Such a shape of the stiffeners  32 . 21  and  32 . 22  makes it possible to limit the stress concentrations. 
     Each core  31 . 0  to  31 . 11  is secured to the skin plate  2 , for example using welds. Each stiffener  32 . 21  or  32 . 22  is fastened to several cores  31 . 0  to  31 . 11  using welds that are made in a plane perpendicular to the axis Z 2 , such as plate P 31 . 2  in  FIG. 1 . As a result, the welds securing the cores  31 . 0  to  31 . 11  to the stiffeners  32 . 21  and  32 . 22  are in the form of circles that extend in a horizontal plane when the leaf  1  is in the in-use position. 
     Such an arrangement of the welds makes it possible to limit the stress concentrations at the interfaces between the cores and the stiffeners, inasmuch as the compression forces and the flexion forces to which the leaf  1  is subjected are essentially transmitted along horizontal planes, so long as the compression forces and the flexion forces are essentially transmitted by the skin plate  2 . 
     The upright  6  also includes a flat beam  61 , as well as a crossbeam  63 . The flat beam  61 , the crossbeam  63 , and the bearing element  60  extend over the majority of the height of the leaf  1  in direction Z. The bearing element  60  here is made up of a profile in the form of a rectilinear rail. On the side of the skin plate  2 , the bearing element  60  has a base that is fastened on the crossbeam  63 . The crossbeam  63  is in turn fastened on the flat beam  61 . The assembly formed by the flat beam  61 , the crossbeam  63  and bearing element  60  is approximately symmetrical relative to the plane P 6 . More specifically, the bearing element  60  is symmetrical relative to the middle plane P 60 . 
     As a result, the bearing element  60  is centered on the middle plane P 60 , in other words the bearing element is at least partially aligned along the middle plane P 60 . As a result, the bearing element  60  is locally tangential to the skin plate  2 , at the side  26  of the skin plate  2 . 
     The flat beam  61  is secured to the structure of the leaf  1 , as described below. 
     On the side opposite the skin plate  2 , the bearing element  60  has a flat bearing surface  62 , provided for bearing of the leaf  1  against the other leaf  101  of the mitre gate  100 . The bearing surface  62  is locally perpendicular to the curve defining a base of the cylinder C 2  in a plane perpendicular to the axis Z 2 . Furthermore, the bearing surface  62  is perpendicular to the middle plane P 60  and is centered on the middle plane P 60 . Furthermore, the bearing surface  62  is generally aligned with the plane P 6 , on side  26 . In other words, the bearing surface  62  is located aligned with the plane P 6  and is intersected by the plane P 6 , since it is perpendicular to the plane P 6 . Inasmuch as the upright  6  is generally aligned along and around the generatrix Z 26 , the forces F 6  are transmitted directly from the skin plate  2  to the lock wall  5 , without causing significant stress concentrations. 
     During use, owing to the arrangement of the bearing elements  40  and  60 , which are aligned with the skin plate  2 , the forces F 4  and F 6  are transmitted from one upright  4  or  6  to the other by passing primarily through the skin plate  2 . The bearing surfaces  42  and  62  of the bearing elements  40  and  60  ensure the transmission of the forces F 4  and F 6  between the lock wall  5  and the uprights  4  and  6  optimally because these surfaces are perpendicular to the forces F 4  and F 6 . Furthermore, since the bearing surfaces of the bearing elements  40  and  60  are centered on the middle plane P 40  or P 60 , the forces F 4  and F 6  are transmitted optimally to the skin plate  2 . Given that the forces F 4  and F 6  pass little or not at all through the cores  31 . 0  to  31 . 11 , the junction between the cores  31 . 0  to  31 . 11  and the skin plate  2 , which, if applicable, is formed using welds, is subjected little or not at all to the fatigue phenomenon, which contributes to improving the fatigue resistance of the leaf  1 . As shown in  FIGS. 1 ,  4  and  5 , the leaf  1  also includes connecting means  7  for connecting the leaf  1  to an actuating member  8 , such as a hydraulic cylinder. 
     The connecting means  7  are connected to one end of the stiffener  32 . 21 . The hydraulic cylinder that forms the actuating member  8  therefore has one end connected to the connecting means  7  and the other end to the lock wall  5 . 
     The width L 100  is equal to approximately 14.3 m. A second ratio that has:
         as numerator: the width L 100  of the mitre gate  100 , measured between the two uprights  4  and  104  that are the furthest apart, and   as denominator: the curve radius R 2  of the cylinder C 2  is equal to approximately 1.1.       

     The width L 100  can be between 6 m and 36 m. The second ratio is between 0.6 and 1.8. In other words, all things also being equal, the smaller the lock angle A 100 , the smaller the curve radius R 2 . The lock angle A 100  can be between 110° and 160°. Such a second ratio makes it possible to optimize the distribution of forces F 4 , F 6  and equivalent, resulting from the pressure P, between the leaves  1  and  101  and their respective uprights  4 ,  6 ,  104  and  106 . 
       FIG. 9  shows one alternative of the invention in which the bearing element  40  is delimited by a convex bearing surface  42  that has the geometry of a cylinder portion C 42 . The longitudinal axis Z 42  of the cylinder C 42  is parallel to the longitudinal axis Z 2  of the cylinder C 2  that defines the geometry of the skin plate  2 , and is comprised in the middle plane P 40 . In other words, the axis Z 42  is aligned with the middle fiber M of the skin plate  2 . The bearing surface  42  is locally perpendicular to the middle plane P 40  and is centered on the middle plane P 40 . The bearing surface  42  is also aligned with the plane P 4 , on the side  24 . Furthermore, the bearing surface  42  bears on a pad  52  that is delimited by a concave surface  54  and that is fastened to the lock wall  5 . The concave surface  54  has a curve radius slightly larger than the radius of the cylinder C 42 . The bearing surface  42  bears on the concave surface  54  of the pad  52 . 
     According to alternatives not shown:
         several uprights can be juxtaposed along the height of the leaf;   the cylinder that forms the enclosure of the skin plate can have an elliptical base; in the particular case where the two foci of the elliptical base are combined, the base is circular, as for the cylinder C 2  of the skin plate  2 ;   the cylinder forming the enclosure can have a parabolic base;   more generally, the cylinder surrounding the skin plate can have a curved base made up of a juxtaposition of convex and/or concave curvilinear segments;   the means for connecting the actuating member to the leaf can be connected to a part of the leaf other than the stiffener.       

     A leaf according to the invention makes it possible to transmit the compression forces to each upright of the leaf. The structures and the positions of the components of the leaf according to the invention make it possible to limit the stress concentrations, and therefore to increase the fatigue strength and useful lifetime of a mitre gate according to the invention.