Abstract:
A tubular resin contains small animal repelling chemical. And canister structure installed in an automobile comprises the above tubular resin on the inner wall of an air inlet port portion of a drain pipe. The canister structure absorbs evaporated fuel from a fuel tank by a absorbent in a main body of a canister and then supplies desorbed fuel from the adsorbent together with the air sucked from the drain pipe to an engine side. The tubular resin prevents entering of a small animal into the drain pipe and also building of its nest.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a vehicle canister structure and a chemical containing resin that can be installed in pipes of the canister structure. 
     2. Description of the Related Art 
     In canister structure in a prior art, fuel adsorbent such as active carbon is filled in inside of a main body of a canister. This main body of the canister is connected to a fuel tank and a suction pipe of an engine via a pipe respectively. 
     Evaporated fuel being generated in the fuel tank is adsorbed by the fuel adsorbent filled in the main body of the canister. In operating the engine, the adsorbed fuel is desorbed from the fuel adsorbent because of the negative pressure in the suction pipe of the engine, then supplied together with the air sucked via the drain pipe to the engine, and then burned in the engine. 
     Japanese Patent Application Publication H9-228904 published in 1997 discloses canister structure in which a separator for vapor-liquid separation is provided to the drain pipe. 
     SUMMARY OF THE INVENTION 
     If a volume of the main body of the canister is increased to improve the adsorption force of the evaporated fuel, a diameter of the drain pipe is also increased inevitably to some extent. Thus, the drain pipe has a structure into which the small animal enters easily. As such small animal, a chiracanthium has been known. Sometimes the chiracanthium enters into the drain pipe to lay eggs. If the chiracanthium builds its nest in the drain pipe, the pipe is blocked. 
     In order to.prevent the entering of such small animal, a mesh may be provided at the end of the air inlet port of the drain pipe. However, in that case, since an opening sectional area of the pipe is reduced, there are caused such problems that not only pressure loss in the pipe is increased but also there is a possibility that the mesh is blocked by the mud or the snow. 
     The overall drain pipe may be constructed by the resin material which is impregnated with the small animal repelling substance containing the repelling agent, the insecticide, etc. However, such drain pipe increases a cost and makes working operability worse. Workers must put on gloves not to directly touch the drain pipe in the assembling operation of the drain pipe. In addition, the worker must pay attention to the drain pipe not to touch the drain pipe in the operation in the neighborhood. 
     The present invention has been made in view of such problems, and it is an object of the present invention to prevent entering of a small animal into a drain pipe without making sacrifice of working operability. 
     In order to attain the above object, there is provided a tubular resin of the present invention comprising small animal repelling chemical for keeping the small animal off. 
     According to this feature, since this tubular resin can be provided on the inner wall of the inlet port of various pipes, entering of the small animal into the pipe can be prevented without disturbing an exhausting function or sucking function of the pipe. 
     Also, if this tubular resin is fitted in a drain pipe or an emergency pipe in canister structure installed in an automobile, entering of the small animal into the drain pipe or the emergency pipe can be prevented. 
     Also, canister structure installed in an automobile, of the present invention comprises a main body of a canister having an evaporated fuel adsorbent in its inside, a drain pipe connected to the main body of the canister for sucking an air from an outside, a supply pipe connected between the main body of the canister and an engine for supplying desorbed fuel from the absorbent together with a sucked air to an engine side. And the canister structure comprises a tubular resin provided onto an inner wall of an air inlet port portion of the drain pipe. The tubular resin contains small animal repelling chemical. 
     According to this feature of the above canister structure installed in the automobile, since the chemical containing resin in which the small animal repelling chemical is contained is fitted onto the inner wall of the air inlet port portion of the drain pipe, entering of the small animal can be prevented effectively at the inlet port of the drain pipe. Therefore, since the chemical containing resin is fitted on the inner wall of the air inlet port portion of the drain pipe, workers do not directly touch such chemical containing resin during the assembling operation of the drain pipe and its neighboring operations after the chemical containing resin has been fitted into the drain pipe, so that the presence of the chemical containing resin never makes worse the operability. Moreover, a cost can be reduced rather than the case where the overall drain pipe is formed by the chemical containing resin. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a sectional view showing a drain pipe portion of canister structure according to an embodiment of the present invention; 
     FIG. 2 is a perspective view showing a chemical containing resin according to the embodiment of the present invention; 
     FIG. 3 is a sectional view showing a structure around an exit of the drain pipe (an area  3  surrounded by a broken line in FIG. 1) in the canister structure of the present invention; 
     FIG. 4 is a sectional view showing a structure in which a chemical containing resin is fitted into the drain pipe (sectional shape taken along a line  4 — 4  in FIG. 1) in the canister structure of the present invention; 
     FIG. 5 is a sectional view showing a drain pipe portion in canister structure according to another embodiment of the present invention; and 
     FIG. 6 is a bottom view showing a rear portion of a vehicle body according to the embodiment of the present invention. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     An embodiment of the present invention will be explained with reference to the accompanying drawings hereinafter. 
     FIG. 6 is a bottom view showing a rear portion of a vehicle body according to an embodiment of the present invention. A main body  10  of a canister according to the present embodiment is arranged in the neighborhood of the side portion of a spare tire pan  14  on a rear floor  13  in the rear of a rear wheel  12 . A vapor pipe  16  connected to a fuel tank (not shown), a purge pipe  18  connected to an engine suction pipe, and a drain pipe  20  for introducing an air from the outside are connected to the main body  10  of the canister respectively. 
     A fuel adsorbent such as active carbon is filled into the main body  10  of the canister. Thus, an evaporated fuel generated in the fuel tank can be adsorbed by the fuel adsorbent in the main body  10  of the canister. During the operation of the engine, the fuel is desorbed from the fuel adsorbent because of the negative pressure in the engine suction pipe, then sucked into the engine together with an air being introduced via a drain pipe  20 , and then burned in the engine. In this manner, the evaporated fuel being adsorbed into the main body  10  of the canister can be utilized effectively. 
     FIG. 1 is a sectional view showing a neighborhood of an air inlet port portion  20 A of the drain pipe  20 . In this embodiment, a separator  20 B for absorbing and eliminating the moisture mixed in the air being sucked from the air inlet port portion  20 A is provided directly on the air inlet port portion  20 A. In this case, the separator  20 B must not always be provided. 
     In order to prevent the entering of the small animal such as a spider belonging to chiracanthium, a chemical containing resin  22  into which small animal repelling chemical is impregnated is fitted .onto an inner wall of the air inlet port portion  20 A of the drain pipe  20 . The chemical containing resin  22  is formed like a tubular shape to come into almost tight contact with an entire periphery of an inner wall of the chemical containing resin  22 . 
     The small animal repelling chemical is the chemical agent that has the activity for keeping off the small animal such as the insects containing the spider, etc. For example, the compound having the small animal repelling activity, the compound having the small animal killing activity, the compound having the taking-feed disturbing activity for the small animal, the compound having the growth control activity for the small animal, etc. are exemplified. 
     As the chemical having such small animal repelling property, there can be listed compound having the growth control activity for the small animal, etc. such as carbamate compound, pyrethlloyd compound, organic phosphorus compound, and their isomer, derivative, analogous substance, and others. 
     Also, as the resin constituting the chemical containing resin in which such small animal repelling chemical is contained, at least one of polyacetal resin and polyamide resin may be used. Further another compound which control to release the chemical may be added to the resin. As such compound, at least one compound selected from the group consisting of sulfonamide derivative, sulfonic ester derivative, carboxylic amide derivative, and carboxylic ester derivative, for example, is used. 
     In addition, in order to increase the controlled release much more and increase the mechanical properties, the fiber-like inorganic filler may be distributed. The above chemical containing resin  22  may be molded by the well known molding method such as the injection molding, etc. 
     FIG. 2 is a perspective view showing the chemical containing resin  22 . Elastic clipping portions  22 α each having a slit on its side surface are formed on the lower end of the chemical containing resin  22  to oppose to each other by 180 degree in the peripheral direction (only the clipping portion  22 α on this side is visible). Keys  22 β are formed respectively at the positions separated from the clipping portions  22 α by 90 degree in the peripheral direction. The clipping portions  22 α and the Keys  22 β constitute engaging portions. Latching holes  20 α into which the clipping portions  22  α are latched and key ways  20 β into which the keys  22 β are fitted are formed on a peripheral wall surface of the air inlet port portion  20 A of the drain pipe  20 . The latching holes  20 α and the key ways  20 β constitute engaged portions. Then, the chemical containing resin  22  can be positioned and fitted to the drain pipe  20  by engaging the clipping portions  22 α into the latching holes  20 α and fitting the keys  22 β into the key ways  20 β. 
     As shown in FIG. 3, a projection height of the keys  22 β in the outer diameter direction is set such that, when the keys  22 β are fitted into the key ways  20 β, they are not projected from the outer peripheral wall surface of the air inlet port portion  20 A of the drain pipe  20  in the outer diameter direction, rather they are retreated from the outer peripheral wall surface of the air inlet port portion  20 A by a dimension S 2 . 
     Similarly, as shown in FIG. 4, a projection height of the clipping portions  22 α in the outer diameter direction is set such that, when the clipping portions  22 α are engaged with the latching holes  20 α, they are not projected from the outer peripheral wall surface of the air inlet port portion  20 A of the drain pipe  20  in the outer diameter direction, rather they are retreated from the outer peripheral wall surface of the air inlet port portion  20 A by a dimension S 3 . 
     In addition, as shown in FIG. 1, when the chemical containing resin  22  is fitted into the drain pipe  20 , it is positioned at the position retreated from an inlet end  20   c  of the air inlet port portion  20 A by a dimension S 1 . 
     A height of the tubular chemical containing resin  22  may be set to any height. In this case, it has been known that an average length of chiracanthium as the main small animal, that enters into the drain pipe to build its nest, is a little less than about 8 mm (for example, about ⅓ inch is set forth on page 583, The Spider Book (published by John Henry Comstock, Comstock Publishing Associates, a division of CORNELL UNIVERSITY PRESS)). Therefore, if the height of the tubular chemical containing resin  22  is set to more than the average length of the chiracanthium, the chiracanthium can be prevented from striding the chemical containing resin  22  to enter into the inside of the drain pipe  20 . 
     In the drain pipe  20  constructed as above, since the chemical containing resin  22  which is impregnated with the small animal repelling chemical is fitted to the air inlet port portion  20 A and also an evaporated gas of the small animal repelling chemical is emitted to the around, it is possible to prevent the entering of the small animal such as the spider belonging to the chiracanthium. 
     Since the chemical containing resin  22  has a tubular shape and thus there is no need to provide a mesh therein, increase of a pressure loss in the pipe can be suppressed and also the drain pipe  20  is not easily blocked by the mud or the snow. 
     The chemical containing resin  22  is fitted onto the inner wall of the air inlet port portion  20 A of the drain pipe  20 . Therefore, if the parts are delivered after the chemical containing resin  22  has been fitted into the drain pipe  20 , workers do not directly touch the chemical containing resin  22  during the assembling operation of the drain pipe  20  and its neighboring operations, so that the presence of the chemical containing resin  22  does not make the working operability worse. Moreover, a cost can be reduced rather than the case where the overall drain pipe  20  is formed by the chemical containing resin. 
     As explained above, the chemical containing resin  22  can be fitted simply into the drain pipe  20  by engaging the clipping portions  22 α into the latching holes  20 α and fitting the keys  22 β into the key ways  20 β. Thus, a time required for the worker to handle the chemical containing resin  22  in the assembling operation can be shortened. 
     The clipping portions  22 α are arranged at the position not to project from the outer peripheral wall surface of the air inlet port portion  20 A of the drain pipe  20  in the outer diameter direction. Similarly, the keys  22 β are arranged at the position not project from the outer peripheral wall surface of the air inlet port portion  20 A of the drain pipe  20  in the outer diameter direction. As a result, workers cannot simply touch the chemical containing resin from the outside once the chemical containing resin  22  has been fitted into the drain pipe  20 , therefore their working operability does not become worse. 
     FIG. 5 is a sectional view showing a drain pipe portion in canister structure according to another embodiment of the present invention. An emergency pipe  20 C which is used as the drain pipe at the time of emergency is connected to the separator  20 B. As shown in FIG. 5, another tubular chemical containing resin  23  may be fitted into the inner wall of the air inlet port portion of the emergency pipe  20 C. In this case, like the chemical containing resin  22  being fitted into the air inlet port portion  20 A of the drain pipe  20 , the chemical containing resin  23  may be fitted by engaging the engaging portions provided onto the chemical containing resin  23  with the engaged portions provided on to the inner wall of the separator  20 B. Also, it is preferable that the chemical containing resin  23  should be positioned to be slightly retreated from the inlet end of the emergency pipe  20 C. In addition, it is preferable that a length of the chemical containing resin  23  should be set to more than 8 mm. 
     Besides, the chemical containing resin  22  may be formed integrally with the drain pipe  20  by the insert molding, i.e., by inserting into the air inlet port portion  20 A of the drain pipe  20 , etc. Similarly, the chemical containing resin  23  may be formed integrally with the inlet port portion of the emergency pipe  20 C. In this case, the above engaging portions can be omitted as the chemical containing resin  22 B is shown in FIG.  5 . 
     There is no necessity that sectional shapes of the tubular chemical containing resin  22 ,  23  should be formed as a complete annular shape. Thus, a C-shaped sectional shape which is formed by cutting away a part of the annular sectional shape may be employed. In addition, the tubular chemical containing resin  22 ,  23  may be formed by combining a plurality of members together to form the tubular shape. 
     The entire contents of Japanese Patent Application H11-245130 (filed Aug. 31, 1999) are incorporated herein by reference. 
     Although the invention has been described above by reference to certain embodiments of the invention, the invention is not limited to the embodiments described above. Modifications and variations of the embodiments described above will occur to those skilled in the art in light of the above teachings.