Abstract:
A toy water shooter includes a water chamber, a nozzle, a piston movable within the water chamber, a trigger for moving the piston against water in the water chamber for emission via the nozzle, an anchoring mechanism interacting with the trigger and the piston for preventing movement of the piston against water in the water chamber upon initial user-application of force to the trigger.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    The present invention relates to toy water shooters. More particularly, although not exclusively, the invention relates to a toy water pistol having a special pulse-firing feature. 
         [0002]    A typical inexpensive known toy water pistol  10  is depicted in  FIGS. 1 and 2 . The water pistol  10  includes a trigger  21  which when squeezed causes firing of a jet of water via nozzle  11 . The toy water pistol includes a cylinder  18  in which there is a reciprocal piston  20  connected to the trigger  21 . There is a water-tight seal  19  between the piston  20  and the internal wall of cylinder  18 . A piston return spring  14  biases the piston  20  and trigger  21  to an extended position. Water from an internal reservoir (not shown) is delivered though a water duct  15  to the cylinder  18  via an inlet valve  17  which is biased into a closed position by an inlet valve spring  16 . Water is delivered from the cylinder  18  to the nozzle  11  via an outlet valve  13  which is biased into a closed position by outlet valve spring  12 . Upon squeezing of trigger  21 , the piston  20  and seal  19  move to pressurize the water within the cylinder  18 . This pressure causes the outlet valve  13  to open against the force of spring  12 . When the trigger  21  is released, the piston return spring  14  biases the piston  20  and trigger  21  to the rest position whereupon outlet valve  13  closes and inlet valve  17  opens to allow the ingress of water via the water inlet duct  15  to replenish the cylinder  18  with water. 
         [0003]    The water-shooting distance will depend upon how rapidly the player squeezes the trigger. For a given nozzle exit hole size, rapid squeezing of the trigger will cause the water jet to fire further, however if the trigger is squeezed slowly, the lower pressure generated inside the cylinder  18  will result in a shorter firing distance. 
         [0004]    During squeezing of the trigger  21 , the piston  20  tends to pressurize water in the cylinder  18 , however as the water jet is concurrently emitted from the nozzle  11 , this tends to relieve pressure in the cylinder  18 . 
         [0005]    The size of the exit hole at nozzle  11  will affect the shooting distance. If the nozzle hole diameter is small, nozzle-induced back-pressure will be high and so the rate of pressure drop in the cylinder  18  will be low—resulting in the water pressure inside the cylinder  18  being maintained at a relatively high level. However the resultant thin water jet will have insufficient momentum to fire a long distance. 
         [0006]    On the other hand, if the exit hole at nozzle  11  is large, the water jet can be thicket and thereby have higher momentum to enable shooting over a long distance. A disadvantage however is that the nozzle-induced back-pressure in the cylinder  18  is low and so the rate of pressure drop in the cylinder  18  is high. As a result, a long firing distance cannot be achieved unless the player squeezes the trigger hard and fast. 
         [0007]    Usually the players of such known water pistols are young children who cannot squeeze the trigger rapidly or apply the necessary dexterity to fire a good long-distance water jet. 
       OBJECTS OF THE INVENTION 
       [0008]    It is an object of the present invention to overcome or substantially ameliorate at least one of the above disadvantages and/or more generally to provide an improved toy water shooter. 
       DISCLOSURE OF THE INVENTION 
       [0009]    There is disclosed herein a toy water shooter, comprising:
       a water chamber;   a nozzle;   a piston movable within the water chamber;   a trigger for moving the piston against water in the water chamber for emission via the nozzle; and   an anchoring mechanism interacting with the trigger and the piston for preventing movement of the piston against water in the water chamber upon initial user-application of force to the trigger.       
 
         [0015]    Preferably, the anchoring mechanism is adapted to prevent movement of the piston against water in the water chamber upon user-application of force to the trigger unless said force exceeds a predetermined threshold. 
         [0016]    Preferably, the anchoring mechanism comprises a release catch and a friction surface against which the release catch bears, the release catch adapted to deflect from the friction surface to enable movement of the piston upon said threshold being reached. 
         [0017]    Preferably, the release catch is attached pivotally to the trigger and wherein the friction surface comprises a ramp fixed with respect to the cylinder. 
         [0018]    The toy water shooter can further comprise a resilient spring attached to or formed integrally with the release catch for biasing the release catch into a configuration enabling the release catch to engage with the friction surface. 
         [0019]    Preferably, the trigger is movable with respect to the piston and the anchoring mechanism comprises a release catch which restrains the piston, the trigger interacting with the release catch when squeezed to release the piston. 
         [0020]    The toy water shooter can further comprise a spring extending between the piston and the trigger which compresses upon squeezing of the trigger prior to set interaction of the trigger with the release catch. 
         [0021]    The toy water shooter can further comprise a tube extending from the trigger and from within which the spring extends. 
         [0022]    Preferably, the release catch is attached pivotally to the toy water shooter, and the shooter can further comprise a resilient spring biasing the release catch into engagement with the piston. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0023]    Whilst a typical example of a prior art toy water pistol is depicted and described above with reference to  FIGS. 1 and 2 , preferred forms of the present invention will now be described by way of example with reference to  FIGS. 3 to 11  of the accompanying drawings, wherein: 
           [0024]      FIG. 3  is a schematic cross-sectional side elevation of the relevant internal components of a toy water shooter prior to squeezing of the trigger; 
           [0025]      FIG. 4  is a schematic cross-sectional side elevation of the same components depicted in  FIG. 3  during squeezing of the trigger; 
           [0026]      FIGS. 5 ,  6  and  7  are schematic side elevations of alternative anchoring mechanisms which might substitute for that shown in  FIGS. 3 and 4 ; 
           [0027]      FIG. 8  is a schematic cross-sectional side elevation of the relevant internal components of an alternative toy water shooter prior to squeezing of the trigger, 
           [0028]      FIG. 9  is a schematic cross-sectional side elevation of the parts shown in  FIG. 8  during squeezing of the trigger as the piston is just about to be released; 
           [0029]      FIG. 10  is a schematic cross-sectional side elevation of the parts shown in  FIGS. 8 and 9  after release of the piston; and 
           [0030]      FIG. 11  is a schematic cross-sectional side elevation of the parts shown in  FIGS. 8 to 11  during return of the trigger to its rest position after squeezing. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0031]      FIGS. 3 and 4  of the accompanying drawings depict schematically a preferred form of the present invention in which parts common with the prior art water pistol described above with reference to  FIG. 2  share the same reference numerals. 
         [0032]    New to the embodiment depicted in  FIGS. 3 and 4  is a anchoring mechanism which comprises a pivotal release catch  22  attached at pivot  24  to trigger  21 , a release catch return coil spring  25  and a ramp surface  23  upon the outer surface of cylinder  18  with which the release catch  22  interacts. 
         [0033]    The distal end of release catch  22  bears frictionally against the ramp surface  23  until user-force applied to trigger  21  is sufficient to overcome the frictional engagement between the release catch  22  and ramp surface  23  so that the release catch  22  snap-pivots against the force of return spring  25  and rides up over the ramp surface  23  as shown in  FIG. 4  whereupon the trigger  21  and piston  20  pulses rapidly against the piston return spring  14 . This quick pulse or “snap” action of the trigger  21  and piston  20  causes a rapid release of water from the nozzle  11  which would be sized in the “large” category described above with reference to the prior art. As a result, a relatively thick, high-inertia water jet impulse is emitted from the nozzle  11 . 
         [0034]    Upon release of trigger  21 , the piston return spring  14  acts in the same manner as described above to return the trigger  21  to its rest position. As the piston returns to its rest position, the distal end of release catch  22  returns by action of release catch return spring  25  to its rest position as depicted in  FIG. 3 . 
         [0035]    Alternative anchoring mechanisms are depicted in  FIGS. 5 ,  6  and  7 . The mechanism depicted in  FIG. 5  comprises a release catch  22 ′ much the same as that depicted in  FIGS. 3 and 4 , but instead of a coil spring  25 , there is a torsion spring  25 ′ fitted about the pivot  24 . The mechanism depicted in  FIG. 6  comprises a release catch  22 ″ having extending from it a resilient plastic spring finger  25 ″ which bears against the trigger  21  to bias the release catch  22 ″ into the rest position. The mechanism depicted in  FIG. 7  includes a release catch  22 ′″ having a mid-location spring seat and a compression coil spring  25 ′″ extending between the spring seat and an opposing spring seat on the trigger  21 . 
         [0036]    An alternative embodiment is depicted in  FIGS. 8 to 11 . This embodiment allows the trigger to be partially depressed prior to release of the piston. In this embodiment, the trigger  21  is movable with respect to the piston  20 . A compression coil spring  30  extends between the trigger  21  and the piston  20 . The spring  30  has one of its ends housed within a tube  26  that extends toward the piston from the back of trigger  21 . A rod  31  extends from the piston  20  toward the trigger  21 . The rod  31  extends into one end of the spring  30 . 
         [0037]    The piston  20  is provided with a latching flange  29  with which a release catch  22  interacts. The release catch  22  is attached pivotally at  24  to a fixed part  28  of the water pistol body. A light return spring  25  biases the release catch  22  into engagement with the latching flange  29  and retains the piston against forward movement as the trigger  21  is squeezed throughout part of its travel. 
         [0038]    The release catch  22  includes a ramp surface  32  against which tube  26  bears as the trigger  21  is squeezed as shown in  FIG. 9 . This interaction causes the release catch  22  to disengage from the latching flange  29  so that the energy of compressed spring  30  causes the piston  20  to release and move rapidly forward as shown in  FIG. 10  against the water within the cylinder  18 . It should be noted here that spring  30  has a higher spring force than return spring  14 . 
         [0039]    Upon release of the trigger, spring  30  extends and when fully extended the return spring  14  pushes the piston  20  back into position whereupon latching flange  28  engages with and is retained in place by catch  22 . 
         [0040]    It should be appreciated that modifications and alterations obvious to those skilled in the art are not be considered as beyond the scope of the present invention. For example in the embodiment of  FIGS. 3 to 7 , rather than attaching the release catch to the trigger, it could instead be attached to a fixed part within the toy gun body in which case the ramp surface would be provided on the trigger. Furthermore, instead of a pivotal release catch, the release catch could be integrally moulded with the trigger (or other fixed part within the toy gun body) and adapted to elastically deflect upon interaction with a ramp surface or other friction surface.