Patent Publication Number: US-2016245238-A1

Title: Canister, and canister vent solenoid valve

Description:
TECHNICAL FIELD 
     The present invention relates to a structure for inserting into a canister a canister vent solenoid valve and an air pump to be employed in diagnosing a leak by using pressure variation in automobile piping, and also relates to the canister and the canister vent solenoid valve. 
     BACKGROUND ART 
     In a popular method of diagnosing a leak in an evaporated fuel processing piping system disposed in an automobile, the leak in the evaporated fuel processing piping system is diagnosed by monitoring pressure variations occurring when a pressure is applied to the inside of the evaporated fuel processing piping system with the evaporated fuel processing piping system hermetically sealed. Then, the methods of diagnosing the leak in the evaporated fuel processing piping system are classified by an engine negative pressure method, an air pump method, an EONV (Engine Off Natural Vacuum) method, and so on based on differences in the pressure applying method. 
     In the engine negative pressure method, the pressure in the evaporated fuel processing piping system is reduced by an engine negative pressure, whereupon a canister vent solenoid valve is closed in order to cut off communication between a canister and an atmosphere side, and subsequent pressure variations are monitored. Further, in the EONV method, the canister vent solenoid valve is closed in order to cut off communication between the canister and the atmosphere side, and pressure variations occurring in the evaporated fuel processing piping system due to natural heat dissipation are monitored by using engine exhaust heat. 
     When the engine negative pressure method and the EONV method are employed, the canister vent solenoid valve is connected to the canister via piping (see Patent Document 1, for example). Alternatively, the canister vent solenoid valve may be inserted into the canister to be integrated therewith. 
     With these methods, however, engine driving is premised, and therefore the methods are not suited to a hybrid vehicle such that the engine is stopped during travel in order to improve the fuel efficiency. 
     On the other hand, in the air pump method in which the engine driving is not premised, the canister vent solenoid valve is closed in order to cut off communication between the canister and the atmosphere side, whereupon a pressure is applied to the inside of the evaporated fuel processing piping system by using an air pump, and subsequent pressure variations is monitored. 
     When the air pump method is employed, a module formed by integrating the canister vent solenoid valve and the air pump may be inserted into the canister. 
     CITATION LIST 
     Patent Document 
     Patent Document 1: Japanese Patent Application Laid-Open No. 2007-205231 
     SUMMARY OF THE INVENTION 
     Problems to be Solved by the Invention 
     The module formed by integrating the canister vent solenoid valve and the air pump to be used in diagnosing the leak in the evaporated fuel processing piping system, as described above, has a larger overall size than a case having the canister vent solenoid valve and the air pump provided separately, and therefore, when the module is inserted into the canister, a position in which the module can be inserted is limited by a positional relationship between the module and a structure on the exterior of the canister. Accordingly, it is difficult to insert the module into the canister in a position where the combined overall size of the module and the canister does not increase, and as a result, it is difficult to install the system for diagnosing the leak in the evaporated fuel processing piping system in a saved space. 
     Further, when the air pump is connected additionally in order to perform the diagnosis by the air pump method using the canister into which the canister vent solenoid valve is inserted integrally, the air pump is connected to the canister via piping, but in this case, a nipple for connecting the piping to the canister must be provided on the canister. When the nipple is provided on the canister, a position in which the nipple can be disposed is limited. It is therefore difficult to dispose the nipple in a position where the combined overall size of the nipple and the canister does not increase, and as a result, it is difficult to install the system for diagnosing the leak in the evaporated fuel processing piping system in a saved space. 
     Furthermore, the canister is manufactured in accordance with the corresponding method such as the engine negative pressure method, the air pump method, the EONV method, and so on, and therefore, when the employed method is changed, it is required to change the canister for one corresponding to that method. Then, when the canister is changed, a great cost including a modification cost of a mold for the canister, a change cost in the piping adapted to the change of the canister, and so on is required. 
     The present invention has been made to solve the problems described above, and an object thereof is to make it possible to install the system for diagnosing the leak in the evaporated fuel processing piping system in a saved space. Another object is to make it possible to change the employed leak diagnosis method without changing the canister. 
     Means for Solving the Problems 
     An insertion structure according to the present invention includes a canister vent solenoid valve inserted into a first insertion port of a canister having a first chamber that stores evaporated fuel and communicates with an engine side and a fuel tank side and a second chamber that communicates with an atmosphere side and the first chamber, the first insertion port being provided in the second chamber, to maintain and cut off communication between the atmosphere side and the first chamber, and an air pump inserted into a second insertion port provided in the second chamber of the canister to pressurize or depressurize the first chamber. 
     Further, a canister according to the present invention includes a first chamber that stores evaporated fuel and communicates with an engine side and a fuel tank side, and a second chamber that communicates with an atmosphere side and the first chamber, and includes a first insertion port into which a canister vent solenoid valve is inserted and a second insertion port into which an air pump that pressurizes or depressurizes the first chamber is inserted. 
     Furthermore, a canister vent solenoid valve according to the present invention includes a main flow path inserted into an insertion port of a canister having a chamber that stores evaporated fuel and communicates with an engine side and a fuel tank side, the insertion port communicating with the chamber, to maintain and cut off communication between the atmosphere side and the chamber, a bypass flow path that connects the atmosphere side to the chamber while bypassing the main flow path, and a first nipple formed on the bypass flow path, and connected to an air pump that pressurizes or depressurizes the chamber. 
     EFFECT OF THE INVENTION 
     According to the present invention, the canister vent solenoid valve and the air pump can be inserted separately into the canister, and therefore a system for diagnosing a leak in an evaporated fuel processing piping system can be installed in a saved space. Moreover, a configuration corresponding to the employed leak diagnosis method can be achieved without changing the canister. 
     Further, according to the invention, the canister includes insertion ports into which the canister vent solenoid valve and the air pump can be inserted separately, and therefore the system for diagnosing the leak in the evaporated fuel processing piping system can be installed in a saved space. Moreover, the configuration corresponding to the employed leak diagnosis method can be achieved without changing the canister. 
     Furthermore, according to the invention, the nipple can be provided in the canister vent solenoid valve instead of the canister, and therefore the system for diagnosing the leak in the evaporated fuel processing piping system can be installed in a saved space. Moreover, the configuration corresponding to the employed leak diagnosis method can be achieved without changing the canister. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a view showing a configuration of an evaporated fuel processing system configured with a canister vent solenoid valve and an air pump insertion structure of a canister according to Embodiment 1 of the present invention; 
         FIG. 2  is a sectional view of the canister vent solenoid valve according to Embodiment 1 of the invention; 
         FIG. 3  is a sectional view of the air pump according to Embodiment 1 of the invention; 
         FIG. 4  is an external view of the canister according to Embodiment 1 of the invention; 
         FIG. 5  is a sectional view taken when the canister vent solenoid valve and the air pump are inserted with the canister vent solenoid valve and the air pump insertion structure of the canister according to Embodiment 1 of the invention; 
         FIG. 6  is an external view of the canister according to Embodiment 1 of the invention; 
         FIG. 7  is a side view and a sectional view taken when the canister vent solenoid valve and the air pump are inserted with the canister vent solenoid valve and the air pump insertion structure of the canister according to Embodiment 1 of the invention; 
         FIG. 8  is a side view and a sectional view taken when the canister vent solenoid valve and the air pump are inserted with the canister vent solenoid valve and the air pump insertion structure of the canister according to Embodiment 1 of the invention; 
         FIG. 9  is a sectional view showing a modified use of the canister vent solenoid valve and the air pump insertion structure of the canister according to Embodiment 1 of the invention; 
         FIG. 10  is an external view of a canister according to Embodiment 2 of the invention; 
         FIG. 11  is a view showing a partial configuration of an evaporated fuel processing system according to Embodiment 2 of the invention; and 
         FIG. 12  is a view showing a partial configuration of a modified example of the evaporated fuel processing system according to Embodiment 2 of the invention. 
     
    
    
     BEST MODE FOR CARRYING OUT THE INVENTION 
     Hereinafter, for illustrating the present invention in more detail, embodiments for carrying out the invention will be described according to the accompanying drawings. Identical or corresponding parts of the drawings are denoted by identical reference symbols, and a content already described with another drawing will be omitted where appropriate. 
     Embodiment 1 
     An evaporated fuel processing system shown in  FIG. 1  is constituted by a fuel tank  1 , a canister  2  that adsorbs and temporarily stores evaporated fuel generated in the fuel tank  1 , an intake manifold  3  that introduces the evaporated fuel collected by the canister  2  to an engine, and a purge solenoid valve  4  that controls the amount of evaporated fuel. An evaporated fuel processing piping system  5  indicated by a bold line in  FIG. 1  is a piping system on which a leak diagnosis is performed. The leak diagnosis is performed on the evaporated fuel processing piping system  5  by a leak diagnosis system including a canister vent solenoid valve  6  that is inserted into the canister  2  to open and shut off the canister  2  to and from an atmosphere side, an air pump  7  that is likewise inserted into the canister  2  to introduce the atmosphere into the canister  2  from the atmosphere side so that the interior of the evaporated fuel processing piping system  5  is pressurized, and a pressure sensor  8  that detects an internal pressure of the evaporated fuel processing piping system  5 . 
       FIG. 2  is a sectional view showing an example of the canister vent solenoid valve  6 . 
     The canister vent solenoid valve  6  is constituted by: a housing  101 ; a coil  102  wound within the housing  101 ; a core  104  that is excited when the coil  102  is biased via a terminal  103 ; a plunger  105  that is capable of reciprocating in accordance with a magnetic attraction force of the core  104 ; a rod  106  that is supported within the core  104  to move in conjunction with the plunger  105 ; a valve seat  110  having an opening portion  107  that communicates with the atmosphere side, an opening portion  108  that communicates with the interior side of a canister  2 , and an opening portion  109  that likewise communicates with the interior side of the canister  2 ; a valve body  111  fixed to a tip end of the rod  106 ; a spring  112  that always biases the valve body  111  in a direction for securing communication between the opening portions  107 ,  108  of the valve seat  110 ; and so on. 
     O-rings  113 ,  114  that seal gaps between the valve seat  110  and the canister  2  side are disposed on an outer peripheral surface of the valve seat  110 . 
     In the excitation, the valve body  111  moves against a biasing force of the spring  112  to block communication between the opening portions  107 ,  108  of the valve seat  110 .  FIG. 2  shows a condition in which the coil  102  is energized so that communication between the opening portions  107 ,  108  of the valve seat  110  is blocked, in other words, the canister vent solenoid valve  6  is closed. 
     Note that even when the valve is closed, the opening portions  107 ,  109  continue communicating with each other via a space in which the spring  112  is disposed. 
       FIG. 3  is a sectional view showing an example of the air pump  7 . 
     The air pump  7  includes a rotor  202  that rotates a plurality of vanes  201 , a first housing  203  that is made of resin and houses the vanes  201  and the rotor  202 , and a motor  205  that is fixed to the first housing  203  via a metal plate  204  sandwiched therebetween to rotationally drive the rotor  202 . Further, an intake port  206  that takes in the atmosphere from the atmosphere side is opened in the first housing  203 , and a first filter  207  is attached to the intake port  206 . 
     A bottom surface side of the first housing  203  is closed by a resin plate  208 , and a second housing  209  that is a resin-made cylindrical component is further attached to the resin plate  208 . The resin plate  208  and the second housing  209  are fastened to the metal plate  204  together with the first housing  203  with screws not shown in the drawing. 
     A fluid inlet  210  is opened in the resin plate  208 , and a fluid outlet  212  is opened in a partition wall  211  of the second housing  209 . Further, an outer side of the partition wall  211  serves as an exhaust port  213  that communicates with the canister  2 , and a second filter  214  is attached to the exhaust port  213 . Furthermore, an O-ring  215  is disposed on an outer peripheral surface of the second housing  209  in order to seal a gap between the second housing  209  and the canister  2  side. 
     A shaft end portion of a check valve  216  penetrates the partition wall  211  of the second housing  209  to be latched thereto. Further, an umbrella-shaped valve body of the check valve  216  is positioned within the exhaust port  213  to close the outlet  212  when pressure is applied thereto from the canister  2  side. 
     A cover  217  is provided around the motor  205 , and the cover  217  is fixed to the metal plate  204 . An O-ring  218  is disposed on an outer peripheral surface of the cover  217  to seal a gap between the cover  217  and the canister  2  side. The motor  205  is energized via a terminal  219 . 
     In the present invention, the canister vent solenoid valve  6  and air pump  7  thus constructed are inserted into the canister  2  separately. 
       FIG. 4  is an external view of the canister  2  in which the canister vent solenoid valve  6  and the air pump  7  are inserted such that respective axes thereof are parallel to each other.  FIG. 5  is a sectional view taken along a line A-A when the canister vent solenoid valve  6  and the air pump  7  are inserted into the canister  2  as shown in  FIG. 4 . Note that the respective axes of the canister vent solenoid valve  6  and the air pump  7  do not have to be strictly parallel to each other, and may be substantially parallel to each other. 
     The canister  2  includes a filter chamber  302  formed with an atmosphere port  301  to which piping that communicates with the atmosphere is connected, a second chamber  304  formed with an insertion port  303  for inserting the canister vent solenoid valve  6  thereinto, a third chamber  306  formed with an insertion port  305  for inserting the air pump  7  thereinto, and a first chamber  308  formed with a purge port  307  to which piping that communicates with the purge solenoid valve  4  is connected and an evaporated fuel port  318  to which piping that communicates with the fuel tank  1  is connected. 
     A filter  310  is supported within the filter chamber  302  by a support material  309 . 
     An adsorbent (activated carbon or the like)  311  that adsorbs evaporated fuel introduced from the fuel tank  1  through the evaporated fuel port  318  is sealed into the first chamber  308 , and the interior of the first chamber  308  is partitioned appropriately by a filter  312  so that the adsorbent  311  does not flow out of the first chamber  308 . 
     The filter chamber  302  and the second chamber  304  communicate via a connecting portion  313 , while the second chamber  304  and the third chamber  306  communicate via a connecting portion  314 . Further, the second chamber  304  and the first chamber  308  communicate via an opening portion  315  that faces the insertion port  303 , while the third chamber  306  and the first chamber  308  communicate via an opening portion  316  that faces the insertion port  305 . 
     The canister vent solenoid valve  6  is inserted into the insertion port  303  such that the O-ring  113  of the canister vent solenoid valve  6  is tightly fitted to an inner peripheral surface of the insertion port  303 , thereby sealing a gap therebetween. Further, at this time, the O-ring  114  of the canister vent solenoid valve  6  is tightly fitted to an inner peripheral surface of the opening portion  315 , thereby sealing a gap therebetween. 
     When the canister vent solenoid valve  6  is opened, the first chamber  308  is connected to the connecting portion  313  via the canister vent solenoid valve  6  such that the atmosphere air passing through the atmosphere port  301 , the filter  310 , and the connecting portion  313  can be introduced into the first chamber  308  through the opening portion  315  via the canister vent solenoid valve  6 . 
     Needless to mention, when the canister vent solenoid valve  6  is closed, no atmosphere passing through the connecting portion  313  flows into the first chamber  308  through the opening portion  315  via the canister vent solenoid valve  6 . As noted above, however, even when the valve is closed, the opening portions  107 ,  109  communicate with each other via the space in which the spring  112  is disposed, and therefore the atmosphere passing through the connecting portion  313  is led out to the connecting portion  314  via the canister vent solenoid valve  6 . 
     The air pump  7  is inserted into the insertion port  305  such that the O-ring  218  of the air pump  7  is tightly fitted to an inner peripheral surface of the insertion port  305 , thereby sealing the gap therebetween. Further, at this time, the O-ring  215  of the air pump  7  is tightly fitted to an inner peripheral surface of the opening portion  316 , thereby sealing the gap therebetween. 
     When operative, the air pump  7  sends out the atmosphere, that passes through the atmosphere port  301 , the filter  310 , and the connecting portion  313  to be led out to the connecting portion  314  via the canister vent solenoid valve  6 , to the first chamber  308 . When the pump is stopped, the atmosphere in the exhaust port  213  of the air pump  7  (in the first chamber  308 ) is prevented from flowing back to the third chamber  306  side by an action of the check valve  216 . 
     When a leak is diagnosed in the evaporated fuel processing piping system  5 , the canister vent solenoid valve  6  is closed to block a flow path between the opening portions  107 ,  108  by which the evaporated fuel processing piping system  5  is connected to the atmosphere side. Further, the purge solenoid valve  4  is closed to block a flow path by which the evaporated fuel processing piping system  5  is connected to an engine side. As a result, the evaporated fuel processing piping system  5  is hermetically sealed. 
     In this condition, the air pump  7  is operated to pressurize the interior of the evaporated fuel processing piping system  5 . When the internal pressure of the evaporated fuel processing piping system  5  falls to or below a predetermined threshold while the pressurized condition is maintained after stopping the air pump  7 , it is diagnosed that a leak occurs. Note that a flow of the atmosphere in which the pressurization is carried out by the air pump  7  during the leak diagnosis is denoted in the drawing as an atmospheric passage F. 
     When the canister vent solenoid valve  6  and the air pump  7  are inserted into the canister  2  separately in this manner, a choice of positions in which the insertion ports  303 ,  305  can be disposed is widened in comparison with a case in which an insertion port is provided to insert an integrated module of the canister vent solenoid valve and the air pump into the canister, as in the prior art. Therefore, the insertion ports  303 ,  305  can be provided in positions where the combined overall size of the canister vent solenoid valve  6 , the air pump  7  and the canister  2  does not increase, and as a result, the system for diagnosing the leak in the evaporated fuel processing piping system  5  can be installed in a saved space. 
     Further, the insertion ports  303 ,  305  are formed such that the canister vent solenoid valve  6  and the air pump  7  are in parallel with each other in the insertion directions, to be thus insertable into the canister  2  with the respective axes thereof being in parallel with each other. Because the canister  2  is manufactured with a mold, such insertion ports  303 ,  305  are adapted, so that after the manufacture of the canister  2 , it can be easily extracted from the mold. 
       FIG. 6  is an external view of the canister  2  in a case where the canister vent solenoid valve  6  and the air pump  7  are inserted therein such that the respective axes thereof are perpendicular to each other.  FIG. 7( a )  is a side view showing the canister  2  of  FIG. 6  from a B direction with the canister vent solenoid valve  6  and the air pump  7  inserted therein, and  FIG. 7( b )  is a sectional view taken along a line C-C shown in  FIGS. 6 and 7 ( a ). Note that the respective axes of the canister vent solenoid valve  6  and the air pump  7  do not have to be strictly perpendicular to each other, and may be substantially perpendicular to each other. 
     A latch portion  317  is provided in the interior of the canister  2 . The latch portion  317  functions as a stopper when the air pump  7  is inserted thereinto, and holds the inserted air pump  7 . Further, the O-ring  114  of the canister vent solenoid valve  6  and the O-ring  215  of the air pump  7  are tightly fitted to the latch portion  317 . 
     When the canister vent solenoid valve  6  and the air pump  7  are inserted thereinto such that the respective axes thereof are perpendicular to each other, as shown in  FIGS. 6 and 7 , a leak diagnosis is performed on the evaporated fuel processing piping system  5  using a similar flow to that described above. 
     More specifically, the canister vent solenoid valve  6  is closed to prevent the atmosphere that enters the filter chamber  302  through the atmosphere port  301  and then passes through the connecting portion  313  from flowing directly into the first chamber  308  via the canister vent solenoid valve  6 . Further, the purge solenoid valve  4  is closed to prevent the atmosphere in the first chamber  308 , which has been pressurized by the air pump  7 , from leaking to the engine side. As a result, the evaporated fuel processing piping system  5  is hermetically sealed. 
     As noted above, however, the opening portions  107 ,  109  of the canister vent solenoid valve  6  communicate with each other via the space in which the spring  112  is disposed, and therefore the atmosphere passing through the connecting portion  313  is led out to the connecting portion  314  via the canister vent solenoid valve  6 . 
     The air pump  7  sends out the atmosphere led out to the connecting portion  314  via the canister vent solenoid valve  6  to the first chamber  308 . 
     When the canister vent solenoid valve  6  and the air pump  7  are inserted into the canister  2  separately in this manner, the choice of positions in which the insertion ports  303 ,  305  can be disposed is widened in comparison with a case in which an insertion port is provided to insert an integrated module of the canister vent solenoid valve and the air pump into the canister, as in the prior art. Therefore, the insertion ports  303 ,  305  can be provided in positions where the combined overall size of the canister vent solenoid valve  6 , the air pump  7  and the canister  2  does not increase, and as a result, the system for diagnosing the leak in the evaporated fuel processing piping system  5  can be installed in a saved space. 
     Further, the insertion ports  303 ,  305  are formed such that the canister vent solenoid valve  6  and the air pump  7  are perpendicular to each other in the insertion directions, to be thus insertable into the canister  2  with the respective axes thereof being perpendicular to each other. Because the canister  2  is manufactured with the mold, such insertion ports  303 ,  305  are adapted, so that after the manufacture of the canister  2 , it can be easily extracted from the mold. 
     Furthermore, an insertion amount of the canister vent solenoid valve  6  is secured such that a projection plane obtained by projecting the air pump  7  inserted into the insertion hole  305  from the insertion direction thereof intersects an insertion side end portion of the canister vent solenoid valve  6  inserted into the insertion port  303 . In  FIG. 7( b ) , for example, the insertion side end portion of the canister vent solenoid valve  6  intersects the projection plane within a range D in the drawing. 
     When the canister vent solenoid valve  6  is inserted thereinto as deeply as possible in this manner, the portion of the canister vent solenoid valve  6  that projects to the exterior side of the canister  2  can be reduced, and as a result, the system for diagnosing the leak in the evaporated fuel processing piping system  5  can be installed in a further saved space. Note that an insertion amount of the air pump  7  may be secured such that a projection plane obtained by projecting the canister vent solenoid valve  6  inserted into the insertion hole  303  from the insertion direction thereof intersects an insertion side end portion of the air pump  7  inserted into the insertion port  305 . 
     Moreover, when the latch portion  317  is provided, an insertion operation can be performed easily by an appropriate insertion amount, and the appropriate insertion amount can be maintained easily under use. 
       FIG. 8 , similarly to  FIG. 7 , shows the canister vent solenoid valve  6  and the air pump  7  inserted into the canister  2  such that the respective axes thereof are perpendicular to each other.  FIG. 8( a )  is a side view seen from the B direction in  FIG. 6 , and  FIG. 8( b )  is a sectional view taken along the line C-C shown in  FIGS. 6 and 8 ( a ). Note that  FIG. 8( b )  shows a side view of the air pump  7 . 
     In the canister  2  shown in  FIG. 8 , the filter chamber  302  communicates with the second chamber  304  via a connecting portion  313   a , while the filter chamber  302  communicates with the third chamber  306  via a connecting portion  313   b . Further, the third chamber  306  communicates with the second chamber  304  via the opening portion  316  that faces the insertion port  305  of the air pump  7 , while the second chamber  304  communicates with the first chamber  308  via a connecting portion  313   c.    
     A leak diagnosis performed on the evaporated fuel processing piping system  5  when the canister vent solenoid valve  6  and the air pump  7  are inserted thereinto as shown in  FIG. 8  will now be described. 
     The canister vent solenoid valve  6  is closed to prevent the atmosphere, that enters the filter chamber  302  through the atmosphere port  301  and then passes through the connecting portion  313   a , from flowing into the first chamber  308  and the second chamber  304  via the canister vent solenoid valve  6 . Note that although the opening portions  107 ,  109  of the canister vent solenoid valve  6  communicate with each other via the space in which the spring  112  is disposed, the O-rings  113 ,  114  are tightly fitted to the insertion port  303 , and therefore no atmosphere flows into the first chamber  308  and the second chamber  304  through the opening portions  107 ,  109 . 
     Further, the purge solenoid valve  4  is closed to prevent the atmosphere in the first chamber  308 , which has been pressurized by the air pump  7 , from leaking to the engine side. As a result, the evaporated fuel processing piping system  5  is hermetically sealed. 
     In this condition, the air pump  7  sends out the atmosphere passing through the connecting portion  313   b  to the first chamber  308  and the second chamber  304 . 
     When the canister vent solenoid valve  6  and the air pump  7  are inserted thereinto in the manner shown in  FIG. 8 , the projection plane obtained by projecting the air pump  7  from the insertion direction thereof intersects a portion further toward the exterior side of the canister  2  than the insertion side end portion of the canister vent solenoid valve  6 , and therefore a similar advantageous effect to that obtained when the canister vent solenoid valve  6  and the air pump  7  are inserted thereinto as shown in  FIG. 7  is achieved. Furthermore, the structure of the canister  2  is simplified by exclusion of the latch portion  317 , and therefore there is also an advantageous effect such that the canister  2  can be manufactured more easily. 
     Note that according to the above description, the air pump  7  is operated when the leak diagnosis is performed on the evaporated fuel processing piping system  5 , but the air pump  7  may also be operated in order to feed the evaporated fuel stored in the canister  2  forcibly to the intake manifold  3  side. 
     Conventionally, the evaporated fuel stored in the canister  2  is fed to the intake manifold  3  side using negative pressure of the engine. In recent years, however, the number of vehicles such as a hybrid vehicle of which the engine is stopped during travel in order to improve the fuel efficiency has increased, which makes it difficult to use the negative pressure of the engine. 
     Hence, when the air pump  7  is operated during travel to pressurize the interior of the first chamber  308 , the evaporated fuel stored in the canister  2  can be fed to the intake manifold  3  side without the negative pressure of the engine. 
     Furthermore, in the above description, the operation when the pressurization is made in the leak diagnosis by the air pump  7  is represented, but instead, the leak diagnosis may be performed with depressurization by the air pump  7 . In this case, a check valve provided in a vertically opposite orientation to the check valve  216  shown in  FIG. 3  is used. Moreover, in this case, the direction of the atmospheric passage F during the leak diagnosis is reversed from that shown in  FIGS. 5 and 7 . 
     In the above description, the leak diagnosis is performed using the air pump method, but the EONV method may be used instead. In the EONV method, the canister vent solenoid valve  6  is closed in order to cut off the canister  2  from the atmosphere side, whereupon pressure variation due to natural heat dissipation can be monitored using engine exhaust heat. Accordingly, the air pump  7  can be omitted. Note that in this case, it is necessary to prevent gas from flowing through the insertion port  305 . 
       FIG. 9  shows the one in which the insertion port  305  into which the air pump  7  is inserted in  FIG. 7  is closed by a lid  9 . An O-ring  10  is provided on the lid  9  and fitted tightly to the inner peripheral surface of the insertion port  305  to seal the gap therebetween. In other words, by only disposing the lid  9 , the canister  2  applied to the air pump method can be applied to the EONV method. 
     Needless to mention, even when the leak diagnosis is performed using the EONV method, the air pump  7  may be provided to feed the evaporated fuel stored in the canister  2  forcibly to the intake manifold  3  side. 
     Thus, the canister  2  can be applied to both the air pump method and the EONV method. 
     According to Embodiment 1 of the present invention, as described above, when the canister vent solenoid valve  6  and the air pump  7  are inserted into the canister  2  separately, the choice of positions in which the insertion ports  303 ,  305  can be disposed is widened in comparison with a case in which an insertion port is provided to insert an integrated module of the canister vent solenoid valve and the air pump into the canister, as in the prior art. Therefore, the insertion ports  303 ,  305  can be provided in positions where the combined overall size of the canister vent solenoid valve  6 , the air pump  7  and the canister  2  does not increase, and as a result, the system for diagnosing the leak in the evaporated fuel processing piping system  5  can be installed in a saved space. 
     Further, when the lid  9  is only inserted into the insertion port  305  in place of the air pump  7  to close the insertion port  305 , the canister  2  applied to the air pump method can be applied to the EONV method. In other words, the common canister  2  can be used irrespective of the method. 
     Furthermore, the insertion direction of the canister vent solenoid valve  6  and the insertion direction of the air pump  7  are perpendicular to each other, and therefore after the manufacture of the canister  2 , it can be easily extracted from the mold. 
     Moreover, when it is configured that one of the canister vent solenoid valve  6  inserted into the insertion port  303  and the air pump  7  inserted into the insertion port  305  intersects the projection plane obtained by projecting the other in the insertion direction thereof, the portions of the canister vent solenoid valve  6  and the air pump  7  that project to the exterior side of the canister  2  can be reduced, and as a result, the system for diagnosing the leak in the evaporated fuel processing piping system  5  can be installed in a further saved space. 
     Further, the insertion direction of the canister vent solenoid valve  6  and the insertion direction of the air pump  7  are parallel to each other, and therefore after the manufacture of the canister  2 , it can be easily extracted from the mold. 
     Furthermore, the air pump  7  is capable of pressurizing the first chamber  308  to feed the stored evaporated fuel to the engine side, and therefore the evaporated fuel stored in the canister  2  can be fed to the intake manifold  3  side without the negative pressure of the engine. 
     Note that for the sake of easy-to-understand description, the second chamber  304  and the third chamber  306  are described as separate chambers in the first embodiment, but the second chamber  304  and the third chamber  306  constitute a second chamber in the claims. 
     Embodiment 2 
       FIG. 10  is an external view of a canister  2   a . The canister  2   a  corresponds to one removing the filter chamber  302  and the third chamber  306  from the canister  2 , and is equivalent to a conventional canister-vent-solenoid-valve integrated canister corresponding to the engine negative pressure method and the EONV method. The first chamber  308 , which is formed with the purge port  307  to which piping that communicates with the purge solenoid valve  4  is connected and the evaporated fuel port  318  to which piping that communicates with the fuel tank  1  is connected, communicates with the second chamber  304 , which is formed with the insertion port  303  for inserting the canister vent solenoid valve  6 , in the interior of the canister  2   a.    
       FIG. 11( a )  shows a configuration extending from the atmosphere side to the canister  2   a . An air cleaner is interposed in piping  401  that communicates with the atmosphere side, and piping  402  bifurcates downstream of the air cleaner.  FIG. 11( b )  is a partial sectional view showing the air pump  7  when extracted from  FIG. 11( a ) . The canister vent solenoid valve  6  includes a valve seat  110   a  having opening portions  115  to  117 . The opening portion  115 , which projects from the space in which the spring  112  is disposed, is inserted into the insertion port  303  of the canister  2   a  and fixed by a snap-fit  319 . The opening portion  117  communicates with the opening portion  115  via the space in which the spring  112  is disposed, and a nipple  118  is provided therein. The opening portion  116  opens or closes the opening portions  115 ,  117  in accordance with operations of the valve body  111 . A flow path extending from the opening portion  116  to the opening portion  115  serves as a main flow path, and a flow path that extends from the opening portion  117  to the opening portion  115  while bypassing the main flow path serves as a bypass flow path. 
     The opening portion  116  communicates with the atmosphere side via the piping  401 . Further, the nipple  118  communicates with the atmosphere side via the piping  402 , and the air pump  7  is provided midway in the piping  402 . 
     The air pump  7  includes a cover  220  on an outer side thereof, and the cover  220  includes an opening portion  221  connected to the piping  402  that communicates with the atmosphere side, and an opening portion  222  connected to the piping  402  that communicates with the nipple  118  side. 
     The opening portion  221  communicates with the intake port  206 , and the opening portion  222  communicates with the exhaust port  213 . 
     A leak diagnosis performed on the evaporated fuel processing piping system  5  in a case where the canister  2   a , the canister vent solenoid valve  6 , the air pump  7 , and the pieces of piping  401 ,  402  are assembled in the above manner will now be described. 
     When the canister vent solenoid valve  6  is closed, the main flow path is blocked, whereby the atmosphere that passes through the piping  401  and is taken in through the opening portion  116  is prevented from escaping to the opening portion  115 . Further, when the purge solenoid valve  4  is closed, the atmosphere in the first chamber  308 , which has been pressurized by the air pump  7 , is prevented from leaking to the engine side. As a result, the evaporated fuel processing piping system  5  is hermetically sealed. 
     In this condition, the air pump  7  sends out the atmosphere, introduced through the piping  402  and the opening portion  221  to the opening portion  222 , to the opening portion  222  and then to the piping  402  via the intake port  206  and the exhaust port  213 . The other end of the side of the piping  402  connected to the opening portion  222  is connected to the nipple  118 , and therefore the atmosphere sent out from the air pump  7  escapes to the opening portion  115  through the opening portion  117  provided with the nipple  118  via the space in which the spring  112  is disposed. This atmosphere sent out by the air pump  7  enters the canister  2   a  through the opening portion  115 . 
     In this manner, when the nipple  118  is provided in the canister vent solenoid valve  6 , which makes it possible to pressurize the interior of the canister  2   a  by the air pump  7 , the leak diagnosis can be performed in the air pump method without addition of any change on the canister  2   a  side. When it is intended that the interior of the canister  2   a  is pressurized by the air pump  7  provided midway in the piping  402  without providing the nipple  118  in the canister vent solenoid valve  6 , a separate opening portion must be provided in the canister  2   a , and the nipple must be disposed therein. As a result, a modification must be added to the canister  2   a . Further, when the nipple is provided in the canister  2   a , a position in which the nipple can be disposed is limited, and as a result, there occurs a possibility that the combined overall size of the nipple and the canister  2   a  increases. 
       FIG. 12( a )  shows a modified example of the configuration extending from the atmosphere side to the canister  2   a .  FIG. 12( b )  is a partial sectional view showing the air pump  7  when extracted from  FIG. 12( a ) . 
     The canister vent solenoid valve  6  shown in  FIG. 12( a )  differs from that of  FIG. 11( a )  in that an opening portion  119  that communicates with the opening portion  116  regardless of whether the canister vent solenoid valve  6  is open or closed is provided in the valve seat  110   a  on the main path, and that a nipple  120  is provided in the opening portion  119 . 
     Further, respective ends of piping  403  are connected to the nipples  118 ,  120 , and the air pump  7  is provided midway in the piping  403 . 
     All other configurations are identical to those shown in  FIG. 11 . 
     The leak diagnosis performed on the evaporated fuel processing piping system  5  in a case where the canister  2   a , the canister vent solenoid valve  6 , the air pump  7 , and the pieces of piping  401 ,  403  is assembled in the above manner will now be described. 
     When the canister vent solenoid valve  6  is closed, the atmosphere that passes through the piping  401  and is taken in through the opening portion  116  is prevented from escaping to the opening portion  115 . Further, when the purge solenoid valve  4  is closed, the atmosphere in the first chamber  308 , which has been pressurized by the air pump  7 , is prevented from leaking to the engine side. As a result, the evaporated fuel processing piping system  5  is hermetically sealed. 
     In this condition, the air pump  7  takes the atmosphere, that enters the opening portion  116  through the piping  401 , into the intake port  206  via the opening portion  119  provided with the nipple  120 , the piping  403 , and the opening portion  221 , and sends out this atmosphere to the opening portion  222  and then to the piping  403  via the exhaust port  213 . The other end of the side of the piping  403  connected to the opening portion  222  is connected to the nipple  118 , and therefore the atmosphere sent out to the piping  403  escapes to the opening portion  115  through the opening portion  117  provided with the nipple  118  via the space in which the spring  112  is disposed. Thus, the atmosphere sent out by the air pump  7  enters the canister  2   a  through the opening portion  115 . 
     In this manner, when the nipple  120  is provided in the canister vent solenoid valve  6  in addition to the nipple  118 , which makes it possible to pressurize the interior of the canister  2   a  by the air pump  7  which is provided midway in the piping  403  that connects the nipples  118 ,  120 , the piping  401  and piping  403  can be provided as completely independent piping. Therefore, in contrast to the configuration shown in  FIG. 11 , the piping  402  that bifurcates from the piping  401  is not required, and as a result, the piping structure can be simplified. 
     According to Embodiment 2 of the present invention, as described above, the configuration for performing the leak diagnosis can be realized by providing the nipple  118  in the opening portion  117  of the bypass flow path, and therefore the nipple  118  does not have to be provided in the canister  2   a . As a result, the system for diagnosing the leak in the evaporated fuel processing piping system  5  can be installed in a saved space. 
     Further, there is provided with the nipple  120  formed in the main flow path, and the nipple  118  is connected to the nipple  120  via the air pump  7 , so that communication with the atmosphere side is achieved via the main flow path, the nipples  118 ,  120  do not have to be provided in the canister  2   a . As a result, the system for diagnosing the leak in the evaporated fuel processing piping system  5  can be installed in a saved space, and the piping structure can be simplified. 
     Furthermore, there is no need to add a configuration for connecting the air pump  7  to the canister  2   a , and therefore the conventional canister-vent-solenoid-valve integrated canister  2   a  corresponding to the engine negative pressure method and the EONV method can be appropriated as the canister  2   a  for the air pump method. 
     Note that the embodiments may be combined freely within the scope of the present invention. Further, any of the constituent elements of the embodiments may be modified or omitted within the scope of the present invention. 
     INDUSTRIAL APPLICABILITY 
     As described above, with the insertion structure, canister, and canister vent solenoid valve according to the present invention, the system for diagnosing the leak in the evaporated fuel processing piping system can be installed in a saved space, and therefore the insertion structure, canister, and canister vent solenoid valve are suitable for use in a vehicle or the like having a small engine room. 
     DESCRIPTION OF REFERENCE NUMERALS and SIGNS 
     
         
           1  fuel tank 
           2 ,  2   a  canister 
           3  intake manifold 
           4  purge solenoid valve 
           5  evaporated fuel processing piping system 
           6  canister vent solenoid valve 
           7  air pump 
           8  pressure sensor 
           9  lid 
           10  O-ring 
           101  housing 
           102  coil 
           103  terminal 
           104  core 
           105  plunger 
           106  rod 
           107  to  109  opening portion 
           110 ,  110   a  valve seat 
           111  valve body 
           112  spring 
           113 ,  114  O-ring 
           115  to  117  opening portion 
           118  nipple 
           119  opening portion 
           120  nipple 
           201  vanes 
           202  rotor 
           203  first housing 
           204  metal plate 
           205  motor 
           206  intake port 
           207  first filter 
           208  resin plate 
           209  second housing 
           210  inlet 
           211  partition wall 
           212  outlet 
           213  exhaust port 
           214  second filter 
           215  O-ring 
           216  check valve 
           217  cover 
           218  O-ring 
           219  terminal 
           220  cover 
           221 ,  222  opening portion 
           301  atmosphere port 
           302  filter chamber 
           303  insertion port 
           304  second chamber 
           305  insertion port 
           306  third chamber 
           307  purge port 
           308  first chamber 
           309  support material 
           310  filter 
           311  adsorbent 
           312  filter 
           313 ,  313   a  to  313   c ,  314  connecting portion 
           315 ,  316  opening portion 
           317  latch portion 
           318  evaporated fuel port 
           319  snap-fit 
           401  to  403  piping