JP2012220220A - Liquid level detection device - Google Patents

Abstract

An object of the present invention is to provide a liquid level detection device that is less affected when the liquid level fluctuates even when the liquid level of a fuel tank is low.
SOLUTION: A warning region liquid level detection unit 15 for detecting a fuel level in a warning region where the remaining amount of fuel in a fuel tank 10 is a predetermined amount or less, and above the warning region liquid level detection unit 15 above the vehicle. And a normal region liquid level detection unit 16 that detects a fuel level in a normal region in which the remaining amount of fuel in the fuel tank 10 is greater than the predetermined amount, and in the warning region liquid level detection unit 15 A liquid level detection device in which the electrode area per unit liquid level is larger than the electrode area per unit liquid level in the normal region liquid level detection unit 16.
[Selection] Figure 1

Description

  The present invention relates to a liquid level detection device, and more particularly to a liquid level detection device that detects a liquid level of a fuel tank from a change in capacitance.

  There are various types of liquid level detection devices for detecting the liquid level of a fuel tank of an automobile or the like, and one of them detects the liquid level by utilizing a change in capacitance.

  An example of such a liquid level detection device includes a first electrode and a second electrode that are spirally wound around the outer periphery of an insulating substrate in parallel with each other, and the insulation so as to face the first electrode and the second electrode. A third electrode surrounding the outer periphery of the conductive substrate, the first electrode and the second electrode are arranged so that the spiral axes thereof are vertical, and the first electrode, the second electrode, and the third electrode There is a liquid level sensor that detects the liquid level of the liquid based on the capacitance between the electrodes when two pairs of electrodes selected in different combinations from the group are immersed in the liquid (patent) Reference 1).

  In the liquid level sensor described in Patent Document 1, there is a liquid level sensor in which the spiral pitch of the first electrode and the second electrode is set so as to gradually become denser from the upper end toward the lower end.

JP 2007-240262 A

  However, even in the liquid level detection device in which the spiral pitch and interval of the electrodes are set to be reduced from the upper side to the lower side of the liquid level detection device, the electrode per unit liquid level is low when the liquid level of the fuel tank is low. Since the area is small, there is a problem that the liquid level is easily affected when the liquid level fluctuates.

  The present invention has been made to solve the above-described problem, and an object of the present invention is to provide a liquid level detection device that has a small influence when the liquid level fluctuates even when the liquid level of the fuel tank is low.

  The invention according to claim 1 relates to a liquid level detection device, a warning area liquid level detection unit for detecting a liquid level of a fuel in a warning area where the remaining amount of fuel in the fuel tank is a predetermined amount or less, and the warning area liquid A normal region liquid level detection unit that is located above the vehicle relative to the level detection unit and detects a fuel level in a normal region in which the remaining amount of fuel in the fuel tank is greater than the predetermined amount, and the warning region The electrode area per unit liquid level in the liquid level detection unit is larger than the electrode area per unit liquid level in the normal region liquid level detection unit.

  In the liquid level detection device according to claim 1, since the electrode area per unit liquid level in the warning area liquid level detection unit is larger than the electrode area per unit liquid level in the normal area liquid level detection unit, the warning area The gradient of the liquid level in the fuel tank with respect to the sensor output in the liquid level detection unit can be made smaller than that in the normal region liquid level detection unit. Therefore, the warning region liquid level detection unit can detect the liquid level with higher resolution than the normal region liquid level detection unit.

  According to a second aspect of the present invention, in the liquid level detection device according to the first aspect, the warning area liquid level detection unit is provided at two or more locations apart from each other.

  In the liquid level detection device according to claim 2, since the warning region liquid level detection unit is provided at two or more locations apart from each other, one warning region liquid level detection unit and the one warning region liquid level are provided. By averaging the liquid level detection results with another warning area liquid level detection unit different from the detection unit, the liquid level is inclined as compared with a liquid level detection device having only one warning area liquid level detection unit. The correct liquid level can be obtained even in this case.

  According to a third aspect of the present invention, in the liquid level detection device according to the first aspect, the warning area liquid level detection unit is bent in a bellows shape.

  In the liquid level detection device according to claim 3, the warning area liquid level detection unit is configured to be bent in a bellows shape, whereby the electrode area per unit liquid level of the warning area liquid level detection unit Is larger than the normal area liquid level detection unit.

  According to a fourth aspect of the present invention, in the liquid level detection device according to the first aspect, the warning region liquid level detection unit is arranged to be inclined with respect to the vertical direction of the fuel tank.

  In the liquid level detection device according to claim 4, the warning area liquid level detection unit is arranged to be inclined with respect to the vertical direction of the fuel tank. The electrode area is larger than that of the normal region liquid level detection unit.

  According to a fifth aspect of the present invention, in the liquid level detection device according to the first aspect, the warning region liquid level detection unit is set to have a larger dimension in the width direction than the normal region liquid level detection unit. It is characterized by that.

  In the liquid level detection device according to claim 5, the warning area liquid level detection unit is set to have a width larger than that of the columnar area, so that the unit liquid level of the warning area liquid level detection unit is set. The per electrode area is larger than that of the normal region liquid level detection unit.

  The invention according to claim 6 is the liquid level detection device according to claim 5, wherein the warning region liquid level detection part is formed in an arc shape or an S shape when viewed from above the fuel tank. And

  In the liquid level detection device according to claim 6, as in the liquid level detection device according to claim 5, the warning region liquid level detection unit is set to have a larger width than the columnar region. Thus, the electrode area per unit liquid level of the warning area liquid level detection unit is larger than that of the normal area liquid level detection unit.

  According to the first aspect of the present invention, since the liquid level can be detected with higher resolution in the warning area liquid level detection unit than in the normal area liquid level detection unit, the remaining amount of fuel in the fuel tank is small. There is provided a liquid level detection device that can meet the needs of a driver who wants to accurately grasp the cruising range.

  According to the invention of claim 2, since the correct liquid level is obtained even when the liquid level is inclined as compared with the liquid level detecting device having only one warning area liquid level detecting unit, the liquid level A liquid level detection device in which the detection result is less affected by the fluctuation of the fuel liquid level is provided.

  According to the invention of claim 3, since the warning region liquid level detection part is formed by bending the tip of the liquid level detection sensor in a bellows shape along the vertical direction of the fuel tank, the warning region liquid There is provided a liquid level detecting device capable of forming a level detecting unit inexpensively and easily.

  According to the fourth aspect of the present invention, the warning area liquid level detection unit is formed by bending the tip of the liquid level detection sensor so as to be inclined with respect to the vertical direction of the fuel tank. There is provided a liquid level detecting device capable of forming a level detecting unit inexpensively and easily.

  According to the invention of claim 5, the liquid level detection sensor having a configuration in which the warning area liquid level detection unit is provided at two or more locations, a bellows-like bent shape, or an obliquely bent shape. Compared with a liquid level detection device comprising: a liquid level detection device that is easier to mount the liquid level detection sensor on the fuel tank and that does not obstruct the mounting of a warning area liquid level detection unit. Is done.

  According to the sixth aspect of the present invention, even when the dimension in the width direction of the warning area liquid level detection unit in the liquid level detection sensor is much larger than that of the normal area liquid level detection part, the warning area There is provided a liquid level detection device in which the liquid level detection unit is less likely to obstruct the mounting of the liquid level detection sensor on the fuel tank.

FIG. 1 is a cross-sectional view illustrating the overall configuration of the fuel tank according to the first embodiment. FIG. 2 is an enlarged view showing a sub-tank provided in the fuel tank of Embodiment 1 and a configuration in the vicinity thereof. FIG. 3 is a perspective view illustrating a configuration of a liquid level detection sensor provided in the fuel tank according to the first embodiment. 4 is a development view of the capacitance sensor shown in FIG. FIG. 5 is a circuit diagram showing an equivalent circuit of the capacitance sensor shown in FIG. FIG. 6 is a graph showing an outline of the relationship between the output (capacitance) in the liquid level detection sensor provided in the fuel tank of Embodiment 1 and the remaining amount of fuel. 7A and 7B are schematic diagrams illustrating the configuration of the liquid level detection sensor according to the second embodiment, in which FIG. 7A is a development view and FIG. 7B is a perspective view. FIG. 8 is a schematic diagram illustrating a configuration of the liquid level detection sensor according to the third embodiment, where (A) is a front view, (B) is a side view, and (C) is a development view. FIG. 9 is a schematic diagram illustrating a configuration of another example of the liquid level detection sensor according to the third embodiment, in which (A) is a front view, (B) is a side view, and (C) is a developed view. 10A and 10B are schematic diagrams illustrating the configuration of the liquid level detection sensor according to the fourth embodiment, in which FIG. 10A is a front view, FIG. 10B is a side view, and FIG. FIG. 11 is a schematic diagram illustrating a configuration of a liquid level detection sensor according to the fifth embodiment, where (A) is a development view, (B) is a perspective view, and (C) is a liquid level detection sensor according to the fifth embodiment. It is a top view which shows another example of.

1. Embodiment 1
Hereinafter, an example of a fuel tank provided with the liquid level measuring device of the present invention will be described with reference to the drawings. In FIG. 1 and subsequent figures, the arrow UP indicates the upper side of the vehicle body.

  The fuel tank 10 is a container having a substantially box shape as shown in FIG. 1, and its shape is determined by the shape of a vehicle body or the like to be installed and the component arrangement. The material of the fuel tank 10 is selected in consideration of resistance to corrosion by fuel (gasoline etc.), mechanical strength, impact resistance and safety in the event of a collision.

  An attachment port 22 for a pump module or the like is provided in the ceiling surface 30 that is the upper surface of the vehicle body of the fuel tank 10, and the internal fuel does not leak outside by a lid portion 28 that closes the attachment port 22 from the outside. So that it is sealed. The mounting port 22 protruding in a cylindrical shape above the vehicle is sealed with a lid portion 28.

  At this time, if the mounting port 22 protrudes from the box-shaped fuel tank 10, space efficiency may be reduced when the mounting port 22 is assembled to the vehicle body. Therefore, the mounting port 22 should be provided so as to be submerged inside the fuel tank 10. desirable. In this case, it is necessary to provide a space in the fuel tank 10 that can clear the attachment port 22 and the lid portion 28.

  As a result, a concave portion 24 whose outer surface is recessed is formed on the upper surface of the vehicle body of the fuel tank 10, and a portion inside the concave portion 24 on the ceiling surface 30 is a convex portion 26 protruding toward the lower side of the vehicle body inside the fuel tank 10. Is formed. Therefore, when the fuel tank 10 is filled with fuel, the liquid level F exceeds the height of the convex portion 26, and the convex portion 26 is immersed in the fuel.

  The fuel tank 10 is generally formed of a steel plate or resin, and a vapor layer is secured by a method such as providing unevenness on the upper surface of the vehicle body as shown in FIG. In other words, the volatile fuel evaporates due to the outside air temperature or heat from the engine or the like, and fills the voids in the fuel tank 10 as volatile gas (vapor). If the entire tank is filled with fuel at this time, the generated volatile gas of the fuel loses escape and the inside of the fuel tank 10 is pressurized. In order to prevent this, a certain amount of air gap (vapor layer) is set in the upper part of the fuel tank 10 to secure a escape space for the pressure of the volatile gas.

  Further, in the fuel tank 10 that secures the vapor layer as described above, pressurization and depressurization are continuously repeated by the fuel temperature up and down (the influence of the temperature, the heat from the road surface and the exhaust pipe) and the fuel consumption, Mechanical stress continues to be applied. For this reason, making the upper surface of the fuel tank 10 into a complicated uneven shape increases the mechanical strength of the fuel tank 10 itself, and also has a meaning as a countermeasure against changes in internal pressure.

  Inside the fuel tank 10 is provided a sub tank 31 which is a bottomed container having an open top surface, and a pump unit 32 is accommodated in the sub tank 31. The fuel inside the fuel tank 10 is pumped out by the pump unit 32 and sent out to the outside by a fuel hose (not shown).

  As shown in FIGS. 1 and 2, a guide column 34 extends from the lower surface of the lid portion 28 toward the bottom surface 20 of the fuel tank 10. The guide column 34 is inserted into a cylindrical guide member 36 provided in the sub tank 31. The sub tank 31 is guided by the guide pillar 34 and the guide member 36 along the vertical direction of the fuel tank 10, in other words, along the vertical direction of the vehicle. The sub tank 31 is urged toward the bottom surface 20 by the coil spring 38 inserted through the guide pillar 34, in other words, toward the bottom of the vehicle, so that the bottom surface of the sub tank 31 faces the bottom surface 20 of the fuel tank 10. Is pressed.

  Hereinafter, the configuration of the liquid level detection device 1 provided in the fuel tank 10 will be described. As shown in FIGS. 1 and 2, the liquid level detection device 1 is connected to the sensor circuit 11 fixed to the upper surface of the lid portion 28, the sensor circuit 11, and the fuel tank 10 from the lower surface of the lid portion 28. And a liquid level detection sensor 12 extending toward the bottom surface 20. As the liquid level detection sensor 12, for example, a capacitance sensor is used.

  As shown in FIGS. 1 to 4, the liquid level detection sensor 12 includes a liquid level detection unit 13 for detecting the fuel level in the fuel tank 10, and a liquid level detection unit at the lower end of the liquid level detection unit 13. 13 and a foot 14 formed substantially at right angles to 13. The liquid level detection part 13 and the foot-like part 14 are integrally formed from a base film 110 such as polyimide resin, aromatic polyamide resin, aromatic polyester resin, polyether ether ketone resin, polyether sulfone resin. The liquid level detection unit 13 is formed in a strip shape, and as shown in FIG. 2, the sub tank 31 so that the foot 14 contacts the bottom surface 20 of the fuel tank 10 when the sub tank 31 is attached to the fuel tank 10. It is attached to the side of the. The liquid level detection sensor 12 and the sensor circuit 11 are connected by a pair of wire harnesses 21.

  As shown in FIGS. 3 and 4, the foot-shaped portion 14 is formed in the shape of two arms extending in a V shape from the liquid level detecting portion 13 when viewed from above the vehicle, and the foot-shaped portion 14. The front end of the fuel tank 10 is bent toward the upper side of the vehicle, in other words, the upper side of the fuel tank 10 to form a warning region liquid level detection unit 15. The liquid level detection unit 13 is also divided into a warning region liquid level detection unit 15 and a normal region liquid level detection unit 16 located above the warning region liquid level detection unit 15.

  The warning region liquid level detection unit 15 detects the fuel level when the fuel remaining in the fuel tank 10 is in a region where the remaining amount of fuel is not more than a predetermined amount, that is, in the warning region. Here, the remaining amount of fuel that becomes the warning region can be defined as the remaining amount of fuel that can travel 10 to 20 km, for example, but may be defined as the remaining amount of fuel that can travel a longer distance.

  A fuel reference measurement unit 17 that measures the electrostatic capacity of the fuel inside the fuel tank 10 is provided near the liquid level detection unit 13 in the foot 14.

  The liquid level detection unit 13 is provided with a liquid level detection electrode 13A, and one of the warning region liquid level detection units 15 formed on the foot 14 is for detecting the liquid level in the warning region. A warning liquid level detection electrode 15A is formed on the other side of the warning area liquid level detection part 15 formed in the foot-like part 14, and a warning liquid level detection electrode 15B for detecting the liquid level in the warning area is also formed. Yes. The fuel reference measurement unit 17 is formed with a fuel reference electrode 17A for detecting the capacitance of the fuel inside the fuel tank 10.

  The liquid level detection electrode 13A, the warning liquid level detection electrode 15A, the warning liquid level detection electrode 15B, and the fuel reference electrode 17A are all formed in a comb shape at regular intervals on the base film 110 as shown in FIG. Comb electrodes 111A, and comb electrodes 111B formed in a comb shape at the same interval as the comb electrodes 111A and arranged alternately with the comb electrodes 111A. All of the liquid level detection electrode 13A, the warning liquid level detection electrode 15A, the warning liquid level detection electrode 15B, and the fuel reference electrode 17A have the same electrode interval, that is, the interval between the comb electrode 111A and the comb electrode 111B.

  As shown in FIGS. 4 and 5, the liquid level detection electrode 13A, the warning liquid level detection electrode 15A, the warning liquid level detection electrode 15B, and the comb-shaped electrode 111A of the fuel reference electrode 17A are parallel to each other by a common lead 18A. It is connected. The liquid level detection electrode 13A, the warning liquid level detection electrode 15A, and the comb-shaped electrode 111B of the warning liquid level detection electrode 15B are connected in parallel by a common lead wire 18B. The common lead wires 18A and 18B are connected to the sensor circuit 11 via one of the pair of wire harnesses 21 at terminals 18C and 18D provided at the upper ends. On the other hand, the comb electrode 111B of the fuel reference electrode 17A is connected to the sensor circuit 11 via the other of the pair of wire harnesses 21 at the lead wire 19 and a terminal 19A formed at the end thereof.

  Hereinafter, a procedure for obtaining the liquid level of the fuel tank 10 in the liquid level detection device 1 will be described. In the sensor circuit 11, a high-frequency current having a predetermined frequency is generated. Here, the liquid level detection electrode 13A, the warning liquid level detection electrode 15A, and the warning liquid level detection electrode 15B are connected in parallel by the common lead wires 18A and 18B as shown in FIG. The high-frequency current is input to the liquid level detection electrode 13A, the warning liquid level detection electrode 15A, and the warning liquid level detection electrode 15B through the common leads 18A and 18B from the terminals 18C and 18D, and the liquid level detection electrode 13A and the warning The impedance between the comb electrode 111A and the comb electrode 111B in the liquid level detection electrode 15A and the warning liquid level detection electrode 15B is measured. The measured impedance is input to the computer, and the sum C of the capacitance c of the liquid level detection electrode 13A, the capacitance c2 of the warning liquid level detection electrode 15A, and the capacitance c3 of the warning liquid level detection electrode 15B is obtained. Desired.

  On the other hand, the high-frequency current generated in the sensor circuit 11 is also input to the fuel reference electrode 17A from the terminal 18C and the terminal 19A through the common lead wire 18B and the lead wire 19, and the comb-shaped electrode 111A in the fuel reference electrode 17A The impedance between the comb electrode 111B is measured. The measured impedance is also input to the computer, and the capacitance d of the fuel reference electrode 17A is obtained.

  Here, when the fuel in the fuel tank 10 is consumed, the space between the comb-shaped electrode 111A and the comb-shaped electrode 111B becomes occupied by the air that was previously occupied by the fuel. The capacity decreases. Therefore, the fuel level can be detected by detecting the decrease in capacitance. At this time, more accurate detection can be performed by comparing the measured values with reference to the capacitance detected by the fuel reference electrode 17A of the fuel reference measurement unit 17 always present in the liquid.

  The computer calculates the liquid level of the fuel tank 10 from the sum C of the capacitances of the liquid level detection electrode 13A, the warning liquid level detection electrode 15A and the warning liquid level detection electrode 15B, and the electrostatic capacitance d of the fuel reference electrode 17A. To do. Further, the computer stores a map showing the relationship between the liquid level and the fuel remaining amount, and the computer obtains the fuel remaining amount in the fuel tank 10 using the liquid level data and this map.

  When the remaining amount of fuel in the fuel tank 10 is greater than the remaining amount of warning, in the liquid level detection sensor 12, the normal region liquid level detection unit 16 in the liquid level detection unit 13 is partially exposed from the liquid level. However, since the warning area liquid level detector 15 is immersed in the fuel, the fuel liquid level is measured only by the normal area liquid level detector 16.

  On the other hand, when the remaining amount of fuel is in the warning region, in the liquid level detection unit 13, the normal region liquid level detection unit 16 is entirely exposed from the fuel level, and the warning region liquid level detection unit 15 A part is exposed from the fuel level. Here, since the liquid level detection unit 13 is formed in a strip shape as described above, the widths of the comb-shaped electrode 111A and the comb-shaped electrode 111B are the normal region liquid level detection unit 16 and the warning region liquid level detection unit 15 respectively. And is equal. However, when the remaining amount of fuel is in the warning region, the feet other than the warning region liquid level detection unit 15 in the liquid level detection unit 13 (hereinafter sometimes referred to as “first warning region liquid level detection unit 15”). Two warning region liquid level detection units 15 (hereinafter, also referred to as “second warning region liquid level detection unit 15, third warning region liquid level detection unit 15”) formed in the shape portion 14 are also used. , A part is exposed from the liquid level of the fuel. Accordingly, the fuel level is detected by the first to third warning region liquid level detection units 15.

  Therefore, in the warning area liquid level detection unit 15, the electrode area per unit liquid level is larger than that in the normal area liquid level detection unit 16, so that the sensor output of the liquid level detection sensor 12 as shown in FIG. The gradient of the remaining amount of fuel with respect to is more gentle in the region in the warning region than in the region where the remaining amount is greater than the remaining amount of warning. In other words, in the area in the warning area, the fuel level, in other words, the remaining fuel quantity can be measured with higher resolution than in the area where the remaining amount is greater than the remaining warning amount.

  Further, as described above, since the warning area liquid level detection unit 15 is provided at three positions, one at the liquid level detection unit 13 and two at the foot-shaped part 14, a liquid is provided between the terminal 18C and the terminal 18D. The sum C of the electrostatic capacity c of the portion corresponding to the warning area liquid level detection unit 15 in the level detection electrode 13A, the electrostatic capacity c2 of the warning liquid level detection electrode 15A, and the electrostatic capacity c3 of the warning liquid level detection electrode 15B is Is output. Therefore, even when the liquid level is inclined for some reason, the correct liquid level can be obtained based on the sum C of the electric capacity.

  As the liquid level detection sensor 12, in addition to the fine capacitance sensor described above for detecting the liquid level by capacitance, an electric resistance sensor for detecting the liquid level by a change in electric resistance can be used.

2. Embodiment 2
Hereinafter, a second example of the liquid level detection sensor used in the liquid level detection apparatus 1 described in the first embodiment will be described with reference to the drawings. As shown in FIGS. 7A and 7B, the liquid level detection sensor 112 according to the second embodiment includes a comb-shaped electrode 111A and a comb-shaped electrode on the surface of a base film 110 formed in a strip shape as a whole. 111B, and a liquid level detection unit 113 for measuring the liquid level, and a foot 114 integrally formed below the liquid level detection unit 113. The leg portion 114 is formed by bending the lower end portion of the liquid level detection unit 113 at a right angle with respect to the liquid level detection unit 113 at a position indicated by a broken line in FIG.

  The liquid level detection unit 113 of the liquid level detection sensor 112 is adjacent above the warning region liquid level detection unit 115 and the warning region liquid level detection unit 115 that detect the fuel level when the remaining amount of fuel is in the warning region. , And a normal region liquid level detection unit 116 that detects the fuel level when the remaining amount of fuel is greater than the remaining amount of warning. In addition, a fuel reference measurement unit 117 is formed in the foot-shaped part 114.

  In the warning region liquid level detection unit 115, the width w2 of the comb electrode 111A and the comb electrode 111B is larger than the width w1 of the comb electrode 111A and the comb electrode 111B in the normal region liquid level detection unit 116. Is formed. Note that the width w3 of the comb-shaped electrode 111A and the comb-shaped electrode 111B in the fuel reference measuring unit 117 is the same as the width w1 of the comb-shaped electrode 111A and the comb-shaped electrode 111B in the normal region liquid level detecting unit 116.

  When the remaining amount of fuel in the fuel tank 10 is greater than the remaining amount of warning, in the liquid level detection sensor 112, in the liquid level detection unit 113, the normal region liquid level detection unit 116 is partially exposed from the liquid level. However, since all of the warning area liquid level detection unit 115 is immersed in fuel, the liquid level of the fuel is measured only by the normal area liquid level detection unit 116.

  On the other hand, when the remaining amount of fuel is in the warning region, the normal region liquid level detection unit 116 is entirely exposed from the fuel level, and the warning region level detection unit 115 is partially from the fuel level. Exposed. Here, as described above, in the warning region liquid level detection unit 115, the width w2 of the comb electrode 111A and the comb electrode 111B is equal to the width of the comb electrode 111A and the comb electrode 111B in the normal region liquid level detection unit 116. Since it is wider than w1, the electrode area per unit liquid level is larger than that of the normal region liquid level detector 116.

  Therefore, as shown in FIG. 6, the gradient of the remaining amount of fuel with respect to the sensor output of the liquid level detection sensor 112 is gentler in the region in the warning region than in the region where the remaining amount is greater than the remaining amount of warning. In other words, in the area in the warning area, the fuel level, in other words, the remaining fuel quantity can be measured with higher resolution than in the area where the remaining amount is greater than the remaining warning amount.

  Further, since the liquid level detection sensor 112 can form the normal region liquid level detection unit 116 and the warning region liquid level detection unit 115 on one strip-shaped base film 110, the liquid level detection sensor 12 in the first embodiment. It is easier to create than Further, since the liquid level detection sensor 112 has an L-shaped form as a whole, unlike the liquid level detection sensor 12 of the first embodiment, it is easy to load the liquid level detection sensor 112 into the sub tank 31. Therefore, the liquid level detection sensor 112 is inserted into the sub tank 31 in addition to the pump unit 32, and then the sub tank 31 is inserted into the fuel tank 10 from the attachment port 22. Therefore, the charging to the fuel tank 10 is much easier than the liquid level detection sensor 12 of the first embodiment.

3. Embodiment 3
Hereinafter, a third example of the liquid level detection sensor used in the liquid level detection device 1 described in the first embodiment will be described with reference to the drawings. As shown in FIGS. 8 (A) to 8 (C) and FIGS. 9 (A) to 9 (C), the liquid level detection sensor 212 according to Embodiment 3 is a base film formed in a strip shape as a whole. A comb-shaped electrode 111 </ b> A and a comb-shaped electrode 111 </ b> B are formed on the surface of 210, and a liquid level detecting unit 213 for measuring the liquid level and integrally formed at the tip of the liquid level detecting unit 213. The fuel reference measurement unit 217 is provided. The fuel reference measurement unit 217 is formed by bending the tip of the liquid level detection unit 213 at a right angle with respect to the liquid level detection unit 113 at a position indicated by a broken line in FIG. Instead of providing the fuel reference measurement unit 217 at the tip of the liquid level detection unit 213, for example, as shown by a two-dot chain line in FIGS. 8B and 9B, a warning region in the liquid level detection unit 213 is provided. The warning area liquid level detection unit 215 may be provided on a surface opposite to the liquid level detection unit 215 so as to extend in the opposite direction.

  The liquid level detection unit 213 of the liquid level detection sensor 212 is adjacent to the warning region liquid level detection unit 215 that detects the fuel level when the remaining amount of fuel is in the warning region, and above the warning region liquid level detection unit 215. , And a normal region liquid level detection unit 216 that detects the fuel level when the remaining amount of fuel is greater than the remaining amount of warning.

  As shown in FIG. 8B, the warning area liquid level detection unit 215 is formed by bending a portion near the foot portion 214 of the liquid level detection unit 213 in a bellows shape in the vehicle vertical direction. In the example shown in FIG. 8B, the liquid level detection unit 213 is bent twice in the vehicle vertical direction to form the warning region liquid level detection unit 215. However, the number of times the liquid level detection unit 213 is bent is as follows. The number of times is not limited to two, and may be one, or may be bent many times, for example, 13 times in the vehicle vertical direction as shown in FIG. 9B. As shown in FIG. 9B, in the form in which the liquid level detection unit 213 is bent many times to form the warning region liquid level detection unit 215, the warning region liquid level detection unit 215 is shown in FIG. 9C. However, when the fuel tank 10 has an L-shaped planar shape, for example, as shown in FIG. 9 (D), the planar shape along the planar shape of the fuel tank 10 may be used. It is good also as a form curved in circular arc shape. The warning area liquid level detection unit 215 is formed such that a bent portion on the vehicle lower side contacts the bottom surface 20 of the fuel tank 10 when the liquid level detection sensor 212 is inserted into the fuel tank 10.

  When the remaining amount of fuel in the fuel tank 10 is greater than the remaining amount of warning, in the liquid level detection sensor 212, the normal region liquid level detection unit 216 is partially exposed from the liquid level. Since all the level detection units 215 are immersed in the fuel, the fuel liquid level is measured only by the normal region liquid level detection unit 216.

  On the other hand, when the remaining fuel amount is in the warning region, the normal region liquid level detection unit 216 is entirely exposed from the fuel level, and the warning region liquid level detection unit 215 is partly from the fuel level. Exposed. Here, the warning area liquid level detection unit 215 is formed by bending a portion in the vicinity of the foot-shaped part 214 of the liquid level detection unit 213 in a bellows shape in the vehicle vertical direction, so that the electrode area per unit liquid level is It is larger than the normal area liquid level detection unit 216.

  Therefore, as shown in FIG. 6, the gradient of the remaining amount of fuel with respect to the sensor output of the liquid level detection sensor 212 is gentler in the region in the warning region than in the region where the remaining amount is greater than the remaining amount of warning. In other words, in the area in the warning area, the fuel level, in other words, the remaining fuel quantity can be measured with higher resolution than in the area where the remaining amount is greater than the remaining warning amount.

  Further, the liquid level detection sensor 212 of the third embodiment forms the warning region liquid level detection unit 215 by bending the tip of the liquid level detection unit 213 in a bellows shape in the vehicle vertical direction. In addition to the features of the liquid level detection sensor 112, it has the feature of being easier to manufacture.

4). Embodiment 4
Hereinafter, a fourth example of the liquid level detection sensor used in the liquid level detection device 1 described in the first embodiment will be described with reference to the drawings. As shown in FIGS. 10A to 10C, the liquid level detection sensor 312 according to the fourth embodiment includes a comb electrode 111 </ b> A and a comb electrode on the surface of a base film 310 that is formed in a strip shape as a whole. 111B and a liquid level detector 313 for measuring the liquid level.

  The lower end portion of the liquid level detection unit 313 is bent obliquely with respect to the vehicle vertical direction, in other words, the vertical direction of the fuel tank 10 as shown in FIG. At the same time, a portion of the liquid level detection unit 313 above the warning region liquid level detection unit 315 is a normal region liquid level detection unit 316. A fuel reference measurement unit 317 is formed at the tip of the warning region liquid level detection unit 315.

  The length of the normal region liquid level detection unit 316 in the liquid level detection sensor 312 and the angle of the warning region liquid level detection unit 315 with respect to the normal region liquid level detection unit 316 are determined by inserting the liquid level detection sensor 312 into the fuel tank 10. Sometimes, the fuel reference measuring unit 317 is set to contact the bottom surface 20 of the fuel tank 10. Further, the normal region liquid level detection unit 316 is formed to extend along the vehicle vertical direction when the liquid level detection sensor 312 is inserted into the fuel tank 10.

  When the remaining amount of fuel in the fuel tank 10 is greater than the remaining amount of warning, in the liquid level detection sensor 312, the normal area liquid level detection unit 316 is partially exposed from the liquid level. Since all the level detection units 315 are immersed in the fuel, the fuel level is measured only by the normal region liquid level detection unit 316.

  On the other hand, when the remaining amount of fuel is in the warning region, the normal region liquid level detection unit 316 is entirely exposed from the fuel level, and the warning region liquid level detection unit 315 is partially from the fuel level. Exposed. Here, when the vehicle is in a horizontal state, the liquid level F of the fuel tank 10 is also horizontal, so the normal area liquid level detection unit 316 is in a state orthogonal to the liquid level F, and the warning area liquid level is detected. The part 315 is inclined with respect to the liquid level F. Accordingly, the electrode area per unit liquid level is larger in the warning area liquid level detection unit 315 than in the normal area liquid level detection unit 216.

  Therefore, as shown in FIG. 6, the gradient of the remaining amount of fuel with respect to the sensor output of the liquid level detection sensor 312 is gentler in the region in the warning region than in the region where the remaining amount is greater than the remaining amount of warning. In other words, in the area in the warning area, the fuel level, in other words, the remaining fuel quantity can be measured with higher resolution than in the area where the remaining amount is greater than the remaining warning amount.

  The liquid level detection sensor 312 of the fourth embodiment forms the warning region liquid level detection unit 315 by bending the lower end portion of the liquid level detection unit 313 obliquely with respect to the vehicle vertical direction. The position detection sensor 212 is easier to manufacture.

5. Embodiment 5
Hereinafter, a fifth example of the liquid level detection sensor used in the liquid level detection device 1 described in the first embodiment will be described with reference to the drawings. As shown in FIG. 11A, the liquid level detection sensor 412 according to the fifth embodiment includes a liquid level detection unit 413 having a cross-shaped planar shape as a whole. The liquid level detection unit 413 is formed at the lower end of the normal region liquid level detection unit 416 and the normal region liquid level detection unit 416 that is generally strip-shaped and extends along the vertical direction of the vehicle, in other words, the vertical direction of the fuel tank 10. A warning area liquid level detection unit 415 extending in the vehicle left-right direction. As shown in FIG. 11B, the warning area liquid level detection unit 415 is bent in an annular shape as a whole. The fuel reference measurement unit 417 is formed at the lower edge of the warning region liquid level detection unit 415 in a direction toward the center point of the warning region liquid level detection unit 415. The configurations of the normal region liquid level detection unit 416, the warning region liquid level detection unit 415, and the fuel reference measurement unit 417 are as described in the second to fourth embodiments.

  Further, the warning area liquid level detection unit 415 may be formed in an S shape centering on the normal area liquid level detection unit 416 in a plan view as shown in FIG.

  Also in the liquid level detection sensor 412 of the fifth embodiment, the warning area liquid level detection unit 415 has a larger electrode area per unit liquid level than the normal area liquid level detection unit 416. Therefore, as shown in FIG. 6, the gradient of the remaining amount of fuel with respect to the sensor output of the liquid level detection sensor 312 is gentler in the region in the warning region than in the region where the remaining amount is greater than the remaining amount of warning. In other words, in the area in the warning area, the fuel level, in other words, the remaining fuel quantity can be measured with higher resolution than in the area where the remaining amount is greater than the remaining warning amount.

  Since the liquid level detection sensor 412 according to the fifth embodiment can be arranged so that the warning region liquid level detection unit 415 surrounds the sub tank 31 inside the fuel tank 10 in addition to the features of the liquid level detection sensor of the second embodiment. Although the warning area liquid level detection unit 415 has a dimension in the width direction that is much larger than that of the normal area liquid level detection unit 416, the warning area liquid level detection unit 415 detects the liquid level detection sensor 412 to the fuel tank 10. It has the feature that there is little obstruction of mounting.

DESCRIPTION OF SYMBOLS 1 Liquid level detection apparatus 10 Fuel tank 12 Liquid level detection sensor 15 Warning area liquid level detection part 16 Normal area liquid level detection part 112 Liquid level detection sensor 113 Liquid level detection part 115 Warning area liquid level detection part 116 Normal area liquid level detection Unit 212 Liquid level detection sensor 213 Liquid level detection unit 215 Warning region liquid level detection unit 216 Normal region liquid level detection unit 217 Fuel reference measurement unit 312 Liquid level detection sensor 313 Liquid level detection unit 315 Warning region liquid level detection unit 316 Normal region Liquid level detection unit 412 Liquid level detection sensor 413 Liquid level detection unit 415 Warning region liquid level detection unit 416 Normal region liquid level detection unit

Claims (6)

A warning region liquid level detection unit for detecting a fuel level in a warning region in which the remaining amount of fuel in the fuel tank is a predetermined amount or less;
A normal region liquid level detection unit that is located above the warning region liquid level detection unit and detects the fuel level in a normal region in which the remaining amount of fuel in the fuel tank is greater than the predetermined amount;
With
The liquid level detection device in which an electrode area per unit liquid level in the warning area liquid level detection unit is larger than an electrode area per unit liquid level in the normal area liquid level detection unit. The liquid level detection device according to claim 1, wherein the warning area liquid level detection unit is provided at two or more locations apart from each other. The liquid level detection device according to claim 1, wherein the warning area liquid level detection unit is bent in a bellows shape. The liquid level detection device according to claim 1, wherein the warning region liquid level detection unit is disposed to be inclined with respect to the vertical direction of the fuel tank. The liquid level detection device according to claim 1, wherein the warning area liquid level detection unit is set to have a larger dimension in the width direction than the normal area liquid level detection unit. The liquid level detection device according to claim 5, wherein the warning area liquid level detection unit is formed in an arc shape or an S shape as viewed from above the fuel tank.

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