JP2013195382A - Low fuel warning system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem that a low fuel level can be overlooked in the absence of a warning thereof.SOLUTION: A low fuel warning system includes; a liquid surface detection device having a float floating on fuel in a tank and detection means for generating a detection value in accordance with the level of the fluid surface on which the float rests; a warning device which warns a user of a low fuel level if a fuel level corresponding to the detected value is less than a predetermined threshold value; failure assessment means S30 which acquires a physical quantity having a correlation with fuel consumption and, if changes in the acquired physical quantity do not conform to the changes in the detection value, determines that the detection means has failed. When the detection means is determined to have failed (S30: NO), a warning display unit (warning device) of a meter device is turned on even if the fuel level corresponding to the detection value is no less than the threshold value and the detection value is within a normal range (S20: YES).

Description

  The present invention relates to a fuel shortage warning system that warns a user when there is a shortage of fuel remaining in a tank.

  Patent Documents 1 to 3 include a float that floats on the fuel in the tank and a detection unit that outputs a detection value corresponding to the level of the liquid surface on which the float floats, and a fuel remaining amount calculated based on the detection value is predetermined. A system is disclosed that warns the user that there is a shortage of fuel when the threshold is less than the threshold.

  Patent Document 1 discloses that when the detected value exceeds the normal range, it is determined that a short circuit or open failure has occurred in any of the electrical paths.

JP 2009-8416 A JP 2002-202179 A JP 2007-240274 A

  However, although the detected value is within the normal range, a failure in which the detected value is a value that does not correspond to the actual liquid level (hereinafter referred to as “normal range failure”) may occur. The present inventor obtained the following knowledge. When this type of failure occurs, an amount larger than the actual remaining fuel amount may be erroneously detected. In this case, even if the fuel is actually in shortage, there is no warning to that effect. Or the warning time is delayed.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a fuel shortage warning system that solves the problem of being overlooked without warning that there is a shortage of fuel.

  The invention for achieving the above object is characterized by the following points. That is, a float that floats on the fuel in the tank, and a liquid level detection device that has a detection means that outputs a detection value corresponding to the level of the liquid level on which the float floats, and a fuel remaining amount corresponding to the detection value is a predetermined threshold value A warning device that warns the user that there is a shortage of fuel, and a physical quantity that correlates with fuel consumption and that is different from the detected value. A failure determination unit that determines that the detection unit has failed when the change in the detection value does not match, and a fuel remaining amount that corresponds to the detection value when the failure determination unit determines that there is a failure. Control means for controlling the alarm device to operate or raise the threshold even if the detected value is a value within a normal range.

  In short, in the above-described invention, when the above-described failure within the normal range is detected, even if the remaining fuel amount corresponding to the detected value is equal to or greater than the threshold, the warning device is activated or the threshold for fuel shortage determination is increased. For this reason, even if a failure within the normal range occurs, the warning device operates (or becomes easier to operate). The problem that the time is delayed can be solved.

  Specific examples of the liquid level detection device according to the present invention include a magnetic device illustrated in FIG. 8 and a resistance device illustrated in FIG. 1. And when a liquid level detection apparatus is a resistance type demonstrated below, the effect by the invention mentioned above is exhibited more notably. The reason will be described in detail below.

  That is, the liquid level detection device slides on the substrate in conjunction with a substrate on which a plurality of electrodes are arranged, an electric resistor in which the plurality of electrodes are connected to different positions, and a displacement of the float. And a sliding portion that contacts any one of the plurality of electrodes, and a voltage corresponding to a resistance value of a current path that flows through the electrode and the electrical resistor that is in contact with the sliding portion, It is a device that outputs as a detection value.

  According to this apparatus, since the resistance value changes according to the liquid level, a detected value of voltage corresponding to the liquid level is output, and the remaining fuel amount can be grasped based on the detected value. However, when the sliding portion slides repeatedly on the electrode (see FIG. 4A), the electrode may be deformed by rolling (see FIG. 4B), and there is a concern that a failure may occur due to a short circuit with the adjacent electrode. The present inventor obtained the following knowledge. In particular, since the float frequently moves up and down at a specific position (for example, a position where the remaining amount of fuel is about half), there is a high probability that only the electrode corresponding to the vicinity of the specific position is short-circuited. Then, although the detected value is within the normal range, it becomes a value that does not correspond to the liquid level, and there is a possibility that an amount larger than the actual fuel remaining amount is erroneously detected.

  As described above, the probability that a failure within the normal range such as outputting a detection value that does not correspond to the actual liquid level even though the detection value is within the normal range is more likely to occur in the resistance type than in the magnetic type. Is higher. Therefore, the above-described invention that eliminates the fact that the fuel shortage is overlooked without warning is effective when applied to a case where the liquid level detection device is a resistance type.

  Here, when a plurality of electrodes are formed by mixing a glass material into a conductive material, the above-described rolling deformation is suppressed because the glass material is a material that is not easily deformed. Therefore, a highly conductive material that is highly corrosive to fuel can be selected as the conductive material. However, there is a case where the glass material is not uniformly mixed and some of the electrodes are easily deformed by rolling. In this case, there is a concern about failure within the normal range. Therefore, if the above invention is applied when a glass material is mixed into a conductive material to form a plurality of electrodes, the above-mentioned effect of eliminating the fact that the fuel shortage is overlooked without warning is suitably exhibited. The

1 is an overall schematic diagram of a fuel shortage warning system according to a first embodiment of the present invention. The top view which shows the electrical resistor and electrode which are shown in FIG. In 1st Embodiment, the graph which shows the relationship between the fuel residual rate according to a liquid level detection value, and its detection value. Sectional drawing explaining the process in which a 1st electrode carries out rolling deformation and short-circuits. The top view which shows the short circuit state of FIG.4 (b). The graph which shows the change of the fuel remaining rate in the case of the short circuit state of FIG. The flowchart which shows the process sequence of the lighting control of a warning display part in 1st Embodiment. The whole schematic diagram of the fuel shortage warning system concerning 2nd Embodiment of this invention.

  Hereinafter, each embodiment in which a fuel shortage warning system according to the present invention is applied to a fuel tank mounted on a vehicle will be described with reference to the drawings. In the following embodiments, parts that are the same or equivalent to each other are denoted by the same reference numerals in the drawings, and the description of the same reference numerals is used.

(First embodiment)
A liquid level detection device 10 shown in FIG. 1 detects liquid level positions F1 and F2 of the fuel FU, and is attached to a sub tank disposed in the fuel tank. The liquid level detection device 10 includes a main body 15, a float 11 that floats on the liquid surface of the fuel FU, a rotating part 13 that can rotate with respect to the main body 15, and a float 11 and a rotating part 13 that are connected to each other. And an arm 12 that converts the vertical motion of 11 into the rotational motion of the rotating unit 13. The ceramic substrate 1 on which the electrode 2 and the electrical resistor 3 are formed is fixed to the main body portion 15, and the sliding portion 14 that slides on the electrode 2 while being electrically connected to the electrode 2 is fixed to the rotating portion 13. Is fixed. The electrode 2, the electrical resistor 3, and the sliding portion 14 correspond to “detecting means”.

  FIG. 1 shows that the liquid level F1 of the fuel FU indicates the lowest level (substantially empty) in the fuel tank, the liquid level F2 indicates the highest level (full tank), and the float 11 at the liquid level F2 The arm 12 is indicated by a two-dot chain line. When the fuel FU changes between the liquid level positions F1 and F2, the float 11 moves up and down in conjunction therewith, and the rotating unit 13 rotates about the rotation center C0 within a predetermined rotation range with respect to the main body unit 15. To do.

  As the rotating part 13 rotates, the sliding part 14 slides on the electrode 2 along an arc centered on the rotation center C0. The sliding portion 14 shown in FIGS. 1 and 2 includes a first sliding portion 141 that slides on a first electrode 21 described later, and a second sliding portion 142 that slides on a second electrode 22 described later. And a connecting portion 143 that electrically connects the sliding portions 141 and 142, and is formed of a conductive metal.

  In the ceramic substrate 1 shown in FIG. 2, the electrode 2 is connected to the first electrode 21 to which the positive voltage terminal 161 is electrically connected and a positive voltage is applied, and the grounding terminal 162 is electrically connected to ground. The second electrode 22 is provided. The first electrode 21 includes a plurality of first electrodes 21 arranged in parallel at equal intervals, and the second electrode 22 is formed as a comb-like electrode. The electrodes 21 and 22 are formed in a thick film by printing and baking a paste made of silver (Ag), palladium (Pd), glass frit, and the like on the ceramic substrate 1.

  In addition, the reason why the second electrode 22 is formed in a comb-like shape and the recess 23 is provided is that the wear generated by the second sliding portion 142 sliding on the second electrode 22 is removed through the recess 23 to the outside. This is to make it flow smoothly. Also in the first electrode 21, wear generated by the sliding of the first sliding portion 141 on the first electrode 21 can smoothly flow out to the outside through the space between the adjacent first electrodes 21. .

  The ceramic substrate 1 is provided with a sliding area A1 in which the first sliding portion 141 slides. The sliding region A1 includes one end side portions of the plurality of first electrodes 21. When the first sliding portion 141 is slid on the sliding area A1, the first electrode 21 is slid. Thereby, the first sliding portion 141 is electrically connected to one or two first electrodes 21.

  Further, the ceramic substrate 1 is provided with a covering region A2 that covers the other end portion of the first electrode 21 with the electric resistor 3. The electrical resistor 3 is formed in a thick film by printing and baking a paste made of ruthenium oxide (RuO2) and glass frit on the ceramic substrate 1.

  As described above, when the fuel FU changes between the liquid level positions F1 and F2, the float 11 moves up and down in conjunction therewith, and the rotating unit 13 rotates with respect to the main body unit 15 within a predetermined rotation range. Rotate around C0. As the rotating unit 13 rotates, the sliding unit 14 slides on the first electrode 21 along an arc centered on the rotation center C0. For this reason, the 1st electrode 21 which the 1st sliding part 141 electrically connects changes with the change of the liquid level position F1, F2. The liquid level detection device 10 includes the electric resistor 3, the electrodes 21, 22 and the sliding portions 141 to 141 according to the first electrode 21 to which the first sliding portion 141 is electrically connected among the plurality of first electrodes 21. The electric resistance value generated by 143 varies.

  Specifically, the electrical resistance value between the terminals 161 and 162 is determined from the terminal 161 from the first electrode 21, the electrical resistor 3, the first electrode 21 (sliding region A <b> 1), the first sliding portion 141, and the connecting portion 143. , The second sliding portion 142, the second electrode 22, and the terminal 162, or an electric resistance value by an electric path formed in the order opposite to this order. For this reason, the electrical resistance value between the terminals 161 and 162 varies depending on the first electrode 21 to which the first sliding portion 141 is electrically connected among the plurality of first electrodes 21. The liquid level detection device 10 is configured to detect the liquid level positions F1 and F2 based on the electrical resistance value that varies depending on the liquid level positions F1 and F2.

  Since the electrodes 21 and 22, the electric resistor 3, and the sliding portions 141, 142, and 143 cannot be incorporated in the main body portion 15, the electrodes 21 and 22, the electric resistor 3, and the sliding portion 141 can be used. , 142 and 143 are immersed in the fuel FU.

  Signals output from the terminals 161 and 162 of the liquid level detection device 10 correspond to liquid level detection values (detection values), and the detection values are input to the meter ECU 20. The meter ECU 20 is an electronic control device that controls the operation of the meter device 30 attached to the instrument panel in the passenger compartment. The meter device 30 includes a vehicle speed meter 31 that displays the vehicle speed, a fuel meter 32 that displays the remaining amount of fuel, and a warning display unit 33 (warning device) that warns the user of fuel shortage.

  The meter ECU 20 includes a well-known microcomputer (microcomputer), and this microcomputer calculates the fuel remaining amount corresponding to the detected value based on the liquid level detection value sequentially input from the liquid level detection device 10. . Further, the operation of the meter device 30 is controlled so that the calculated fuel remaining amount is displayed on the fuel gauge 32.

  FIG. 3 is a graph showing the relationship between the remaining fuel ratio corresponding to the liquid level detection value and the detection value. The liquid level detection value is a voltage value indicating a potential difference between the terminals 161 and 162. When the remaining amount of fuel is reduced and the position of the float 11 is lowered, the position of the sliding portion 14 is lowered to the lower side in FIG. 1 and the electric resistance value is increased. Therefore, the potential difference between the terminals 161 and 162 increases, and the liquid level detection value (voltage) increases.

  As shown in the figure, when the fuel remaining rate is F or more, the liquid level detection value becomes the minimum value H2, and the fuel gauge 32 displays that the fuel is full. On the other hand, when the remaining fuel ratio is equal to or less than E, the liquid level detection value is the maximum value H3, and the fuel gauge 32 displays that the fuel is empty. Further, the warning determination threshold value HW is set to a value smaller than the maximum value H3 by a predetermined value, and when the detected value becomes larger than the warning determination threshold value HW, a warning is given to the user that fuel is insufficient. Therefore, the warning display unit 33 is lit up.

  Here, if a harness (not shown) connecting the terminals 161 and 162 and the meter ECU 20 is disconnected or an open failure occurs such that the terminals 161 and 162 are damaged, the liquid level detection value exceeds the maximum value H3. It becomes a large value. In addition, when a short circuit failure occurs in which the terminals 161 and 162 are short-circuited or the harness is short-circuited, the liquid level detection value becomes a small value exceeding the minimum value H2. That is, when an open failure or a short failure occurs, the value of the liquid level detection value becomes an abnormal value exceeding the range (normal range) between the minimum value H2 and the maximum value H3 described above.

  FIG. 4A is a cross-sectional view showing the ceramic substrate 1, the first electrode 21, and the first sliding portion 141. The plurality of first electrodes 21 are arranged side by side in a predetermined direction (left-right direction in FIG. 4). Yes. The surface on which the first electrode 21 comes into contact with the first sliding portion 141 is formed in an arc shape with the first sliding portion 141 side as a top. The surface where the first sliding portion 141 contacts the first electrode 21 is formed in an arc shape with the first electrode 21 side as a top portion. The arc radius of the first sliding portion 141 is set larger than the arc radius of the first electrode 21. The first sliding portion 141 can be in contact with the two first electrodes 21 at the same time, and is always in contact with one of the first electrodes 21.

  When the usage period of the liquid level detection device 10 becomes longer, the first sliding portion 141 slides back and forth repeatedly in the direction in which the first electrodes 21 are arranged (the predetermined direction). Then, as shown in FIG.4 (b), the circular-arc top part of the 1st electrode 21 may carry out rolling deformation. In this case, the rolling deformation progresses, and there is a concern that the end portions 21a of the adjacent first electrodes 21 come into contact with each other and short-circuit as shown by the alternate long and short dash line in the figure.

  FIG. 5 shows an example in which the end portions 21a are short-circuited in the region indicated by the alternate long and short dash line Ma. When the first sliding portion 141 is located in the short-circuited region Ma, the position is located in the region Ma. The electric resistance value is the same regardless of which of the plurality of first electrodes 211 to 217 is in contact. That is, when the float 11 is in the range corresponding to the short-circuit region Ma, the liquid level detection value does not change even if the fuel remaining amount actually decreases and the float 11 position is lowered. Specifically, even when the first sliding portion 141 is in contact with the first electrode 217, the detection value is the same as that of the first electrode 211.

  FIG. 6 is a graph showing the change in the remaining fuel ratio in accordance with the detected value when short-circuited as shown in FIG. 5, and at time t1 when the position of the float 11 has decreased to a position corresponding to the first electrode 211. In the period Mb from the time point until the position corresponding to the first electrode 217 is lowered to the point corresponding to the detected value in spite of the fact that the remaining fuel ratio actually decreases as shown by the dotted line in the figure. The fuel remaining rate does not decrease. Thereafter, at time t3 when the position of the float 11 is lowered to a position where the first sliding portion 141 moves away from the first electrode 217 and contacts only the first electrode 218, a detection value that matches the actual fuel remaining rate is output. Become so.

  In short, in the period Mb in which the first sliding portion 141 is located in the short-circuit region Ma, a decrease in the fuel remaining rate is not detected, and a value greater than the actual fuel remaining rate is calculated. However, in the case of erroneous detection due to this rolling deformation, the detected value falls within the normal range, unlike the open failure and short failure described above. Hereinafter, the state of erroneous detection caused by rolling deformation is referred to as “normal range failure”.

  In the example of FIG. 6, if a failure within the normal range has not occurred, the detected value becomes larger than the warning determination threshold value HW at time t2. That is, the calculated value of the fuel remaining rate is smaller than the threshold value W. Therefore, the warning display unit 33 is turned on at the time t2. On the other hand, if a failure within the normal range occurs, the lighting display is performed at time t3, and the lighting start timing is delayed. In addition, if the end portions 21a are short-circuited between the first electrodes 217, 218, and 219, the same fuel remaining rate is calculated from the time point t3 and after the time point t1, and a warning is given even if the fuel becomes empty. The display unit 33 is not lit.

  In view of this problem, in the present embodiment, lighting control of the warning display unit is performed by the process shown in FIG. This process is repeatedly executed at a predetermined cycle by the microcomputer of the meter ECU 20.

  First, in step S10, it is determined whether there is an open failure or a short failure based on the liquid level detection value. For example, if the detected value is larger than the open determination value H4 set larger than the maximum value H3 shown in FIG. Further, if the detected value is smaller than the short determination value H1 set smaller than the minimum value H2 shown in FIG.

  When it is determined that an open failure or a short failure is caused by such a method (S10: YES), the warning display unit 33 is turned on in step S60 (control means). If it is not determined that there is an open failure or a short failure (S10: NO), it is determined in step S20 whether or not the detected value is in a normal range (H2 to H3). If it is within the normal range (S20: YES), it is determined in step S30 (failure determination means) whether or not there is a change in the detected value corresponding to “actual fuel consumption”.

  The “actual consumption” used in this determination is a value calculated from a physical quantity that is different from the liquid level detection value among physical quantities that correlate with fuel consumption, and is, for example, injected from the fuel injection valve of the engine. A physical quantity that correlates with the fuel consumption such as the fuel injection amount and the travel distance of the vehicle is acquired, and a value calculated from the acquired value (physical quantity correlated with the fuel consumption) is used. The fuel injection amount may be acquired from the engine ECU 40 (see FIG. 1) that controls the operation of the engine.

  In short, if a failure within the normal range occurs, the detected value should not change as illustrated in the Mb period of FIG. 6 even though the actual consumption has increased, and the actual consumption If there is a change in the detected value corresponding to, a failure in the normal range should not have occurred.

  Therefore, if it is determined that there is no change in the detection value corresponding to the actual consumption (S30: NO), the failure flag in the normal range is set to ON in step S40, and the warning display unit 33 is displayed in step S60. Lights up. The flag is set off when a normal range fault is repaired. For example, a repair worker may set it off manually.

  Even if it is determined in step S30 that there is a change in the detected value corresponding to the actual consumption (S30: YES), if the flag is set on (S50: NO), step S60 The warning display unit 33 is turned on. On the other hand, if the flag is set to OFF (S50: YES), the warning display unit 33 is turned off.

  Here, in the case illustrated in FIG. 6, it is determined that there is a failure temporarily in the period Mb (S30: NO), and it is determined that there is no failure after time t3 (S30: YES). However, even in this case, if the failure within the normal range is repaired and the flag is not set to OFF, the lighting of the warning display unit 33 in step S60 is continued. As a result, it is possible to avoid turning off the warning display unit 33 due to a change in the detection value corresponding to the actual consumption amount even though the failure in the normal range is not repaired.

  As described above, according to the present embodiment, even if a failure in the normal range in which the first electrodes 21 are short-circuited due to rolling deformation occurs, the occurrence of the failure is detected and the warning display unit 33 is turned on. Even if it is in a shortage state, it is possible to solve the problem that the warning is not given or the warning time is delayed. In the example of FIG. 6, the normal range failure flag is set to ON immediately after the time t1, and the warning display unit 33 is turned on at a time before the time t2.

(Second Embodiment)
In the said 1st Embodiment, the resistance-type liquid level detection apparatus 10 comprised so that an electrical resistance value might change according to the position change of the float 11 is employ | adopted. On the other hand, in the present embodiment shown in FIG. 8, a magnetic liquid level detection device 10 </ b> A configured to change the magnetic detection amount in accordance with the position change of the float 11 is employed.

  That is, the liquid level detection device 10A includes a magnet holder 17 that rotates together with the arm 12, and a body 18 that is fixed so as not to rotate. The magnet holder 17 holds a pair of magnets 17a (detection means), and the body 18 holds a hall element 18a (detection means). The hall element 18 a is disposed at the center position of the magnetic flux between the magnets 17 a and at the center position of rotation of the magnet holder 17.

  When the rotation position of the magnet holder 17 changes with the rotation of the arm 12, the amount of magnetic flux detected by the Hall element 18a changes. As a result, a liquid level detection value corresponding to the remaining amount of fuel is output from the hall element 18a. Incidentally, the rotation range of the arm 12 is restricted by the stopper portion 22b of the arm 12 coming into contact with the stopper portion 23b of the body 18.

  Even in the case of such a magnetic liquid level detection device 10A, a detection value that does not correspond to the actual liquid level even though the detection value is within the normal range due to a failure of the Hall element 18a, for example. A failure within the normal range, such as output, may occur. Therefore, even in the case of the magnetic liquid level detection device 10A, the effect of solving the above-described problem can be solved by performing the same control as in FIG. Is suitably exhibited.

(Other embodiments)
In each of the above embodiments, the warning display unit 33 is turned on when a failure within the normal range is detected. However, instead of this control, the warning determination threshold HW is set to be high when a failure within the normal range is detected. It may be changed. This also makes it possible to advance the timing at which the warning display unit 33 is turned on, so that it is possible to prevent the warning timing from being delayed when a failure within the normal range occurs.

  Further, after the warning display unit 33 is turned on, the fuel gauge 32 may be forcibly displayed as E (display indicating that the fuel remaining rate is equal to or less than E). However, if E is displayed simultaneously with the start of lighting of the warning display unit 33, there is a concern that the user may not even move to a nearby repair shop. Until the vehicle travels a predetermined distance, the above-described forced E display may be prohibited. In this case, the predetermined distance may be set to a distance that the vehicle is assumed to be able to move to the repair shop.

  In addition, this invention is not limited to the description content of the said embodiment, You may make it combine the characteristic structure of each embodiment arbitrarily, respectively.

  2 ... Electrode (detection means), 3 ... Electric resistor (detection means), 10, 10A ... Liquid level detection device, 11 ... Float, 14 ... Sliding part (detection means), 17a ... Magnet (detection means), 18a ... Hall element (detection means), 33 ... Warning display section (warning device) of meter device, S30 ... Failure determination means, S60 ... Control means.

Claims (4)

A liquid level detection device (10, having a float (11) floating on the fuel in the tank and detection means (2, 3, 14, 17a, 18a) for outputting a detection value corresponding to the level of the liquid level on which the float floats 10A) and
A warning device (33) that warns the user that there is a shortage of fuel when the remaining fuel amount corresponding to the detected value is less than a predetermined threshold (W);
When a physical quantity that is correlated with fuel consumption and is different from the detected value is acquired, and the change in the acquired physical quantity is not consistent with the change in the detected value, the detecting means has failed. Failure determination means for determining (S30);
If the failure determination means determines that there is a failure, whether the warning device is to be activated even if the remaining amount of fuel corresponding to the detection value is greater than or equal to the threshold and the detection value is within a normal range Control means (S60) for controlling to increase the threshold;
A fuel shortage warning system comprising: The liquid level detection device is:
A substrate (1) on which a plurality of electrodes (21) are arranged side by side;
An electrical resistor (3) in which the plurality of electrodes are respectively connected to different positions;
A sliding portion (14) that slides on the substrate in conjunction with the displacement of the float and contacts any of the plurality of electrodes;
2. The fuel shortage warning according to claim 1, wherein the detection value is output in accordance with a resistance value of a current path flowing through the electrode and the electric resistor in contact with the sliding portion. system.   The fuel shortage warning system according to claim 2, wherein the plurality of electrodes are formed by mixing a glass material with a conductive material.   The control according to any one of claims 1 to 3, wherein, when the failure determination unit temporarily determines a failure, control by the control unit is continued even after the failure is not determined. The fuel shortage warning system described.

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