FUEL TANK STRUCTURE

A fuel tank structure includes: a fuel tank that is installed in an automobile and that accommodates fuel; a bag-shaped member that is fixed to a ceiling portion of an interior of the fuel tank, and that is formed in the shape of a bag and includes a reflecting film that reflects laser light, and whose state of contact with the fuel is maintained due to the bag-shaped member inflating or deflating in accordance with a height of a liquid surface of the fuel accommodated in the fuel tank; and a distance meter that irradiates laser light toward the bag-shaped member from the ceiling portion or a bottom portion of the fuel tank, and detects reflected light that is reflected from the reflecting film, and measures a distance to a contacting portion of the bag-shaped member and the fuel.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority under 35 USC 119 from Japanese Patent Application No. 2015-121261 filed Jun. 16, 2015, the disclosure of which is incorporated by reference herein.

BACKGROUND

Technical Field

The present invention relates to a fuel tank structure.

Related Art

A fuel tank structure, in which an expanding/contracting film that is bag-shaped (a bag-shaped member) that can inflate and contract is provided within a fuel tank, is disclosed in Japanese Patent Application Laid-Open (JP-A) No. H8-170568 as a fuel tank structure that is installed in an automobile. Further, this JP-A No. H8-170568 discloses a technique of suppressing the generation of evaporated fuel from the liquid surface of the fuel by inflating or contracting the expanding/contracting film so as to cover the liquid surface of the fuel.

SUMMARY

However, in a case in which a fuel meter is disposed within the fuel tank that is disclosed in the above-described document, the float of the fuel meter interferes with the bag-shaped member, and therefore, it is difficult to sense the remaining amount of the fuel well. Further, if the bag-shaped member is made to be small and the fuel meter is disposed within the fuel tank, the surface area over which the fuel is covered by the bag-shaped member is small, and the effect of suppressing the generation of evaporated fuel is reduced.

In view of the above-described circumstances, an object of the present invention is to provide a fuel tank structure that can sense the remaining amount of fuel well, while suppressing generation of evaporated fuel.

A fuel tank structure of a first aspect includes: a fuel tank that is installed in an automobile and that accommodates fuel; a bag-shaped member that is fixed to a ceiling portion of an interior of the fuel tank, and that includes a reflecting film that reflects laser light, a state of contact of the bag-shaped member with the fuel being maintained due to the bag-shaped member inflating or deflating in accordance with a height of a liquid surface of the fuel accommodated in the fuel tank; and a distance meter that irradiates laser light toward the bag-shaped member from the ceiling portion or a bottom portion of the fuel tank, and detects reflected light that is reflected from the reflecting film thereby measuring a distance to a contacting portion of the bag-shaped member and the fuel.

In the fuel tank structure of the first aspect, the bag-shaped member is fixed to the ceiling portion of the fuel tank interior. This bag-shaped member maintains a state of contact with the fuel by inflating or deflating in accordance with the height of the liquid surface of the fuel. Due thereto, the liquid surface of the fuel can be covered by the bag-shaped member, regardless of the height of the liquid surface of the fuel. Namely, generation of evaporated fuel can be suppressed.

The bag-shaped member is structured to include the reflecting film that reflects laser light. Further, the fuel tank structure is provided with the distance meter that irradiates laser light toward the bag-shaped member from the ceiling portion or the bottom portion of the fuel tank, and detects the reflected light that is reflected at the reflecting film. Due thereto, in a case in which laser light is irradiated from the ceiling portion of the fuel tank, when the laser light irradiated from the distance meter reaches the contacting portion of the bag-shaped member and the fuel, the laser light is reflected by the reflecting film that structures the bag-shaped member. Due to the distance meter sensing the reflected light, the distance meter can measure the distance from the ceiling portion of the fuel tank to the liquid surface of the fuel. On the other hand, in a case in which laser light is irradiated from the bottom portion of the fuel tank, when the laser light that is irradiated from the distance meter passes-through the fuel and reaches the contacting portion of the bag-shaped member and the fuel, the laser light is reflected by the reflecting film that structures the bag-shaped member. Due to the distance meter sensing the reflected light, the distance meter can measure the distance from the bottom portion of the fuel tank to the liquid surface of the fuel. By measuring the distance to the contacting portion of the bag-shaped member and the fuel in this way, the remaining amount of the fuel can be sensed well.

In a fuel tank structure of a second aspect, in the first aspect, the bag-shaped member is made to be a three-layer structure in which both surfaces of the reflecting film are sandwiched by resin layers, and one of the resin layers that is positioned at a side onto which laser light is irradiated with respect to the reflecting film is formed of a resin that is transparent.

In the fuel tank structure of the second aspect, the reflecting film can be prevented from contacting fuel or air, due to the both surfaces of the reflecting film being sandwiched by the resin layers. Due thereto, the reflecting film is protected, and the state of the reflecting film can be maintained good. Further, by forming the resin layer, that is at the side onto which the laser light is irradiated, from a resin that is transparent, the laser light can be transmitted all the way to the reflecting film even in a case in which the reflecting film is protected by the resin layer.

In a fuel tank structure of a third aspect, in the first aspect or the second aspect, the distance meter irradiates laser light from the ceiling portion of the fuel tank toward the bottom portion of the fuel tank.

In the fuel tank structure of the third aspect, because the laser light that is irradiated from the distance meter does not pass-through the fuel, a deterioration in the accuracy of the distance meter can be suppressed as compared with a structure in which laser light is irradiated from the bottom portion.

As described above, in accordance with the fuel tank structure of the first aspect, there is the excellent effect that the remaining amount of fuel can be sensed well, while generation of evaporated fuel is suppressed.

In accordance with the fuel tank structure of the second aspect, there is the excellent effect that a deterioration in the sensing accuracy of the distance meter, that is due to deterioration of the bag-shaped member over time, can be suppressed.

In accordance with the fuel tank structure of the third aspect, there is the excellent effect that the accuracy of sensing the remaining amount of fuel can be maintained good.

DETAILED DESCRIPTION

First Embodiment

A fuel tank structure relating to a first embodiment is described hereinafter with reference toFIG. 1throughFIG. 5. Note that arrow UP that is shown appropriately in the respective drawings indicates the upper side of a fuel tank. Further, in the present embodiment, the upper side of the fuel tank and the upper side in the vehicle vertical direction coincide with one another.

As shown inFIG. 1, a fuel tank10, that structures the fuel tank structure relating to the present embodiment, is formed in a hollow shape, and is formed in a shape (e.g., the shape of a substantially parallelepiped box) that can accommodate liquid fuel (hereinafter called “fuel GS”) in the interior thereof. Further, the lower surface of the fuel tank10is supported by an unillustrated tank band. The fuel tank10is mounted to an unillustrated floor panel due to this tank band being fixed to the floor panel via brackets or the like.

A filler pipe12that is substantially tubular is connected to the fuel tank10. A refueling port12A is formed in the upper end portion of the filler pipe12. Refueling is carried out due to a refueling gun being inserted into this refueling port12A and the fuel GS being filled into the fuel tank10. Note that, in a case in which there is a large amount of the fuel GS within the fuel tank10, some of the fuel GS is accommodated in the filler pipe12as well.

The refueling port12A at the upper end of the filler pipe12is opened and closed by a fuel cap14. An unillustrated fuel lid, that is provided at a side panel or the like of the vehicle body, is disposed at the outer side of the fuel cap14.

In the closed state, the fuel cap14closes-off the refueling port12A, and limits access of a refueling gun to the filler pipe12. In contrast, when the fuel cap14is opened, the refueling port12A of the filler pipe12is opened, and access of a refueling gun to the refueling path is possible.

Further, an unillustrated fuel pump is disposed within the fuel tank10. The fuel GS that is accommodated in the fuel tank10is supplied to an engine by this fuel pump.

Here, a bag-shaped member16is fixed to a ceiling portion10A of the fuel tank10interior. The bag-shaped member16is formed in the shape of a bag that can inflate and deflate and whose upper portion is open. Due to the upper end portion of the bag-shaped member16being fixed to the ceiling portion10A, the opening is blocked by the ceiling portion10A. Further, as shown inFIG. 4, the bag-shaped member16is made to be a three-layer structure that includes a metal film20that serves as a reflecting film, and a resin layer18and a resin layer22that are provided at the both surfaces of the metal film20so as to sandwich the metal film20. Note that the upper side in the drawing ofFIG. 4is the inner surface side of the bag-shaped member16, and the lower side in the drawing is the outer surface side of the bag-shaped member16. Further, “can inflate and deflate” here is not limited to a structure in which the bag-shaped member16itself expands and contracts, and includes members that are bag-shaped and whose volumes are variable such that they deflate by being folded-up and inflate by being unfolded.

The metal film20that structures the bag-shaped member16is formed of a metal such as aluminum or an aluminum alloy or the like that reflects laser light. Further, the resin layer18and the resin layer22are formed of thermoplastic resins, and the resin layer18is layered on the inner surface side of the metal film20. Moreover, the resin layer18is formed from a resin that is transparent. On the other hand, the resin layer22is layered on the outer surface side of the metal film20, and is formed from a resin that is opaque. Note that “transparent” here is not limited to a structure that transmits all types of light, including visible light, therethrough, and includes the concept of transmitting at least some types of light.

As shown inFIG. 1, an introducing pipe24for introducing air into the bag-shaped member16is connected to the ceiling portion10A of the fuel tank10. Further, one end portion of the introducing pipe24is disposed within the fuel tank10, and communicates with the internal space of the bag-shaped member16.

The other end portion of the introducing pipe24branches-off into a pipe25for opening to the atmosphere and an air supply pipe27. A pressure regulating valve26is connected to the pipe25for opening to the atmosphere. An opening25A that opens to the atmosphere is formed at the end portion of the pipe25for opening to the atmosphere.

On the other hand, a compressor28is connected to the air supply pipe27. Further, an opening27A that opens to the atmosphere is formed at the end portion of the air supply pipe27. Moreover, the pressure regulating valve26and the compressor28are electrically connected to an ECU (Electronic Control Unit)30that is a control section.

Here, due to the ECU30controlling the pressure regulating valve26and the compressor28, the bag-shaped member16is inflated or deflated in accordance with the height of the liquid surface of the fuel GS that is accommodated in the fuel tank10. Namely, due to the ECU30controlling the pressure regulating valve26and the compressor28, the state of contact of the bag-shaped member16and the fuel GS is maintained. Concretely, as shown inFIG. 2, in a case in which the amount of the fuel GS decreases and the height of the liquid surface falls, the pressure regulating valve26is closed by a signal from the ECU30. Further, the compressor28is operated, and compressed air is introduced into the bag-shaped member16via the air supply pipe27and the introducing pipe24. Due thereto, the bag-shaped member16inflates, and the state of contact of the bag-shaped member16and the liquid surface of the fuel GS is maintained.

On the other hand, in a case in which the liquid surface rises due to the amount of the fuel GS increasing due to refueling or the like, the pressure regulating valve26is opened by a signal from the ECU30. Further, in a case in which the compressor28is operating, the compressor28is stopped by a signal from the ECU30. Due thereto, the pressure of the internal space of the bag-shaped member16falls to atmospheric pressure. Therefore, as the liquid surface of the fuel GS rises, the air at the interior of the bag-shaped body16is pushed-out into the introducing pipe24and is discharged-out from the opening25A. In this way, the state of contact of the bag-shaped member16and the liquid surface of the fuel GS is maintained.

Here, the ECU30is electrically connected to a distance meter32and a display portion34. The distance meter32is disposed at the upper portion of the fuel tank10, and is formed in a substantially cylindrical shape. Further, as shown inFIG. 3, the distance meter32is disposed at the central portion of the fuel tank10, as seen from a bottom portion10B side.

Moreover, as shown inFIG. 1, an illuminating section, that is not shown and that irradiates laser light, and a light-receiving section, that is not shown and that receives reflected light, are provided at the distance meter32. Further, a through-hole10C is formed in the ceiling portion10A of the fuel tank10, and the laser light can be irradiated from this through-hole10C toward the bottom portion10B of the fuel tank10. Note that, because the through-hole10C communicates with the internal space of the bag-shaped member16, the laser light is irradiated from the distance meter32toward the interior of the bag-shaped member16. Further, the region between the distance meter32and the fuel tank10is sealed, and the air at the interior of the bag-shaped member16is prevented from leaking from the through-hole10C.

The laser light that is irradiated from the distance meter32advances directly to contacting portion P of the bag-shaped member16and the fuel GS, and is reflected by the metal film20that structures the bag-shaped member16. Further, the reflected light that is reflected at the metal film20is detected by the distance meter32. Then, the distance meter32measures distance L1from the distance meter32to the reflecting portion (the contacting portion P of the bag-shaped member16and the fuel GS) by determining the difference between the wavelength of the reflected light and a reference wavelength.

The distance L1that is measured by the distance meter32is transmitted to the ECU30. Here, the relational expression of the remaining amount of the fuel GS and the distance that is measured by the distance meter32(the distance from the distance meter32to the contacting portion P) is as per the graph shown inFIG. 5. As shown by this graph, the shorter the distance from the distance meter32to the contacting portion P, the greater the remaining amount of the fuel GS, and, the longer the distance from the distance meter32to the contacting portion P, the smaller the remaining amount of the fuel GS. On the basis of this relational expression shown inFIG. 5, the ECU30computes the remaining amount of the fuel GS, and displays the remaining amount of the fuel GS on the display portion34that is a fuel meter or the like that can be seen by a vehicle occupant.

Operation and effects of the fuel tank structure relating to the present embodiment are described next.

The present embodiment uses the distance meter32that irradiates laser light and detects the reflected light thereof and measures the distance, and is structured so as to detect the remaining amount of the fuel GS from this distance that has been measured by the distance meter32. Therefore, there is no need to place a fuel meter such as a float or the like within the fuel tank10. Due thereto, the entire liquid surface of the fuel GS can be covered by the bag-shaped member16, without a fuel meter and the bag-shaped member16interfering with one another. Namely, the remaining amount of the fuel GS can be detected well, while generation of evaporated fuel is suppressed.

Further, in the present embodiment, as shown inFIG. 4, the metal film20can be protected by the structure in which the both surfaces of the metal film20are sandwiched by the resin layer18and the resin layer22. Namely, oxidization and corrosion of the metal film20, due to metal film20contacting the fuel GS or the moisture or the air or the like that is within the fuel tank10, is suppressed, and the state of the metal film20can be maintained good. Further, by forming the resin layer18, that is at the side onto which the laser light is irradiated, to be transparent, the laser light can be transmitted all the way to the metal film20. As a result, the reflected light can be detected well by the distance meter32, and the accuracy of sensing the remaining amount of the fuel GS can be maintained good. Moreover, by providing the metal film20, it is difficult for evaporated fuel to pass-through the bag-shaped member16, as compared with a case in which the bag-shaped member16is formed only by the resin layer18or the resin layer22. Namely, discharging of evaporated fuel into the atmosphere can be suppressed.

Further, because the present embodiment is structured such that laser light is irradiated from the ceiling portion10A of the fuel tank10toward the bottom portion10B, the laser light does not pass-through the fuel GS. In particular, in the present embodiment, because laser light is irradiated onto the inner side of the bag-shaped member16, the laser light does not hit evaporated fuel. Due thereto, a deterioration in the accuracy of the distance meter32can be suppressed as compared with a structure in which laser light passes-through the fuel GS.

Moreover, in the present embodiment, as shown inFIG. 3, the distance meter32is disposed at the central portion of the fuel tank10. Due thereto, as compared with a structure in which the distance meter32is disposed in the vicinity of a side wall of the fuel tank10, the height of the liquid surface of the fuel GS at the position of measurement does not fluctuate greatly, even in a state in which the fuel tank10is tilted. As a result, the detection accuracy of the distance meter32can be ensured even in a state in which the fuel tank10is tilted.

Second Embodiment

A fuel tank structure relating to a second embodiment is described next with reference to FIGS.

6through8. Note that structures that are similar to those of the first embodiment are denoted by the same reference numerals, and description thereof is omitted as appropriate. Further, inFIG. 6, because the structures before the introducing pipe24are similar to those ofFIG. 1, illustration thereof is omitted.

As shown inFIG. 6, a bag-shaped member52is fixed to a ceiling portion50A of a fuel tank50. Here, as shown inFIG. 7, the bag-shaped member52is a three-layer structure that includes a metal film62that serves as a reflecting film, and a resin layer60and a resin layer64that are provided at the both surfaces of the metal film62so as to sandwich the metal film62. Note that the upper side in the drawing ofFIG. 7is the inner surface side of the bag-shaped member52, and the lower side in the drawing is the outer surface side of the bag-shaped member52.

The metal film62that structures the bag-shaped member52is formed of a metal such as aluminum or an aluminum alloy or the like that reflects laser light. Further, the resin layer60and the resin layer64are formed of thermoplastic resins, and the resin layer60is layered on the inner surface side of the metal film62. Moreover, the resin layer60is formed from a resin that is non-transparent. On the other hand, the resin layer64is layered on the outer surface side of the metal film62, and is formed from a resin that is transparent. Namely, in the present embodiment, the resin layer64that is transparent is provided at the outer surface side onto which laser light is irradiated with respect to the metal film62.

As shown inFIG. 6, a concave portion50C is formed in the central portion of a bottom portion50B of the fuel tank50. A fuel pump54, a filter56and a distance meter58are disposed in this concave portion50C.

The filter56is disposed at the bottom surface of the concave portion50C, and is structured such that the fuel GS, that has passed-through the filter56, is introduced into the fuel pump54. Due thereto, foreign matter within the fuel GS is trapped by the filter56before the fuel GS is introduced into the fuel pump54.

The fuel pump54is a pump that supplies the fuel GS, that is accommodated within the fuel tank50, to the engine. Due to the fuel pump54being disposed in the concave portion50C, the fuel GS can be supplied to the engine even in a case in which the amount of the fuel GS has become low.

The distance meter58has an illuminating portion that is not shown and that irradiates laser light. The distance meter58irradiates laser light from the bottom portion50B of the fuel tank50toward the ceiling portion50A. Further, a light-receiving portion, that is not shown and that detects reflected light, is provided at the distance meter58. The distance meter58measures distance L2from the distance meter32to the reflecting portion (the contacting portion P of the bag-shaped member52and the fuel GS) by determining the difference between the wavelength of the reflected light and a reference wavelength.

Further, the distance meter58is electrically connected to the ECU30(seeFIG. 1). The ECU30computes the remaining amount of the fuel GS on the basis of the results of measurement of the distance meter58. Concretely, the ECU30computes the remaining amount of the fuel GS on the basis of the graph shown inFIG. 8. The graph ofFIG. 8illustrates the relationship between the remaining amount of the fuel GS and the distance measured by the distance meter58(the distance from the distance meter58to the contacting portion P). Further, as shown by this graph, the shorter the distance from the distance meter58to the contacting portion P, the smaller the remaining amount of the fuel GS, and, the longer the distance from the distance meter58to the contacting portion P, the greater the remaining amount of the fuel GS. On the basis of this relational expression of the graph shown inFIG. 8, the ECU30computes the remaining amount of the fuel GS, and displays the remaining amount of the fuel GS on the display portion34that is a fuel meter or the like that can be seen by a vehicle occupant (seeFIG. 1).

Operation and effects of the fuel tank structure relating to the present embodiment are described next.

In the present embodiment, because the distance meter58is disposed at the interior of the fuel tank50, there is no need to ensure space for placement of the distance meter at the outer side of the fuel tank50, as compared with the first embodiment.

Further, because the distance meter58and the fuel pump54are disposed in the concave portion50C, the distance meter58and the fuel pump54interfering with the bag-shaped member52can be suppressed, even in a state in which the bag-shaped member52inflates and contacts the bottom portion50B of the fuel tank50. Other operations are similar to those of the first embodiment.

Although a first embodiment and a second embodiment of the present invention have been described above, the present invention is not limited to the above-described structures and can, of course, be implemented in various forms other than the above-described structures within a scope that does not depart from the gist thereof. For example, although the bag-shaped member is a three-layer structure the above-described embodiments, embodiments are not limited to this, and the bag-shaped member may be a two-layer structure in which a metal film is deposited on a resin layer.

Further, although the above-described embodiments employ a metal film as the reflecting film, embodiments are not limited to this. For example, a sheet that is made of resin and is light-reflective, or the like, may be used.