Abstract:
A rodent bait station for retention of sachet bait, which is a malleable bait retained within a porous bag or package having sidewardly protruding flaps. The bait station may be a molded plastic structure with a lid hinged to a base. Base walls define a bait compartment sized to receive the sachet bait such that the flaps overlie the opposed bait compartment base walls. The lid has downwardly protruding bait compartment walls which overlie the base bait compartment walls. Undulating or jagged teeth are formed on the lid and base bait compartment walls. When the lid is closed on the base, the teeth projecting from the lid cooperate with the teeth protruding from the base, thereby engaging and clamping a retained sachet bait package flaps to thus retain the package with the bait station even after a rodent has broken into the package to access the poison contained therein.

Description:
CROSS REFERENCES TO RELATED APPLICATIONS 
       [0001]    Not applicable. 
       STATEMENT AS TO RIGHTS TO INVENTIONS MADE UNDER FEDERALLY SPONSORED RESEARCH AND DEVELOPMENT 
       [0002]    Not applicable. 
       BACKGROUND OF THE INVENTION 
       [0003]    The present invention relates to rodent bait stations in general, and to bait stations configured to retain sachet baits in particular. 
         [0004]    Rodents such as mice and rats are a significant hazard to human populations, and can spread disease and consume or spoil stored commodities. Palatable rodent baits laced with appropriate rodenticide can effectively control these pests. However, in order to restrict access to the poisonous rodenticide compounds, the baits are restrained within rodent bait stations—containers which allow the admission of the targeted rodent species, but which can provide physical obstacles to access to the contained bait by children or non-targeted animals such as pets or livestock. 
         [0005]    Soft baits are various compounds which have a soft consistency, and may omit the usual paraffin composition which allows a bait to take on a definite structure. To restrain the bait within a bait station, the soft bait is contained within a paper package or bag which is easily tearable and which is permeable allowing the escape of aromas, permiting the targeted rodents to readily identify the palatable contents. Conventional soft bait has dynamic viscosity of 1×10 8  cP, i.e., a putty-like consistency. Dynamic viscosity in the SI derived unit is measured in grams/(cm·sec) or poise, more commonly expressed, particularly in ASTM standards, as centipoise (cP). Where peanut butter is about 250,000 cP and window putty is 1×10 8  cP, at room temperature i.e., 20° C. 
         [0006]    Conventionally, the soft bait and its surrounding bag are held within a bait station by piercing the bait and bag with a spike or narrow-diameter rod which is fixed within the bait station. The bag keeps the contained bait supported on the rod until accessed by the rodent. Even should the bag contents lose its consistency due to the influence of the elevated temperatures which can be encountered in temperate climates, the bag retains the contents mounted to the rod. Another known station uses an array of multiple molded plastic pins extending from the bait station base and lid to engage the bag. 
         [0007]    However, when rodents encounter the bait bag, they will gnaw through the paper packaging to access the bait within. If the torn paper bag is not well retained on the central spike or array of pins, it may readily be removed from the bait station either in pieces or as a whole. These scraps of paper can then be strewn around the vicinity of the station in an unsightly or unsanitary fashion. What is needed is an arrangement which takes advantage of the benefits of packaged soft bait while limiting the escape of paper components from a bait-containing station. 
       SUMMARY OF THE INVENTION 
       [0008]    Sachet bait packages are retained within a rodent bait station of this invention by providing gripping teeth on mating lid and base walls of a bait compartment within the bait station. The bait station may be a molded plastic structure with a lid hinged to a base. The base walls define a bait compartment sized to receive the sachet bait such that the flaps overlie the opposed bait compartment base walls. The lid has downwardly protruding bait compartment walls which overlie the base bait compartment walls. Undulating or jagged teeth are formed on the lid and base bait compartment walls, which work together to retain the package. When the lid is closed on the base, the teeth projecting from the lid cooperate with the teeth protruding from the base, thereby engaging, gripping and clamping a retained sachet bait package flaps to thus retain the package within the bait station even after a rodent has broken into the package to access the bait contained therein. The lid and base teeth may interdigitate, or they may extend alongside one another to grip the material of the bait package. 
         [0009]    It is an object of the present invention to retain a sachet bait package within a rodent bait station by gripping the paper of the which the package is formed. 
         [0010]    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 
         [0011]      FIG. 1  is an isometric view of the bait station of this invention with the lid shown in phantom view. 
           [0012]      FIG. 2  is a top perspective view, partially broken away, of the bait station of  FIG. 2 . 
           [0013]      FIG. 3  is a side cross-sectional view of the bait station of  FIG. 2 , taken along section line  3 - 3 . 
           [0014]      FIG. 4  is an isometric view, partially broken away in section of an alternative embodiment rodent bait station of this invention having two bait dispensing compartments. 
           [0015]      FIG. 5  is a fragmentary cross-sectional view of the bait station of  FIG. 3 , taken along section line  5 - 5 . 
           [0016]      FIG. 6  is a fragmentary cross-sectional view of an alternative embodiment bait station of this invention in which the bait compartment base wall and lid wall are positioned to overlap in the closed configuration. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0017]    Referring more particularly to  FIGS. 1-6  wherein like numbers refer to similar parts, a rodent bait station  20  is shown in  FIGS. 1-3  and  5 . The bait station  20  may be injection molded of plastic, and has a base  22  with a lid  24  which is connected to a base rear wall  26  by a hinge  28 . The lid  24  has a latch structure, not shown, which engages with two deflectable prongs  30  extending upwardly from the base  22 . The prongs and the latch structure define a lock  32  which holds the lid  24  closed on the base. 
         [0018]    The base  22  rear wall  26  extends upwardly from a bottom wall  34 . A curved base front wall  36  also extends upwardly from the bottom wall. Two rodent access openings  38  are defined between the base rear wall  26  and the base front wall  36 . A bait compartment  40  is defined within the base by upwardly extending base bait compartment walls  42  and downwardly extending lid bait compartment walls  44 . The base bait compartment walls include a front wall  46  which has a rodent inlet  48  defined therein through which a rodent can gain access to the bait compartment  40 . The rodent access openings  38  provide access to a rodent corridor  49  which is defined between the base front wall  36  and the bait compartment  40 . The corridor  49  provides communication for the rodents between the rodent access openings  38  and the bait compartment rodent inlet  48 . The bait compartment is dimensioned to accept a conventional sachet bait assembly  54 , sometimes called a place pack. Alternatively, the compartment can receive a conventional rodent bait block. 
         [0019]    The sachet bait assembly  54  contains a quantity of soft bait which is formed into an integral unit  50 . The soft bait  50  may be of any composition which is palatable and attractive to rodents, and in most cases will contain a suitable rodenticide, although in some cases where tracking only is the objective, the bait may omit a rodenticide and contain other elements which allow the targeted rodents to be tracked as they follow their habitual paths within the infested area. 
         [0020]    The sachet bait assembly  54  has a sealed exterior envelope or package  56  which is formed of an aroma-permeable sheet material, such as the porous paper from which teabags are commonly fabricated, for example, paper made of abacá fibers, i.e., a very thin and long fiber hemp, which may be augmented with a minor portion of synthetic fibers. The envelope sheet material is such as to allow rodents to detect the bait contained therein. The sheet material is an insignificant obstacle to the targeted rodent species rending it and accessing the interior bait  50 . The package  56  may be formed of a single sheet folded over and sealed with an adhesive seal, at a transverse seam  57 . The ends of the tube thus formed are then adhesive sealed and crimped to define opposed end seal regions or flaps  58 , as shown in  FIG. 1 . The bait unit may be a ring about 1⅛ inches in diameter, and the package measured along the transverse seam may be about 3⅛ inches long, with each end flap  58  being about ½ inch wide. It is the end flap regions which are configured for gripping by the bait station and retention therein. 
         [0021]    The base bait compartment front wall  46  is connected to two rearwardly extending side walls  60  which extend to the base rear wall  26 . The bait compartment base side walls  60  are positioned parallel to one another and spaced apart to define the bait compartment. The lid  24  bait compartment walls  44  include a front wall  61  which connects two lid bait compartment side walls  62 . The bait compartment lid side walls  62  are positioned parallel to one another and spaced apart to overlie the two bait compartment base walls  60 . 
         [0022]    As shown in  FIG. 2 , the sachet bait assembly  54  is disposed within the interior of the bait compartment such that the bait component  50  is retained within the bait compartment so the rodent bait is presented to only target species. As best shown in  FIG. 3 , each of the bait compartment side walls is terminated by a plurality of projections or teeth  64  which extend up to an upper perimeter  66 . The teeth  64  may define a saw tooth arrangement where each tooth extends rearwardly about 3.7 times the height it extends above the trough  68  between teeth. The teeth  64  are formed integrally with the base bait compartment side walls. The lid bait compartment side walls  62  are also provided with a plurality of projections or teeth  70 . The lid teeth  70  cooperate with the base teeth  64  to engage a sachet bait package which is disposed within the bait compartment. The sachet bait package  56  rests within the bait compartment with flaps  58  of the bait package extending outside of the bait compartment to extend over the base teeth  64 . When the lid is closed on the base, the opposed flaps of the bait container are gripped between the lid teeth and the base teeth, to thereby clamp the two opposed flaps of the bait package within the bait compartment. In the arrangement of  FIGS. 1-3  and  5  the lid teeth interdigitate with the base teeth, so each upper tooth is received within a trough defined between two base teeth. 
         [0023]    To achieve the desired result of holding the bait component  50  within the bait compartment  40  before it is consumed by the targeted rodent, and to retain as much of the paper package  56  as possible within the bait station  20  while the bait is being consumed, the edges/ends of the package must be fixed to the bait station and more particularly to the walls forming the bait compartment  40 . This means it is desirable to grip the edges of the package as firmly as possible and still allow the sachet bait assembly/package  54 ,  56  to be installed and its remains to be removed when rebating the station  20 . The clamping force made available by the opposed lid  24  and base  22  is limited or nonexistent in a typical bait station because of the flexibility of the materials used in constructing the bait station  20  e.g. plastic or sheet metal. If the opposed structures are lengthened so as to engage with more force when the lid is closed, it can become difficult to close the bait station. However, by utilizing the principle embodied in the so-called capstan or belt friction equation, aka Eytelwein&#39;s formula, (T load =T hold e μφ  where φ is the wrap angle and μ is the coefficient of friction) which relates the hold-force to the load-force if a flexible line is wound around a cylinder, it is possible to greatly increase the frictional engagement of the paper package  56  with the structures of the bait station  20 . In particular, this is accomplished by interdigitating the teeth which causes an end flap  58  of the package  56  to wrap around the interdigitating teeth as shown in  FIG. 5 , or over the teeth when the teeth are offset, such that they do not directly engage, as shown in  FIG. 6 . The benefit of using this principle is that the paper package  56  is held securely at many points without creating high local stresses which would facilitate the paper package being torn. The final result is that the package is securely held before it is a chewed on by the rodent. The large peripheral edge of the paper package is held even as the integrity of the paper package is destroyed. This results in much of the paper package being retained within the bait station and the bait compartment even while the bait is consumed. 
         [0024]    As shown in  FIG. 4 , an alternative embodiment bait station  72  has two bait compartments  74 . The bait station  72  has a molded plastic base  76  with a joined plastic lid  78 . The base  76  has a bottom wall  80  with an upwardly extending rear wall  82  and a single rodent corridor  84  which extends from a first rodent access opening  86  to a second rodent access opening  88 . Each of the two bait compartments  74  is defined by a base bait compartment side wall  90  which extends upwardly from the base bottom wall  80  and which extends parallel to the base rear wall  82 . The two bait compartments  74  are accessible by the rodent from an antechamber  92  which opens off the rodent corridor  84 . Each bait compartment  74  has a front wall  94  with a rodent inlet  96  which adjoins the antechamber  92 . The lid  78  closes over the base, and has two downwardly extending bait chamber lid side walls  98  which overlie the base lid side walls  90 . The base bait compartment side walls  90  have upwardly extending teeth  100  and the lid bait compartment side walls have downwardly extending teeth  102  which interdigitate with one another when the lid is closed on the base. Each bait compartment  74  can receive a sachet bait therein, or, alternatively, a conventional rodent bait block. For additional securement, the bait compartments may have an upwardly projecting pin or rod  106  which pierces the sachet bait assembly  54 . The sachet bait assemblies  54  when received within the bait compartments  74  are positioned such that one of the package  56  flaps  58  protrudes out over the base teeth  100  on the side walls  90 . When the lid is closed on the base, such as on a hinge (not shown), the interdigitating base and lid teeth  100 ,  102 , grip the paper of the package  56  and retain the package to the bait station, even once the contents of the package have been consumed by rodents. 
         [0025]    Another alternative embodiment bait station  108  is shown in  FIG. 6 . The bait station  108  has a lid  118  which fits on a base  120  to define an internal bait compartment  122  and is substantially identical to the bait station  20 , with the exception that the bait compartment lid side walls  110  have downwardly projecting teeth  112  which do not interdigitate with the upwardly projecting teeth  114  of the base bait compartment side walls  116 . Instead the lid bait compartment side walls  110  extend downwardly alongside the base bait compartment side walls  116 . This arrangement can offer a greater wrap angle of the package material with the teeth of the walls, and hence even greater frictional engagement of the bait package  56 . 
         [0026]    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.