JP2012036734A - Evaporation fuel treatment device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an evaporation fuel treatment device in which evaporation fuel generated in refueling is smoothly absorbed with ventilation resistance lowered and evaporation fuel generated in parking is effectively prevented from discharging into atmosphere.SOLUTION: The evaporation fuel treatment device 12 includes a blow-by prevention part 66 which diverges from a bypass 50. A route open-and-close valve 46 is closed in parking, an upstream bypass chamber 50A and a downstream bypass chamber 50B are not communicated with each other, and thereby gas flows through the blow-by prevention part 66. The route open-and-close valve 46 is opened under a pressure of the gas acting during a refueling, the upstream bypass chamber 50A and the downstream bypass chamber 50B are communicated with each other, and thereby most of the gas directly flows from the upstream bypass chamber 50A to the downstream bypass chamber 50B.

Description

  The present invention relates to a fuel vapor processing apparatus.

  In an evaporative fuel processing device for processing evaporative fuel generated in a fuel tank or the like, evaporative fuel generated in a large amount in a short time during refueling and non-refueling during parking or driving (hereinafter referred to as “parking” as appropriate) It is preferable to appropriately treat both of the evaporated fuel generated continuously over a long time. For example, in Patent Document 1, an adsorbent layer inside a casing is partitioned into a first adsorbent layer and a second adsorbent layer, and the second adsorbent layer is further divided into a first small adsorbent layer. And a second small adsorbent layer are described (cantilever arrangement). In this canister, a valve that opens when a large amount of evaporated fuel flows is attached, so that it flows to both the first small adsorbent layer and the second small adsorbent layer when refueling, and the valve is closed when parking. Thus, only the first small adsorbent layer of the second adsorbent layer flows.

  However, in the configuration of Patent Document 1, since the evaporated fuel flows to both the first small adsorbent layer and the second small adsorbent layer during refueling, it is preferable to reduce these ventilation resistances (pressure loss). However, if it is too low, evaporated fuel is likely to be released to the atmosphere during parking.

  That is, there is provided an evaporative fuel processing apparatus that can smoothly adsorb evaporative fuel generated during refueling with a low ventilation resistance and that can effectively suppress atmospheric emission from evaporative fuel generated during parking. desired.

JP 2000-64915 A

  In consideration of the above fact, the present invention can smoothly adsorb the evaporated fuel generated during refueling by reducing the airflow resistance, and can effectively suppress the release of air to the evaporated fuel generated during parking. It is an object to obtain an evaporative fuel processing apparatus.

  According to the first aspect of the present invention, when a gas containing the evaporated fuel generated in the fuel tank is passed, a canister main body that adsorbs the evaporated fuel with an adsorbent, and an air opening portion that opens the canister main body to the atmosphere. A blow-off prevention part which is branched from the atmosphere opening part by a branch part and is opened to the atmosphere through a high resistance part having a higher airflow resistance than the atmosphere opening part, and is provided on the atmosphere opening part side of the branch part. A path opening / closing valve for opening and closing the section.

  Therefore, in this fuel vapor processing apparatus, the gas containing the fuel vapor generated in the fuel tank passes through the canister body, and the fuel vapor is adsorbed by the adsorbent in the canister body. The gas path that has passed through the canister main body is branched by the branching portion into the atmosphere opening portion and the blowout prevention portion, and a path opening / closing valve is provided on the atmosphere opening portion side of the branching portion. Therefore, when refueling, the path open / close valve is opened, and the gas is passed through the air-released part that is open to the atmosphere, thereby reducing the airflow resistance for the evaporated fuel generated during refueling and adsorbing the canister body. The agent can be adsorbed smoothly (at this time, part of the gas may pass through the penetration preventing part).

  On the other hand, at the time of parking, if the gas is allowed to pass through the blow-off prevention part having a high resistance part having a higher ventilation resistance than the air release part by closing the path opening / closing valve and closing the air release part, Ventilation resistance can be increased against the evaporated fuel that is sometimes generated, and atmospheric emission can be effectively suppressed.

  According to a second aspect of the present invention, in the first aspect of the present invention, the path opening / closing valve closes the atmosphere opening portion in a normal state, and a tank internal pressure during refueling acts on the fuel tank. It is provided with a valve body that moves in order to open the atmosphere opening portion.

  That is, the path opening / closing valve may be, for example, a valve (electromagnetic valve) that is electromagnetically controlled according to the internal pressure of the fuel tank, but as described in claim 2, By adopting a configuration including a valve body that moves when the tank internal pressure is applied, it is possible to open and close the atmosphere opening portion with a simple structure.

  According to a third aspect of the present invention, in the first or second aspect of the present invention, the high resistance portion includes a second adsorbent that adsorbs the evaporated fuel.

  Therefore, when the gas passes through the high resistance portion during parking, the evaporated fuel can be adsorbed by the second adsorbent. In particular, by using a different type of adsorbent for the canister body as the second adsorbent, it is possible to adsorb evaporated fuel that could not be adsorbed by the adsorbent for the canister body.

  According to a fourth aspect of the present invention, in the third aspect of the present invention, there is provided a flow path expanding portion that locally increases a cross-sectional area of the flow path between the branch portion and the second adsorbent. ing.

  Therefore, when the gas that has passed through the branch portion reaches the flow path enlarged portion, the flow velocity is reduced. In addition, when the evaporated fuel remains slightly in the gas, the evaporated fuel is diffused in the gas, and the concentration of the evaporated fuel is made uniform (however, it is not necessary to be completely uniform). ). For this reason, the adsorption efficiency of the evaporated fuel by the second adsorbent is increased.

  The invention according to claim 5 is the housing according to any one of claims 1 to 4, wherein the housing accommodates the canister body portion, the air release portion, the blow-out prevention portion, and the path opening / closing valve. Have

  In this way, by accommodating the canister main body portion, the air release portion, the blow-off prevention portion, and the path opening / closing valve in the housing, it is possible to reduce the size of the evaporated fuel processing apparatus.

  Since the present invention has the above-described configuration, it is possible to smoothly adsorb the evaporated fuel generated during refueling by reducing the airflow resistance, and to effectively suppress the release of air to the evaporated fuel generated during parking.

It is sectional drawing which shows schematic structure of the evaporative fuel processing apparatus of one Embodiment of this invention. It is sectional drawing which shows the evaporative fuel processing apparatus of one Embodiment of this invention in the state in parking. It is sectional drawing which shows the evaporative fuel processing apparatus of one Embodiment of this invention in the state during refueling. It is sectional drawing which shows the evaporative fuel processing apparatus of one Embodiment of this invention in the state at the time of a purge. It is sectional drawing which shows the evaporative fuel processing apparatus of one Embodiment of this invention in the state at the time of a leak diagnosis.

  FIG. 1 shows a fuel vapor processing apparatus 12 according to an embodiment of the present invention. The fuel vapor processing apparatus 12 has a housing 14 formed in a cylindrical shape or a box shape. Inside the housing 14, filter membranes 18A and 18B made of a nonwoven fabric or the like are provided in parallel to the one end wall 14A and the other end wall 14B.

  Partitions 22 and 30 are provided in the housing 14. The space defined by one partition wall 22, the two filter films 18 </ b> A and 18 </ b> B, and the peripheral wall 14 </ b> S of the housing 14 is filled with an adsorbent 24 made of, for example, pellet-shaped activated carbon, and the first activated carbon layer 26 is formed. It is configured. The first activated carbon layer 26 serves as a canister body 28 according to the present invention. A coil spring 16 is interposed between the other end wall 14B and the filter membrane 18B so that the first activated carbon layer 26 can be maintained in a predetermined shape (capacity).

  A tank-side port 32 and a purge port 34 are provided on the one end wall 14 </ b> A at a position corresponding to the first activated carbon layer 26. A paper pipe is connected to the tank side port 32, and a gas containing evaporated fuel generated in a fuel tank (not shown) is sent into the first activated carbon layer 26. A purge pipe is connected to the purge port 34. During purging, a purge valve (not shown) is opened (or duty controlled), so that the negative pressure of the engine acts on the first activated carbon layer 26. Then, the desorbed evaporated fuel is sent to the engine through the intake pipe and burned.

  In the space defined by the partition wall 22 and the partition wall 30, a second activated carbon layer 38, an on-off valve storage chamber 40, and a pump storage chamber 42 are formed in this order from the other end wall 14B side. An atmospheric side port 36 is provided on the one end wall 14 </ b> A at a position corresponding to the pump housing chamber 42. An atmosphere communication pipe is connected to the atmosphere side port so as to communicate with the atmosphere, and the gas after the evaporated fuel is adsorbed by the evaporated fuel processing device 12 is released to the atmosphere. At the time of purging, the atmosphere is introduced into the evaporated fuel processing apparatus 12 from the atmosphere communication pipe through the atmosphere side port 36.

  The pump storage chamber 42 stores a leak diagnostic pump (not shown). The evaporative fuel processing device 12 has a leakage diagnosis mode that is also controlled by a control circuit (not shown). When this leakage diagnosis mode is executed, a predetermined negative pressure is generated, and this negative pressure is blown through, which will be described later. It acts on the prevention part 66, the 2nd activated carbon layer 38, the 1st activated carbon layer 26, etc.

  In the present embodiment, the second activated carbon layer 38 is filled with the adsorbent 24 composed of pellet-like activated carbon substantially the same as the first activated carbon layer 26. In the present embodiment, the first activated carbon layer 26 and the second activated carbon layer 38 constitute a canister body 28 according to the present invention. However, instead of the second activated carbon layer 38, a hollow layer that is not filled with the adsorbent 24 may be provided. In this case, the first activated carbon layer 26 and the hollow layer constitute the canister body 28. Will be.

  The path opening / closing valve 46 accommodated in the opening / closing valve accommodating chamber 40 includes a flat cylindrical valve holder 48 disposed on the upper side as viewed in FIG. 1 and a bypass portion 50 disposed on the lower side. . In the bypass portion 50, a filter membrane 52A is disposed on the second activated carbon layer 38 side, and a filter membrane 52B is disposed on the pump storage chamber 42 side. A partition wall 54 is provided between the filter membrane 52A and the filter membrane 52B to partition the bypass portion 50 into an upstream bypass chamber 50A on the second activated carbon layer 38 side and a downstream bypass chamber 50B on the pump storage chamber 42 side. Yes.

  The valve holder 48 has a double cylinder structure having an inner cylinder 48N and an outer cylinder 48G, and a diaphragm valve element 56 formed of elastic resin or rubber is accommodated inside the inner cylinder 48N. ing.

  The outer peripheral part of the diaphragm valve body 56 is fixed to the inner peripheral part of the inner cylinder 48N. A compression coil spring 58 is disposed between the upper bottom portion 48U of the inner cylinder 48N and the diaphragm valve body 56. The compression coil spring 58 presses the diaphragm valve body 56 toward the upper end of the partition wall 54 disposed on the opposite side of the compression coil spring 58. In the state where the diaphragm valve body 56 is in contact with the partition wall 54, the upstream bypass chamber 50A and the downstream bypass chamber 50B are not in communication and the gas does not move.

  From the opposite side (lower side in FIG. 1) of the compression coil spring 58, the pressure of the gas in the upstream bypass chamber 50 </ b> A (the gas that has passed through the canister main body 28) acts on the diaphragm valve body 56. Then, by this pressure, the diaphragm valve body 56 is deformed against the pressing force of the compression coil spring 58, and when separated from the partition wall 54, the upstream bypass chamber 50A and the downstream bypass chamber 50B communicate with each other, and the gas flows into the upstream bypass chamber. It becomes possible to move from 50A to the downstream bypass chamber 50B. In addition, the part from the bypass part 50 to the atmosphere side port 36 through the pump storage chamber 42 is the atmosphere release part 60 according to the present invention.

  The valve opening pressure of the diaphragm valve body 56 is not opened by the pressure of gas acting from the fuel tank through the first activated carbon layer 26, the second activated carbon layer 38, and the upstream bypass chamber 50A during parking (including when the vehicle is running). However, during refueling, the valve is set to open at the pressure of the gas acting from the fuel tank through the first activated carbon layer 26, the second activated carbon layer 38, and the upstream bypass chamber 50A.

  A back pressure chamber 62 is formed between the inner cylinder 48N and the outer cylinder 48G of the valve holder 48, and a communication hole 64 is formed in the inner cylinder 48N to communicate the interior with the back pressure chamber 62. The back pressure chamber 62 is opened to the atmosphere by an open pipe (not shown) so that the deformation of the diaphragm valve body 56 is not affected.

  Between the peripheral wall 14 </ b> S of the housing 14 and the partition wall 30, a blow-off prevention unit 66 is accommodated and incorporated in the evaporated fuel processing device 12. The first activated carbon layer 26, the second activated carbon layer 38, the atmosphere opening part 60, the blow-off preventing part 66, and the path opening / closing valve 46 are substantially accommodated in one housing 14.

  The blow-off prevention part 66 is branched from the upstream bypass chamber 50A (atmospheric release part 60) by a branch part 68 provided in the partition wall 30, and is prevented from blowing into the downstream bypass chamber 50B by a merge part 70 similarly provided in the partition wall 30. A tube 72 is provided. After merging at the merging portion 70, the air is communicated with the atmosphere via the pump housing chamber 42.

  The blow-off prevention pipe 72 is bent at a predetermined position, and a blow-through prevention main body 74 is provided at an intermediate portion thereof. The blow-off prevention unit main body 74 is configured by partially expanding the blow-through prevention pipe 72 and accommodating the adsorbent 76 in the enlarged diameter portion. The adsorbent 76 is different from the activated carbon constituting the adsorbent 24 of the first activated carbon layer 26 or the second activated carbon layer 38 (for example, honeycomb-shaped or granular activated carbon, or an activated carbon and an inorganic substance such as a ceramic are mixed). Low adsorbent activated carbon), which is a “second adsorbent” according to the present invention. The adsorbent 76 has a higher gas flow resistance than the adsorbent 24 and is also a “high resistance portion” according to the present invention. On the other hand, the adsorbent 24 is set to have a higher ability to adsorb evaporated fuel than the adsorbent 76, and can adsorb a large amount of evaporated fuel in a short time.

  The blow-off prevention pipe 72 is provided with a throttle 78 at a portion communicating with the upstream bypass chamber 50A. This restriction 78 also increases the airflow resistance of the blow-through prevention pipe 72 to the gas. Particularly in this embodiment, the ventilation resistance is higher than the valve opening pressure of the diaphragm valve body 56.

  Between the aperture 78 and the blow-through prevention main body 74, there is provided an enlarged diameter portion 80 in which the cross-sectional area of the blow-through prevention pipe 72 is locally enlarged. The enlarged diameter portion 80 constitutes a “flow channel enlarged portion” according to the present invention. The flow velocity of the gas that has flowed through the blow-through prevention pipe 72 via the restriction 78 is reduced by the enlarged diameter portion 80. Further, when the evaporated fuel remains slightly in the gas, the remaining evaporated fuel is diffused into the gas in the enlarged diameter portion 80.

  Next, the operation of this embodiment will be described.

  When the vehicle is parked, the internal pressure of the fuel tank acts on the diaphragm valve body 56 through the first activated carbon layer 26, the second activated carbon layer 38, and the upstream bypass chamber 50A. However, the valve opening pressure of the diaphragm valve body 56 is set so as not to open with the fuel tank internal pressure during parking. Therefore, as shown in FIG. 2, the diaphragm valve body 56 maintains the state in contact with the partition wall 54 by the pressing force of the compression coil spring 58 (closed), and the upstream bypass chamber 50 </ b> A and the downstream bypass chamber 50 </ b> B are not in communication. It is said.

  The gas containing the evaporated fuel generated in the fuel tank first passes through the first activated carbon layer 26 and the second activated carbon layer 38 as indicated by an arrow F1 in FIG. ).

  Since the diaphragm valve body 56 is closed and the upstream bypass chamber 50A and the downstream bypass chamber 50B are not in communication with each other, the gas then flows from the upstream bypass chamber 50A through the blow-off prevention portion 66 to the downstream bypass chamber 50B. Then, the air is released from the atmosphere side port 36 and the standby communication pipe through the pump storage chamber 42.

  Even after the gas containing the evaporated fuel generated in the fuel tank during parking passes through the first activated carbon layer 26 and the second activated carbon layer 38, the evaporated fuel remains in the gas. Sometimes. In this case, the remaining evaporated fuel can be adsorbed by the adsorbent 76 of the blow-by prevention unit main body 74.

  In particular, in the present embodiment, the enlarged diameter portion 80 is provided between the diaphragm 78 and the blow-by prevention portion main body 74, and the cross-sectional area of the blow-through prevention tube 72 is locally enlarged. Therefore, the evaporated fuel in the gas is diffused by the enlarged diameter portion 80, and the concentration deviation is made uniform. For this reason, the adsorption efficiency when adsorbing the evaporated fuel by the adsorbent 76 of the blow-by preventing part main body 74 is improved.

  When fuel is supplied to the fuel tank, the internal pressure of the fuel tank acts on the diaphragm valve body 56 via the first activated carbon layer 26, the second activated carbon layer 38, and the upstream bypass chamber 50A. The valve opening pressure of the diaphragm valve body 56 is set so as to open at the fuel tank internal pressure when fuel is supplied to the fuel tank. For this reason, as shown in FIG. 3, the diaphragm valve body 56 moves against the pressing force of the compression coil spring 58 and moves away from the partition wall 54 (opens), so that the upstream bypass chamber 50A and the downstream bypass chamber 50B are separated from each other. Communicated. The gas containing the evaporated fuel generated in the fuel tank first passes through the first activated carbon layer 26 and the second activated carbon layer 38 as indicated by arrows F2 and F3 in FIG. It is adsorbed by the body 24). Thereafter, since the diaphragm valve body 56 is opened and the upstream bypass chamber 50A and the downstream bypass chamber 50B are communicated with each other, most of the gas is directly downstream from the upstream bypass chamber 50A as indicated by an arrow F2. The flow to the chamber 50 </ b> B, that is, the portion where the ventilation resistance is lower than the blow-through preventing portion 66 flows. In particular, since the blow-off prevention unit 66 is configured with a throttle 78, the ventilation resistance is higher than the valve opening pressure of the diaphragm valve body 56 as compared with the one without the throttle 78. For this reason, the amount of gas flowing through the blow-off prevention unit 66 is smaller than the amount of gas passing through the diaphragm valve body 56 (however, the throttle 78 completely prevents a part of the gas from flowing into the blow-through prevention unit 66). Not a thing). Then, the air is released from the atmosphere side port 36 and the standby communication pipe through the pump storage chamber 42.

  As described above, in the evaporative fuel processing apparatus 12 of the present embodiment, when the fuel is supplied to the fuel tank, the ventilation resistance of the evaporative fuel processing apparatus is reduced for the evaporated fuel generated in a large amount in the fuel tank in a short time. Therefore, the first activated carbon layer 26 and the second activated carbon layer 38 can be smoothly adsorbed to the adsorbent 24. Further, the evaporated fuel generated over a long time from the fuel tank during parking can be passed through the blow-off prevention unit 66 having a high ventilation resistance, so that the amount of evaporated fuel released to the atmosphere can be reduced.

  At the time of purging, as shown in FIG. 4, the negative pressure of the engine acts on the evaporated fuel processing device 12 from the purge port 34, and the atmosphere is introduced from the atmosphere side port 36. At this time, since a negative pressure acts on the diaphragm valve body 56 in the valve closing direction, the diaphragm valve body 56 is maintained in the valve closing state. Then, the introduced atmosphere passes through the pump storage chamber 42, the downstream bypass chamber 50B, the blow-by prevention portion 66, the upstream bypass chamber 50A, the second activated carbon layer 38, and the first activated carbon layer 26 as indicated by an arrow F4. At this time, the evaporated fuel adsorbed by the adsorbers 76 and 24 is desorbed. The detached evaporated fuel is sucked into the intake pipe and fueled by the engine according to the control of the valve for the bar (for example, duty control).

  In particular, in the evaporative fuel processing apparatus 12 of the present embodiment, as described above, it is not necessary for the entire amount of the gas including the evaporative fuel to pass through the blow-through prevention unit 66 during refueling to the fuel tank. For this reason, it is possible to raise the ventilation resistance of the blow-off prevention unit 66 to a ventilation resistance that allows gas to pass at least during purging.

  When the leakage diagnosis mode is executed, the leakage diagnosis pump generates a predetermined negative pressure, and this negative pressure is indicated by an arrow F5, and the blow-by prevention unit 66, the second activated carbon layer 38, and the first activated carbon are used. It acts on the layer 26. Also at this time, the diaphragm valve body 56 is maintained in a closed state. Then, since the negative pressure is transmitted to the fuel tank through the downstream bypass chamber 50B, the blow-through prevention portion 66, the upstream bypass chamber 50A, the second activated carbon layer 38, and the first activated carbon layer 26, evaporation is caused by the negative pressure value. It is possible to detect fuel leakage in the system from the fuel processing device 12 to the fuel tank.

  In the above description, as the path opening / closing valve of the present invention, the one provided with the diaphragm valve body 56 opened by the tank internal pressure at the time of fuel supply to the fuel tank has been described. However, as the type of the path opening / closing valve, It is not limited to valves. Further, it does not have to be a mechanically structured valve. For example, the path opening / closing valve may be an electromagnetic valve, and fuel supply to the fuel tank may be detected by a sensor (for example, a lid opening / closing sensor for a fuel supply port) to switch the electromagnetic valve.

  Further, in the above, a structure in which the first activated carbon layer 26, the second activated carbon layer 38, the atmosphere opening portion 60, the blow-off preventing portion 66, and the path opening / closing valve 46 are accommodated and integrated in one housing 14 is exemplified. However, some of these may be separate from others. When the housing is housed and integrated in one housing 14 as in the above embodiment, the fuel vapor processing apparatus 12 can be downsized.

12 Evaporative Fuel Processing Device 14 Housing 24 Adsorbent (Adsorbent)
26 First activated carbon layer 28 Canister main body 32 Tank side port 34 Purge port 36 Atmospheric side port 38 Second activated carbon layer 46 Path open / close valve 50 Bypass part 60 Atmospheric release part 66 Blow-off prevention part 68 Branch part 70 Junction part 74 Blow-off prevention Body 76 adsorbent (second adsorbent)
78 Aperture (path reduction part)
80 Diameter expansion part (path expansion part)

Claims (5)

A canister body that adsorbs the evaporated fuel by an adsorbent when a gas containing the evaporated fuel generated in the fuel tank is passed;
An air release portion for opening the canister body to the atmosphere;
A blow-off prevention part that is branched from the atmosphere opening part by a branch part and is opened to the atmosphere through a high resistance part having a higher ventilation resistance than the atmosphere opening part,
A path on-off valve that opens and closes the atmosphere opening part provided on the atmosphere opening part side of the branch part;
An evaporative fuel processing apparatus.   2. The path opening / closing valve includes a valve body that closes the atmosphere opening portion in a normal state and moves by opening a tank internal pressure when refueling the fuel tank to open the atmosphere opening portion. The evaporative fuel processing apparatus of description.   The evaporated fuel processing apparatus according to claim 1, wherein the high resistance portion includes a second adsorbent that adsorbs the evaporated fuel.   The evaporative fuel processing apparatus according to claim 3, wherein a flow path enlargement section that locally widens a cross-sectional area of the flow path is provided between the branch portion and the second adsorbent.   The evaporative fuel processing apparatus of any one of Claims 1-4 which have the housing which accommodates the said canister main-body part, the said air | atmosphere release part, the said blow-off prevention part, and the said path | route on-off valve.

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