JP2007303447A - Fuel tank - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel tank ensuring supply of fuel to an engine by using an evaporation fuel processor, even if a fluid level of the fuel in the fuel tank is tilted. <P>SOLUTION: The fuel tank can prevent a fuel fluid level 46 of a chamber 20 from lowering and can reliably supply the fuel to the engine through a pump module 26, even if a tank body 11 has less fuel left therein. For the purpose, a surplus fuel in a sub tank 13, which has been conventionally sent to the outside of the chamber 20 through a second communication passage P2, is sent back to the inside of the chamber 20 not the outside of the chamber 20, even if the fuel in the tank body 11 shifts to one side thereof in a direction opposite to the chamber 20 in which the pump module 26 is accommodated, during driving on a sloping road or in a curve. In particular, the surplus fuel in the sub tank 13 is sent back to the chamber 20 not by gravity but by a jet pump 38 in an active manner. Thus the fuel tank can reliably prevent the fuel fluid level 46 of the chamber 20 from lowering, exceeding a limit level. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a fuel tank in which a tank body and a sub tank communicate with each other through a communication path, and the sub tank and the canister communicate with each other through a charge path.

  A sub-tank that is placed in a lower temperature environment than the main tank is provided separately from the main tank of an automobile fuel tank, and liquefied by supplying evaporated fuel from the gas phase part of the high temperature main tank to the liquid phase part of the low temperature sub tank By returning the liquefied fuel to the main tank, the load on the canister charged with the evaporated fuel is reduced, and the concentration of the evaporated fuel purged from the canister to the intake passage of the engine is lowered to reduce the concentration of the evaporated fuel to the combustion of the engine. It is known from Patent Document 1 below that the effect is reduced.

  By the way, the above-mentioned conventional one can liquefy evaporated fuel generated in the main tank in the sub tank when the temperature of the sub tank is lower than the temperature of the main tank, but the temperature of the sub tank is higher than the temperature of the main tank. In this state, the evaporative fuel cannot be liquefied. Therefore, in order to always allow the evaporative fuel to be liquefied, it is necessary to lower the temperature of the sub tank using the cooling device, and the battery consumes the power consumed by the cooling device. There was a problem of multiplying.

Therefore, according to Japanese Patent Application No. 2005-376027, the present applicant has disclosed a tank body, a sub-tank accommodated in the tank body, a first communication path for communicating a gas phase portion of the tank body and a liquid phase portion of the sub-tank, The vapor communication portion of the fuel tank and the liquid phase portion of the tank main body are connected to each other, and the charge passage that allows the sub tank to communicate with the canister. An evaporative fuel treatment device that can be liquefied effectively was proposed.
Japanese Patent No. 3659005

  By the way, if the fuel tank is made thin to improve its mounting on the vehicle body and the pump module is placed away from the center of the tank body due to layout requirements, it will tilt when running on a slope or turning. There is a possibility that the pump module is exposed upward from the fuel liquid level and hinders fuel supply. In order to solve this problem, it is conceivable to arrange a chamber in the tank body with a small change in the fuel liquid level and to store the pump module in this chamber. It was inevitable that the fuel level would drop and the fuel supply to the engine would become unstable.

  The present invention has been made in view of the above-described circumstances, and an object thereof is to ensure that fuel can be supplied to an engine by using an evaporative fuel processing device even when the fuel level in the fuel tank is inclined. And

  In order to achieve the above object, according to the first aspect of the present invention, the tank main body, the sub tank accommodated in the tank main body, the gas phase portion of the tank main body, and the liquid phase portion of the sub tank are communicated. 1 communication path, 2nd communication path which connects the gas phase part of a sub tank, and the liquid phase part of a tank main body, the charge path which connects a sub tank to a canister, and it arrange | positions in a tank main body and accommodates a pump module in an inside And a fuel tank evaporative fuel discharge suppressing device for supplying at least a part of surplus fuel supplied from the pump module to the engine to the sub tank, wherein the second communication path is connected to the internal space of the chamber. A fuel tank is provided, which is provided with suction means for sucking the fuel in the sub-tank into the chamber through the second communication passage.

  According to a second aspect of the present invention, in addition to the structure of the first aspect, the suction means is a jet pump that operates with a surplus of fuel supplied to the engine. Is proposed.

  The second jet pump 38 of the embodiment corresponds to the jet pump or suction means of the present invention.

  According to the configuration of the first aspect, the gas phase part of the tank body and the liquid phase part of the sub tank are communicated with each other through the first communication path, and the gas phase part of the sub tank and the liquid phase part of the tank body are communicated with each other through the second communication path. In addition, since the sub-tank and the canister are communicated with each other through the charge passage, when the temperature of the tank body rises, the number of moles of the air / vapor fuel mixture that can exist in the gas phase portion of the tank body decreases, and at the same time As the vapor pressure rises, evaporated fuel is generated from the liquid phase portion to the gas phase portion, so that the air-fuel mixture of the gas phase portion of the tank body and the vaporized fuel mixture are transferred to the liquid phase portion of the sub tank via the first communication path. Supplied. In the air / vapor fuel mixture supplied to the sub tank, the partial pressure of the evaporated fuel is higher than the fuel vapor pressure in the sub tank, so the difference is liquefied in the liquid phase portion of the sub tank.

  Further, when the temperature of the tank body decreases, the number of moles of air-fuel mixture that can exist in the gas phase portion of the tank body increases, and at the same time, the fuel vapor in the gas phase portion becomes liquid phase as the fuel vapor pressure decreases. In order to be liquefied into the part, the air / vapor fuel mixture is supplied from the gas phase part of the sub tank to the liquid phase part of the tank body through the second communication path. At this time, since a mixture of air and evaporated fuel having a relatively low concentration of evaporated fuel is supplied from the canister to the gas phase portion of the sub tank, generation of evaporated fuel from the liquid phase portion according to the fuel vapor pressure of the sub tank Is promoted, the fuel component changes, so-called “withering” occurs, and the fuel vapor pressure in the sub tank decreases. Thereby, liquefaction to the liquid phase part of a sub tank when the temperature of a tank main body rises is accelerated | stimulated.

  Thus, when the temperature of the tank body rises, the evaporated fuel is liquefied in the sub-tank, and conversely, when the temperature of the tank body drops, the evaporated fuel is liquefied in the tank body and the fuel vapor pressure of the sub-tank is lowered. Thus, when the temperature of the tank body rises next time, liquefaction of the evaporated fuel in the sub tank can be promoted.

  Even if the fuel in the tank body is biased in the direction opposite to the chamber due to the inclination or turning of the road surface when the remaining amount of fuel in the tank body is low, it is conventionally returned to the tank body via the second communication path. The surplus fuel in the sub-tank is returned to the chamber instead of the tank body, so that the fuel level in the chamber can be prevented from being lowered and fuel can be supplied to the engine without any problem. In particular, the surplus fuel in the sub tank is not returned to the chamber by gravity, but is actively returned to the chamber by the suction means, so that it is possible to reliably prevent the fuel liquid level in the chamber from falling below the limit value.

  According to the second aspect of the present invention, since the suction means is configured by the jet pump that operates with the surplus of fuel supplied to the engine, the fuel in the subtank is placed in the chamber with a simple structure that does not require a special drive source. Can be aspirated.

  DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below based on examples of the present invention shown in the accompanying drawings.

  1 and 2 show an embodiment of the present invention. FIG. 1 is a cross-sectional view of a fuel tank equipped with an evaporative fuel processing device as viewed from the rear. FIG. 2 shows a state in which the fuel level is biased to the right. FIG.

  As shown in FIG. 1, a fuel tank T of an automobile includes a tank main body 11, and a sub tank 13 whose periphery is covered with a heat insulating material 12 is provided at a high position inside the tank main body 11. The inside of the tank body 11 is divided into a liquid phase portion 14 filled with fuel and a gas phase portion 15 filled with evaporated fuel. When the fuel level 16 changes due to fuel replenishment or fuel consumption, The volume of the phase portion 14 and the volume of the gas phase portion 15 vary. The interior of the sub tank 13 is divided into a liquid phase portion 17 filled with fuel and a gas phase portion 18 filled with evaporated fuel, and the fuel liquid level 19 is basically constant.

  A container-like chamber 20 having an open upper surface is disposed inside the tank main body 11, and a pump module 26 in which a filter 21, a fuel pump 22, a strainer 23, a pressure regulator 24, and a relief valve 25 are integrated is housed therein. Is done. The internal space of the tank main body 11 and the internal space of the chamber 20 communicate with each other through a small communication hole, and the fuel liquid level 16 of the tank main body 11 and the fuel liquid level 46 of the chamber 20 basically coincide with each other. Even if the fuel liquid level 16 of the tank main body 11 fluctuates, the fuel liquid level 46 of the chamber 20 hardly changes.

  The pressure regulator 24 and the relief valve 25 are disposed in the middle of return pipes 28 and 29 that branch from a feed pipe 27 that extends from the strainer 23 to an engine (not shown) and return to the bottom of the chamber 20. A fuel supply passage 30 branched from the return pipes 28 and 29 downstream of the relief valve 25 communicates with the inside of the sub tank 13 via the orifice 31. A first jet pump 33 that sucks the fuel in the tank body 11 into the chamber 20 is provided at the downstream end of the first jet pump passage 32 branched from the fuel supply passage 30 between the relief valve 25 and the orifice 31.

  The gas phase portion 15 of the tank body 11 and the liquid phase portion 17 of the sub tank 13 are connected by the first communication path P1, and the gas phase portion 18 of the sub tank 13 and the liquid phase portion 14 of the tank body 11 (actually the chamber 20) The liquid phase portion is connected by the second communication path P2. An intermediate portion of the first communication passage P1 is exposed upward from the upper surface of the tank body 11, and an evaporated fuel return passage 34 branched from the exposed portion is connected to the vicinity of the fuel filler 36 at the upper end of the filler tube 35. Accordingly, the gas phase portion 15 of the tank body 11 is connected to the vicinity of the fuel filler port 36 via a part of the first communication path P1 and the evaporated fuel return path 34. The evaporative fuel return passage 34 returns the evaporative fuel in the gas phase portion 15 of the tank body 11 to the vicinity of the fuel supply port 36 when the fuel is supplied from the fuel supply port 36 to the filler tube 35 with the fuel supply gun, and ejects it from the fuel supply gun. By returning to the tank body 11 together with the fuel to be discharged, it has a function of preventing outside air from being sucked into the tank body 11. A downstream end of the second communication passage P <b> 2 extending inside the chamber 20 is connected to a second jet pump 38 provided in a second jet pump passage 37 that branches from an intermediate portion of the first jet pump passage 32.

  The height at which the fuel supply passage 30 opens to the sub tank 13 is set equal to the height at which the second communication passage P2 opens to the sub tank 13, and the height is the height of the fuel level 19 of the sub tank 13. The height at which the fuel supply passage 30 opens to the sub tank 13 may be made higher than the height at which the second communication passage P2 opens to the sub tank 13.

  The canister 39 capable of adsorbing evaporated fuel includes a charge port 40, a purge port 41, and a drain port 42. The charge port 40 is connected to a float valve 44 provided at the upper end of the sub-tank 13 by a charge passage 43. 41 is connected to an intake passage (not shown) of the engine via a purge passage 45, and the drain port 42 is released to the atmosphere.

  The fuel level 19 of the sub-tank 13 is higher than the fuel level 16 when the tank body 11 is full, and the height Hp from the fuel level 16 of the tank body 11 to the fuel level 19 of the sub-tank 13 is the first series. The passage P1 is set to be larger than the height Hp ′ at which the passage P1 is submerged below the fuel level 19 of the sub tank 13.

  The height Hv from the opening to the chamber 20 of the second communication path P2 to the fuel liquid level 16 of the tank body 11 is the height Hv from the fuel liquid level 19 of the sub tank 13 to the highest point of the first communication path P1. It is set smaller than ′.

  Next, the operation of the embodiment of the present invention having the above configuration will be described.

  Although the temperature of the fuel tank T rises as the outside air temperature rises during the daytime, the temperature of the tank body 11 is higher than the temperature of the sub-tank 13 covered with the heat insulating material 12, so the gas phase portion of the tank body 11 The number of moles of the air / vapor fuel mixture that can exist in the fuel tank 15 decreases, and at the same time, fuel vapor is generated from the liquid phase portion 14 to the gas phase portion 15 of the tank body 11 as the fuel vapor pressure increases. As a result, the air / vapor fuel mixture in the gas phase portion 15 of the tank body 11 is discharged as bubbles to the liquid phase portion 17 of the sub tank 13 via the first communication path P1 (see arrow a). Since the partial pressure of the evaporated fuel supplied from the tank body 11 is higher than the partial pressure of the evaporated fuel existing in the sub tank 13, the difference is liquefied and dissolved in the liquid phase portion 17 of the sub tank 13. Thereby, the ratio of the evaporated fuel charged in the canister 39 through the charge passage 43 among the evaporated fuel generated in the gas phase portion 15 of the tank body 11 can be reduced, and the canister 39 can be downsized.

  Although the temperature of the fuel tank T also decreases as the outside air temperature decreases at night, the temperature of the tank main body 11 is lower than the temperature of the sub tank 13 covered with the heat insulating material 12, so that the gas phase portion of the tank main body 11 The number of moles of air-fuel mixture that can exist in the fuel tank 15 increases, and at the same time, the evaporated fuel liquefies from the gas phase portion 15 to the liquid phase portion 14 of the tank body 11 as the fuel vapor pressure decreases. As a result, the air-fuel mixture in the gas phase portion 18 of the sub tank 13 is introduced into the liquid phase portion 14 (that is, the chamber 20) of the tank body 11 via the second communication path P2 (see arrow b).

  As described above, when the evaporated fuel in the gas phase portion 18 of the sub tank 13 is sucked by the negative pressure generated in the gas phase portion 15 of the tank main body 11, the outside air sucked from the drain port 42 of the canister 39 causes the canister 39 to enter the canister 39. The charged evaporated fuel is purged, and the purged evaporated fuel flows into the gas phase portion 18 of the sub tank 13 through the charge passage 43 and returns to the liquid phase portion 14 (that is, the chamber 20) of the tank body 11 from there. Thus, a so-called back purge that liquefies is enabled. By performing the back purge while the engine is stopped, the amount (weight) of the evaporated fuel charged in the canister 39 can be kept low, whereby the canister 39 evaporates from the canister 39 to the intake passage of the engine. When purging the fuel, the amount of evaporated fuel in the purge air can be reduced to minimize the influence on the accuracy of engine air-fuel ratio control.

  The air-fuel mixture supplied from the canister 39 to the gas phase portion 18 of the sub-tank 13 by the back purge has a relatively low concentration of evaporated fuel, so that the liquid phase portion 17 corresponds to the fuel vapor pressure of the gas phase portion 18 of the sub-tank 13. Generation of evaporated fuel from the fuel is promoted, and a phenomenon in which the fuel component changes (so-called withering) occurs, and the fuel vapor pressure in the gas phase portion 18 of the sub tank 13 decreases. When the fuel vapor pressure in the gas phase portion 18 of the sub-tank 13 decreases in this way, the liquefaction of the evaporated fuel supplied from the tank body 11 to the sub-tank 13 is more effectively promoted when the temperature of the tank body 11 rises. can do.

  The back purge occurs even in a conventional fuel tank that does not have a sub tank. In this case, the relatively low concentration evaporated fuel purged from the canister is supplied to the fuel tank. The amount of evaporated fuel dissolved in the water becomes relatively small. On the other hand, in the present embodiment, the evaporated fuel purged from the canister 39 is supplied to the tank body 11 (that is, the chamber 20) through the sub-tank 13 to increase its concentration. The amount of evaporated fuel that is dissolved and recovered is relatively large.

  When the fuel level 19 of the sub tank 13 becomes lower than the opening end of the first communication path P1, the evaporated fuel supplied from the tank body 11 via the first communication path P1 can be directly introduced into the liquid phase portion 17 of the sub tank 13. In addition, the fuel in the liquid phase portion 17 is not returned to the tank body 11 via the second communication path P2, and the fuel may become old and change its component, so that the fuel pump 22 supplies the engine to the engine. The excess fuel is supplied to the sub tank 13 via the pressure regulator 24, the relief valve 25, the orifice 31 and the fuel supply passage 30. When the fuel level 19 of the sub-tank 13 becomes higher than the opening at the upper end of the second communication path P2 due to the fuel supplied from the fuel supply path 30, excess fuel passes through the second communication path P2 and the chamber of the tank body 11 By returning to 20, the fuel liquid level 19 of the sub tank 13 is always maintained at a constant height.

  In the present embodiment, the height Hp from the fuel liquid level 16 of the tank body 11 to the fuel liquid level 19 of the sub tank 13 is the height Hp ′ at which the second communication path P2 is submerged below the fuel liquid level 19 of the sub tank 13. The technical meaning is as follows.

  In order to supply the evaporated fuel from the gas phase portion 15 of the tank body 11 to the liquid phase portion 17 of the sub tank 13 via the first communication path P1, the gas phase portion 15 of the tank body 11 and the gas phase portion 18 of the sub tank 13 The pressure difference needs to be larger than the pressure of the fuel column having the height Hp ′. On the other hand, when the pressure difference between the gas phase portion 15 of the tank body 11 and the gas phase portion 18 of the sub tank 13 is larger than the pressure of the fuel column having the height Hp, the fuel in the tank body 11 passes through the second communication path P2. It flows back into the sub tank 13. Therefore, in order to supply the evaporated fuel from the tank body 11 to the sub tank 13 while preventing the fuel from flowing back from the tank body 11 to the sub tank 13, it is necessary to satisfy Hp> Hp ′.

  The height Hp from the fuel level 16 of the tank body 11 to the fuel level 19 of the sub-tank 13 changes according to the fuel level 16 of the tank body 11, and the front fuel level 16 is when the tank body 11 is full. Highest. Therefore, if it is set so that Hp> Hp ′ is satisfied when the tank main body 11 is full, the evaporated fuel is supplied from the tank main body 11 to the sub tank 13 no matter how the liquid level of the tank main body 11 changes. be able to.

  When Hp> Hp ′ is not established when the fuel level 16 of the tank body 11 reaches a predetermined height, the fuel liquid level 16 above the predetermined height supplies evaporated fuel from the tank body 11 to the sub tank 13. Can not do. However, when the fuel level 16 is equal to or higher than the predetermined height, the volume of the gas phase portion 15 is reduced and the amount of evaporated fuel is reduced, so that the fuel level 16 of the tank body 11 is equal to or higher than the predetermined height. Even if it abandons the supply of the evaporated fuel from the tank body 11 to the sub tank 13, there is no particular problem in practical use.

  In the present embodiment, the height Hv from the opening of the second communication path P2 to the tank body 11 (that is, the chamber 20) to the fuel liquid level 16 of the tank body 11 is from the fuel liquid level 19 of the sub tank 13 to the first level. Although it is set smaller than the height Hv ′ up to the highest point of the single communication path P1, the technical meaning thereof is as follows.

  When the pressure of the gas phase portion 18 of the sub tank 13 becomes higher than the pressure of the gas phase portion 15 of the tank main body 11, the evaporated fuel in the gas phase portion 18 of the sub tank 13 is supplied to the tank main body 11 via the second communication path P2. In order to supply the liquid phase portion 15, a pressure difference that overcomes the pressure of the fuel column having a height of Hv is required. On the other hand, when the pressure difference is larger than the pressure of the fuel column having the height Hv ′, the fuel in the liquid phase portion 17 of the sub tank 13 flows backward to the tank body 11 via the first communication path P1. Accordingly, in order to supply the evaporated fuel from the sub tank 13 to the tank body 11m via the second communication path P2 while preventing the fuel from flowing backward from the sub tank 13 to the tank body 11m via the first communication path P1, It is necessary to satisfy Hv <Hv ′.

  As described above, according to the present embodiment, when the temperature of the tank main body 11 rises, the evaporated fuel in the gas phase portion 15 of the tank main body 11 passes through the first communication passage P1 and the liquid in the low-temperature sub tank 13. When the temperature of the tank main body 11 decreases, the vaporized fuel in the gas phase portion 18 of the sub-tank 13 is supplied to the liquid phase portion 14 of the low-temperature tank main body 11 via the second communication path P2. By supplying the liquefied gas to the tank, the generation of the evaporated fuel can be effectively suppressed regardless of the temperature state of the tank body 11 and the sub tank 13. As a result, even if the capacity of the canister 39 is reduced, it is possible not only to prevent the evaporated fuel from being released into the atmosphere, but also to reduce the evaporated fuel purged from the canister 39 to the engine intake system. The accuracy of air-fuel ratio control can be increased.

  Now, as shown in FIG. 2, when the fuel in the tank body 11 is biased to the right side due to the inclination of the road surface or turning due to the remaining amount of fuel in the tank body 11, the fuel liquid in the chamber 20 on the left side The surface 46 is lowered as indicated by the chain line, which may interfere with the fuel supply to the engine by the pump module 26. Therefore, in the present embodiment, the surplus fuel in the sub-tank 13 that has been returned to the outside of the chamber 20 through the second communication path P2 is returned to the inside of the chamber 20 instead of the outside of the chamber 20. The height of the fuel level 46 in the chamber 20 can be forcibly maintained at a high position as shown by the solid line, and fuel can be supplied to the engine without any trouble.

  In particular, the surplus fuel in the sub tank 13 is not returned to the chamber 20 by gravity, but is actively sucked back to the chamber 20 by the second jet pump 38, so that the fuel in the tank body 11 is sucked into the chamber 20. The first jet pump 33 can be assisted by the second jet pump 38 to reliably prevent the fuel liquid level 46 in the chamber 20 from falling beyond the limit value. In addition, since the second jet pump 38 operates with an excess amount of fuel supplied from the pump module 26 to the engine, a special drive source is not required and the structure can be simplified.

  The embodiments of the present invention have been described above, but various design changes can be made without departing from the scope of the present invention.

  For example, in the embodiment, the sub tank 13 and the chamber 20 are spaced apart in the left-right direction, but may be spaced apart in the front-rear direction.

A cross-sectional view of a fuel tank equipped with an evaporative fuel treatment device as seen from the rear The figure which shows the state where the fuel level is biased to the right

Explanation of symbols

11 Tank body 13 Sub tank 14 Liquid phase portion 15 Gas phase portion 17 Liquid phase portion 18 Gas phase portion 20 Chamber 26 Pump module 38 Second jet pump (jet pump, suction means)
39 Canister 43 Charge passage P1 First communication passage P2 Second communication passage

Claims (2)

A tank body (11);
A sub tank (13) housed in the tank body (11);
A first communication path (P1) for communicating the gas phase part (15) of the tank body (11) and the liquid phase part (17) of the sub tank (13);
A second communication path (P2) for communicating the gas phase part (18) of the sub tank (13) and the liquid phase part (14) of the tank body (11);
A charge passage (43) for communicating the sub tank (13) with the canister (39);
A chamber (20) disposed in the tank body (11) and containing the pump module (26) therein,
A fuel tank for supplying at least a part of surplus fuel supplied to the engine from the pump module (26) to the sub tank (13),
A suction means (38) for connecting the second communication path (P2) to the internal space of the chamber (20) and sucking the fuel in the sub tank (13) into the chamber (20) through the second communication path (P2). A fuel tank provided. 2. The fuel tank according to claim 1, wherein the suction means is a jet pump (38) that operates with a surplus of fuel supplied to the engine.

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