Abstract:
A rodent trap particularly adapted for rats has a plastic base to which a plastic upper jaw is pivotably mounted by a steel pin. A spring is engaged between the base and the upper jaw and urges the jaw to close upon the base. A trigger is pivotably mounted by the pin to ears which project upwardly from the base. A catch mechanism operates to restrain the upper jaw in a set position until the trigger is actuated. A plastic bait container has radially protruding flanges which permit it to be extended through a hole in the base beneath the trigger and secured to the base such that the bait within the container is accessible through another hole in the trigger. In one embodiment, the bait container is generally cylindrical and is twisted into place. The bait container is readily removed for replenishment.

Description:
CROSS REFERENCES TO RELATED APPLICATIONS 
     Not applicable 
     STATEMENTS AS TO RIGHTS TO INVENTIONS MADE UNDER FEDERALLY SPONSORED RESEARCH AND DEVELOPMENT 
     Not applicable 
     BACKGROUND OF THE INVENTION 
     The present invention relates to rodent traps in general, and to baited rodent traps in particular. 
     Rodents such as mice and rats are perennial pests, devouring food stores, spreading disease, soiling dwellings and storage and production facilities, and degrading fixtures and structures by gnawing, scratching, and nesting. Some rodent infestations may be dealt with by the distribution of poisoned bait. In other situations, where it is desirable to avoid the use of rodenticide, or where the retention of the targeted rodent is necessary, mechanical rodent traps may be employed. 
     Although a wide variety of mechanical rodent traps are effective for capture of mice, successful trapping of rats presents greater challenges. Not only are rats larger than mice, they are generally more cautious and more difficult to trap. 
     Because of the high level of striking force required to effectively dispatch a rat, traps will typically employ one or more substantial coil springs which act upon a sturdy bail. Conventional wooden-base traps use a heavy gauge steel wire bail retained in the set position by some type of clasp which is released when the trap trigger is depressed. Although providing effective striking forces, the open metal bails are subject to corrosion, provide minimal isolation between the operator arid the soiled portions of the activated trap, and are limited in their possible ergonomic configurations. Moreover, these wire bails are usually smooth and rounded, and thus a rodent may be able to extract a limb engaged beneath such a bail. 
     Rat traps with closed plastic bails are known. These traps advantageously place a barrier between the operator and the trapped rodent. In addition, when fabricated of plastic, a wide variety of shapes are possible, including those which facilitate convenient and low stress setting of the trap, and subsequent discharge of rodents caught in the trap. However, because the closed plastic bail covers the trigger when the trap is sprung, any bait to be placed in the trap must be positioned with the bail in a set or partially set condition—thereby presenting the potential of activating the spring-loaded bail during the process of loading the trap with bait. 
     What is needed is a rodent trap which can be conveniently loaded with bait without imperiling the operator. 
     SUMMARY OF THE INVENTION 
     The rodent trap of this invention has a plastic base to which a plastic upper jaw is pivotably mounted by a steel pin. A spring is engaged between the base and the upper jaw and urges the jaw to close upon the base. A trigger is pivotably mounted by the pin to ears which project upwardly from the base. A catch mechanism operates to restrain the upper jaw in a set position until the trigger is actuated. A plastic bait container has radially protruding flanges which permit it to be extended through a hole in the base beneath the trigger and secured to the base such that the bait within the container is accessible through another hole in the trigger. In one embodiment, the bait container is generally cylindrical and is twisted into place. The bait container is readily removed for replenishment. The base and the upper jaw are provided with sinusoidal interdigitating teeth which contribute to retaining the rodent in connection with the trap even if only a small portion of the rodent, such as a limb, is caught within the teeth. Moreover, the trap can be readily set by foot. 
     It is an object of the present invention to provide a mechanical rodent trap which can be safely baited while in the set position or in the sprung position. 
     It is another object of the present invention to provide a rodent trap which may be conveniently set by foot. 
     It is also an object of the present invention to provide a plastic rodent trap with adequate striking force to incapacitate a rat. 
     Further objects, features and advantages of the invention will be apparent from the following detailed description when taken in conjunction with the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is an exploded isometric view of the rodent trap of this invention. 
     FIG. 2 is a cross-sectional view of the trap of FIG. 1 shown in a sprung position. 
     FIG. 3 is an exploded cross-sectional view of the trap of FIG. 2 shown in a set position. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring more particularly to FIGS. 1-3, wherein like numbers refer to similar parts, a rodent trap  20  of this invention is shown in FIG.  1 . The trap has a plastic base  22  to which a plastic trigger  24  and upper jaw  26  are pivotably connected by a metal pin  28 . A catch mechanism  30  extends from the base  22  and engages with the trigger and the upper jaw  26  to retain the upper jaw  26  in a set position against the force of a spring  32  which tends to urge the upper jaw  26  into a sprung or trapping position. A bait container  33  is removably connected to the base  22 . The plastic parts may be injection molded of for example, ABS plastic or polystyrene. 
     The trap  20  is preferably large enough to accommodate rats. The base  22  may be about 5.6 inches long and three inches wide. The base  22  has a horizontal platform wall  34  with vertically extending side walls  36  and a front wall  38  and a rear wall  40 . The platform wall  34  is supported about 0.20 inches above the support surface on which the trap rests, and preferably has a pattern of reinforcing ribs on its underside, not shown. The front wall  38  has a series of undulating teeth  42  which continue along portions of the side walls  36 . The teeth  42  preferably interdigitate with downwardly facing teeth  44  which project from the upper jaw  26  in a manner similar to the teeth disclosed in U.S. Application Ser. No. 09/560,362, filed Apr. 28, 2000, entitled Rodent Trap with Entrapping Teeth, the disclosure of which is incorporated by reference herein. The interdigitating teeth act advantageously to grip a portion of a rodent, such as a limb, and prevent the rodent from escaping from the trap even if the descent of the upper jaw does not kill the rodent. 
     The spring  32  is a torsion wire spring formed of black oxide plated music wire, having a central U-shaped segment  46  which connects two coiled segments  48  of about nine coils each, and which each terminate in a J-shaped hook  50 . To assist in the assembly and positioning of the spring  32 , the base is provided with a central flange  52  which projects upwardly and frontwardly over the center arm  54  of the U-shaped segment  46 , and two shallow rectangular nubbins  56  which project on either side of the legs  58  of the U-shaped segment. The spring hooks  50  extend upwardly and engage with the side walls  60  of the upper jaw  26 . The point at which the spring hooks  50  engage the upper jaw side walls  60  will be selected in conjunction with the spring force of the spring  32  to obtain the desired kinetic energy on impact to strike the captured rodent, and the desired holding force once the trap is sprung. 
     Positioned between the legs  58  of the U-shaped segment  46  of the spring  32  and frontwardly of the center arm  54  are two upwardly projecting semicircular ears  62 . The trigger  24  is pivotably mounted to the base  22  between the ears  62  by the L-shaped steel pin  28  which extends through aligned vertical slots  64  in the base side walls  36  and slots  66  in the ears. The horizontal segment  68  of the pin  28  also pivotably connects the upper jaw  26  to the base  22 . The horizontal segment  68  of the pin  28  extends through the coiled segments  48  of the spring  32  and thereby fastens the spring to the base  22 . 
     The trigger  24  has a forward trigger plate  70  which is positioned above the base platform wall  34  and spaced inwardly about one-half inch from each toothed side wall  36 . The trigger  24  has an arm  72  which extends rearwardly from the trigger plate  70 . Two flanges  74  extend downwardly from the arm  72 , on either side of the ears  62 . The pin  28  extends through holes in the trigger arm flanges  74  thereby pivotably mounting the trigger to the base. A pair of stops  76  extends downwardly from the arm  72  rearward of the flanges  74 . The stops  76  restrict the rearward pivoting of the trigger  24  when they engage the platform wall  34  of the base  22 . 
     As shown in FIG. 3, a narrow cylindrical stud  78  extends downwardly from the underside of the trigger plate  70  frontwardly of the arm  72 . The stud  78  is received within an upwardly extending cup  80  which protrudes from the base  22 . A small coil spring  82  is positioned within the cup  80  to encircle the stud  78  and provide an upwardly acting force on the trigger plate which causes it to return to a nearly horizontal orientation when the upper jaw  26  is opened. 
     A slot  84  extends in the front-to-back direction along the trigger arm  72 , allowing portions of a plastic pawl  86  to extend therethrough. As shown in FIG. 3, the pawl  86  has a metal axle  88  which pivotably mounts the pawl between two rear ears  90  which adjoin the base rear wall  40 . The pawl  86  has an upper block  92  above a rearwardly opening groove  94 . When the upper jaw  26  is pressed back into the set position, as shown in FIG. 3, a molded horizontal rod  96  suspended from the top wall  98  of the upper jaw is engaged within the groove  94  beneath the block  92 . The action of the pressing the rod  96  into the groove  94  presents the pawl  86  such that the curved upper surface of the forward segment  100  of the pawl passes upwardly through the trigger arm slot  84 . The underside  102  of the pawl forward segment  100  is approximately parallel to the top surface of the carrier arm forward of the slot  84 . This arrangement holds the trigger plate  70  upward until it is depressed to actuate the trap, as shown in FIG.  2 . 
     The spring  82 , by holding the trigger plate in a near horizontal position, presents the trigger plate to be engaged by the pawl, whereas if the trigger plate were pivoted forwardly, the pawl would not engage the trigger plate at all. 
     As shown in FIG. 1, for convenience of manufacture and assembly, the rear ears  90  may be formed to permit the pawl  86  with sidewardly projecting rod  88  to be inserted from beneath the base  22 . Each of the rear ears  90  has a downwardly opening groove  110  which connects with a sidewardly extending cutaway  112  in the base platform  34 . A wedge shaped rod support  114  extends upwardly from the base platform  34  at the end of each cutaway  112  directly outside each rear ear groove  110 . The top of each rod support  114  has a semicircular depression  116  which opens towards the groove  110 , but which is closed on the opposite side. The pawl  86  with inserted rod  88  is installed by passing the forward segment  100  through an opening between the two rear ears  90  which joins the grooves  110 . The pawl forward segment  100  extends between the stops  76  of the trigger arm  72 . The rod  88  is urged upwardly within the grooves  110  such that the ends of the rod bear against the wedge shaped portions of the rod support  114  causing the plastic to resiliently deform outwardly until the rod  88  passes onto the semicircular depressions  116 , at which point the rod is retained for pivotal motion of the pawl  86 . 
     As shown in FIG. 1, the upper jaw side walls  60  are terminated by protruding cylindrical rings  118  through which the pin  28  extends. A conical surface  120  is preferably provided on the interior of one of the rings  118  on the side of the upper jaw  26  where the pin  28  enters. The conical surface  120  assists in centering the pin in the pin holes centered within each ring  118 , thereby facilitating rapid assembly of the trap  20 . This assembly is further aided by pairs of vertically extending parallel ribs  132  which project inwardly from each base side wall  36  on either side of the side wall slots  64 . The rings  118  are positioned by the ribs  132  to properly align the upper jaw  26  with respect to the base  22 . To provide for mold release, the interior surfaces of the side walls  36  are inclined outwardly with respect to the base platform wall  34 . However, for a better bearing between the upper jaw and the base, zero-draft sections  134  may be provided between the ribs  132  where the side walls engage the upper jaw rings  118 . 
     The top wall  60  of the upper jaw  26  has a forward section  122  which extends generally over the portions of the upper jaw having teeth  44 , an intermediate section  126  which is approximately parallel to the forward section and spaced below it, a foot section  124  which extends from the intermediate section at an angle of about 135 degrees, and a rear section  128  which projects from the foot section and terminates the upper jaw  26 . The foot section is preferably provided with a plurality of protruding ridges  130  to help with frictional engagement of the upper jaw  26  by an operator&#39;s foot. The rear section  128  may also have one or more ridges  130 . The foot section  124  and the rear section  128  are positioned rearwardly of the axis defined by the pin  28 , such that when the operator steps on the rear section and the foot section, the upper jaw pivots rearwardly until the trap is in a set position as shown in FIG.  2 . 
     The trap  20  may be set by clasping the rear of the trap in one hand and applying force to bring the upper jaw rod  96  into engagement with the pawl groove  94 . The configuration of the trap  20  is also, however, well-suited to hands-free setting of the trap. With the trap resting on a support surface, an operator may approach the trap and place a foot on the rear section  128  of the upper jaw top wall  98 . As foot pressure is applied, the upper jaw  26  pivots rearwardly bringing the foot section  128  into contact with the operator&#39;s foot, allowing broader contact between the foot and the upper jaw to apply force to overcome the spring  32  and set the trap. Foot operation has the advantage of allowing a trap to be set by an operator without the need to bend down, or allow the hands to come in contact with a possibly soiled trap. Moreover, persons suffering from reduced hand strength can still effectively set the trap  20 . 
     When the trap is sprung, as shown in FIG. 2, the trigger plate  70  is covered by the upper jaw. Thus, if it is desired to place bait downwardly on the trigger, it must be done when the upper jaw is pivoted rearwardly, such as shown in FIG.  3 . However, in order to pivot the upper jaw rearwardly it is necessary to impart energy to the spring  32  and thereby present the possibility that the upper jaw may return and strike the fingers of the operator attempting to place bait on the trigger. The trap  20  provides for baiting of the trap while it is in either a set or a sprung configuration by supplying the readily removable bait container  33 , as shown in FIG.  3 . 
     The bait container  33  is a generally cylindrical plastic element which has an upwardly opening bait cavity  136  into which an operator may place substances which are alluring to the targeted rodents, for example peanut butter. This bait  160  may attract rodents to depress the trigger. The cavity  136  extends to about ½ the depth of the container  33 . A grasping tab  138  extends downwardly beneath the cavity  136 . The grasping tab  138  is a vertical segment of plastic which can be engaged by an operator&#39;s fingers for rotating the bait container  33 . As best shown in FIG. 1, the bait container extends through a bait container opening  140  formed in the platform wall  34  of the base  22 , and through a circular trigger opening  142  formed in the trigger plate  70  above the bait container opening  140 . The bait within the bait container is thus presented to the targeted rodent in the central region of the trigger plate  70  to encourage the rodent to approach the trigger and depress it. The bait container  33  is removably secured to the base  22 . Many engagement mechanisms may be employed, including snap connections, bayonet connections, sliding connections, separable adhesive connections, etc., such engagement mechanisms providing a means for removably securing the bait container to the base. The mechanism illustrated employs a twisting motion to engage the bait container  33  to the base  22 . 
     The bait container has two horizontal lower flanges  144 , shown in FIG. 1, and two parallel upper flanges  146  which are spaced above the lower flanges  144  about the thickness of the base flanges  148  which project into the bait container opening  140 . The bait container upper flanges  146 , although they are positioned above the bait container lower flanges  144 , are not directly above the lower flanges. Thus the bait container  33  may be inserted into the bait container opening  140  so that the upper flanges  146  pass between the two base flanges  148 . By rotating the bait container  33 , the upper flanges  146  pass up narrow ramps  150  formed on each base flange  148  and then pass over the base flanges, until a thin protruding ridge  152  formed on the underside of each upper flange engages within a narrow groove  154  formed on the upper surface of each base flange. In this final position, the lower flanges  144  will be positioned beneath portions of the base flanges  148 . 
     The bait container  33  allows an operator to conveniently and rapidly load the trap  20  with bait without the need to first set the traps. Hence the bait container is movable with respect to the trigger between a first position wherein the bait container is secured to the base and is positioned adjacent the trigger, and a second position in which the bait cavity is spaced from the trigger at distance greater than the first distance and is accessible for loading with bait In addition, because of the modular self-contained nature of the bait containers, an operator may choose to preload a number of bait containers for replacing baits in the field in previously distributed traps, or the manufacturer may prepare sealed preloaded bait containers, with the seal being removable in the field to expose the contained bait prior to installation in a trap  20 . 
     The upper jaw  26  top wall  98  is preferably reinforced with downwardly extending ribs  156  in an “X” pattern. A strut  158 , shown in FIG. 2, extends downwardly from the ribs  156  where they intersect. The strut  158  is positioned to engage the trigger  24  rearwardly of the bait container opening  140  to depress the trigger when the trap is sprung. The strut depresses the trigger sufficiently to avoid the possibility of the pawl remaining engaged above the trigger arm when the trap is attempted to be reset. By so depressing the trigger when the trap is sprung, the strut  158  insures that the trap may be reset repeatedly. 
     It should be noted that the pawl, trigger slot, and related structure comprise a catch mechanism which allows the trap to be set and activated with the desired level of sensitivity. However, other rodent trap catch mechanisms may be employed with the removable bait container of this invention. Moreover, the removable bait container may be used in connection with traps employing over center hinge mechanisms, such as the one disclosed in U.S. patent application Ser. No. 09/560,362, filed Apr. 28, 2000. In addition, a number of structures have been disclosed which facilitate the manufacture and assembly of the trap parts, including structure adapted for injection molding, however, the parts may be made otherwise, or using processes other than injection molding. 
     It is understood that the invention is not limited to the particular construction and arrangement of parts herein illustrated and described, but embraces all such modified forms thereof as come within the scope of the following claims.