JP4670836B2 - Gas flow promotion mechanism - Google Patents

Description

  The present invention relates to a gas flow promoting mechanism, and in particular, temporarily adsorbs fuel vapor generated in a fuel tank of a vehicle, and promotes gas flow in the vicinity of a canister that supplies the temporarily adsorbed fuel vapor together with air to an intake system of an engine. The present invention relates to a gas flow promotion mechanism.

  A device called a canister is used as a device for preventing fuel evaporated in a fuel tank in a vehicle from diffusing into the atmosphere. This canister contains activated carbon having the property of adsorbing the fuel vapor in contact with the surface and releasing the fuel vapor by the flow of air. Therefore, by disposing the canister between the fuel tank and the intake system of the engine, the fuel vapor generated in the fuel tank can be adsorbed and temporarily stored, and the atmosphere can be introduced into the canister. Thus, the fuel vapor can be supplied together with the atmosphere to the intake system of the engine.

  This activated carbon has a property that the higher the temperature, the easier the fuel vapor can be released, so that the purge capability can be improved, while the lower the temperature, the easier the fuel vapor can be adsorbed. Therefore, while the engine is running, the canister temperature is kept high to improve the purge capacity. Conversely, after the engine is stopped, the canister temperature is kept low to improve the ability to adsorb the fuel vapor generated in the fuel tank. It is desirable to make it.

  As a technique examined from such a viewpoint, for example, techniques described in Patent Documents 1 to 3 can be cited.

  In the canister arrangement structure described in Patent Document 1, the canister is arranged in a front fender isolated from the engine room, and a duct member having an intake port is provided behind a radiator fan arranged in the front part of the vehicle body. In this way, the radiator exhaust air is guided to the canister.

  In addition, in the in-vehicle fuel vapor adsorption device described in Patent Document 2, the canister is disposed in the vicinity of a heat source (muffler or the like) in the vehicle, and a heat shield plate is disposed between the heat source and the canister. The shielding plate is moved according to the temperature of the canister.

  In addition, the fuel tank described in Patent Document 3 makes the inside of the canister negative by the negative pressure in the surge tank, so that high-temperature air in the space between the tank shells flows into the canister, and in the air cleaner or Air having a low temperature is caused to flow into the space between the tank shells from the passenger compartment.

JP-A-8-135525 Japanese Utility Model Publication No. 5-6146 JP 2001-130272 A

  However, in the canister arrangement structure described in Patent Document 1, since the canister is mounted in the vicinity of the fuel tank, piping of the duct member is likely to be difficult in design. In addition, in the in-vehicle fuel vapor adsorption device described in Patent Document 2, since it is necessary to mount a canister in the vicinity of a heat source such as a muffler, the arrangement of the canister and other components is restricted, and the shielding plate is moved. It requires a lot of power to do. Further, in the fuel tank described in Patent Document 3, since the entire fuel tank has a double structure, the fuel tank is increased in size, and there is a possibility that the arrangement of the fuel tank is restricted.

  Therefore, the present invention has been made in view of the above problems, and provides a gas flow promotion mechanism capable of improving the purge performance while avoiding the influence on the arrangement of canisters and other components as much as possible. For the purpose.

  In order to solve the above problems, the present invention covers at least a part of a canister that temporarily adsorbs fuel vapor generated in a fuel tank of a vehicle and supplies the temporarily adsorbed fuel vapor together with air to an intake system of an engine. And a cover part for forming a gas flow path around the canister, the cover part, and a negative pressure generating part for generating a negative pressure by using a venturi effect by a gas flow generated around the vehicle or in the vehicle And a piping part that connects between the two.

  According to this, by the piping part, the cover part that forms a gas flow path around the canister, and the negative pressure generating part that generates a negative pressure by using the venturi effect due to the gas flow generated around the vehicle or in the vehicle, Are connected to each other, the negative pressure generated in the negative pressure generating portion causes the piping portion to also become a negative pressure, so that a gas flow from the periphery of the canister to the negative pressure generating portion occurs. In addition, gas flows from the outside into the channel around the canister. Therefore, even if the canister is likely to be cooled below the temperature of the surrounding gas due to the heat of desorption when the fuel vapor is desorbed in the canister, the surrounding gas flows into the vicinity of the canister. The cooling of the canister can be suppressed as much as possible. Moreover, since the cover part is provided in a state of covering at least a part of the canister, the cover part hardly disturbs the arrangement of the peripheral members. That is, it is possible to improve the canister purge performance while avoiding the influence on the arrangement of the canister and other components as much as possible. Also, by allowing the gas to flow, the canister can be prevented from becoming extremely hot due to the heat of adsorption that occurs when the fuel vapor is adsorbed in the canister. It is also possible to do it automatically.

  In this case, the fuel tank may be disposed in the vicinity of the canister, and the cover portion may form a gas flow path around the fuel tank. In such a case, since the fuel tank can be cooled by allowing the surrounding gas to flow in the vicinity of the fuel tank, the generation of fuel vapor in the fuel tank can be suppressed as much as possible.

  In the present invention, the gas flow generated in the negative pressure generating portion can be either a vehicle speed wind during traveling of the vehicle or a fan wind by a blower fan provided in the vehicle. In the former case, there is an advantage that it is not necessary to prepare a special mechanism for generating a gas flow.

  In this case, the negative pressure generating part has a flow pipe whose inside is the flow path of the gas flow, and the pipe part connects between the cover part and the flow pipe. be able to.

  In the present invention, the gas flow generated in the negative pressure generating unit can be an exhaust gas flow of the vehicle. In such a case, there is an advantage that it is not necessary to prepare a special mechanism for generating the gas flow.

  In this case, the negative pressure generating part has an exhaust gas pipe whose inside is a flow path for the exhaust gas flow, and the pipe part connects between the cover part and the exhaust gas pipe. Can be.

  In this case, it is good also as providing the backflow suppression mechanism which is provided in a part of the said piping part, and suppresses the backflow of the said exhaust gas, and the edge part by the side of the said exhaust gas pipe of the said piping part is the said exhaust gas. It may be inserted into the exhaust gas pipe from the side wall of the pipe, and the center of the opening end of the piping portion may be located below the center of the opening end of the exhaust gas pipe in the gravity direction. good. In the former case, by providing a backflow suppression mechanism, for example, when the exhaust gas pipe is submerged, it is possible to suppress the backflow of exhaust gas to the piping part side. Even if the gas pipe is submerged, the water first enters the pipe portion, so that the exhaust gas can be prevented from flowing backward. Therefore, in any case, it is possible to prevent an excessive temperature rise of the canister due to the backflow of the high-temperature exhaust gas.

  Further, in the present invention, when the gas flow generated in the negative pressure generating portion is an exhaust gas flow of a vehicle, the negative pressure generating portion includes an exhaust gas pipe whose inside is a flow path of the exhaust gas flow. The piping part may have one end connected to the cover part and the other end provided in the vicinity of the exhaust gas outlet of the exhaust gas pipe. In such a case, in addition to the venturi effect due to the exhaust gas flow, the venturi effect due to the vehicle speed wind can also be expected. Therefore, even in a vehicle such as a hybrid vehicle where the engine stops while the vehicle is running, the gas around the canister Can be effectively distributed.

  In this case, the other end portion of the pipe portion may be provided on the upper side in the gravity direction of the exhaust gas pipe, and the other end portion of the pipe portion may be the outlet of the exhaust gas pipe. It may have an annular shape surrounding the periphery with a predetermined interval. In the former case, even if the exhaust gas pipe is submerged, the exhaust gas does not flow back through the piping, and in the latter case, the venturi effect of the exhaust gas is efficiently received, so that the inflow of gas around the canister is effective. Can be done automatically.

  ADVANTAGE OF THE INVENTION According to this invention, the gas distribution promotion mechanism which can improve the purge performance of a canister can be provided, avoiding the influence on arrangement | positioning etc. of a canister and another component as much as possible.

<< First Embodiment >>
Hereinafter, a first embodiment of the present invention will be described in detail with reference to FIGS.

  FIG. 1 schematically shows a partial cross-section of an automobile 100 provided with the gas flow promoting mechanism of the present invention. As shown in FIG. 1, an automobile 100 includes a fuel tank 20, a fuel supply pipe 22 and a fuel supply port 24 for supplying fuel such as gasoline into the fuel tank 20, and a canister disposed in the vicinity of the fuel tank 20. 10, an air cleaner 12 and an outside air introduction pipe 14 through which air passes when taking outside air into the canister 10, and an exhaust gas pipe 30 for exhausting exhaust gas generated by an engine (not shown) to the outside The catalyst 34 and the muffler 32 are provided respectively in the middle of the exhaust gas pipe 30.

  As shown in FIG. 2, the canister 10 includes a box-shaped housing 40, an adsorbent 42 made of activated carbon or the like provided in the housing 40, a connecting pipe 44 that connects the fuel tank 20 and the housing 40, A purge pipe 46 that connects the housing 40 and an intake system (not shown) of the engine, and a purge control valve 48 for adjusting the flow rate provided in the purge pipe 46 are provided. Further, one end of the above-described outside air introduction pipe 14 is connected to the housing 40.

  In the canister 10, for example, when fuel vapor (vapor) is generated in the fuel tank 20 whose temperature has been increased by solar heat, the fuel vapor is introduced into the housing 40 through the connection pipe 44 and is adsorbed on the surface of the adsorbent 42. Adsorbed and temporarily stored. Thereby, it is possible to effectively prevent the evaporated fuel in the fuel tank 20 from being released to the atmosphere. Further, when the outside air is introduced into the housing 40 through the air cleaner 12 and the outside air introduction pipe 14, the fuel vapor temporarily stored on the surface of the adsorbent 42 is supplied to the intake system of the engine together with the outside air (purge). To be). In this case, the adsorbent 42 has a property that the higher the temperature, the easier the adsorbed fuel vapor is released (that is, the higher the temperature of the adsorbent 42, the better the purging ability). In contrast, the lower the temperature of the adsorbent 42, the more the adsorption of fuel vapor on the surface of the adsorbent 42 is promoted (that is, the lower the temperature of the adsorbent 42, the higher the adsorption capacity). is doing.

  FIG. 3 shows an enlarged view of the vicinity of the canister 10 and the fuel tank 20 of FIG. As shown in FIG. 3, a gas flow promotion mechanism 50 is provided in the vicinity of the canister 10 to promote the flow of gas in the vicinity of the canister 10.

  This gas flow promotion mechanism 50 includes a pipe 52 having one end connected to a part of a flow pipe 49 that passes vehicle speed wind (wind flowing from left to right in FIG. 3) flowing under the floor of the automobile 100, and a pipe. The cover part 54 to which the other end part of the part 52 was connected, and the plate-shaped member 56 provided on the fuel tank 20 are provided. The cover portion 54 is provided so as to substantially cover the lower surface and the right surface of the canister 10.

  According to the gas flow promoting mechanism 50 configured as described above, as shown in FIG. 4, when the vehicle speed wind passes through the flow pipe 49 in the direction of arrow A, the inside of the flow pipe 49 is caused by the venturi effect due to this vehicle speed wind. The pressure is reduced (becomes negative pressure). Along with this, the pressure in the piping 52 is also reduced, so that the gas around the canister 10 passes through the gap between the canister 10 and the guide 52 as shown by the dotted arrow B in FIG. 52 and the flow pipe 49. As a result, the area around the canister 10 is also depressurized, and as indicated by the dotted arrow C, gas or the like existing in front of the fuel tank 20 (on the left side of the paper) flows into the area around the canister 10. Yes. The plate-like member 56 has a function as a guide for effectively guiding the gas from the front (left side of the drawing) of the fuel tank 20 to the canister 10.

  As described above, in the first embodiment, since the circulation of the gas around the canister 10 can be promoted, the heat of desorption from the canister 10 (adsorbent 42) when the fuel vapor desorbs in the canister 10. Even if the temperature of the canister 10 is likely to be lower than that of the surrounding gas, the canister 10 is warmed by the gas flowing in from the outside, so that the temperature reduction of the canister 10 can be suppressed as much as possible.

  FIG. 5 schematically shows a simulation result comparing fuel vapor desorption characteristics when the gas flows around the canister 10 and when the gas does not flow. This simulation result shows the relationship between the weight of the canister 10 performing purge (desorption of fuel vapor) and the integrated purge amount. In FIG. 5, the smaller the canister weight is as the integrated purge amount is increased, the better the fuel vapor is desorbed.

  As shown in FIG. 5, when comparing the state in which the gas is introduced into the vicinity of the canister 10 and the state in which the gas is not introduced into the vicinity of the canister 10, the case where the gas is introduced into the vicinity of the canister 10 is It can be seen that the desorption characteristics are better than when not. Further, in this simulation, it has been found that the desorption characteristics when the temperature of the gas flowing into the vicinity of the canister 10 is normal are 10% or more better than when the gas is not allowed to flow into the vicinity of the canister 10.

  As described above in detail, according to the first embodiment, the pipe portion 52 causes the cover portion 54 that forms a gas flow path around the canister 10 and the venturi due to vehicle speed wind generated by the movement of the automobile 100. Since the effect is utilized to connect the flow pipe 49 that generates negative pressure, the negative pressure generated in the flow pipe 49 causes a gas flow from the periphery of the canister 10 to the flow pipe 49. Along with this, gas flows into the flow path around the canister 10 from the outside. Therefore, even if the canister 10 is likely to be cooled below the temperature of the surrounding gas due to the heat of desorption when the fuel vapor is desorbed in the canister 10, the surrounding gas flows into the vicinity of the canister 10. Thus, cooling of the canister 10 can be suppressed as much as possible. Moreover, since the cover part 54 is provided in the state which covers a part of canister 10, the cover part 54 hardly interferes with arrangement | positioning of a peripheral member. That is, the purge performance of the canister 10 can be improved while avoiding the influence on the arrangement of the canister 10 and other components as much as possible. Further, even when the fuel vapor is adsorbed in the canister 10, it is possible to prevent the canister 10 from becoming extremely high due to adsorption heat generated by adsorbing the fuel vapor in the canister 10. It is possible to effectively adsorb the fuel vapor by the adsorbent 42).

  In this case, since the negative pressure is generated by using the Venturi effect due to the vehicle speed wind generated when the automobile 100 moves, the fuel vapor is removed (purged) while the engine is operating (the automobile is moving). By doing so, it is possible to perform an efficient purge.

  Further, in the first embodiment, since the gas flow is generated in the vicinity of the canister 10 by using the negative pressure generated when the vehicle speed wind passes through the flow pipe 49, it is possible to use a separate fan fan or the like. It is not necessary to provide the mechanism in the automobile 100. As a result, it is possible to reduce the number of parts and reduce the power used. However, the present invention is not limited to such a case, and a negative pressure is generated using a fan wind from a blower fan installed in an automobile, and a gas is generated near the canister 10 using the negative pressure. May be distributed.

  In addition, although the case where the gas flow promotion mechanism 50 was employ | adopted was demonstrated in the said 1st Embodiment, it is not restricted to this, The gas flow promotion mechanism 50 as shown to Fig.6 (a) and FIG.6 (b) is shown. It is good to adopt '. In this gas flow promotion mechanism 50 ′, as shown in FIG. 6 (b), the cover member 54 ′ has a size enough to cover approximately half of the upper surface of the fuel tank 20 and substantially the entire upper surface of the canister 10. A plate-like member is adopted. A U-shaped edge 55 is provided on the upper surface of the cover member 54 'so as to protrude upward when viewed from above.

  In the gas flow promotion mechanism 50 ′ configured as described above, when the vehicle speed wind passes through the flow pipe 49 as in the gas flow promotion mechanism 50 of the first embodiment, the flow pipe 49 is caused by the venturi effect of the vehicle speed wind. Since the inside is depressurized (becomes negative pressure) and the inside of the piping part 52 is also depressurized accordingly, as shown by a dotted arrow in FIG. A gas flows into the upper side of 20, and the gas passes through the upper side of the canister 10 and flows into the flow pipe 49 through the pipe portion 52.

  Therefore, according to the gas flow promoting mechanism 50 ′, heat that stays in the upper part of the canister 10 and the upper part of the fuel tank 20 even if the canister 10 becomes high temperature due to adsorption heat generated by adsorbing fuel vapor in the canister 10. Can be eliminated by gas flowing in from the outside. Thereby, adsorption of fuel vapor by canister 10 (adsorbent 42) can be performed effectively. Moreover, it is possible to reduce the generation of fuel vapor by cooling the fuel tank 20. Furthermore, since the temperature of the canister 10 can be prevented from being extremely lowered by the desorption heat taken when the fuel vapor is desorbed in the canister 10, the purge performance of the canister 10 can be improved. is there.

<< Second Embodiment >>
Next, a second embodiment of the present invention will be described based on FIGS. 7 (a) and 7 (b).

  FIG. 7A shows a gas flow promoting mechanism 150 according to the second embodiment. As can be seen from a comparison with the first embodiment (see FIG. 3 and the like) described above, the gas flow promoting mechanism 150 is replaced with a cover portion instead of the piping portion 52 that connects the cover portion 54 and the flow tube 49. The difference is that a pipe portion 52 ′ is provided to connect between the exhaust gas pipe 54 and the exhaust gas pipe 30.

  As shown in FIG. 7B, one end of the piping part 52 ′ is inserted into the exhaust gas pipe 30. Further, the opening on the one end side of the pipe portion 52 ′ is open toward the rear in the direction in which the exhaust gas flows.

  In the second embodiment, by adopting the configuration as described above, the inside of the exhaust gas pipe 30 becomes a negative pressure due to the venturi effect due to the exhaust gas flowing through the exhaust gas pipe 30, and accordingly, the piping portion 52 ′. Since the inside also has a negative pressure, the gas around the canister 10 flows into the exhaust gas pipe 30 through the pipe portion 52 ′ and the fuel tank 20 is also placed around the canister 10, as in the first embodiment. Gas flows in from the front (left side of the paper).

  As described above, according to the gas flow promotion mechanism 150 of the second embodiment, as in the first embodiment, the canister is moved by the desorption heat that is lost when the fuel vapor is desorbed in the canister 10. Even if it is likely to be cooled below the temperature of the surrounding gas, the cooling of the canister is suppressed as much as possible by the temperature of the inflowing gas. Moreover, since the cover part 54 is provided in a state of covering a part of the canister 10, the cover part 54 hardly interferes with the arrangement of peripheral members. That is, the purge performance of the canister 10 can be improved while avoiding the influence on the arrangement of the canister 10 and other components as much as possible. Further, even when the fuel vapor is adsorbed in the canister 10, it is possible to prevent the canister 10 from becoming extremely high due to adsorption heat generated by adsorbing the fuel vapor in the canister 10. It is possible to effectively adsorb the fuel vapor by the adsorbent 42).

  Further, in the second embodiment, when the amount of air sucked in the intake system of the engine is large, that is, as the purge amount is large, the inflow of gas to the periphery of the canister 10 increases, so the canister is cooled. Effective suppression can be performed and effective purging can be performed.

  Further, according to the second embodiment, in order to generate a gas flow in the vicinity of the canister 10, the negative pressure generated when the exhaust gas flow passes through the exhaust gas pipe 30 is used. It is not necessary to provide another mechanism in the automobile 100. As a result, it is possible to reduce the number of parts and reduce the power used.

  In the second embodiment as well, the cover portion 54 can be changed to a cover portion 54 ′ as shown in FIGS. 6 (a) and 6 (b). In this way, even if the canister 10 reaches a high temperature due to the adsorption heat generated by adsorbing the fuel vapor in the canister 10, the heat staying in the upper part of the canister 10 and the upper part of the fuel tank 20 flows from the outside. The gas can be eliminated by the gas to be absorbed, so that the fuel vapor can be effectively adsorbed by the canister 10. In addition, since the temperature of the canister 10 can be prevented from being drastically reduced due to the heat of desorption when the fuel vapor is desorbed in the canister 10, the purge performance of the canister 10 can be improved. is there. Furthermore, it is possible to reduce the generation of fuel vapor by cooling the fuel tank 20.

  In addition to the configuration of the second embodiment, as shown in FIG. 8A, a check valve (check valve) 60 may be provided in the pipe portion 52 '. By providing such a check valve 60, even when the exhaust gas pipe 30 is submerged, it is possible to prevent the hot exhaust gas from flowing back to the vicinity of the canister 10. Thereby, it is possible to suppress an excessive temperature rise of the canister 10.

  For example, as shown in FIG. 8B, one end of the pipe portion 52 ′ is below the exhaust gas pipe 30 (that is, the center of the pipe portion 52 ′ is the exhaust gas pipe 30). It may be provided at a position located below the center). Even if such a configuration is adopted, as shown in FIG. 8C, when the exhaust gas pipe 30 is submerged, water first enters the pipe portion 52 ', thereby preventing the backflow of the exhaust gas. Therefore, it is possible to suppress an excessive temperature rise of the canister 10 due to the high-temperature exhaust gas flowing backward to the canister 10 side through the pipe portion 52 ′. In the case of FIG. 8B as well, a check valve similar to that in FIG. 8A may be provided in order to improve the exhaust gas backflow prevention capability.

  Further, as shown in FIG. 7B to FIG. 8C, the present invention is not limited to the case where one end portion of the pipe portion 52 ′ is inserted into the exhaust gas pipe 30. For example, as shown in FIG. One end portion of the pipe portion 52 ′ may be provided near the end portion of the exhaust gas pipe 30. Even in this case, it is possible to promote the circulation of the gas in the vicinity of the canister 10 by using the negative pressure generated by the venturi effect of the exhaust gas flow. Further, in the configuration of FIG. 9A, since one end of the pipe portion 52 ′ is provided outside the exhaust gas pipe 30, it is generated due to the Venturi effect of vehicle speed wind generated around the exhaust gas pipe 30. It is also possible to promote the circulation of the gas in the vicinity of the canister 10 using the negative pressure.

  Further, instead of FIG. 9A, as shown in FIG. 9B, a diffuser 61 is provided in a state of surrounding the exhaust gas pipe 30, and one end portion of the pipe portion 52 ′ is attached to the diffuser 61. It may be connected. Also in this case, as in the case of FIG. 9A, the negative pressure generated due to the exhaust gas flow in the exhaust gas pipe 30 and the vehicle speed passing through the gap between the diffuser 61 and the exhaust gas pipe 30. It is possible to promote the circulation of gas in the vicinity of the canister 10 by using the negative pressure generated due to the wind.

  9 (a) and 9 (b), the vicinity of the canister 10 is obtained by using the negative pressure generated due to the exhaust gas flow and the negative pressure generated due to the vehicle speed wind. For example, by applying this example to a hybrid vehicle in which the engine stops even during operation, it is possible to effectively distribute the gas around the canister 10. is there.

  In each of the above embodiments, the case where an external gas is allowed to flow around the canister has been described. However, the present invention is not limited to this. For example, a high-temperature gas (for example, the exhaust gas pipe 30 is warmed around the canister). It is also possible to provide a mechanism (a mechanism including a switching valve) that can selectively flow either a gas or the like and a low-temperature gas (external gas). In this case, when the canister 10 is cold, purge is promoted by flowing a high-temperature gas, and when the canister 10 is warm, low-temperature gas is flowed to promote adsorption of fuel vapor. It can be. As this switching valve, a control valve that switches based on the detection result of the temperature sensor may be used, or a thermostat that automatically switches according to the ambient temperature may be used.

  The embodiment described above is a preferred embodiment of the present invention. However, the present invention is not limited to this, and various modifications can be made without departing from the scope of the present invention.

It is a figure which shows roughly the automobile provided with the gas distribution promotion mechanism of the present invention in a partial cross section. It is a figure which shows the internal structure of the canister of FIG. It is a figure which expands and shows the vicinity of the canister and fuel tank of FIG. It is a figure for demonstrating the flow of the gas in the structure of FIG. It is a figure which shows the effect of 1st Embodiment. It is a figure which shows the modification of 1st Embodiment. It is a figure which shows 2nd Embodiment. It is FIG. (1) which shows the modification of 2nd Embodiment. It is a figure (the 2) which shows the modification of 2nd Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Canister 20 Fuel tank 30 Exhaust gas pipe 49 Distribution pipe 52 Piping part 54 Cover part 60 Check valve 100 Automobile

Claims (11)

Temporarily adsorbs fuel vapor generated in the fuel tank of the vehicle, covers at least part of the canister that supplies the temporarily adsorbed fuel vapor to the intake system of the engine together with air, and forms a gas flow path around the canister A cover part to be
A gas flow promotion mechanism comprising: the cover portion; and a piping portion that connects between a negative pressure generating portion that generates a negative pressure using a venturi effect generated by a gas flow generated around or in the vehicle. The fuel tank is disposed in the vicinity of the canister;
The gas flow promotion mechanism according to claim 1, wherein the cover part also forms a gas flow path around the fuel tank. The gas flow generated in the negative pressure generating unit is either a vehicle speed wind during traveling of the vehicle or a fan wind by a blower fan provided in the vehicle. Gas distribution promotion mechanism. The negative pressure generating part has a flow pipe whose inside is a flow path of the gas flow,
The said piping part connects between the said cover part and the said distribution pipe, The gas distribution promotion mechanism of Claim 3 characterized by the above-mentioned. The gas flow promotion mechanism according to claim 1 or 2, wherein the gas flow generated in the negative pressure generating portion is an exhaust gas flow of the vehicle. The negative pressure generating portion has an exhaust gas pipe whose inside is a flow path for the exhaust gas flow,
The gas distribution promotion mechanism according to claim 5, wherein the pipe portion connects the cover portion and the exhaust gas pipe. The gas flow promotion mechanism according to claim 6, further comprising a backflow suppression mechanism that is provided in a part of the piping portion and suppresses the backflow of the exhaust gas. The end of the pipe part on the exhaust gas pipe side is inserted into the exhaust gas pipe from the side wall of the exhaust gas pipe, and the center of the open end of the pipe part is the opening of the exhaust gas pipe The gas flow promotion mechanism according to claim 6, wherein the gas flow promotion mechanism is located below the center of the end in the direction of gravity. The negative pressure generating portion has an exhaust gas pipe whose inside is a flow path for the exhaust gas flow,
6. The gas flow promotion according to claim 5, wherein one end of the pipe part is connected to the cover part and the other end is provided in the vicinity of the exhaust gas outlet of the exhaust gas pipe. mechanism. The gas flow promotion mechanism according to claim 9, wherein the other end portion of the pipe portion is provided on the upper side in the gravity direction of the exhaust gas pipe. The gas flow promotion mechanism according to claim 9, wherein the other end of the pipe portion has an annular shape surrounding the outlet of the exhaust gas pipe with a predetermined interval.

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