United States Patent (19)
`Wakashiro et al.
`
`||||||IIII
`US005456236A
`11
`Patent Number:
`5,456,236
`45) Date of Patent:
`Oct. 10, 1995
`
`(54 EVAPORATIVE EMISSION CONTROL
`SYSTEM FOR INTERNAL COMBUSTION
`ENGINES
`
`I75) Inventors: Teruo Wakashiro; Takeshi Hara;
`Kouichi Hidano, Kazumi Yamazaki,
`all of Wako; Tomoyuki Kawakami,
`Tochigi, all of Japan
`(73) Assignee: Honda Giken Kogyo Kabushiki
`Kaisha, Tokyo, Japan
`
`21 Appl. No.: 335,373
`22 Filed:
`Nov. 3, 1994
`30
`Foreign Application Priority Data
`Nov. 4, 1993 (JP)
`Japan .................................... 5-298.931
`(51
`Int. Cl. ............................. F02M 25/08
`52 U.S. Cl. ........................................................... 123/519
`58) Field of Search ..................................... 123/516, 518,
`123/519, 520
`
`56)
`
`References Cited
`U.S. PATENT DOCUMENTS
`1/1982 Hiramatsu et al. ..................... 1231519
`4,308,840
`4,790,283 12/1988 Uranishi et al. ....
`... 1231519
`4,817,576 4/1989 Abe et al. .......
`... 1231519
`4,894,072
`1/1990 Turner et al. ...
`... 1231519
`4,915,643 8/1990 Sato et al........
`... 1231519
`4,919,103 4/1990 Ishiguro et al.
`... 123,519
`5,056,494 10/1991 Kayanuma ............................. 123,519
`5,111,795 5/1992 Thompson .............................. 1231519
`5,143,041
`9/1992 Franzke ................................... 1231516
`
`
`
`5,209,210 5/1993 Ikeda et al. ............................. 1231516
`FOREIGN PATENT DOCUMENTS
`1-159455 6/1989 Japan.
`Primary Examiner-Thomas N. Moulis
`Attorney, Agent, or Firm-Nikaido, Marmelstein, Murray &
`Oram
`ABSTRACT
`57
`An evaporative emission control system for an internal
`combustion engine includes a canister for adsorbing evapo
`rative fuel generated in the fuel tank, a first introducing
`passage for introducing evaporative fuel generated in the
`fuel tank into the canister on an occasion other than at
`refueling, a purging passage for purging evaporative fuel
`adsorbed in the canister into the intake passage of the
`engine, and a first air-inlet passage communicating between
`the canister and the atmosphere. First and second adsorbent
`chambers are formed in the canister and each accommodat
`ing an adsorbent. The first introducing passage and the
`purging passage are connected to the first adsorbent cham
`ber. The first air-inlet passage is connected to the second
`adsorbent chamber. A communication passage communi
`cates between the first adsorbent chamber and the second
`adsorbent chamber. A second introducing passage is con
`nected to the first and second adsorbent chambers, for
`introducing evaporative fuel generated in the fuel tank into
`the canister at refueling. A second air-inlet passage commu
`nicates between the first adsorbent chamber and the atmo
`sphere. An electromagnetic valve is arranged across the
`second introducing passage, for opening the same at refu
`eling.
`
`12 Claims, 9 Drawing Sheets
`
`12.N.Al
`Cov4110 eate
`
` MAHLE-1015
`U.S. Patent No. RE38,844
`
`

`

`U.S. Patent
`U.S. Patent
`
`Oct. 10, 1995
`Oct. 10, 1995
`
`Sheet 1 of 9
`Sheet 1 of 9
`
`5,456,236
`5,456,236
`
`F.G. 1
`FIG. 1
`
`
`
`COMBUSTION ENGINE
`
`12 Al
`INTERNAL
`COMBW410N 2Nettle
`
`

`

`U.S. Patent
`U.S. Patent
`
`Oct. 10, 1995
`Oct. 10, 1995
`
`Sheet 20f 9 5,456,236
`Sheet 2 of 9
`5,456,236
`
`FIG. 2
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`

`U.S. Patent
`
`Oct. 10, 1995
`
`Sheet 3 of 9
`
`5,456,236
`
`FIG. 3
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`

`U.S. Patent
`U.S. Patent
`
`Oct. 10, 1995
`Oct. 10, 1995
`
`Sheet 4 of 9
`Sheet 4 of 9
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`5,456,236
`5,456,236
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`U.S. Patent
`U.S. Patent
`
`Oct. 10, 1995
`Oct. 10, 1995
`
`Sheet 5 of 9
`Sheet 5 of 9
`
`5,456,236
`5,456,236
`
`F.G. 5
`FIG. 5
`
`------------4-
`-
`
`COMBUSTION ENGINE
`
`INTERNAL
`
`

`

`U.S. Patent
`U.S. Patent
`
`Oct. 10, 1995
`Oct. 10, 1995
`
`Sheet 6 of 9
`Sheet 6 of 9
`
`5,456,236
`5,456,236
`
`FIG. 6
`FIG. 6
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`U.S. Patent
`
`Oct. 10, 1995
`
`Sheet 7 of 9
`
`5,456,236
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`33a
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`US. Patent
`U.S. Patent
`
`Oct. 10, 1995
`Oct. 10, 1995
`
`Sheet 8 of 9
`Sheet 8 of 9
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`5,456,236
`5,456,236
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`33a
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`U.S. Patent
`U.S. Patent
`
`Oct. 10, 1995
`Oct. 10, 1995
`
`Sheet 9 of 9
`Sheet 9 of 9
`
`5,456,236
`5,456,236
`
`FIG. 9
`FIG. 9
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`

`5,456,236
`5,456,236
`
`1
`1
`EVAPORATIVE EMISSION CONTROL
`EVAPORATIVE EMISSION CONTROL
`SYSTEM FOR INTERNAL COMBUSTION
`SYSTEM FOR INTERNAL COMBUSTION
`ENGINES
`ENGINES
`
`2
`2
`fuel tank into the canister on an occasion other than at
`fuel tank into the canister on an occasion other than at
`refueling, a purging passage for purging the evaporative fuel
`refueling, a purging passage for purging the evaporative fuel
`adsorbed in the canister into the intake passage of the
`adsorbed in the canister into the intake passage of the
`engine, and a first open-to-atmosphere passage connected to
`engine, anda first open-to-atmosphere passage connected to
`the canister and communicating with the atmosphere.
`the canister and communicating with the atmosphere.
`The evaporative emission control system according to the
`The evaporative emission control system accordingto the
`invention is characterized by comprising:
`invention is characterized by comprising:
`a first adsorbent chamber formed in the canister and
`a first adsorbent chamber formed in the canister and
`accommodating an adsorbent, the first introducing pas
`accommodating an adsorbent,the first introducing pas-
`sage and the purging passage being connected to the
`sage and the purging passage being connected to the
`first adsorbent chamber;
`first adsorbent chamber;
`a second adsorbent chamber formed in the canister and
`a second adsorbent chamber formed in the canister and
`accommodating an adsorbent, the first open-to-atmo
`accommodating an adsorbent, the first open-to-atmo-
`sphere passage being connected to the second adsor
`sphere passage being comnected to the second adsor-
`bent chamber;
`bent chamber;
`a communication passage formed in the canister and
`a communication passage formed in the canister and
`communicating between the first adsorbent chamber
`communicating between the first adsorbent chamber
`and the second adsorbent chamber,
`and the second adsorbent chamber;
`a second introducing passage connected to the first and
`a second introducing passage connected to the first and
`second adsorbent chambers, for introducing the evapo
`second adsorbent chambers, for introducing the evapo-
`rative fuel generated in the fuel tank into the canister at
`rative fuel generated in the fuel tank into the canister at
`refueling;
`refueling;
`a second open-to-atmosphere passage connected to the
`a second open-to-atmosphere passage connected to the
`first adsorbent chamber and communicating with the
`first adsorbent chamber and communicating with the
`atmosphere; and
`atmosphere; and
`valve means arranged across the second introducing pas
`valve meansarranged across the second introducing pas-
`sage, for opening the same at refueling.
`sage, for opening the sameat refueling.
`The adsorbent accommodated in the first adsorbent cham
`The adsorbent accommodatedin thefirst adsorbent cham-
`ber and the adsorbent accommodated in the second adsor
`ber and the adsorbent accommodated in the second adsor-
`bent chamber may be of substantially the same kind.
`bent chamber may be of substantially the same kind.
`Alternatively, the adsorbent accommodated in the first
`Alternatively, the adsorbent accommodated in the first
`adsorbent chamber and the adsorbent accommodated in the
`adsorbent chamber and the adsorbent accommodated in the
`second adsorbent chamber have different adsorption char
`second adsorbent chamber have different adsorption char-
`acteristics from each other.
`acteristics from each other.
`Advantageously, the evaporative emission control system
`Advantageously, the evaporative emission control system
`may further includes heater means for heating the adsorbent
`may further includes heater means for heating the adsorbent
`accommodated in the first adsorbent chamber.
`accommodated in the first adsorbent chamber.
`Also advantageously, the evaporative emission control
`Also advantageously, the evaporative emission control
`system includes second valve means arranged across the
`system includes second valve means arranged across the
`second air-inlet passage, for opening the same at refueling.
`second air-inlet passage, for opening the sameat refueling.
`In a preferred embodiment of the invention, the first and
`In a preferred embodimentof the invention, the first and
`second open-to-atmosphere passages have ends thereof con
`second open-to-atmosphere passages have endsthereof con-
`nected, respectively, to the second and first adsorbent cham
`nected, respectively, to the secondandfirst adsorbent cham-
`bers at one side of the canister, the communication passage
`bers at one side of the canister, the communication passage
`being arranged at another side of the canister opposite the
`being arranged at another side of the canister opposite the
`one side, the second introducing passage having an end
`one side, the second introducing passage having an end
`thereof opening into the communication passage.
`thereof opening into the communication passage.
`In another embodiment of the invention, the evaporative
`In another embodimentof the invention, the evaporative
`emission control system is characterized by comprising:
`emission control system is characterized by comprising:
`a first adsorbent chamber formed in the canister and
`a first adsorbent chamber formed in the canister and
`accommodating an adsorbent, the first introducing pas
`accommodating an adsorbent,the first introducing pas-
`Sage and the purging passage being connected to the
`sage and the purging passage being connected to the
`first adsorbent chamber,
`first adsorbent chamber;
`a second adsorbent chamber formed in the canister and
`a second adsorbent chamber formed in the canister and
`accommodating an adsorbent, the first open-to-atmo
`accommodating an adsorbent, the first open-to-atmo-
`sphere passage being connected to the second adsor
`sphere passage being connected to the second adsor-
`bent chamber;
`bent chamber;
`a third adsorbent chamber formed in the canister and
`a third adsorbent chamber formed in the canister and
`accommodating an adsorbent, the third adsorbent
`accommodating an adsorbent,
`the third adsorbent
`chamber being interposed between the first adsorbent
`chamber being interposed between thefirst adsorbent
`chamber and the second adsorbent chamber;
`chamber and the second adsorbent chamber;
`a first communication passage formed in the canister and
`a first communication passage formed in the canister and
`communicating between the second adsorbent chamber
`communicating between the second adsorbent chamber
`and the third adsorbent chamber;
`and the third adsorbent chamber;
`a second communication passage formed in the canister
`a second communication passage formed in the canister
`
`BACKGROUND OF THE INVENTION
`BACKGROUND OF THE INVENTION
`
`Field of the Invention
`Field of the Invention
`This invention relates to an evaporative emission control
`This invention relates to an evaporative emission control
`system for internal combustion engines, which prevents
`system for internal combustion engines, which prevents
`emission of evaporative fuel generated in a fuel tank of the
`emission of evaporative fuel generated in a fuel tank of the
`engine into the atmosphere.
`engine into the atmosphere.
`
`10
`10
`
`15
`15
`
`20
`20
`
`25
`25
`
`30
`30
`
`Prior Art
`Prior Art
`An evaporative emission control system of this kind has
`An evaporative emission control system of this kind has
`been proposed, e.g. by Japanese Provisional Patent Publi
`been proposed, e.g. by Japanese Provisional Patent Publi-
`cation (Kokai) No. 1-159455, which includes not only an
`cation (Kokai) No. 1-159455, which includes not only an
`ordinary canister which adsorbs evaporative fuel generated
`ordinary canister which adsorbs evaporative fuel generated
`in a fuel tank of the engine during parking of a vehicle in
`in a fuel tank of the engine during parking of a vehicle in
`which the engine is installed or during operation of the
`which the engine is installed or during operation of the
`engine, but also a canister for exclusive use in refueling,
`engine, but also a canister for exclusive use in refueling,
`which adsorbs evaporative fuel generated during refueling
`which adsorbs evaporative fuel generated during refueling
`into the fuel tank. According to the proposed evaporative
`into the fuel tank. According to the proposed evaporative
`emission control system, to overcome the disadvantage with
`emission control system, to overcome the disadvantage with
`conventional canisters that they have an insufficient adsorb
`conventional canisters that they have an insufficient adsorb-
`ing efficiency due to a high flow velocity of evaporative fuel
`ing efficiency dueto a high flow velocity of evaporative fuel
`generated during refueling, the canister for exclusive use in
`generated during refueling, the canister for exclusive use in
`refueling has a plurality of layers of adsorbents formed of
`refueling has a plurality of layers of adsorbents formed of
`activated carbon defined therein by one or more partitions,
`activated carbon defined therein by one or morepartitions,
`wherein the flow path of evaporative fuel is deflected so as
`wherein the flow path of evaporative fuel is deflected so as
`to enhance the adsorbing efficiency without increasing the
`to enhance the adsorbing efficiency without increasing the
`size (ratio L/D(length/diameter)) of the canister.
`size (ratio L/D(length/diameter)) of the canister.
`However, the canister for exclusive use in refueling is not
`However, the canister for exclusive use in refueling is not
`used on occasions other than at refueling, and becomes
`used on occasions other than at refueling, and becomes
`empty after evaporative fuel adsorbed therein is discharged
`empty after evaporative fuel adsorbed therein is discharged
`or purged into the engine. Thus, the utilization factor of the
`or purged into the engine. Thus,the utilization factor of the
`activated carbon is low. Further, two batches of activated
`activated carbon is low. Further, two batches of activated
`carbon have to be provided as adsorbents, one for the
`carbon have to be provided as adsorbents, one for the
`canister for exclusive use in refueling, and the other for the
`canister for exclusive use in refueling, and the other for the
`ordinary canister, leading to use of a large amount of
`ordinary canister,
`leading to use of a large amount of
`activated carbon and hence an increased cost. Moreover, at
`activated carbon and hence an increased cost. Moreover, at
`least two purging passages connecting between the respec
`least two purging passages connecting between the respec-
`tive canisters and the intake passage of the engine have to be
`tive canisters and the intake passageof the engine have to be
`provided to discharge evaporative fuel adsorbed in the
`provided to discharge evaporative fuel adsorbed in the
`canisters, resulting in that the evaporative emission control
`canisters, resulting in that the evaporative emission control
`system has a complicated construction.
`system has a complicated construction.
`
`35
`35
`
`40
`40
`
`45
`45
`
`50
`50
`
`55
`55
`
`60
`60
`
`SUMMARYOF THE INVENTION
`SUMMARY OF THE INVENTION
`It is an object of the invention to provide an evaporative
`It is an object of the invention to provide an evaporative
`emission control system for internal combustion engines,
`emission control system for internal combustion engines,
`which is capable of enhancing the utilization factor of
`which is capable of enhancing the utilization factor of
`adsorbents employed therein and hence curtailing the
`adsorbents employed therein and hence curtailing the
`amount of adsorbents used.
`amount of adsorbents used.
`Another object of the invention is to provide an evapo
`Another object of the invention is to provide an evapo-
`rative emission control system for internal combustion
`rative emission control system for internal combustion
`engines, which has a simplified construction involving a
`engines, which has a simplified construction involving a
`purging passage connecting between a canister and the
`purging passage connecting between a canister and the
`intake system of the engine.
`intake system of the engine.
`To attain the above objects, the present invention provides
`To attain the above objects, the present invention provides
`an evaporative emission control system for an internal
`an evaporative emission control system for an internal
`combustion engine having an intake passage, and a fuel
`combustion engine having an intake passage, and a fuel
`tank, the system including a canister for adsorbing evapo
`tank, the system including a canister for adsorbing evapo-
`rative fuel generated in the fuel tank, a first introducing
`rative fuel generated in the fuel tank, a first. introducing
`passage for introducing the evaporative fuel generated in the
`passage for introducing the evaporative fuel generatedin the
`
`65
`65
`
`

`

`5,456,236
`5,456,236
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`10
`10
`
`15
`15
`
`20
`20
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`25
`25
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`30
`30
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`35
`35
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`40
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`45
`45
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`4
`3
`4
`3
`23 of an internal combustion engine 1 provided with a filler
`and communicating between the first adsorbent cham
`23 of an internal combustion engine 1 provided withafiller
`and communicating between the first adsorbent cham-
`cap 22 which is opened in refueling, a canister 26 accom
`cap 22 which is opened in refueling, a canister 26 accom-
`ber and the third adsorbent chamber;
`ber and the third adsorbent chamber;
`modating adsorbents 24 and 24' which are formed of acti
`modating adsorbents 24 and 24' which are formedofacti-
`a second introducing passage connected to the second and
`a second introducing passage connectedto the second and
`wated carbon, a first charging passage (first introducing
`vated carbon, a first charging passage (first introducing
`third adsorbent chambers, for introducing the evapora
`third adsorbent chambers, for introducing the evapora-
`passage) 27 for operation on ordinary occasions, connecting
`passage) 27 for operation on ordinary occasions, connecting
`tive fuel generated in the fuel tank into the canister at
`tive fuel generated in the fuel tank into the canister at
`between the canister 26 and the fuel tank 23, with an end
`between the canister 26 and the fuel tank 23, with an end
`refueling;
`refueling;
`thereof opening into an upper space within the fuel tank 23,
`thereof opening into an upper space within the fuel tank 23,
`a second open-to-atmosphere passage connected to the
`a two-way valve 52 arranged across the first charging
`a second open-to-atmosphere passage connected to the
`a two-way valve 52 arranged across the first charging
`first adsorbent chamber and communicating with the
`passage 27, a second charging passage (second introducing
`first adsorbent chamber and communicating with the
`passage 27, a second charging passage (second introducing
`atmosphere; and
`passage) 33 for operation at refueling, connecting between
`atmosphere; and
`passage) 33 for operation at refueling, connecting between
`the canister 26 and the fuel tank 23, with an end thereof
`valve means arranged across the second introducing pas
`the canister 26 and the fuel tank 23, with an end thereof
`valve means arranged across the second introducing pas-
`opening into a space within the fuel tank 23 in the vicinity
`sage, for opening the same at refueling.
`opening into a space within the fuel tank 23 in the vicinity
`sage, for opening the sameat refueling.
`of the filler cap 22, an electromagnetic valve 34 arranged
`The above and other objects, features, and advantages of
`of the filler cap 22, an electromagnetic valve 34 arranged
`The above and other objects, features, and advantages of
`across the second charging passage 33 for selectively open
`the invention will be more apparent from the following
`across the second charging passage 33 for selectively open-
`the invention will be more apparent from the following
`ing and closing the same, a purging passage 10 connecting
`detailed description taken in conjunction with the accom
`ing and closing the same, a purging passage 10 connecting
`detailed description taken in conjunction with the accom-
`panying drawings.
`between the canister 26 and an intake pipe 2 of the engine
`between the canister 26 and an intake pipe 2 of the engine
`panying drawings.
`1, with an end thereof opening into the intake pipe 2 at a
`1, with an end thereof opening into the intake pipe 2 at a
`location downstream of a throttle valve 3, and a purge
`location downstream of a throttle valve 3, and a purge
`control valve 36 arranged across the purging passage 10 for
`control valve 36 arranged across the purging passage 10 for
`selectively opening and closing the same. The electromag
`selectively opening and closing the same. The electromag-
`netic valve 34 and the purge control valve 36 are controlled
`netic valve 34 and the purge control valve 36 are controlled
`by control signals from an electronic control unit (ECU), not
`by control signals from an electronic control unit (ECU),not
`shown.
`shown.
`The canister 26 has a first activated carbon chamber (first
`The canister 26 has a first activated carbon chamber(first
`adsorbent chamber) 42 and a second activated carbon cham
`adsorbent chamber) 42 and a second activated carbon cham-
`ber (second adsorbent chamber) 43 formed therein and
`ber (second adsorbent chamber) 43 formed therein and
`partitioned from each other by a partition 41. The first and
`partitioned from each otherby a partition 41. The first and
`second activated carbon chambers 42,43 are each defined by
`secondactivated carbon chambers42,43 are each defined by
`a canister casing 26a, upper and lower retainer plates 46 and
`a canister casing 26a, upper and lowerretainer plates 46 and
`47, and the partition 41. The upper and lower retainer plates
`47, andthe partition 41. The upper and lowerretainer plates
`46, 47 are formed of a porous material and have filters 48
`46, 47 are formed of a porous material and havefilters 48
`and 49 applied over respective inner side surfaces thereof.
`and 49 applied over respective inner side surfaces thereof.
`The first and second activated carbon chambers 42, 43 are
`The first and second activated carbon chambers 42, 43 are
`densely charged, respectively, with the adsorbents 24, 24
`densely charged, respectively, with the adsorbents 24, 24’
`which are formed of almost the same kind of activated
`which are formed of almost the same kind of activated
`carbon and in almost the same amount as each other. The
`carbon and in almost the same amount as each other. The
`canister 26 has an inlet port 27a for use on ordinary
`canister 26 has an inlet port 27a for use on ordinary
`occasions, an air-inlet port 28a, and a discharge port 10a,
`occasions, an air-inlet port 28a, and a discharge port 10a,
`which are provided in an upper portion of the canister 26 in
`which are provided in an upperportion ofthe canister 26 in
`or above the first activated carbon chamber 42, and con
`or above the first activated carbon chamber 42, and con-
`nected, respectively, to the first charging passage 27, an
`nected, respectively,
`to the first charging passage 27, an
`air-inlet passage (second air-inlet passage) 28 communicat
`air-inlet passage (secondair-inlet passage) 28 communicat-
`ing with the atmosphere, and the purging passage 10. The
`ing with the atmosphere, and the purging passage 10. The
`inlet port. 27a for use on ordinary occasions extends through
`inlet port 27a for use on ordinary occasions extends through
`the upper retainer plate 46 and the filter 48 to directly open
`the upperretainer plate 46 andthefilter 48 to directly open
`into the activated carbon adsorbent 24. Further, the canister
`into the activated carbon adsorbent 24. Further, the canister
`26 has an air-inlet port 25a provided in an upper portion of
`26 has an air-inlet port 25a provided in an upper portion of
`the canister 26 above the second activated carbon chamber
`the canister 26 above the second activated carbon chamber
`43 and opening into a gap defined between the casing 26a
`43 and opening into a gap defined between the casing 26a
`and the upper retainer plate 46. The air-inlet port 25a is
`and the upper retainer plate 46. The air-inlet port 25a is
`connected to an air-inlet passage (first air-inlet passage) 25
`connected to an air-inlet passage(first air-inlet passage) 25
`communicating with the atmosphere. A gap (communication
`communicating with the atmosphere. A gap (communication
`passage) 50 is defined between the casing 26a and the lower
`passage) 50 is defined between the casing 26a and the lower
`retainer plate 47 at a location just below a lower end of the
`retainer plate 47 at a location just below a lower end of the
`partition 41, and through which the first and second acti
`partition 41, and through which the first and second acti-
`wated carbon chambers 42, 43 are communicated with each
`vated carbon chambers 42, 43 are communicated with each
`other. Another inlet port 33a is connected to the canister 26
`other. Another inlet port 33a is connected to the canister 26
`in a fashion directly opening into the gap 50 at a lengthwise
`in a fashion directly openinginto the gap 50 at a lengthwise
`middle point thereof. The port 33a is connected to a second
`middle point thereof. The port 33a is connected to a second
`charging passage 33 for operation at refueling. A normally
`charging passage 33 for operation at refueling. A normally-
`open electromagnetic valve 25b and a one-way valve 28b
`open electromagnetic valve 25b and a one-way valve 28b
`are arranged across the first and second air-inlet passages 25,
`are arranged acrossthe first and secondair-inlet passages 25,
`28 for opening and closing the same, respectively.
`28 for opening and closing the same, respectively.
`Mounted in the intake pipe 2 at locations downstream of
`Mountedin the intake pipe 2 at locations downstream of
`an end of the purging passage 10 opening into the intake
`an end of the purging passage 10 opening into the intake
`pipe 2 are fuel injection valves 6 which are connected to the
`pipe 2 are fuel injection valves 6 which are connected to the
`fuel tank 23 through a fuel supply pipe 7 and a fuel pump 8
`fuel tank 23 through a fuel supply pipe 7 and a fuel pump 8
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`BRIEF DESCRIPTION OF THE DRAWINGS
`FIG. 1 is a schematic diagram showing the whole arrange
`FIG. 1 is a schematic diagram showing the whole arrange-
`ment of an evaporative emission control system for an
`ment of an evaporative emission control system for an
`internal combustion engine according to a first embodiment
`internal combustion engine accordingto a first embodiment
`of the invention;
`of the invention;
`FIG. 2 is a sectional view of a canister appearing in FIG.
`FIG.2 is a sectional view of a canister appearing in FIG.
`1, useful in explaining how there occurs in the canister a
`1, useful in explaining how there occurs in the canister a
`flow of evaporative fuel normally generated in a fuel tank,
`fiow of evaporative fuel normally generated in a fuel tank,
`e.g. during parking of a vehicle in which the engine is
`e.g. during parking of a vehicle in which the engine is
`installed, with the engine in stoppage, or during operation of
`installed, with the engine in stoppage,or during operation of
`the engine;
`the engine;
`FIG. 3 is a similar view to FIG. 2, useful in explaining
`FIG. 3 is a similar view to FIG. 2, useful in explaining
`how there occurs in the canister a flow of evaporative fuel
`how there occurs in the canister a flow of evaporative fuel
`generated in the fuel tank during refueling;
`generated in the fuel tank during refueling;
`FIG. 4 is a similar view to FIG. 2, useful in explaining
`FIG. 4 is a similar view to FIG. 2, useful in explaining
`how there occurs a flow of evaporative fuel in the canister
`how there occurs a flow of evaporative fuel in the canister
`during purging;
`during purging;
`FIG. 5 is a schematic diagram showing the whole arrange
`FIG. 5 is a schematic diagram showing the whole arrange-
`ment of an evaporative emission control system for internal
`ment of an evaporative emission control system for internal
`combustion engine according to a second embodiment of the
`combustion engine according to a second embodimentof the
`invention;
`invention;
`FIG. 6 is a sectional view of a canister appearing in FIG.
`FIG.6 is a sectional view of a canister appearing in FIG.
`5, useful in explaining how there occurs in the canister a
`5, useful in explaining how there occurs in the canister a
`flow of evaporative fuel normally generated in a fuel tank,
`flow of evaporative fuel normally generated in a fuel tank,
`e.g. during parking of the vehicle with the engine in stop
`e.g. during parking of the vehicle with the engine in stop-
`page, or during operation of the engine;
`page, or during operation of the engine;
`FIG. 7 is a similar view to FIG. 6, useful in explaining
`FIG.7 is a similar view to FIG. 6, useful in explaining
`how there occurs in the canister a flow of evaporative fuel
`how there occurs in the canister a flow of evaporative fuel
`generated in the fuel tank during refueling;
`generated in the fuel tank during refueling;
`FIG. 8 is a similar view to FIG. 6, useful in explaining
`FIG. 8 is a similar view to FIG. 6, useful in explaining
`how there occurs a flow of evaporative fuel in the canister
`how there occurs a flow of evaporative fuel in the canister
`during purging; and
`during purging; and
`FIG. 9 is a sectional view of a canister according to a
`FIG. 9 is a sectional view of a canister according to a
`variation of the invention, which is provided with a heater.
`variation of the invention, which is provided with a heater.
`
`50
`50
`
`55
`55
`
`60
`60
`
`65
`65
`
`DETAILED DESCRIPTION
`DETAILED DESCRIPTION
`The invention will now be described in detail with refer-
`The invention will now be described in detail with refer
`ence to t