JP2014145745A - Fuel tank structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel tank structure capable of reducing errors in liquid level detection even if fuels different in electrostatic capacity characteristics are supplied.SOLUTION: A fuel tank structure has a cylindrical body 38 which surrounds a side of a liquid level detection sensor 26L arranged along the vertical direction in the inside of a fuel tank 14 and extends in the vertical direction. When a state where a lid of an oil supply port is opened and fuel is supplied to the fuel tank from an inlet pipe is detected, a fuel pump 40 is driven, fuel in a sub cup 24 is sucked from a fuel suction port 42 and the sucked fuel is sent out to an engine through a fuel send-out pipe 44. Furthermore, fuel is introduced into a cylindrical body via the branched fuel introduction piping 50A through a fuel introduction pipe 50 from the fuel pump, the liquid level is detected by the liquid level detection sensor arranged inside an outer wall 38A of the cylindrical body, and fuel properties are detected by a fuel property detection sensor 26R arranged on the sub cup side of an inner wall 38B. An oil supply state is determined on the basis of opening/closing of the lid, the presence/absence of fluctuation of a fuel liquid level, the presence/absence of change of fuel properties and so on.

Description

  The present invention relates to a fuel tank structure.

  In a fuel tank of an automobile, it is desired to accurately detect the liquid level of the contained fuel. For example, Patent Document 1 describes a liquid level measuring device in which first to third cylinders penetrating the upper and lower sides of a sub tank are provided, and a measurement electrode unit and a reference electrode unit are configured by these cylinders. In this liquid level measuring device, the reference electrode portion is filled with fuel in the sub tank, and the liquid level is detected by the measuring electrode portion communicated with the main tank.

  By the way, fuel with different capacitance characteristics (for example, fuel with different mixing ratio of gasoline and ethanol) may be supplied into the fuel tank. In the structure in which the liquid level is detected from the capacitance of the capacitance sensor, it may be difficult to accurately detect the liquid level when fuel having different capacitance characteristics contacts the capacitance sensor.

Japanese Patent Laid-Open No. 2-087022

  In view of the above facts, an object of the present invention is to obtain a fuel tank structure capable of reducing an error in liquid level detection even when fuels having different capacitance characteristics are supplied.

  According to the first aspect of the present invention, a fuel tank capable of containing fuel therein, and a liquid level detection sensor that is disposed along the vertical direction inside the fuel tank and whose capacitance changes according to the fuel contact range. And a cylinder that surrounds the side of the liquid level detection sensor and extends in the vertical direction and is open at the bottom, and a sub-cup that is provided in the fuel tank and accommodates fuel in the fuel tank And a fuel supply state detection means for detecting a fuel supply state to the fuel tank, and an introduction means for introducing the fuel in the sub-cup into the cylinder when the fuel supply state detection means detects the fuel supply to the fuel tank. Have.

  In this fuel tank structure, the liquid level of the fuel in the fuel tank can be detected from the capacitance of the liquid level detection sensor.

  The side of the liquid level detection sensor is surrounded by a cylinder over the vertical direction, but the lower part of the cylinder is open. Therefore, fuel can enter and exit from the bottom of the cylinder.

  In this fuel tank structure, part of the fuel in the fuel tank is accommodated (stored) in the sub-cup.

  At the time of fuel supply detection in which it is detected that the fuel is supplied to the fuel tank by the fuel supply state detection sensor, the introducing means introduces the fuel in the sub cup into the cylinder. The introduced fuel is discharged from the bottom of the cylinder to the outside of the cylinder (inside the fuel tank), and the liquid level in the cylinder becomes equal to the liquid level outside the cylinder (inside the fuel tank).

  Therefore, even when fuel having characteristics different from the fuel remaining in the fuel tank (hereinafter referred to as “different fuel”) is supplied, the fuel remaining in the sub-cup before refueling. Is introduced into the cylinder. Since the fuel properties are made uniform in the cylinder, it is possible to reduce errors in the detected liquid level by the liquid level detection sensor.

  In addition, when fuel is supplied to the fuel tank, the fuel in the sub-cup is introduced into the cylinder, and the fuel properties are made uniform in the cylinder. Therefore, even when the liquid level is detected in a short time after refueling, it is possible to reduce the error in the detected liquid level.

  According to a second aspect of the present invention, in the first aspect of the present invention, the introduction means includes a fuel pump for sending the fuel in the sub-cup to the outside of the fuel tank, and fuel sucked by the fuel pump. A fuel delivery pipe for delivering the fuel to the outside, and an introduction pipe communicating from the fuel delivery pipe to the cylindrical body.

  The fuel pump pumps up the fuel in the sub-cup and sends it out of the fuel tank. Compared with a configuration without a sub-cup, the phenomenon of fuel separating from the suction port of the fuel pump can be suppressed.

  The fuel sucked by the fuel pump flows through the fuel delivery pipe. A part of the fuel in the fuel delivery pipe can be introduced into the cylinder through the introduction pipe. In practice, the fuel in the sub cup can be introduced into the cylinder with a simple structure in which the introduction pipe is provided.

  According to a third aspect of the present invention, in the first aspect of the present invention, the introduction means includes a pump that pumps fuel in the fuel tank into the sub-cup and a sub that closes the upper surface of the sub-cup. A cup lid, and an introduction flow path communicating with the cylindrical body from an introduction hole formed in the sub-cup lid.

  Since the upper surface of the sub cup is closed by the sub cup lid, when the fuel is pumped into the sub cup by the pump, a part of the fuel in the sub cup is taken from the introduction hole formed in the sub cup lid, It is introduced into the cylinder through the introduction channel. The introduction means can be configured with a simple structure in which a pressure pump, a sub-cup lid and an introduction flow path are provided.

  According to a fourth aspect of the present invention, in the first aspect of the present invention, the outlet of the fuel from the introduction means in the cylinder is more than the full tank level of the fuel tank. Is also above.

  If the outlet of the fuel from the introduction means is below the full tank level in the cylinder, the fuel in the cylinder will flow out of the introduced fuel when the introduced fuel flows out into the cylinder while the outlet is submerged. Become resistance to flow. On the other hand, when the outlet is above the full tank level in the cylinder, such resistance does not occur, and smooth fuel introduction is possible.

  The invention according to claim 5 is the property detection sensor according to any one of claims 1 to 4, wherein the property detection sensor is arranged inside the fuel tank and changes in capacitance according to the property of the fuel. Have.

  In the property detection sensor, the capacitance changes according to the property of the fuel. Based on this, the liquid level detected by the liquid level detection sensor can be corrected, and more accurate liquid level detection is possible.

  According to a sixth aspect of the present invention, in the fifth aspect of the present invention, the property detection sensor is provided in the sub cup.

  Since the fuel is contained in the sub-cup and the property detection sensor is provided, the fuel in the sub-cup becomes the property detection sensor even when the fuel level is inclined as compared to the configuration without such a sub-cup. The contact state can be maintained more reliably.

  Since the present invention has the above-described configuration, errors in liquid level detection can be reduced even when fuels having different capacitance characteristics are supplied.

It is the front which shows the fuel tank structure of 1st Embodiment of this invention with an engine and fuel supply piping. It is a schematic perspective view which shows the fuel pump module which comprises the fuel tank structure of 1st Embodiment of this invention. FIG. 3 is a cross-sectional view taken along line 3-3 of FIG. 2 showing the fuel pump module constituting the fuel tank structure of the first embodiment of the present invention together with a part of the fuel tank. FIG. 4 is a cross-sectional view taken along line 4-4 of FIG. 2 showing the fuel pump module constituting the fuel tank structure of the first embodiment of the present invention. It is a front view which shows partially the electrostatic capacitance sensor unit used for the fuel tank structure of 1st Embodiment of this invention. It is sectional drawing which shows the state before the fuel supply in the fuel tank structure of 1st Embodiment of this invention with the cross section similar to FIG. It is sectional drawing which shows the state during fueling in the fuel tank structure of 1st Embodiment of this invention by the cross section similar to FIG. It is a flowchart which shows the flow of the liquid level determination in the fuel tank structure of 1st Embodiment of this invention. It is sectional drawing which shows the fuel pump module which comprises the fuel tank structure of a comparative example with a part of fuel tank. It is a graph which shows the electrostatic capacitance of the liquid level detection sensor after refueling to a fuel tank, and the electrostatic capacitance ratio of a liquid level detection sensor and a fuel property sensor in each case of 1st Embodiment of this invention and a comparative example. It is sectional drawing which shows the fuel pump module which comprises the fuel tank structure of 2nd Embodiment of this invention with a cross section similar to FIG. 3 with a part of fuel tank. It is sectional drawing which shows the fuel pump module which comprises the fuel tank structure of 3rd Embodiment of this invention with a cross section similar to FIG. 3 with a part of fuel tank. It is sectional drawing which shows the fuel pump module which comprises the fuel tank structure of 4th Embodiment of this invention by the cross section similar to FIG. 3 with a part of fuel tank. It is a front view which shows partially the electrostatic capacitance sensor unit of the structure different from FIG. 5 applicable to this invention.

  FIG. 1 shows a fuel tank structure 12 according to a first embodiment of the present invention together with a fuel supply pipe 52 for supplying fuel to an engine 20. FIG. 2 is a perspective view of the fuel pump module 22 (sub-cup 24 and the vicinity thereof) used in the fuel tank structure 12.

  The fuel tank structure 12 has a fuel tank 14 that can contain fuel therein. The fuel tank 14 is formed in a substantially rectangular parallelepiped box shape as a whole. In particular, the fuel tank 14 of the present embodiment has a structure in which the volume of the fuel tank 14 is variable by the bottom wall 14B and the top wall 14U approaching or separating from each other.

  A lower portion of the inlet pipe 82 is inserted into the upper wall 14U of the fuel tank 14. An opening portion at the upper end of the inlet pipe 82 is an oil supply port 82H. The fuel filler port 82H is closed by a fuel cap 84. However, it is possible to remove the fuel cap 84 and insert a fuel gun into the fuel filler port 82H to supply fuel into the fuel tank 14.

  A lid 86 is provided outside the fuel cap 84 on the vehicle body. The lid 86 is fixed to the vehicle body panel in a normal state, but is released when the refueling operator presses the lid opening switch 88. Therefore, the refueling worker can open the lid 86 and remove the fuel cap 84. become. The open / closed state of the lid 86 is detected by the lid open / close sensor 90, and the information is sent to the engine control device 70. Alternatively, the lid 86 may be automatically opened and closed by a switch operation.

  In the present embodiment, the engine control device 70 can drive the fuel pump 40 when the lid opening / closing sensor 90 detects that the lid 86 has been opened even when the engine 20 is stopped. Further, the engine control device 70 can stop the fuel pump 40 when the lid opening / closing sensor 90 detects that the lid 86 is closed.

  In the fuel tank 14, a full tank liquid level HL and a warning liquid level LL are set. The full tank liquid level HL is a liquid level that is set so that when the fuel level reaches the full tank liquid level HL when the fuel tank 14 is refueled, no further fuel can be supplied. Therefore, normally, the liquid level in the fuel tank 14 does not exceed the full tank liquid level HL. Further, the warning liquid level LL is a liquid level set so that when the fuel in the fuel tank 14 is consumed, a warning or the like is given until the liquid level reaches the warning liquid level LL and fueling is promoted. .

  An insertion port 16 is formed in the upper wall 14U of the fuel tank 14. The fuel pump module 22 can be inserted from the insertion port 16. The insertion port 16 is closed with a lid member 18 from the outside of the fuel tank 14.

  The fuel pump module 22 disposed in the fuel tank 14 can send the fuel in the fuel tank 14 to the engine 20. As shown in detail in FIG. 2, the fuel pump module 22 has a substantially cylindrical sub-cup 24 having an open upper surface.

  One or a plurality (two in this embodiment) of guide bars 34 extending downward from the lid member 18 are inserted into the guide cylinder of the sub cup 24. Thereby, even when the bottom wall 14B and the top wall 14U approach or separate from each other, the position and posture of the sub cup 24 are stably maintained. In particular, the guide rod 34 is provided with a compression coil spring that biases the guide cylinder downward with respect to the lid member 18. With this urging force, the bottom wall 24B of the sub cup 24 can be maintained in contact with the bottom wall 14B of the fuel tank 14.

  As shown in FIG. 3, a fuel pump 40 is provided in the sub cup 24. A fuel suction pipe 36 for sucking fuel is connected to the lower portion of the fuel pump 40. A fuel suction port 42 through which fuel can be sucked is provided at the lower end of the fuel suction pipe 36. By driving the fuel pump 40, the fuel in the sub cup 24 is sucked from the fuel suction port 42. Then, the fuel in the sub cup 24 can be sent out toward the engine 20 (see FIG. 1) through the fuel delivery pipe 44. The “fuel delivery pipe” of the present invention includes the fuel delivery pipe 44 and the fuel suction pipe 36.

  A fuel filter 46 is attached to the fuel suction port 42 of the fuel pump 40. The fuel filter 46 is formed in a bag shape by a mesh-like member, and the fuel suction port 42 is located therein. The fuel filter 46 has a function of removing foreign matters in the fuel when the fuel in the sub cup 24 is sucked from the fuel suction port 42.

  A part of the fuel in the fuel tank 14 is stored in the sub cup 24. Therefore, even when the fuel is inclined and unevenly distributed with respect to the fuel tank 14, it is possible to suppress a phenomenon (so-called fuel shortage) in which a part of the fuel stored in the sub cup 24 is separated from the fuel filter 46.

  As can be seen from FIG. 2, a concave portion 24 </ b> D is formed in the lower portion of the peripheral wall 24 </ b> S of the sub-cup 24 by curving the peripheral wall 24 </ b> S partially inward. A jet pump 48 is disposed in the recess 24D.

  The jet pump 48 is connected to a jet pump introduction pipe 50B described later. A negative pressure is generated inside the jet pump 48 by the fuel introduced from the jet pump introduction pipe 50B. Due to this negative pressure, fuel is sucked from the outside of the sub-cup 24 (inside the fuel tank 14) through the suction port 48B, and the fuel enters the sub-cup 24 through the through hole 24H (see FIG. 4) formed in the recess 24D. Has the action of feeding (pressure feeding).

  As shown in FIGS. 3 and 4, a partition wall 24 </ b> P is erected from the bottom wall 24 </ b> B in the sub cup 24. The partition wall 24P surrounds the through hole 24H with a part of the peripheral wall 24S, and is formed lower than the height of the peripheral wall 24S. And the temporary accommodating part 24T is comprised between a part of surrounding wall 24S and the partition 24P. The fuel introduced from the jet pump 48 through the through hole 24H is temporarily stored in the temporary storage portion 24T. The fuel overflowing from the temporary storage unit 24T passes through the partition wall 24P and is stored in the sub cup 24 (an area other than the temporary storage unit 24T). Hereinafter, the term “inside the sub-cup 24” or “inside the sub-cup 24” refers to a region other than the temporary storage portion 24T in the sub-cup 24.

  3 is a cross-sectional view taken along the line 3-3 in FIG. 2, the line 3-3 is also shown in FIG. 4 to indicate the cross-sectional position.

  As shown in FIGS. 2 and 3, the fuel pump module 22 includes a cylindrical body 38 positioned outside the sub cup 24. The cylinder 38 is formed to a position higher than the full tank liquid level HL of the fuel tank 14.

  In this embodiment, as can be seen from FIGS. 3 and 4, the cylindrical body 38 includes an outer wall 38 </ b> A that is far from the sub-cup 24, an inner wall 38 </ b> B that is on the sub-cup 24 side, and an outer wall 38 </ b> A and an inner wall 38 </ b> B. Are formed in a cylindrical shape having a substantially horizontal cross section. And the cylinder 38 exists in a part of outer periphery of the subcup 24 by planar view. A part of the cylindrical body 38 (a part from the middle to the lower part of the inner wall 38 </ b> B) has a structure shared by the peripheral wall 24 </ b> S of the sub cup 24.

  The cylinder 38 is opened upward. A fuel inlet / outlet port 56 is formed in the lower part of the cylindrical body 38 (in the vicinity of the bottom wall 14B). That is, the cylinder 38 is opened up and down.

  The fuel in the fuel tank 14 enters and exits the cylinder 38 through the fuel inlet / outlet 56. Therefore, as can be seen from FIGS. 6, 7, etc., the liquid level L <b> 1 in the fuel tank 14 and the liquid level L <b> 2 in the cylinder 38 are substantially equal.

  Further, the fuel pump module 22 includes a capacitance sensor unit 26. As shown in detail in FIG. 2, the capacitance sensor unit 26 includes a sensor circuit unit 26C mounted on the upper surface of the lid member 18, and extends downward from the sensor circuit unit 26C through the sub-cup lid 32. And a sensor main body 26S that has been taken out.

  As shown in FIG. 5, the sensor body 26 </ b> S has a base 28. The base 28 is formed in a substantially long shape as a whole by a bendable insulator such as a resin film. The tip of the base 28 is bifurcated to form a first base portion 28A and a second base portion 28B.

  As shown in FIGS. 2 and 3, the first base portion 28 </ b> A is inserted into the cylindrical body 38 from above, and the tip reaches the vicinity of the lower portion of the cylindrical body 38. The second base portion 28 </ b> B is inserted into the sub cup 24, and the tip reaches the vicinity of the bottom wall 24 </ b> B of the sub cup 24.

  A plurality of electrodes 30 are arranged on the surface of the first base portion 28A at regular intervals along the longitudinal direction of the base 28, and a liquid level detection sensor 26L is configured. The highest position of the liquid level detection sensor 26L is higher than the full tank liquid level HL of the fuel tank 14. Since the first base portion 28A is inserted into the cylinder 38, the cylinder 38 surrounds the liquid level detection sensor 26L.

  On the surface of the second base portion 28B, a plurality of electrodes 30 are arranged at regular intervals along the longitudinal direction of the base 28, and a property detection sensor 26R is configured. However, the property detection sensor 26R is shorter than the liquid level detection sensor 26L, and is formed only at the tip portion of the second base portion 28B. The tip of the second base portion 28B reaches the vicinity of the bottom wall 24B of the sub cup.

  The plurality of electrodes 30 constituting the liquid level detection sensor 26L and the property detection sensor 26R have different capacitance values between the portion in contact with the fuel and the portion not in contact with the fuel. Also, the capacitance value varies depending on the nature of the fuel in contact. Using the difference in capacitance value, a signal corresponding to the width of the fuel contact range in the capacitance sensor unit 26 can be output.

  Output signals from the property detection sensor 26R and the liquid level detection sensor 26L are sent to the sensor circuit unit 26C. Further, information on the fuel properties and the liquid level is sent to the engine control device 70, and fuel injection and the like in the engine 20 are controlled.

  Here, in a normal state, the fuel level in the sub-cup 24 reaches the upper end position of the sub-cup 24 (the sub-cup 24 is full), and fuel is injected into the sub-cup 24 by the jet pump 48. It has been sent. For this reason, the entire property detection sensor 26R is immersed in the fuel. The property detection sensor 26R can detect the fuel property in the fuel tank 14 by utilizing the fact that the capacitance varies according to the property of the fuel in contact.

  On the other hand, the liquid level detection sensor 26L is disposed in the vertical direction in the cylinder 38. For this reason, according to the amount of fuel in the cylinder 38, the length of the portion immersed in the fuel changes, and the capacitance takes different values. By utilizing this, the amount of fuel in the fuel tank 14 can be detected.

  In particular, in the present embodiment, the liquid level detection sensor 26L is disposed along the outer wall 38A of the cylindrical body 38, and is separated from the inner wall 38B with a predetermined interval.

  In the present embodiment, the property detection sensor 26 </ b> R and the liquid level detection sensor 26 </ b> L are configured on one base 28. In other words, the property detection sensor 26R and the liquid level detection sensor 26L are integrated to form the capacitance sensor unit 26, and an increase in the number of parts is suppressed.

  As shown in FIG. 3, one end of a fuel introduction pipe 50 is connected to the fuel pump 40. The fuel introduction pipe 50 is branched at an intermediate portion into a cylinder introduction pipe 50A and a jet pump introduction pipe 50B. Note that one end of the fuel introduction pipe 50 may be connected to a vapor discharge hole of the fuel pump 40 or a return pipe of a pressure regulator. The “introduction pipe” of the present invention is constituted by the cylinder introduction pipe 50 </ b> A and the intermediate part (branch part) once in the fuel introduction pipe 50.

  When the fuel pump 40 is driven, fuel is pumped up through the fuel suction pipe 36, and part of the pumped fuel flows into the fuel introduction pipe 50. Further, a part of the fuel in the fuel introduction pipe 50 is introduced into the jet pump 48 from the jet pump introduction pipe 50B.

  The inner wall 38B of the cylindrical body 38 is formed with a separating portion 38D that is bent in a direction partially separating from the outer wall 38A. In the portion where the spacing portion 38D is formed, the distance between the outer wall 38A and the inner wall 38B is partially enlarged in the inner dimension of the cylindrical body 38, and an enlarged portion 38W is configured.

  The cylindrical body introduction pipe 50 </ b> A passes through the separation portion 38 </ b> D, and the outlet 50 </ b> C at the tip opens into the enlarged portion 38 </ b> W of the cylindrical body 38. When the fuel pump 40 is driven, the portion of the fuel that has flowed into the fuel introduction pipe 50 that has not been introduced from the jet pump introduction pipe 50B into the jet pump 48 flows through the cylinder introduction pipe 50A and flows from the outlet 50C to the cylinder 38. Introduced in.

  In particular, in the present embodiment, the position of the outlet 50C is above the full tank liquid level HL. Therefore, even if the liquid level L2 reaches the full tank liquid level HL in the cylinder 38, the outlet 50C is not submerged, so that the fuel introduced (discharged) from the outlet 50C receives resistance during the discharge. Absent.

  The enlarged portion 38W is provided with an opposing wall 60 that faces the outlet 50C of the cylinder introduction pipe 50A. The facing wall 60 is an example of a contact member (gas separation member). The fuel introduced into the cylinder 38 from the outlet 50C flows down by hitting the opposing wall 60, and bubbles inside the fuel are separated from the liquid portion.

  In the present embodiment, the facing wall 60 is disposed close to the general portion 38G (a portion other than the separation portion 38D) on the inner wall 38B. As a result, the fuel that has flowed down along the facing wall 60 flows down along the inner wall 38 </ b> B below the facing wall 60. That is, the facing wall 60 is a member that also has an effect of guiding the fuel to flow away from the liquid level detection sensor 26L in the cylindrical body 38.

  In the illustrated example, the opposing wall 60 is integrally formed continuously from the cylindrical body 38, but is formed separately from the cylindrical body 38 and fixed in the cylindrical body 38 using a fixture such as a bracket. It may be a structure.

  As shown in FIG. 2, a gas discharge hole 62 is formed in the upper wall 38 </ b> E between the separation portion 38 </ b> D and the opposing wall 60. The gas separated from the fuel in the cylinder 38 is discharged from the gas discharge hole 62 to the outside of the cylinder 38 (in the fuel tank 14).

  As shown in FIG. 3, a sub-cup lid 32 is disposed on the upper surface of the sub-cup 24, and fuel outflow when the fuel in the sub-cup 24 is inclined is suppressed. A gap G <b> 1 is formed between the sub cup lid 32 and the cylinder 38, and has an effect of discharging the gas in the sub cup 24 when fuel is introduced into the sub cup 24.

  A fuel inflow hole 66 is formed in the bottom wall 24 </ b> B of the sub cup 24. Further, the fuel inflow hole 66 is provided with a one-way valve 68 that allows fuel movement from the fuel tank 14 into the sub cup 24 and prevents fuel movement in the reverse direction. Therefore, when the liquid level in the fuel tank 14 rises, the fuel in the fuel tank 14 flows into the sub cup 24 from the fuel inflow hole 66, so that the fuel liquid levels in the fuel tank 14 and the sub cup 24 become equal. On the other hand, when the liquid level in the fuel tank 14 is lowered, the fuel in the sub cup 24 does not flow out into the fuel tank 14 through the fuel inflow hole 66.

  Next, the operation of the fuel tank structure 12 of this embodiment will be described.

  In the fuel tank structure 12, by driving the fuel pump 40, the fuel stored in the sub cup 24 can be sucked (pumped) by the fuel suction pipe 36 and sent to the engine or the like through the fuel delivery pipe 44.

  As shown in FIG. 6, the fuel exists in the sub cup 24 even when the amount of fuel in the fuel tank 14 is reduced. Therefore, even if the fuel is inclined and unevenly distributed in the fuel tank 14, the fuel in the sub cup 24 is held in the vicinity of the fuel suction port 42. For this reason, it is possible to suppress a phenomenon (so-called fuel shortage) in which the fuel leaves the fuel filter 46 and the oil film of the fuel filter 46 is cut. Moreover, it becomes easy to maintain the state in which the fuel in the subcup 24 is in contact with the property detection sensor 26R.

  When the fuel pump 40 is driven, part of the fuel is introduced into the jet pump 48 through the jet pump introduction pipe 50B. Thereby, since the jet pump 48 is driven, fuel is sent to the temporary storage unit 24T. The fuel overflowing from the temporary storage portion 24T is stored in the sub cup 24 beyond the partition wall 24P.

  Here, consider the case of refueling the fuel tank 14 of the present embodiment. In particular, in the present embodiment, it is assumed that the fuel remaining in the fuel tank 14 is supplied with fuel having a specific gravity different from that of the fuel.

  Hereinafter, a large specific gravity fuel HF having a relatively large specific gravity and a small specific gravity fuel LF having a small specific gravity are distinguished. As an example of the small specific gravity fuel LF, gasoline (a fuel in which ethanol or the like is not mixed) is used. As an example of the large specific gravity fuel HF, an ethanol fuel (a fuel in which ethanol is mixed with gasoline at a predetermined ratio, or only ethanol is used. A structured fuel).

  First, the case where the low specific gravity fuel LF is supplied into the fuel tank 14 in the state where the high specific gravity fuel HF exists in the fuel tank 14 will be described.

  When only the high specific gravity fuel HF exists in the fuel tank 14 and the fuel pump 40 is driven by driving the engine 20 before refueling, the jet pump 48 is driven by return fuel from the fuel supply pipe 52. The For this reason, the high specific gravity fuel HF in the fuel tank 14 is introduced into the sub cup 24.

  When refueling in this state, the liquid level in the fuel tank 14 is detected according to the flow shown in FIG.

  First, in step S102, it is determined whether or not the engine 20 is being driven. If it is determined that the engine 20 is being driven, no fuel is supplied, so this flow is terminated.

  If it is determined in step S102 that the engine 20 is stopped, it is considered that the fuel pump 40 is also stopped. Therefore, in step S104 (# 1), it is determined whether or not fuel is being supplied to the fuel tank 14 (fuel supply determination). For this refueling determination, it is possible to use various detection objects shown in Table 1 and determination devices corresponding thereto.

  For example, in the present embodiment, since the open / closed state of the lid 86 is detected by the lid open / close sensor 90, in step S104, when the open state of the lid 86 is detected, there is a possibility that refueling is possible ( It can be determined that the oil supply state).

  If it is determined in step S104 that the fuel supply state is not set, the process proceeds to step S112, and the liquid level in the cylinder 38 is determined based on the electrostatic capacity of the liquid level detection sensor 26L.

  If it is determined in step S104 that the fuel supply state is set, the process proceeds to step S106, and the fuel pump 40 is driven. In step S108 (# 2), it is determined whether refueling to the fuel tank 14 is stopped. Various judgment materials shown in Table 1 can also be used for this judgment. In the present embodiment, the determination is easy by using the lid opening / closing sensor 90 as in step S104. That is, when the lid opening / closing sensor 90 detects the open state of the lid 86, it is determined that the fuel supply state is continued. Then, the process returns to step S106, and the fuel pump 40 is continuously driven.

  On the other hand, when the closed state of the lid 86 is detected, it is determined in step S108 that the oil is not supplied (non-oiled state). In step S110, the fuel pump 40 is stopped. In step S112, the liquid level in the cylinder 38 is determined based on the capacitance of the liquid level detection sensor 26L. The liquid level determination may be performed after the engine 20 is driven (or the ignition is turned on). Further, it is possible to perform the liquid level determination in step S112 without stopping the charge pump 40.

  The determination in step S108 does not need to use the same detection target and determination device as in step S104. For example, it may be determined that the non-oil supply state is present because the liquid level fluctuation detected by the liquid level detection sensor 26L is eliminated. Further, in step S108, the elapsed time after entering the refueling state in step S104 may be measured by a timer, and it may be determined that the non-refueling state is reached after a predetermined time (presumed refueling time).

  When the small specific gravity fuel LF is supplied into the fuel tank 14 in which the large specific gravity fuel HF remains, the small specific gravity fuel LF is converted into the large specific gravity fuel in the fuel tank 14 (outside the sub cup 24) as shown in FIG. It is located above the HF and may temporarily have two layers (the high specific gravity fuel HF and the low specific gravity fuel LF are mixed over time).

  Here, in this embodiment, the fuel pump 40 is driven as described above during refueling. A part of the fuel pumped up by the fuel suction pipe 36 is introduced into the jet pump from the jet pump introduction pipe 50B. As a result, the jet pump 48 is driven, so that the high specific gravity fuel HF in the fuel tank 14 is sent into the sub cup 24 by the jet pump 48, as indicated by an arrow F4.

  Further, as shown by an arrow F1 in FIG. 7 by driving the fuel pump 40, the fuel that has not flown into the jet pump introduction pipe 50B out of the pumped fuel in the fuel suction pipe 36 is the fuel introduction pipe 50 (particularly the cylindrical body) It flows out from the outlet 50C into the cylinder 38 through the introduction pipe 50A).

  In the cylinder 38, the liquid level L2 rises while the high specific gravity fuel HF is in contact with the liquid level detection sensor 26L. Further, the high specific gravity fuel HF is discharged from the opening 56H through the fuel inlet / outlet 56 and the fuel storage member 58, and the liquid level L2 in the cylinder 38 is maintained in a state where it matches the liquid level L1 in the fuel tank 14. Is done.

  And if the engine 20 is driven after refueling, it will transfer to step S112 and will detect a liquid level. In the present embodiment, by driving the fuel pump 40 during refueling, a part of the pumped fuel pumped up from the sub cup 24 is introduced into the cylinder 38. Therefore, compared with a configuration in which a part of the pumped fuel is not introduced into the cylinder 38, the fuel properties in the cylinder 38 are made uniform.

  Further, since the state in which the large specific gravity fuel HF is stored is maintained in the sub cup 24, the large specific gravity fuel HF is in contact with the property detection sensor 26R.

  As described above, even when the low specific gravity fuel LF, which is a different type of fuel, is supplied to the fuel tank 14, the fuel having a uniform electrostatic characteristic (fuel property) (high specific gravity fuel HF) is the liquid level detection sensor 26L and the properties. Since the state in contact with the detection sensor 26R can be maintained, the liquid level detection sensor 26L can detect the liquid level with high accuracy.

  In particular, in the present embodiment, as can be understood from the above description, the fuel in the sub-cup 40 is introduced into the cylinder 38 when the fuel tank 14 is refueled, and the fuel properties are made uniform in the cylinder 38. Figured. Even when the liquid level is detected by the liquid level detection sensor 26L in a short time after refueling, the fuel properties are already made uniform in the cylinder 38, so that the fuel in the sub cup 40 is supplied to the cylinder 38 during refueling. It is possible to reduce the error of the detection liquid level as compared with the configuration not introduced into the inside.

  In order to actually detect the liquid level in the fuel tank 14, first, the property of the fuel is detected by the property detection sensor 26R. That is, the property detection sensor 26R has a different capacitance value depending on the type of fuel in contact, and therefore, using this capacitance value, the contact fuel is the low specific gravity fuel LF, or It can be seen whether the fuel is high specific gravity fuel HF (in the case of this embodiment, it is known that it is high specific gravity fuel HF).

  Next, the capacitance of the liquid level detection sensor 26L is measured. That is, since the capacitance of the liquid level detection sensor 26L changes according to the contact range of the fuel to the liquid level detection sensor 26L, the liquid level L2 in the cylinder 38 is known from the value of this capacitance, and further Can know the liquid level L1 in the fuel tank 14.

  Thus, in this embodiment, even when the low specific gravity fuel LF is supplied to the fuel tank 14 in which the large specific gravity fuel HF remains, the liquid level detection sensor 26L remains in the sub cup 24. The high specific gravity fuel HF, which is the same type of fuel as the fuel used, is in contact. By using the capacitance value detected by the property detection sensor 26R as a reference and obtaining the liquid level from the capacitance value detected by the liquid level detection sensor 26L, more accurate liquid level detection is possible. This point will be described in detail below.

  FIG. 9 shows the fuel pump module 122 of the fuel tank structure 112 of the comparative example. In the comparative example, the cylinder body 38 and the fuel inlet / outlet port 56 according to the first embodiment are not provided, and the partition wall 24 </ b> P is not formed in the sub cup 24. The liquid level detection sensor 26L is disposed outside the peripheral wall 24S of the sub cup 24. A property detection sensor 26 </ b> R is provided in the sub-cup 24.

  Therefore, in the fuel tank 114 according to the comparative example, when the small specific gravity fuel LF is supplied in a state where the large specific gravity fuel HF remains, the large specific gravity fuel HF is relatively below, so that it contacts the liquid level detection sensor 26L. The specific gravity of the fuel is gradually reduced from the lower part to the upper part of the contact point.

  FIG. 10 shows the value of the capacitance at the liquid level detection sensor 26L and the capacitance at the liquid level detection sensor 26L in the case of this embodiment and the comparative example. An example of the value (capacitance ratio) divided by the capacitance is shown.

  In this example, in both this embodiment and the comparative example, the actual liquid level in the fuel tank is set to 40 mm for convenience. Further, the capacitance value of the property detection sensor 26R in contact with the high specific gravity fuel HF is a constant value (5000 pF).

  When the uniform fuel (high specific gravity fuel HF in the illustrated example) is in contact with the liquid level detection sensor 26L as in the first embodiment, the capacitance of the liquid level detection sensor 26L is indicated by a solid line C11. As shown, it is proportional to the liquid level L2 (fuel contact area). Since the capacitance value of the property detection sensor 26R is a constant value, the capacitance ratio is proportional to the liquid level L2, as indicated by the solid line C12 in FIG. 10, and is above the target value indicated by the broken line C01.

Generally, when the area of two electrodes is S, the distance between the electrodes is d, and the dielectric constant is ε, the capacitance C is C = ε × (S / d). Further, the capacitance ratio when the capacitance of the liquid level detection sensor 26L and the property detection sensor 26R is C _26L and C _26R , respectively,
(C _26L / C _26R ) (1)
It becomes.

  In particular, in the graph of FIG. 10, the liquid level detection sensor 26 </ b> L and the property detection are performed so that the capacitance ratio becomes 1 in a state where the liquid level detection sensor 26 </ b> L is immersed in the fuel (liquid level = 100 mm). The area S of the electrode of the sensor 26R and the distance d between the electrodes are adjusted.

When the liquid level is 40 mm, the capacitance value of the liquid level detection sensor 26L is 2000 pF, and the capacitance ratio is 2000 pF / 5000 pF = 0.4. Since the capacitance ratio when the liquid level is 100 mm is set to 1, the actual liquid level can be calculated as 100 mm × 0.4 = 40 mm. That is, in this embodiment, since the capacitance ratio (C _26L / C _26R ) is proportional to the liquid level, the liquid level L 2 can be easily and accurately known.

  On the other hand, in the fuel tank structure 112 of the comparative example, when the liquid level rises due to the refueling of the low specific gravity fuel LF, the high specific gravity fuel HF contacts the liquid level detection sensor 26L and the low specific gravity fuel is on the upper side. While the LF is in contact, the amount of the low specific gravity fuel LF increases. For this reason, the capacitance value of the liquid level detection sensor 26L is not proportional to the liquid level in the fuel tank, and may take a value smaller than the solid line C11 as the liquid level rises as indicated by a two-dot chain line C31. . In the comparative example, the capacitance ratio between the capacitance at the liquid level detection sensor 26L and the capacitance at the property detection sensor 26R is also smaller than the actual value as indicated by the broken line C32. For example, when the liquid level is 40 mm, the capacitance value of the liquid level detection sensor 26L in the comparative example is 900 pF. From this, the liquid level in the fuel tank 114 is calculated to be 18 mm, which is 22 mm lower than the actual level.

  Thus, in this embodiment, it turns out that it can suppress that an error like a comparative example arises in the value of the liquid level obtained based on the electrostatic capacitance of the liquid level detection sensor 26L.

  In the above, the case where the low specific gravity fuel LF is supplied into the fuel tank 14 in which the high specific gravity fuel HF remains is illustrated. On the contrary, even when the high specific gravity fuel HF is supplied to the fuel tank 14 where the low specific gravity fuel LF remains, the low specific gravity fuel LF, which is the remaining fuel, is cylinderized by driving the jet pump 48. Since the fuel is introduced into the body 38 and the fuel properties in the cylinder 38 are made uniform, more accurate liquid level detection is possible.

  In the present embodiment, the introduced fuel hits the opposing wall 60 provided in the cylindrical body 38 (enlarged portion 38 </ b> W), so that the introduced fuel spreads along the opposing wall 60. Thereby, when the introduction fuel of the same volume is considered, since the surface area of the introduction fuel becomes large, the internal bubbles are separated from the liquid portion. In addition, the amount of gas in the fuel in the cylinder 38 is reduced. Further, it is possible to suppress bubbles in the fuel from coming into contact with the liquid level detection sensor 26L. Thus, the liquid level detection by the liquid level detection sensor 26L can be performed more accurately.

  Since the gas separated from the fuel is discharged from the gas discharge hole 62 (or from the open portion at the top of the cylinder 38) to the outside of the cylinder 38, the gas component is prevented from staying in the cylinder 38. Is done.

  Further, when the introduced fuel hits the facing wall 60, the flow velocity of the introduced fuel becomes small. Thereby, the scattering of the fuel when the introduced fuel flows down to the liquid level in the cylinder 38 is suppressed.

  In addition, since the opposing wall 60 is disposed close to the general portion 38G of the inner wall 38B of the cylindrical body 38, the fuel that has flowed down against the opposing wall 60 flows down along the inner wall 38B below the opposing wall 60. . Since the inner wall 38B is at a position away from the liquid level detection sensor 26L, it is possible to prevent the fuel in the middle of flowing down from inadvertently coming into contact with the liquid level detection sensor 26L (the portion not immersed in the fuel), and more accurately. Liquid level detection is possible.

  Furthermore, since the fuel flows down along the inner wall 38B, scattering in the cylinder 38 is suppressed. Since the scattered fuel is also prevented from coming into contact with the liquid level detection sensor 26L (portion not immersed in the fuel), more accurate liquid level detection is possible in this respect as well.

  In order to introduce the fuel in the sub cup 24 into the cylinder 38, for example, a communication pipe that communicates between the sub cup 24 and the cylinder 38, and the fuel in the sub cup 24 through the communication pipe. A configuration may be provided in which a pump or the like for pumping the gas into the cylinder 38 is provided. Compared to this, in the first embodiment, there is no need for continuous piping or a pump, and the number of parts is small.

  Next, a second embodiment of the present invention will be described. In the second embodiment, the structure of the introduction flow path for introducing the fuel into the cylinder 38 is different from that of the first embodiment, but the overall configuration of the fuel tank structure is the same as that of the first embodiment. Illustration is omitted.

  As shown in FIG. 11, in the second embodiment, the cylinder introduction pipe 50A and the jet pump introduction pipe 50B are separated. One end of the jet pump introduction pipe 50B is connected to the fuel pump 40 (or the vapor discharge hole of the fuel pump 40, the return pipe of the pressure regulator, etc.), and one end of the cylinder introduction pipe 50A is connected to the fuel delivery pipe 44. .

  In the second embodiment, a part of the pumped fuel when the fuel pump 40 is driven flows from the fuel suction pipe 36 to the jet pump introduction pipe 50B, and the jet pump 48 is driven. Further, another part of the pumped fuel when the fuel pump 40 is driven flows from the fuel delivery pipe 44 to the cylinder introduction pipe 50A.

  Therefore, also in the second embodiment, when fuel is supplied to a different type from the fuel remaining in the fuel tank 14, one of the pumped fuel pumped up from the sub-cup 24 by driving the fuel pump 40 during fueling. The part can be introduced into the cylinder 38. Since the fuel property in the cylinder 38 can be made uniform, it is possible to reduce the error of the liquid level detection. In particular, the error can be reduced when the liquid level is detected in a short time after refueling.

  Next, a third embodiment of the present invention will be described. As shown in FIG. 12, in 3rd Embodiment, the pressure regulator 84 is further provided in the middle of 50 A of cylinder introduction piping in 2nd Embodiment. In other words, in the configuration having the pressure regulator 84 for adjusting the pressure of the fuel delivered from the fuel delivery pipe 44, the tip of the return pipe (outlet 50C) that discharges excess fuel (return fuel) from the pressure regulator 84. ) Is connected to the cylinder 38. Except for this, the third embodiment has the same configuration as the second embodiment, and a description thereof will be omitted. Further, the overall configuration of the fuel tank structure of the third embodiment is the same as that of the first embodiment, and hence illustration is omitted.

  Also in the third embodiment, when a fuel of a different type from the fuel remaining in the fuel tank 14 is supplied, a part of the pumped fuel pumped up from the sub cup 24 by driving the fuel pump 40 is used as the cylinder 38. Can be introduced within. Since the fuel property in the cylinder 38 can be made uniform, it is possible to reduce the error of the liquid level detection. In particular, the error can be reduced when the liquid level is detected in a short time after refueling.

  Note that the first embodiment and the second embodiment are often configured to include a pressure regulator in practice. In the third embodiment, the return pipe of the pressure regulator 84 also serves as the cylinder introduction pipe 50A, and it is not necessary to newly provide the cylinder introduction pipe 50A, so the number of parts is small.

  Next, a fourth embodiment of the present invention will be described. In the fourth embodiment, the structure of the fuel pump module is different from those of the first to third embodiments. However, the overall configuration of the fuel tank structure is the same as that of the first embodiment, and therefore illustration is omitted.

  As shown in FIG. 13, in the fourth embodiment, the upper surface of the sub-cup 24 is closed by the sub-cup lid 32, but the vicinity of the cylinder 38 is opened and the cylinder is surrounded by the opening. A fuel introduction wall 63 facing the body 38 extends upward. A fuel introduction path 64 is formed between the fuel introduction wall 62 and the cylindrical body 38. When the jet pump 48 is driven, a part of the fuel overflowing from the sub-cup 24 (however, the outflow into the fuel tank 14 is suppressed by the sub-cup lid 32), as indicated by the arrow F1, is a fuel introduction path. 64 and flows into the cylinder 38 from above. The fuel introduction means 60 of the present invention includes a sub cup lid 32, a fuel introduction path 64 and a jet pump 48. The jet pump 48 is an example of a pressure feed pump in the fourth embodiment.

  Therefore, in the fourth embodiment, when the fuel pump 40 is driven, a part of the pumped fuel is introduced into the jet pump 48 through the introduction pipe 54. Thereby, since the jet pump 48 is driven, fuel is sent to the temporary storage unit 24T. Then, the fuel overflowing from the temporary storage unit 24T passes through the partition wall 24P and is stored in the sub cup 24 (an area other than the temporary storage unit 24T). Further, the fuel in the sub cup 24 is introduced into the cylinder 38 through the fuel introduction path 64.

  Also in the fourth embodiment, the fuel in the sub cup 24 can be introduced into the cylinder 38 by driving the fuel pump 40 during refueling. Since the fuel properties in the cylinder 38 can be made uniform, the liquid level detection by the liquid level detection sensor 26L can be performed with high accuracy when different types of fuel are supplied to the fuel tank 14. In particular, the error can be reduced when the liquid level is detected in a short time after refueling.

  In the fourth embodiment, the introduction means can be realized with a simple structure by the jet pump 48, the sub-cup lid 32, and the fuel introduction path 64. In particular, the jet pump 48 is a member provided for pumping fuel into the cylinder 38 in addition to the purpose of introducing fuel into the cylinder 38. Therefore, if the sub-cup lid 32 and the fuel introduction path 64 are substantially provided in the configuration provided with the jet pump 48, the introduction means can be configured.

  In the fourth embodiment, the pressure pump is not limited to the jet pump 48. For example, an electric pump driven by the engine control device 70 may be used.

  In each of the above embodiments, the position of the property detection sensor 26R is not limited to within the sub-cup 24, but if it is disposed within the sub-cup 24, the property of the fuel delivered to the engine 20 can be detected by driving the fuel pump 40. Instead of this, it is also possible to dispose the cylinder body 38 in the lower portion, and in this arrangement, it is possible to detect the fuel property in the vicinity of the liquid level detection sensor 26L.

  Further, in each of the above embodiments, the capacitance sensor unit 76 having the shape shown in FIG. 14 can be used.

  The electrostatic capacitance sensor unit 76 has a base 28, and a liquid level detection sensor 76L substantially the same as the structure shown in FIG. 5 is provided in the first base portion 28A. In the second base portion 28B, a liquid level detection sensor 76M is provided instead of the property detection sensor 26R shown in FIG.

  The liquid level detection sensor 76M has the same height as the liquid level detection sensor 26L. The upper end portion of the liquid level detection sensor 76M has a width equal to or greater than that of the liquid level detection sensor 26L, but the width is gradually reduced downward, and has an inverted triangular shape as a whole. Yes.

  In the liquid level detection sensor 76L, the capacitance and the liquid level are proportional, and there is no difference in sensitivity depending on the liquid level. On the other hand, in the liquid level detection sensor 76M, the sensitivity is lower when the liquid level is low (when the remaining amount of the fuel GS decreases).

Further, in this capacitance sensor unit 76, even if the properties of the fuel GS change, the capacitance ratio between the liquid level detection sensor 76L and the liquid level detection sensor 76M (the static level of the liquid level detection sensor 76L and the liquid level detection sensor 76M). C _76M / C _76L ) when the electric capacities are C _76L and C _76M , respectively, it is possible to detect an accurate liquid level.

  Even in the configuration using the capacitance sensor unit 76, when fuel of a different type from the fuel remaining in the fuel tank 14 is supplied, the fuel stored in the fuel storage member 58 is stored in the cylinder 38. The same type of fuel comes into contact with the entire range of the liquid level detection sensor 26L. For this reason, the precision of a liquid level detection becomes high.

  In the configuration using the capacitance sensor unit 76, the liquid level detection sensor 76 </ b> M may be disposed in the sub-cup 24, but may be disposed in the cylindrical body 38.

  In each embodiment, a structure without the property detection sensor 26R shown in FIG. 5 or a structure without the liquid level detection sensor 76M shown in FIG. 14 may be used. That is, by introducing the fuel in the sub-cup 24 into the cylinder 38 when fuel of a different type from the remaining fuel in the fuel tank 14 is supplied, it is possible to make the fuel properties uniform in the cylinder 38. I just need it.

12 Fuel tank structure 14 Fuel tank 24 Sub cup 26L Liquid level detection sensor 26R Property detection sensor 32 Sub cup lid 36 Fuel suction pipe (fuel delivery pipe)
38 cylinder 40 fuel pump (introduction means)
44 Fuel delivery pipe 48 Jet pump (pressure feed pump)
50 Fuel introduction piping (introduction means)
50A Tube introduction pipe (introduction means)
50C Outlet 64 Fuel introduction path (introduction flow path)
90 Lid open / close sensor (oil supply state detection means)

Claims (6)

A fuel tank capable of containing fuel, and
A liquid level detection sensor which is arranged along the vertical direction inside the fuel tank and whose capacitance changes according to the fuel contact range;
A cylindrical body that surrounds the side of the liquid level detection sensor and extends in the vertical direction, and the lower part is opened,
A sub-cup provided in the fuel tank and storing the fuel in the fuel tank;
Refueling state detecting means for detecting a fueling state to the fuel tank;
Introducing means for introducing the fuel in the sub-cup into the cylindrical body at the time of refueling detection to the fuel tank by the refueling state detecting means,
Having fuel tank structure. The introducing means is
A fuel pump for delivering fuel in the sub-cup to the outside of the fuel tank;
A fuel delivery pipe for delivering the fuel sucked by the fuel pump to the outside;
An introduction pipe communicating from the fuel delivery pipe to the cylinder;
The fuel tank structure according to claim 1, comprising: The introducing means is
A pump for pumping the fuel in the fuel tank into the sub-cup;
A subcup lid for closing the upper surface of the subcup;
An introduction flow path communicating from the introduction hole formed in the sub-cup lid into the cylindrical body,
The subcup structure according to claim 1, wherein   The fuel tank structure according to any one of claims 1 to 3, wherein an outlet of fuel from the introduction means is located above a full tank liquid level in the fuel tank.   The fuel tank structure according to any one of claims 1 to 4, further comprising a property detection sensor disposed inside the fuel tank and having a capacitance that varies according to the property of the fuel.   The fuel tank structure according to claim 5, wherein the property detection sensor is provided in the sub cup.

Images