Patent Publication Number: US-10309326-B2

Title: Evaporated fuel processing apparatus for internal combustion engine

Description:
TECHNICAL FIELD 
     The present invention relates to an evaporated fuel processing apparatus for an internal combustion engine, which processes evaporated fuel in a fuel tank. 
     BACKGROUND OF THE INVENTION 
     In an internal combustion engine for an automobile where gasoline is used as fuel, a canister has been generally used as an evaporated fuel processing device in order to prevent evaporated fuel in a fuel tank from being discharged into the atmosphere. 
     However, in an internal combustion engine being difficult to generate negative pressure in an intake system like an internal combustion engine for an automobile using a supercharger, it is difficult to restore a canister by separating evaporated fuel adsorbed to the canister. Therefore, Patent Document 1 (JP 2007-332855 A) has disclosed an art: negative pressure is generated in an ejector by using supercharging pressure depending on a supercharger, and a purge in the canister is conducted by the negative pressure. 
     SUMMARY OF THE INVENTION 
     However, in the above-mentioned art that negative pressure is forcibly generated by the ejector using supercharging pressure, in case that the supercharging pressure is low, it is difficult to generate a sufficient negative pressure. Therefore, it is also difficult to secure a sufficient flow rate of purge gas. Especially, in an internal combustion engine subjected to down-sizing by using a supercharger, supercharging pressure is relatively low, and the flow rate of the purge gas tends to be insufficient due to influences of pressure loss in the ejector itself and pressure loss in a purge control valve which controls the flow rate of the purge gas. Furthermore, a general ejector has a mechanism to simply generate negative pressure with respect to a pressurizing force, so it is difficult in principal to sufficiently increase negative pressure to be generated. 
     Therefore, it is an object of the present invention to provide a new evaporated fuel processing apparatus for an internal combustion engine in which to sufficiently secure a flow rate of purge gas is possible regardless of operation conditions of an engine such as supercharging pressure, engine rotation speed, etc. 
     According to one aspect of the present invention, an evaporated fuel processing apparatus for an internal combustion engine comprising:
         a canister to which evaporated fuel in a fuel tank is adsorbed temporarily, and   a purge passage that supplies a purge gas including the evaporated fuel separated from the canister to an intake system of the internal combustion engine therethrough, is characterized in that the evaporated fuel processing apparatus further comprises:   a pulsation pump that supplies the purge gas to the intake system by using a pumping action responding to intake pulsation generated in a intake passage of the internal combustion engine,
           the pulsation pump comprising:
               a first chamber,   a communication passage communicating with the first chamber and the intake passage,   an elastic body constituting at least a part of a wall part sealing up the first chamber and being deformed depending on pressure fluctuation of the first chamber,   a second chamber formed so as to surround the elastic body,   a suction port provided with a check valve allowing inflow of gas into the second chamber, and   a discharge port provided with a check valve allowing outflow of gas from the second chamber.   
               
               

    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a configuration diagram simply illustrating an evaporated fuel processing apparatus for an internal combustion engine according to a first embodiment of the present invention. 
         FIG. 2  is a cross-section view of a pulsation pump according to the first embodiment. 
         FIG. 3  is an exploded perspective view of the pulsation pump according to the first embodiment. 
         FIG. 4  is a characteristic graph showing characteristics in a vicinity of an inlet port of an ejector according to the first embodiment. 
         FIG. 5  is a configuration diagram simply illustrating a gas flow in supercharging in an evaporated fuel processing apparatus for an internal combustion engine according to a second embodiment of the present invention. 
         FIG. 6  is a configuration diagram simply illustrating a gas flow in non-supercharging in the evaporated fuel processing apparatus for an internal combustion engine according to the second embodiment. 
         FIG. 7  is a characteristic graph showing flow rates of purge in a supercharging purge line and a pulsation purge line. 
         FIG. 8  is a configuration diagram simply illustrating an evaporated fuel processing apparatus for an internal combustion engine according to a third embodiment of the present invention. 
         FIG. 9  is a configuration diagram simply illustrating an evaporated fuel processing apparatus for an internal combustion engine according to a fourth embodiment of the present invention. 
         FIG. 10  is a configuration diagram simply illustrating an evaporated fuel processing apparatus for an internal combustion engine according to a fifth embodiment of the present invention. 
         FIG. 11  is a cross-section view of a pulsation pump according to a sixth embodiment of the present invention. 
         FIG. 12  is an exploded perspective view of the pulsation pump according to the sixth embodiment. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     According to the present invention, a pulsation pump using intake pulsation unavoidably generated during operation of an internal combustion engine is used. A purge gas is supplied to an intake system by a pumping action of the pulsation pump, so it becomes easy to secure a flow rate of the purge gas. 
     Therefore, even in an internal combustion engine such as an internal combustion engine provided with a turbo supercharger, which is difficult to secure the flow rate of the purge gas by using negative pressure because of not generating negative pressure in the intake system depending on an operation condition of the engine, it is possible to sufficiently secure the flow rate of the purge gas. 
     As one preferable aspect of the present invention, the purge passage is provided with an ejector to carry the purge gas, and thereby the evaporated fuel processing apparatus is configured so that air sucked from the suction port is supplied to the ejector from the discharge port as an operation gas. 
     As another preferable aspect of the present invention, the suction port is connected to the purge passage, and thereby the evaporated fuel processing apparatus is configured so that the purge gas discharged from the discharge port is supplied to the intake system. 
     Furthermore, the present invention is particularly effective for an internal combustion engine in which negative pressure is difficult to be generated in an intake system. Therefore, as another preferable aspect of the present invention, the evaporated fuel processing apparatus includes a compressor of a supercharger to pressurize an intake air supplied to the internal combustion engine. 
     Hereinafter, the present invention will be explained in detail, based on illustrated embodiments. 
       FIG. 1  is a configuration diagram simply illustrating an evaporated fuel processing apparatus for an internal combustion engine according to a first embodiment of the present invention. A combustion chamber  3  is defined on an upper part of a piston  2  of the internal combustion engine  1 . To the combustion chamber  3 , an intake passage  4  is connected through an intake valve  5 , and an exhaust passage  6  is connected through an exhaust valve  7 . Furthermore, a fuel injection valve  8  is provided in the combustion chamber  3 . In the exhaust passage  6 , a muffler  9  for silencing is provided. In the intake passage  4 , a throttle valve  11  adjusting the volume of intake air is provided. In an upstream side from the throttle valve  11 , an air cleaner  12  for removing extraneous materials and dust is provided. 
     A canister  14  is one of main parts of the evaporated fuel processing apparatus. As is well known, the canister  14  is can-shaped, wherein an inside of the canister  14  is filled with an adsorbing agent such as activated carbon. Furthermore, the canister  14  has a vapor passage  16  connected to a fuel tank  15 ; a purge passage  17  connected to the intake system; and an atmospheric passage  18  opening to the atmosphere. 
     At the time of stopping of the engine, evaporated fuel generated in the fuel tank  15  is introduced into the canister  14  through the vapor passage  16 , the evaporated fuel is adsorbed to the adsorbing agent, and clean air, in which the evaporated fuel has been removed, is discharged to the atmosphere through the atmospheric passage  18 . During the engine operation, first, the air is supplied to the inside of the canister  14  through the atmospheric passage  18  by a suction action due to negative pressure generated in the intake system. By a flow of the air, purge gas including the evaporated fuel separated from the adsorbing agent in the canister  14  is supplied to the intake system of the internal combustion engine through the purge passage  17 . Furthermore, the purge gas is sent to the combustion chamber  3  of the internal combustion engine  1  through the intake passage  4 , and it is burned and removed there. Thereby, the canister  14  is restored. 
     The purge passage  17  is a passage to return the purge gas to the intake system from the canister  14 . One end of the purge passage  17  is connected to the canister  14 , and the other end of the purge passage  17  is connected to the intake passage  4  which is located in a downstream side from the throttle valve  11 . The purge passage  17  is provided with a purge control valve  19 , which is an electromagnetic valve to adjust the flow rate of the purge gas. Operation of the purge control valve  19  is controlled by a control section (not shown), according to the operation condition of the engine as with the throttle valve  11 . 
     Furthermore, the purge passage  17  branches on its way and is connected to a negative pressure port  21  of an ejector  20  for carrying the purge gas. As is well known, the ejector  20  is provided with a throttled part  24  in the middle of the flow of operation gas from an inlet port  22  toward an outlet port  23 . The throttled part  24  is where a flow passage cross-sectional area is made small. Furthermore, the ejector  20  is configured as follows: the purge gas is sucked from the negative pressure port  21  by negative pressure generated when the operation gas passes through the throttled part  24 , and the purge gas is supplied and carried to the intake passage  4  through the outlet port  23 . 
     As a pump to supply a pressurized operation gas to the inlet port  22  of the ejector  20 , a pulsation pump  30  which is a main part of the present embodiment is used. 
     The pulsation pump  30  is what uses a pumping action responding to intake pulsation unavoidably generated in the intake passage  4  during operation of an internal combustion engine. Concretely, as shown in  FIG. 2  and  FIG. 3 , the pulsation pump  30  includes a case  31  being can-shaped. The case  31  is composed of a case body  32  and a cover  33 , which are made of synthetic resin. The case body  32  is cylinder-shaped, and its one end is opened. The cover  33  is connected to the open end of the case body  32  so as to seal up the open end. 
     An elastic body  34 , which is made of rubber, is contained in the inside of the case  31  so as to be surrounded. As to the elastic body  34 , its base end is opened, and its top end is sealed, that is, the elastic body is bottomed cylinder-shaped. A peripheral wall of the elastic body  34  is bent-formed into a bellows shape to be deformable in an axial direction (vertical direction in  FIG. 3 ). A flange part  35  extending outwardly in a radial direction is provided at the base end of the elastic body  34 . The flange part  35  is held between the cover  33  and a fitting part  36  of the case body  32 , and thereby the elastic body  34  is held in the case  31 . 
     An internal space of the elastic body  34  shut by the wall part of the elastic body  34  is defined as a first chamber  37 . Furthermore, a space between the elastic body  34  and the case  31  is defined as a second chamber  38 . That is, the internal space of the case  31  is air-tightly partitioned into the first chamber  37  and the second chamber  38 . 
     A cylindrical communication pipe  39  is formed in a center part of the cover  33 . The first chamber  37  and the intake passage  4  (More concretely, a position of the intake passage  4  which is in a downstream side from the air cleaner  12  and in an upstream side from the throttle valve  11 ) are communicated with each other by a communication passage  40  passing through the communication pipe  39 . 
     An upper wall part of the case body  32  is provided with a suction port  41  and a discharge port  42 . The suction port  41  is provided with a suction valve  45  as a check valve including a spring  44  which energizes a valve body  43  in a valve close direction (direction opposite to a flow of sucked gas; upward direction in  FIG. 2 ). The suction valve  45  allows inflow of gas into the second chamber  38  and prevents outflow of gas from the second chamber  38 . Similarly, the discharge port  42  is provided with a discharge valve  48  as a check valve including a spring  47  which energizes a valve body  46  in a valve close direction (direction opposite to a flow of discharged gas; obliquely downward direction in  FIG. 2 ). The discharge valve  48  allows outflow of gas from the second chamber  38  and prevents inflow of gas into the second chamber  38 . 
       FIG. 1  is referred again. In this first embodiment, the suction port  41  of the pulsation pump  30  is connected to the intake passage  4  (in more detail, a position of the intake passage  4  which is in a downstream side from the air cleaner  12  and in an upstream side from the throttle valve  11 ). Furthermore, the discharge port  42  is connected to the inlet port  22  of the ejector  20 . 
     According to the above structure, in an operation condition where negative pressure is generated in a downstream side from the throttle valve  11  during operation of the internal combustion engine, the purge gas is supplied to the intake passage  4  in the downstream side from the throttle valve  11  through the purge passage  17 , and the flow rate of the purge gas is controlled by the purge control valve  19 . 
     Furthermore, during operation of the internal combustion engine, intake pulsation is unavoidably generated in the intake passage  4 . The intake pulsation affects the first chamber  37  communicating with the intake passage  4  through the communication passage  40 . Therefore, by pressure fluctuation in the first chamber  37  due to the intake pulsation, the elastic body  34 , which defines the first chamber  37 , is elastically deformed in an axial direction. The elastic deformation of the elastic body  34  changes pressure of the second chamber  38  in the case  31 . Thereby, the gas flows into the second chamber  38  from the suction port  41  through the suction valve  45 , and the gas is discharged from the second chamber  38  into the discharge port  42  through the discharge valve  48 . The gas discharged into the discharge port  42  is introduced into the inlet port  22  of the ejector  20  and pressurized there. Such a pumping action of the pulsation pump  30  generates pressure difference between the inlet port  22  and the outlet port  23  in the ejector  20 . The pressure difference makes an operation gas flow from the inlet port  22  to the outlet port  23 , and a venturi effect when the operation gas passes through the throttled part  24  decreases pressure. Thereby, negative pressure is generated. By the negative pressure, the purge gas is sucked through the negative pressure port  21  and carried to the intake passage  4  through the outlet port  23 . In this way; the sequential passage of the purge gas, which branches from the purge passage  17  and continues to the intake passage  4  via the negative pressure port  21  and the outlet port  23  of the ejector  20 , constitutes a pulsation purge line  51  to carry the purge gas to the intake system, apart from a main purge line  50  to carry the purge gas to the downstream side from the throttle valve  11  through the purge passage  17 . 
     In the present embodiment described above, the apparatus is configured to carry the purge gas to the intake system by using the pulsation pump  30  using intake pulsation, so it is possible to sufficiently secure a flow rate of the purge gas even in the operation condition where it is difficult to supply the purge gas to the downstream side from the throttle valve  11  through the purge passage  17  due to a small negative pressure of the downstream side from the throttle valve  11 . Therefore, in an internal combustion engine where negative pressure in the downstream side from the throttle valve  11  is small, such as an internal combustion engine provided with a supercharger; and an internal combustion engine capable of adjusting the amount of intake air by a variable valve system, it is possible to sufficiently secure the flow rate of the purge gas. 
       FIG. 4  shows test results of the flow rate and the pressure to affect the inlet port  22  of the ejector  20  in case of using an elastic body  34  having a diameter of 65 mm and a length of 80 mm. As shown in  FIG. 4 , a structure of the elastic body  34  is adjusted/set so that the oscillation (amplitude) in an axial direction of the elastic body  34  gets a peak in a low speed operation region where oscillation of the intake pulsation causes a low frequency. Thereby, it is possible to sufficiently secure the purge gas even in a low frequency region (low speed operation region) where negative pressure is difficult to be generated in a downstream side from a throttle valve  11 . 
     In the embodiments explained below, parts different from the previously explained embodiment will mainly be explained. The same components as the previously explained embodiment are given the same reference numerals, and an overlap explanation will properly be omitted. 
       FIG. 5  and  FIG. 6  show a second embodiment of the present invention. In the second embodiment, a turbocharger  54  to supercharge intake air in an internal combustion engine is provided. As is well known, the turbocharger  54  is provided with a compressor  55  to supercharge the intake air; and a turbine  56  rotationally driven by exhaust gas. The compressor  55  and the turbine  56  are arranged back to back with each other on a shaft  57 . The intake passage  4  is provided with an intercooler  58  in a downstream side from the compressor  55 . The intercooler  58  cools supercharged air. Furthermore, the intake passage  4  is provided with an ejector  60  for supercharging in addition to the ejector  20 . The ejector  60  for supercharging includes an inlet port  62 , an outlet port  64 , and a negative pressure port  65 . The inlet port  62  is connected to a downstream side part  61  from the compressor  55  in the intake passage  4 . The outlet port  64  is connected to an upstream side part  63  from than the compressor  55  in the intake passage  4 . The negative pressure port  65  is connected to the purge passage  17 . 
       FIG. 5  shows a flow of gas including the purge gas in supercharging. Solid arrows show a flow of positive pressure. Broken arrows show a flow of negative pressure. As shown in  FIG. 5 , negative pressure is not generated in the downstream side of the throttle valve  11  in supercharging, so the purge gas is not suppled to the downstream side of the throttle valve  11  through the purge passage  17 . On the other hand, in supercharging, pressure difference is generated between the upstream side part  63  and the downstream side part  61  respectively from the compressor  55  in the intake passage  4 . The pressure difference generates a flow of operation gas toward the outlet port  64  from the inlet port  62  of the ejector  60  for supercharging. Furthermore, negative pressure is generated when the operation gas passes through a throttled part  66 . By the negative pressure, the purge gas is sucked from the negative pressure port  65  and supplied to the upstream side part  63  from the compressor  55  in the intake passage  4  through the outlet port  64 . In this way, the flow of the purge gas, which branches from the purge passage  17  and continues to the intake system via the negative pressure port  65  and the outlet port  64  of the ejector  60  for supercharging, constitutes a supercharging purge line  59  to carry the purge gas to the intake system, apart from a main purge line  50  of the purge passage  17  and the pulsation purge line  51 . 
     Moreover, as with the first embodiment, the purge gas is further supplied to the intake system through the pulsation purge line  51  by the pumping action of the pulsation pump  30  using intake pulsation unavoidably generated during operation the internal combustion engine. 
       FIG. 6  shows a flow of gas including the purge gas in non-supercharging. As shown in  FIG. 6 , negative pressure is generated in the downstream side of the throttle valve  11  in non-supercharging, so the purge gas is provided for the downstream side of the throttle valve  11  through the purge passage  17 . On the other hand, in non-supercharging, differential pressure is not generated between the upstream side part  63  and the downstream side part  61  respectively from the compressor  55  in the intake passage  4 . Therefore, the ejector  60  for supercharging doesn&#39;t operate, and to provide the purge gas is not supplied by the supercharging purge line  59 . 
     Furthermore, the intake pulsation occurs also in non-supercharging, so the pumping action of the pulsation pump  30  using the intake pulsation supplies the purge gas to the intake system through the pulsation purge line  51  as with in supercharging. 
       FIG. 7  is a characteristic graph showing a relation between the engine rotation speed and the purge flow rate. A solid line in  FIG. 7  represents a purge flow rate obtained through the supercharging purge line  59 . A broken line in  FIG. 7  represents a purge flow rate obtained through the pulsation purge line  51 . If trying to secure the purge flow rate by only the ejector  60  for supercharging without the pulsation pump  30  and the ejector  20 , the purge flow rate lacks in a low speed operation region (low frequency region) where supercharging pressure is difficult to be obtained. In contrast, if using the pulsation pump  30  and the ejector  20  in addition to the ejector  60  for supercharging, the purge flow rate obtained through the pulsation purge line  51  (represented by the broken line) is added to the characteristic represented by the solid line in  FIG. 7 . Therefore, it is possible to sufficiently secure the purge flow rate even in the low speed operation region (low frequency region) where the purge flow rate tends to lack. 
       FIG. 8  shows a third embodiment of the present invention. In the third embodiment, a gas line is shared so that the ejector  20  fulfills the function of the ejector  60  for supercharging of the second embodiment. That is, the inlet port  22  of the ejector  20  is connected to both of the downstream side part  61  from the compressor  55  in the intake passage  4  and the discharge port  42  of the pulsation pump  30  by a shared passage  67  where the gas line is shared. Therefore, to the inlet port  22  of the ejector  20 , pressurized operation gas is always supplied from a discharge port  42  side of the pulsation pump  30 . Furthermore, in supercharging, supercharged operation gas is supplied to the inlet port  22  of the ejector  20  also from the upstream part  63  of the compressor  55  in the intake passage  4 . 
     According to the third embodiment, the same effect as the second embodiment can be obtained. Furthermore, the functions of the ejector  20  and the ejector  60  for supercharging are shared by one ejector  20 . Therefore, it is possible to reduce the number of parts and to conduct shortening of the passage pipe by the sharing. 
       FIG. 9  shows a fourth embodiment of the present invention. In the fourth embodiment, the pulsation pump  30  and the ejector  20  are integrally formed as compared with the third embodiment. That is, the inlet port  22  side of the ejector  20  is directly installed in the discharge port  42  side of the pulsation pump  30 , and a passage therebetween is omitted. Thereby, it is possible to fulfill a further simplification and a shortening of the passage. Furthermore, instead of the shared passage  67 , a supercharging passage  68  is installed. The supercharging passage  68  connects the downstream side part  61  from the compressor  55  in the intake passage  4  to the inlet port  22  of the ejector  20 . 
       FIG. 10  shows a fifth embodiment of the present invention. In the fifth embodiment, the ejector ( 20 ) connected to the discharge port  42  of the pulsation pump  30  is omitted as compared with the second embodiment. 
     Furthermore, the suction port  41  of the pulsation pump  30  is connected to the purge passage  17 . The discharge port  42  of the pulsation pump  30  is connected to the upstream side part  63  from the compressor  55  in the intake passage  4 . According to such a structure, as shown by the arrow in  FIG. 10 , the purge gas sucked through the suction port  41  of the pulsation pump  30  by the pumping action of the pulsation pump  30  using intake pulsation is discharged from the discharge port  42  and supplied to the upstream part  63  from the compressor  55  in the intake passage  4 . In this way, the flow of the purge gas, which branches from the purge passage  17  and continues to the intake system via the suction port  41  and the discharge port  42  of the pulsation pump  30 , constitutes a pulsation purge line  69  to supply the purge gas to the intake system, apart from the main purge line  50 . 
     According to the fifth embodiment, the ejector ( 20 ) is omitted, nevertheless, as with the second embodiment, it is possible to surely supply the purge gas to the intake system by using the pumping action of the pulsation pump  30  even in an operation condition where negative pressure is not generated in the downstream side of the throttle valve  11 . 
       FIG. 11  and  FIG. 12  show a pulsation pump  30 A according to a sixth embodiment of the present invention. The pulsation pump  30 A can be used instead of the pulsation pump  30  according to the first to fifth embodiments. The pulsation pump  30 A is different from the pulsation pump  30  of the first embodiment; that is, a peripheral wall of an elastic body  34 A is simply cylinder-shaped, not bellows-shaped. Furthermore, it is not required to be deformed in an axial direction, so length of the peripheral wall in the axial direction is formed to be short. Furthermore, a rubber film  71  is provided in a disk-shaped upper wall part of the elastic body  34 A. 
     Also in the pulsation pump  30 A of the sixth embodiment, as with the pulsation pump  30  of the first embodiment, when intake pulsation is propagated to the first chamber  37  in the elastic body  34 A through the communication passage  40 , the rubber film  71  is displaced (vibrated) in the axial direction. Thereby, volume of the first chamber  37  fluctuates. Moreover, the fluctuation of the volume of the first chamber  37  makes volume of the second chamber  38  in the case  31  fluctuate, and thereby pressure in the second chamber  38  fluctuates. Thereby, the gas flows into the first chamber  37  from the suction port  41  through the suction valve  45 , and the gas is discharged into the discharge port  42  from the second chamber  38  through the discharge valve  48 . 
     As described above, the present invention has been explained based on the concrete embodiments, but the present invention is not limited to the embodiments and may include various modifications. For example, the elastic body deformed by responding to pressure fluctuation of the first chamber does not necessarily form all of the wall part sealing up the first chamber, and that may form at least a part of the wall part. 
     Furthermore, in the embodiments, a check valve and a purge control valve (electromagnetic valve) have not been provided in the pulsation purge line and the supercharging purge line. However, the check valve to prevent a backward flow and the purge control valve to adjust a flow rate may be provided. 
     The entire contents of Japanese Patent Application No. 2016-242867 filed Dec. 15, 2016 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. The scope of the invention is defined with reference to the following claims.