Patent Publication Number: US-7713337-B2

Title: Canister device

Description:
PRIORITY APPLICATION 
   This application claims priority from Japanese Patent Application Nos. 2006-344294, filed Dec. 21, 2006, the contents of which are hereby incorporated by reference in their entirety. 
   BACKGROUND OF INVENTION 
   1. Field of the Invention 
   The present invention relates to a canister device for temporarily absorbing fuel to supply fuel evaporated from a fuel tank to a suction passage. 
   2. Description of the Related Art 
   In the related art, a canister includes an atmosphere-side tubular portion and an opposite device-side tubular portion. Both tubular portions are in fluid communication with each other in the bottoms thereof to enhance processing capacity. Such a canister is disclosed in Japanese Patent Application No. 2005-16329. 
   In a gas/electric hybrid vehicle and an idle-stop vehicle (i.e. a vehicle that turns off the engine when the vehicle is stopped), there may be limited opportunity for vaporized fuel absorbed by the canister to be processed for its desorption. In such situations, enhancement of the vaporized fuel absorption performance of the canister is beneficial to avoid releasing vaporized fuel into the atmosphere. 
   SUMMARY OF THE INVENTION 
   In accordance with embodiments of the present invention, a canister device is provided. The canister device includes a main canister, a sub-canister, and a hose. The main canister includes a charging port, a purging port, and a main canister-side connection port. The sub-canister is separated from the main canister and located on a side of the main canister, and includes a drain port opened to the atmosphere and disposed on the same side as the main canister-side connection port of the main canister and a sub-canister side connection port disposed on the opposite side from the drain port. The hose provides fluid communication between the main canister-side connection port and the sub-canister-side connection port. 
   In accordance with embodiments of the present invention, a canister device is provided. The canister device includes a main canister, a sub-canister. The main canister includes charging means for fluid communication with a fuel tank, purging means for fluid communication with an engine, and a main canister-side connection port. The sub-canister is separated from the main canister and located on a side of the main canister, and includes a drain port opened to the atmosphere and disposed on the same side as the main canister-side connection port of the main canister and a sub-canister side connection port disposed on the opposite side from the drain port. The canister device further includes connection means for providing fluid communication between the main canister-side connection port and the sub-canister-side connection port. 
   Other aspects and advantages of the invention will be apparent from the following description and the appended claims. 

   
     BRIEF DESCRIPTION OF DRAWINGS 
       FIG. 1A  is a plan view of a canister in accordance with an embodiment of the present invention. 
       FIG. 1B  is a front view of the canister shown in  FIG. 1A . 
       FIG. 1C  is a side view of the canister shown in  FIG. 1A . 
       FIG. 1D  is a cross-sectional view taken along line D-D of  FIG. 1A . 
       FIG. 2  is a schematic of the canister of  FIG. 1A  in use with a vehicle in accordance with an embodiment of the present invention. 
   

   DETAILED DESCRIPTION 
   In  FIGS. 1A-1D , a canister in accordance with an embodiment of the present invention is shown. When the canister is assembled into a vehicle, the upper directions in  FIGS. 1B ,  1 C and  1 D are each coincident with the upper direction of the vehicle. The upper direction of the vehicle is shown in the figures. 
   The canister  1  shown in  FIGS. 1A-1D  includes a main canister  10  and a sub-canister  20  interconnected by a hose  30 . In the embodiment, the sub-canister  20  is used in addition to the main canister  10 . The additional capacity provided by the sub-canister  20  may, for example, be useful for hybrid vehicles or idle-stop vehicles, which generally need greater canister capacity than vehicles that do not turn off their engines during use. 
   When a capacity-increased canister exclusively used for hybrid vehicles is designed for use in place of the canister developed for normal engines, the cost can increase as a result of the specialized design and lower production quantities. To avoid this, the embodiment shown in  FIGS. 1A-1D  may use a sub-canister in addition to the same main canister as that in the normal engine. 
   The main canister  10  includes a first body  11  and a second body  12 . The main canister  10  is a so-called U-turn canister having a communication path interconnecting the bottoms  5  of the first body  11  and the second body  12 , through which the vaporized fuel flows. The first body  11  and the second body  12  contain vaporized fuel absorbing material of, for example, activated carbon. As shown in  FIG. 1D , the centers of the first body  11  and the second body  12  are substantially aligned. 
   As shown in  FIG. 1A , a charging pipe  111  and a purging pipe  112  protrude from the side of the first body  11 , which is opposite to the bottom  5  side thereof. An opening of the charging pipe  111  is a charging port  111   a . An opening of the purging pipe  112  is a purging port  112   a , A connection pipe  121  protrudes from the side of the second body  12 , which includes the charging port  111   a  and the purging port  112   a  (opposite to the bottom  5 ). An opening part of the connection pipe  121  is a connection port. 
   The sub-canister  20 , as shown in  FIG. 1A , is arranged in parallel with the main canister  10 . The sub-canister  20  is provided with a connection pipe  21  and a drain pipe  22 . The connection pipe  21  may be located at the end of the sub-canister  20  that is opposite to the connection pipe  121  of the main canister  10 . An opening of the connection pipe  21  is a connection port. The drain pipe  22  protrudes from the side opposite to the connection pipe  21 . An opening of the drain pipe  22  is a drain port  22   a . The sub-canister  20  may contain an activated carbon shaped in a honeycomb. The honeycomb of activated carbon may extend from the connection pipe  21  to the drain port  22   a  to reduce pressure loss when air passes. 
   The connection pipe  121  of the main canister  10  is coupled to the connection pipe  21  of the sub-canister  20  by the hose  30 . The hose  30  is made of rubber, for example. When viewed from top in  FIG. 1A , the hose  30  takes a C-shape while extending by the sub-canister  20 . C-shaped arms  23   a  and  23   b  each opened at the top end may be integrally coupled to the side of the sub-canister  20 . The hose  30  is firmly held within the C-shaped arms  23   a  and  23   b . In  FIG. 1A , the C-shaped arm  23   a  is positioned at a point distanced from the connection pipe  21  by about ¼ of the entire length of the sub-canister  20 . The C-shaped arm  23   b  is positioned at a point distanced from the drain pipe  22  by about ¼ of the entire length of the sub-canister  20 . Those having ordinary skill in the art will appreciate that scope of the present invention is not limited by the manner in which the hose  30  is held in place relative to the sub-canister  20 . 
   In an installed position, the connection pipe  21  of the sub-canister  20 , as shown in  FIG. 1C , is higher than the connection pipe  121  of the main canister  10 . To connect the connection pipe  121  and the connection pipe  21 , which are thus positioned, the hose  30  is at almost the same height as the connection pipe  121  near its connection part to the connection pipe  121 , and then tilted to reach almost the same height as the connection pipe  21  near its connection part to the connection pipe  21 . The tilted portion of the hose  30  is located between the C-shaped arms  23   a  and  23   b  ( FIG. 1A ). The C-shaped arms  23   a  and  23   b  act as clamps to hold the hose  30  at a substantially fixed height. 
   In  FIG. 2 , a canister in accordance with an embodiment of the present invention is applied to a vehicle. As shown, the charging pipe  111  of the canister  1  is in fluid communication with a fuel tank  3  through a charging pipe  3   a . Vaporized fuel generated in the fuel tank  3  flows from the charging pipe  111  to the main canister  10  of the canister  1 , through the charging pipe  3   a , and is absorbed by the vaporized-fuel absorbing material. The vaporized fuel still left after passing through the main canister  10  flows through the hose  30  and is absorbed by the sub-canister  20 . 
   The purging pipe  112  is in fluid communication with a suction passage  2   a  of the engine  2  through a purging pipe  2   b . The drain pipe  22  is in fluid communication with an opened-to-atmosphere pipe  4 . To treat the fuel having been absorbed into the vaporized-fuel absorbing material, a suction negative pressure of the engine  2  is introduced into the canister  1 . Upon introduction of the negative pressure, the absorbed fuel is sucked into the engine  2  through the purging pipe  112  together with the air introduced through the opened-to-atmosphere pipe  4 , and combusted in the engine  2 . 
   The canister device in accordance with embodiments disclosed herein may provide one or more of the following advantages. 
   With reference to  FIG. 2 . the canister  1  is mounted to the vehicle by coupling the canister to the charging pipe  3   a , the purging pipe  2   b  and the opened-to-atmosphere pipe  4 , which are fixed to the vehicle body. In most cases, the canister  1  is located near the fuel tank  3 . In the case of the front engine vehicle, the canister is mounted on the rear side of the rear seat (the under part of the trunk room). Accordingly, it is required that the worker mounts the canister  1  to the vehicle from the underside of the vehicle. This makes it difficult for the worker to mount the canister. 
   It is noted that in the canister  1  of the embodiment, the charging pipe  111 , the purging pipe  112 , and the drain pipe  22  are located on the same side and parallel to one another. With this structural feature, when the worker mounts the canister  1  to the vehicle in the assembling plant or replaces it with a new one in a maintenance factory, it is easy for the worker to connect the charging pipe  3   a  to the charging pipe  111 , to connect the purging pipe  2   b  to the purging pipe  112 , and to connect the opened-to-atmosphere pipe  4  to the drain pipe  22 . 
   The canister of the embodiment is arranged such that the connection pipe  121  on the front side of the main canister  10  is coupled to the connection pipe  21  on the rear side of the sub-canister  20  by the hose  30 . Accordingly, the overall length of the hose  30  is long. The canister absorbs the vaporized fuel generated in the fuel tank, sucks air when a predetermined desorption condition holds, and feeds the fuel together with the air to the engine to combust it. When the fuel desorption is taken into consideration, the canister first desorbs the vaporized fuel in a place where the concentration of the vaporized fuel is high. Therefore, if the main canister  10  is located close to the sub-canister  20 , the following problem arises. 
   When the vaporized fuel is desorbed from the sub-canister  20 , the fuel desorption is affected by the main canister  10 , and the desorption is performed first in the main canister  10  having high absorption fuel concentration. In such a case, if the engine stops in a state that the vaporized fuel desorption from the canister is insufficient, the desorption amount of the vaporized fuel from the main canister  10  is large, but the desorption amount from the sub-canister  20  is not large enough. When in such a state, fuel evaporates from the fuel tank again and the amount of vaporized fuel reaches the absorption capacity of the main canister  10 , the fuel that is absorbed in the previous absorption is still left in the sub-canister  20 , and the absorption capacity of the sub-canister  20  is small. As a result, there is a risk that the vaporized fuel is released to the atmosphere. 
   To minimize or avoid the release of vaporized fuel, the canister  1  may be arranged such that the entire length of the hose  30  is selected to be long so as to connect the connection pipe  121  on the front side of the main canister  10  to the connection pipe  21  on the rear side of the sub-canister  20 . As a result, the distance between the main canister  10  and the sub-canister  20  is increased to thereby isolate the desorbing operation in the sub-canister  20  from the fuel having been absorbed to the main canister  10 . With such a structural arrangement, the vaporized fuel is easily desorbed from the sub-canister  20 . Even after the main canister  10  absorbs the fuel up to its full absorption capacity, the sub-canister  20  shows its fuel absorption ability satisfactorily, and the vaporized fuel is not released to the atmosphere. 
   Further, it is noted that in the embodiment, the connection pipe  21  of the sub-canister  20  is located at a position higher than the connection pipe  121  of the main canister  10 . Since the specific gravity of the vaporized fuel is greater than that of air, the vaporized fuel left after passing through the main canister  10  is hard to flow to the sub-canister  20  and tends to stay in the hose  30 . This results in enhancement of the vaporized fuel absorbing ability of the sub-canister  20 . 
   Further, since the connection pipe  21  of the sub-canister  20  is located at a position higher than the connection pipe  121  of the main canister  10 , the hose  30  has a tilted portion. The condensed fuel flows down along the tilted part and tends to stay in the hose  30 . 
   In the embodiment, the tilted portion of the hose  30  lies between the C-shaped arms  23   a  and  23   b , namely, the hose  30  has a length half of the entire length of the sub-canister  20 . In an alternative, the tilted portion of the hose  30  may be formed over the entire length of the sub-canister  20 . In this case, the condensed fuel is easy to flow down and the fuel is easily absorbed by the main canister  10 . If the tilted portion of the hose  30  is shortened and the hose  30  is bent at almost a right angle to be stepped, the air passage resistance increases. In this case, the flow of the vaporized fuel to the sub-canister  10  after passing through the main canister  10  is impeded. Thus, depending on the length of the tilted portion of the hose  30 , the vaporized fuel is hard to reach the sub-canister  20  or the vaporized fuel, after condensed, is easy to flow down to the main canister  10 . Accordingly, the tilted portion of the hose  30  may be selected according to the characteristics of the engine. In the canister  1  illustrated in  FIG. 1 , the two cases just mentioned are well balanced. 
   In the embodiment, the hose  30  is held with the C-shaped arms  23   a  and  23   b  each opened at the top end, which act as clamps. Accordingly, the hose  30  may be attached by merely fitting the hose  30  into those C-shaped arms to facilitate assembling work. In this respect, the assembling work is easy. When the C-shaped arms are provided on the lower part of the sub-canister  20 , there is a possibility that the hose  30  drops. In the embodiment, the C-shaped arms are provided on the side of the sub-canister  20 . Therefore, there is no possibility that the hose  30  drops. In the embodiment, with provision of the C-shaped arms, the mounting work of the hose  30  and the maintenance performance are both enhanced without any contradiction. 
   It is to be understood that the invention is not limited to the illustrated and described forms of the invention contained herein. It will be apparent to those skilled in the art that various alterations and modification may be made without departing from the scope of the invention, and the invention is not considered limited to what is shown in the drawing and described in the specification. Accordingly, the scope of the invention should be limited only by the attached claims.