Abstract:
An automatic gate opening device is claimed comprising: a gate drive axis ( 134 ), movable between a gate closed position and a gate open position; a treadle ( 102 ) and a rechargeable energy storage means ( 16, 118 ). The device also comprises an energy conversion means to convert stored energy into rotational movement of the drive axis ( 134 ) in a gate opening and energy conversion means to convert stored energy into rotational movement of the drive axis in a gate closing direction. The treadle ( 102 ) is configured such that, with the drive axis ( 134 ) in its gate open position, a single actuation of said treadle ( 102 ) recharges the energy storage means with sufficient energy to move the drive axis from its gate open position to its gate closed position and back to its gate open position.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application is a 35 U.S.C. §371 of and claims priority to PCT International Application Number PCT/GB2010/000445 (Publication No. WO 2010/103282A1), which was filed 11 Mar. 2010 (11 Mar. 2010), and was published in English, and this application claims priority to UK Patent Application No. 0904316.7 which was filed 13 Mar. 2009 (13 Mar. 2009), the teachings of which are incorporated herein by reference. 
     FIELD OF THE INVENTION 
     This application relates to a mechanism for opening and closing a barrier, in particular this mechanism related to an automatic gate opening device. 
     BACKGROUND OF THE INVENTION 
     Gates are commonly used in fence lines or farmyards to allow access and to secure vehicles, property or livestock. 
     However, for a vehicle to pass through the gate the driver has to vacate the vehicle to open the gate and then return it to the closed position once the vehicle has been driven through the gate. The opening and closing of gates can thus become time consuming. 
     Conventional gate opening mechanisms make use of electric motors in order to drive the opening and closing of the gate. Such mechanisms consume power and require connection to a power source upon installation, which can be problematic when the gate is to be installed a distance from the nearest premises or power lines. In addition, conventional powered gate mechanisms resist manual operation and thus inhibit use by pedestrians. 
     Some gate opening devices are known that utilise fluid power for opening and closing gates, the fluid being compressed by a vehicle driving over an actuator as it approaches a gate, the compressed fluid then opening a gate, and vice versa as the vehicle drives away from the gate. Although this goes some way to solving the problem if electrically powered gates problems arise when the gate borders directly a public road it is not usually possible to position the actuator in the public road. A further type of device is disclosed in the applicants prior PCT publication WO 2007/119062 which discloses a mechanical device that uses gravity to close the gate. 
     The present invention seeks to provide an improved mechanism for opening and closing a barrier. 
     BRIEF SUMMARY OF THE INVENTION 
     According to a first aspect of the present invention there is provided an automatic gate opening device comprising:
         a gate drive axis for driving a gate, movable between a gate closed position and a gate open position;   a treadle;   rechargeable energy storage means; energy conversion means to convert stored energy into rotational movement of the drive axis in a gate opening direction; and   energy conversion means to convert stored energy into rotational movement of the drive axis in a gate closing;   wherein the treadle is configured such that, with the drive axis in its gate open position, a single actuation of said treadle recharges the energy storage means with sufficient energy to move the drive axis from its gate open position to its gate closed position and back to its gate open position.       

     Preferably the rechargeable energy storage means comprises a pair of springs. More preferably the springs are spiral springs, preferably of the constant force type, which are charged in their extended state. 
     By the present invention the gate is already primed with sufficient energy to open the gate when it is in its closed position. When the gate is opened and a vehicle drives through, the weight of the vehicle passing over the treadle recharges the energy storage means so that they contain sufficient energy to close the gate and then to open it again when needed. By the provision of constant force type springs a constant closing force is applied. This ensures that, even if the shutting of the gate is halted, e.g. by a strong gust of wind, once the cause of the problem is removed, the gate will continue to be closed with the same force. 
     Preferably the rechargeable energy storage means further comprises a releasable latch mechanism for retaining each spring in its charged state. In this way the energy can be released to open or close the gate by means of a simple latch opening device that may be automated. 
     In a preferred arrangement the energy conversion means to convert stored energy into rotational movement of the drive axis in a gate closing direction comprises a first drive rod connected to the energy storage means and movable between an extended and a retracted position; and the energy conversion means to convert stored energy into rotational movement of the drive axis in a gate opening direction comprises a second drive rod connected to the energy storage means and movable between an extended and a retracted position. Preferably the drive rods are supported on linear bearings. 
     More preferably the automatic gate opening device further comprises: a first quadrant attached to the first drive rod, the first quadrant mounted on the same axis as the gate drive axis and rotateable relative thereto; a second quadrant attached to the second drive rod, the second quadrant mounted on the same axis as the gate drive axis and rotateable relative thereto; and a drive arm attached to the gate drive axis and extending therefrom, the drive arm having a drive pin attached to its distal end substantially perpendicular thereto, the drive pin configures such as to be driven by the first quadrant in one direction and by the second quadrant in the other direction. Preferably the first and second quadrant each comprise two arms extending from an axis of rotation substantially perpendicular one another and the arms may be at least partially connected by a web. 
     Preferably each quadrant has a driven arm and a driving arm, the driven arms connected to the drive rods at substantially the same distance from the gate drive axis. In this manner the same distance of movement of the drive rod will result in the same angular rotation of the gate drive axis. 
     In a preferred arrangement the driving arm of the second quadrant extends radially beyond the drive pin and is located such that when rotated it comes into contact with the drive pin, thereby rotating the drive arm, and preferably the driving arm of the first quadrant does not extend radially as far as the drive pin such that the drive arm of the first quadrant can freely rotate about the gate drive axis inside the arc of the drive pin, the driving arm of the first quadrant further comprising a ratchet mechanism extending from its distal end so as to allow the drive arm of the first quadrant to rotate freely inside the drive pin in a first direction and to engage with the drive pin when the first quadrant is rotated in a second direction. Preferably the automatic gate opening device further comprises a ratchet release mechanism that is activated when the gate is substantially in its closed position so as to disengage the drive pin from the ratchet mechanism. 
     In this manner the gate drive axis can me manually freely rotated from its closed position to its open position without effecting the drive mechanism. 
     In a preferred arrangement at least the latch associated with the spring that opens the gate is remotely releasable. More preferably at least the latch associated with the spring that opens the gate is electrically driven and has associated therewith a small power source and the latch is activated to release the spring by a wireless controller. In this manner a driver of a vehicle can remotely activate the latch so as to enable the gate to open without needing to get out of their vehicle or to drive it over any specific object. 
     In a preferred arrangement the latch associated with the spring that closes the gate is also electrically driven and is activated to release the spring by a wireless controller. In this manner a driver of a vehicle can remotely activate the latch so as to enable the gate to close without needing to get out of their vehicle or to drive it over any specific object. In an alternative arrangement the latch activates automatically a predetermined time interval after the gate is opened or after the latch associated with the spring that opens the gate is released. In this manner the driver need not take a specific action to cause the gate to close, merely they can drive through and continue with their journey and the gate will close of its own accord after the time interval has passed. 
     In a preferred arrangement the treadle is located substantially under the gate when the gate is in its closed position. Accordingly the treadle may be operated by the passage of a vehicle thereover as it passes through the gate. 
     In a preferred arrangement the treadle comprises a pivot lever therein for converting a lesser vertical movement into a greater horizontal movement. Preferably the horizontal movement displaces the springs into their charged position. 
     In one arrangement the automatic gate opening device further comprising a gate latch for, in use, maintaining the gate in its closed position, the gate latch being manually and remotely activated. In this manner the ratchet mechanism is be released as the gate enters its closed position and the gate will still be maintained in its closed position by virtue of the gate latch. If the gate is required to be manually operated the latch can be manually released and the gate opened. If the gate is to be automatically operated the gate latch will be automatically released, either shortly before, concurrent with, or shortly after the opening spring latch is released 
     According to a second aspect of the invention there is provided a gate comprising an automatic gate opening device according to any preceding claim and a gate barrier having a free end and a pivoted end mounted thereon, the pivoted end being concentric with the gate drive axis. 
     Preferably the gate further comprises a gate post wherein the gate latch secures the free end of the gate to the gate post. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
       The invention will now be described, by way of example only, with reference to the drawings in which: 
         FIG. 1  shows a side view of a gate opening device in accordance with the invention; 
         FIG. 2  shows a side view of the energy storage and conversion means of  FIG. 1 ; 
         FIG. 3  shows a top view of the energy storage and conversion means of  FIG. 1 ; 
         FIG. 4  shows an enlarged detail of  FIG. 3 ; 
         FIGS. 5 and 6  show side views of the treadle in its raised and depressed position respectively; 
         FIGS. 7 and 8  show end views of the treadle in its depressed and raised position respectively; 
         FIGS. 9 to 13  shows the sequence of operation of the gate opening device; and 
         FIG. 14  shows a plan view of a gate of the invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring to  FIGS. 1 to 4  an automatic gate opening device  100  is shown comprising a treadle section  102  and a working section  104 . The treadle  102  section is described in more detail with reference to  FIGS. 4 to 6  below. The working section  104  has two drive rods  106   108  that protrude through a bulkhead  110  separating the working section  104  from the treadle section  102 . The drive rods  106 ,  108  are supported in linear bearings  112 ,  114  in a manner in which they can pass therethrough in linear motion. The drive rods are parallel to one another and separated in the horizontal and vertical directions 
     Energy storage means in the form of spiral springs  116 ,  118  are attached to a chassis  120  such that they can extend therefrom. The free end of each spiral springs is attached to the one of the drive rods  106 ,  108  such that the drive rods are biased by the springs towards a portion in which a greater proportion of the drive rods passes through the bulkhead. Each drive rod  106 ,  108  has a shock absorber  122 ,  124  attached thereto such that movement of the drive rods is dampened. The drive rods  106 ,  108  each have a groove  126 ,  128  therein into which a releasable latch  228 ,  230  can engage. 
     The drive rods  106 ,  108  are each connected to a quadrant  130 ,  132  via link arms  152   154 . Each of the quadrants  130 ,  132  are arranged for rotation about gate drive axis  134 . The gate drive axis is rotatable about its central axis in the bearing  136 . A drive arm  138  is attached to the gate drive axis  134  such that it rotates with it. The drive arm is located in a horizontal plane interposed the two quadrants and has a drive pin  140  extending vertically upwards and downwards therefrom. Each quadrant has a driver arm  142 ,  144  which in use engages with the drive pin  140  and a driven arm  146   148  that is connected to a drive rod  106   108  by link arm  152   154 . The driver arm and driven arm of each quadrant are joined to one another by a web. The driver arms  142 ,  144  of the two quadrants are of different lengths, one of which  142  extends from the gate drive axis  134  at least as far as the drive pin  140  such that movement of that driver arm acts directly on the drive pin  140 . The other driver arm  144  is extends from the gate drive axis  134  to a distance short of the drive pin  140  such that it can rotate freely inside it. Driver arm  144  has a ratchet mechanism  150  attached to the distal end thereof and extending therefrom such that when the driver arm  144  is rotated in one direction the ratchet mechanism  150  engages with the drive pin  140 , and when rotated in the opposite direction the ratchet mechanism  150  allows the driver arm  144  to rotate freely past the drive pin  140 . The way in which the mechanism operates is described more fully with reference to  FIGS. 8 to 12 . 
     Referring now to  FIGS. 5 to 8  the treadle unit  102  is shown in more detail. The treadle comprises an outer casing  202  and two activation surfaces  204   206  extending diagonally upwards therefrom. The activation surfaces  204   206  are pivotally attached to the casing  202  at their lower edges and are pivotally connected to one another in sliding arrangement at their upper edges such that when a mass is applied to the surfaces they can collapse from their extended position shown in  FIG. 7  to their depressed position shown in  FIG. 8 . A treadle drive arm  208  joins the activation surfaces to a pivot lever  210  which is in turn joined to a drive plate  212  via a pivot link  214 , the drive plate acting on the ends of the drive rods  106   108  which extend into the treadle unit  102 . Drive plate  212  is supported on two horizontal guides  216   218  to locate in as it slides between its two positions. 
     The pivot lever  210  is substantially triangular in shape and is dimensioned such that the movement of the treadle drive arm is amplified into a greater movement of the drive rods  106   108 . The treadle drive arm  208  is connected at either end via a universal joint  220 . Spiral springs (omitted for clarity) are disposed within the casing  202  and are connected to the drive plate such that they are extended when the treadle surfaces  204   206  are depressed therefore providing a resilient force urging the drive plate  212  and the treadle surfaces  204   206  back to their original position. 
     Referring now to  FIGS. 9 to 14  the sequence of operation of the device is shown. In  FIG. 9  the system is uncharged and the gate  222  is in the open position. A vehicle can then pass through the gate  222 , depressing the treadle as it does so. As the treadle is depressed, the drive rods  106   108  are extended to and the associated springs are stretched. Quadrant  132  is rotated in a clockwise manner and quadrant  130  is rotated in a counter-clockwise direction and the components finish in the position shown in  FIG. 10 . As it does so the ratchet passes by the drive pin such that driver arm  144  is in a position in which counter-clockwise rotation thereof will cause the ratchet to engage with the drive pin thereby rotating the drive arm and gate drive axis. A latch mechanism engages with the drive rods to maintain them in position when the vehicle releases the treadle allowing the treadle to return to its extended position. 
     When remotely activated by a user (for example via a wireless controller  232 ) the latch  230  retaining drive rod  106 , is released. Spring  116  (see  FIG. 3 ) then acts on drive rod  108  causing it to move towards an unextended position. As the drive rod is attached to the driver arm  148  via link arm  152  the quadrant  132  also rotates moving the drive arm  138  and the gate drive axis  134  in a counter-clockwise direction as depicted in  FIG. 11 . At the end of its travel the quadrant has moved through approximately 90 degrees to the position shown in  FIG. 11 , thereby shutting the gate. As the drive arm  144  reaches the end of its travel the pawl of the ratchet  150  comes into contact with a disengager (omitted for clarity) which causes it to rotate about its pivot point and release the drive pin  140  therefrom, the components finishing in the position shown in  FIG. 12 . In this position a secondary latch mechanism  226  will activate on a gate post  224  to retain the gate  222  in its closed position. The secondary latch mechanism  226  is preferably a remotely activated latch and has a manual override such that pedestrians or drivers without a remote activator can still pass through the gate by opening it manually. 
     When the gate  222  is required to be opened, the operator, via a remote activation means, activates the secondary latch  226  to release the gate from its position and also activates the latch, retaining drive rod  108 , in its extended position. The two latches may be interlinked such that a single remote signal de activates both latches. Spring  118  (see  FIG. 3 ) then acts on drive rod  108  causing it to move towards an unextended position. As the drive rod  108  is attached to the driven arm  146  via link arm  154  the quadrant  130  also rotates. The driver arm  142  acts on the drive pin  140  and moves the drive arm  138 , and the gate drive axis  134 , in a clockwise direction from a closed position towards an open position, as depicted in  FIG. 13 . 
     When the gate  222  is fully open the components are returned to the positions shown in  FIG. 9 . 
     It will be appreciated by the person skilled in the art that the use of directional terms, such as clockwise and counter-clockwise apply only to the embodiment depicted in the drawing to illustrate rotational movement in opposite directions and that the actual direction of movement could vary depending on the orientation of the gate and components relative one another and such alternative arrangements are encompassed by the scope of the invention.