JP2006242777A - Liquid level detection device and its output adjusting method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve detection accuracy of a liquid level detection device equipped with a float. <P>SOLUTION: This liquid level detection device 1 includes the float 2 floating on the liquid surface 91 of a liquid storing vessel 10; an arm 3 mounted on the float 2, for converting a vertical motion of the float 2 into a rotational motion around a rotating shaft; and rotation angle detectors 6, 7 for detecting the rotation angle θ of the arm 3, and outputting an output value related to the position of a liquid level. The rotation angle detectors 6, 7 is constituted so as to output an approximately middle value between each output value when the float 2 is positioned at an equal distance in the vertical direction (θ=-90, +90) from the standard position relative to the standard position (θ=0) wherein the axial center of the float 2 is positioned at the same height as the axial center Z of the rotating shaft. Hereby, the detection accuracy of the liquid level detection device 1 can be improved. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a liquid level detection apparatus including a float that floats on a liquid level and an output adjustment method thereof.

  The liquid level detection device is used to monitor the level of fuel stored in a fuel tank of an automobile.

  For example, as a liquid level detection device, a float, a holder for holding a magnet, an arm for connecting them, a main body for holding the holder in a rotatable manner, and a main body so as to intersect the magnetic flux of the magnet And an arithmetic processing means for adjusting the output of the magnetoelectric conversion element to a predetermined output characteristic are disclosed (see Patent Document 1).

  Specifically, the float floats on the liquid to be measured, and the arm converts the vertical movement of the float into the rotational movement of the holder. The magnetoelectric transducer detects the magnetic flux density of the intersecting magnets, and this liquid level detection device can detect the rotation angle of the holder, that is, the liquid level.

Here, the reference outputs at the bottom and top surfaces of the liquid level are DOE and DOF, the outputs from the magnetoelectric transducers at these two positions are DSE and DSF, and the output at the time of detection from the magnetoelectric transducer is DSθ. The adjustment output is DOθ. In this case, the arithmetic processing means calculates the adjustment output DOθ by the following equation: DOE + {(DOF−DOE) / (DSF−DSE)} · (DSθ−DSE).
JP 2001-124617 A

  In patent document 1, the calculation by a linear approximation is performed using the reference output in the lowermost surface and the uppermost surface of a liquid level. However, the liquid level is in the relationship (SINθ) between the arm rotation angle θ and the sine (SIN), and the output from the magnetoelectric transducer also has a relationship including the arm rotation angle θ and the sine (SIN). . Therefore, the liquid level has a complicated relationship including the output from the magnetoelectric transducer, the arm rotation angle θ, and the sine (SIN).

  As a result, in the calculation based on the linear approximation described above, it is difficult to adjust the variation in the characteristics of the magnetoelectric conversion element and the variation in the output characteristics due to the variation in its assembly to the predetermined output characteristics. The accuracy may be reduced.

  The same can be said for a liquid level detection device having a float as well as the liquid level detection device disclosed in Patent Document 1.

  The present invention has been made in view of the above points, and an object of the present invention is to improve the detection accuracy of a liquid level detection device having a float.

  The present invention employs the following technical means to achieve the above object.

  The liquid level detection device according to claim 1 is configured to rotate a float floating on a liquid level in a liquid storage tank, and a vertical movement of the float attached to the float according to a liquid level level of the liquid level around a rotation axis. An arm that converts to motion, and a rotation angle detector that outputs an output value related to the position of the liquid level by detecting the rotation angle of the arm, and the rotation angle detector has the axis of the float as the rotation axis. At the reference position located at the same height as the axis center, the configuration is such that a substantially intermediate value of each output value is output when the float is located at an equal distance in the vertical direction from the reference position.

  In this configuration, the rotation angle detector is configured so that each float axis center is located at an equal distance in the vertical direction from the reference position at the reference position where the axis center of the float is located at the same height as the axis center of the rotation axis. It is comprised so that the substantially intermediate value of an output value may be output.

  Thereby, the output characteristic of the liquid level detection device (rotation angle detector) with respect to the rotation angle of the arm can be brought close to the relationship between the level of the liquid level (height in the vertical direction) with respect to the rotation angle of the arm. As a result, the output characteristic of the liquid level detection device with respect to the level of the liquid level can be made a simpler relationship, and the detection accuracy of the liquid level detection device can be improved.

  According to a second aspect of the present invention, the liquid level detection device includes a guide unit that linearly moves and guides the vertical movement of the float.

  In this configuration, since the guide portion that moves and guides the vertical movement of the float linearly is provided, the liquid level detection device can be saved in the left-right direction.

  According to a third aspect of the present invention, there is provided a liquid level detection apparatus comprising output adjusting means for adjusting the output value of the rotation angle detector to a predetermined output characteristic corresponding to the position of the float in the vertical movement direction.

  In this configuration, output adjustment means for adjusting the output value of the rotation angle detector to a predetermined output characteristic is provided. As described above, according to the present invention, the output characteristic of the liquid level detection device (rotation angle detector) with respect to the level of the liquid level can be set to a simpler relationship. For this reason, the output adjustment means can easily adjust the output value of the rotation angle detector to a predetermined output characteristic.

  For this reason, the dispersion | variation in the output characteristic of a liquid level detection apparatus can be reduced, As a result, the detection accuracy of a liquid level detection apparatus can be improved.

  The liquid level detection apparatus according to claim 4 is configured such that the output adjustment means adjusts the output value of the rotation angle detector so as to have a linear characteristic with respect to the position of the float in the vertical movement direction.

  In this configuration, the output adjusting means adjusts the output value of the rotation angle detector so as to have a linear characteristic with respect to the position of the float in the vertical movement direction. Thereby, the output of a liquid level detection apparatus can be easily utilized for control.

  In the liquid level detection device according to the fifth aspect, the output adjusting means is arranged in the rotation angle detector.

  In this configuration, since the output adjustment means is disposed in the rotation angle detector, the configuration of the liquid level detection device can be simplified.

  The liquid level detection device according to claim 6 includes a magnet in which the rotation angle detector is fixed so as to intersect the magnetic flux of the magnet and not to rotate. A conversion element, wherein the rotation angle of the arm is detected by measuring the magnetic flux density of a magnet intersecting the magnetoelectric conversion element by the magnetoelectric conversion element.

  In this configuration, the rotation angle detector includes the magnet and the magnetoelectric conversion element, and the above-described effects can be obtained even in this configuration.

  The output adjustment method of the liquid level detection device according to claim 7 includes a float that floats on the liquid level in the liquid storage tank, an arm that is attached to the float and converts the vertical movement of the float into a rotational movement around the rotation axis, A rotation angle detector for detecting the rotation angle of the arm, and the rotation angle detector is at a reference position where the float is located at the same height as the rotation axis, and when the float is located at an equal distance in the vertical direction from the reference position. An output adjustment method for a liquid level detection device configured to output a substantially intermediate value of each output value, wherein the output value of the rotation angle detector is a predetermined output corresponding to the position of the float in the vertical movement direction. This is an adjustment method for adjusting to characteristics.

  In this adjustment method, the rotation angle detector outputs a substantially intermediate value of each output value when the float is positioned at the same height as the rotation axis and at the same distance in the vertical direction from the reference position. In the liquid level detection device configured to do this, the output value of the rotation angle detector is adjusted to a predetermined output characteristic corresponding to the position of the float in the vertical movement direction.

  As a result, in the liquid level detection device in which the output characteristic with respect to the level of the liquid level has a simpler relationship, it can be easily adjusted to the predetermined output characteristic. For this reason, the dispersion | variation in the output characteristic of a liquid level detection apparatus can be reduced, As a result, the detection accuracy of a liquid level detection apparatus can be improved.

  Hereinafter, a case where the liquid level detection device according to the present invention is applied to a fuel level gauge 1 which is a liquid level detection device mounted on an automobile will be described with reference to the drawings.

(First embodiment)
FIG. 1 is a front view of a fuel level gauge 1 which is a liquid level detection device according to a first embodiment of the present invention.

  2 is a cross-sectional view taken along line II-II in FIG.

  3 is a cross-sectional view taken along line III-III in FIG.

  FIG. 4 is a schematic diagram for explaining the magnetic flux distribution of the magnet 6 constituting a part of the rotation angle detector provided in the fuel level gauge 1 shown in FIG.

  FIG. 5A is a schematic diagram for explaining the rotation angle θ and the level L of the liquid surface 91, and FIG. 5B shows the positional relationship between the Hall element 7 and the magnet 6 that are magnetoelectric conversion elements with respect to the rotation angle θ. FIG.

  FIG. 6A is a characteristic diagram showing the relationship of the level L of the liquid level 91 with respect to the rotation angle θ, and FIG. 6B shows the relationship of the voltage V1 output from the Hall element 7 with respect to the rotation angle θ. FIG. 6C is a characteristic diagram showing the relationship between the output voltage V1 of the Hall element 7 and the adjustment voltage V2 with respect to the level L of the liquid level 91. FIG.

  FIG. 7 is a circuit configuration diagram for explaining an electrical circuit configuration of the fuel level gauge 1 which is the liquid level detection device according to the first embodiment of the present invention.

  In FIG. 1, FIG. 2, and FIG. 5 (a), the upper part indicated by the arrow in each figure indicates the upper part in a state where the fuel level gauge 1 is attached to the automobile.

  The fuel level gauge 1 detects the level 91 of the fuel 9 and is fixed in a fuel tank 10 which is a liquid storage tank schematically shown in FIG. 1 and 2, the liquid level 91 of the fuel 9 shows the lowest level.

  The float 2 is made of resin or the like, and has an apparent specific gravity so as to surely float on the liquid level 91 of the fuel 9.

  The arm 3 is formed of, for example, a metal rod, and connects the float 2 and the magnet holder 4. As shown in FIG. 1, the float 2 is fixed to one end of the arm 3, and the other end of the arm 3 is fixed to the magnet holder 4. When the float 2 moves in the vertical direction (the vertical direction indicated by the arrow in the figure) as the level of the liquid level 91 changes, this movement is transmitted to the magnet holder 4 by the arm 3 and is the axis center of the rotation axis. The rotational movement of the magnet holder 4 is converted around the rotational axis Z.

  The magnet holder 4 is made of resin or the like, and as shown in FIG. 2, incorporates a magnet 6 that constitutes a part of the rotation angle detector and engages with a body 5 described later so as to be rotatable. As shown in FIGS. 1 and 2, the magnet holder 4 includes a hole portion 41 that is rotatably fitted to a shaft portion 51 provided in the body 5, and a locking portion 42 that holds and fixes the arm 3. And a through hole 43.

  Two locking portions 42 are arranged on the end surface of the magnet holder 4 opposite to the body 5 and are formed as shown in FIG. FIG. 3 shows a state in which the arm 3 is not attached, and the arm 3 is indicated by a one-dot chain line.

  The locking part 42 has an inner diameter D2 that is smaller than the outer diameter D1 of the arm 3, and an opening dimension W of the locking part 42 that is smaller than its inner diameter D2. The two locking portions 42 are arranged with their central axes aligned.

  As shown in FIGS. 1 and 2, the through hole 43 is formed in parallel with the hole 41 of the magnet holder 4. The inner diameter dimension of the through hole 43 is equal to or slightly smaller than the outer diameter dimension D1 of the arm 3. As shown in FIG. 1, the through-hole 43 is arranged so that its central axis intersects with the central axes of both locking portions 42.

  The magnet 6 built in the magnet holder 4 is made of, for example, a ferrite magnet, and has a cylindrical shape and is arranged concentrically with the hole 41. Furthermore, since the magnet 6 is magnetized in the radial direction as shown in FIG. 4, the magnetic flux of the magnet 6 is generated in the radial direction of the hole 41. The magnet 6 is integrally insert-molded when the magnet holder 4 is resin-molded.

  The body 5 includes a stopper 53 for restricting the rotation range of the magnet holder 4. In addition, a hall element 7 which is a magnetoelectric conversion element for detecting the rotation angle of the magnet holder 4 is incorporated, and a terminal 8 for electrically connecting the hall element 7 to the outside is provided.

  The hall element 7 constitutes a part of a rotation angle detector, and as shown in FIG. 2, the hall element 7 is disposed in the shaft portion 51, and a magnet 6 fixed to the magnet holder 4 is disposed on the outer peripheral side of the shaft portion 51. 51 and concentric. For this reason, the Hall element 7 always receives the magnetic flux M of the magnet 6 as shown in FIG.

  The Hall element 7 is made of a semiconductor, and generates a Hall voltage proportional to the magnetic flux density of the magnetic field that passes through the Hall element 7 when a magnetic field is applied from the outside while a voltage is applied to the Hall element 7. Since the magnetic flux density of the magnetic field passing through the Hall element 7 changes when the magnet holder 4 rotates due to the fluctuation of the liquid level 91, the Hall voltage that is the output voltage of the Hall element 7 changes. By detecting the Hall voltage, the rotation angle of the magnet holder 4, that is, the level of the liquid level 91 can be measured.

  The Hall element 7 and the magnet 6 constitute a rotation angle detector.

  The terminal 8 is made of a conductive metal, and one end thereof is electrically connected to the lead 71 of the Hall element 7 as shown in FIG. This connection is, for example, by caulking or fusing. On the other hand, the other end of the terminal 8 protrudes outward from the end of the body 5 and is connected to a connector (not shown) of an external wire harness (not shown).

  After the Hall element 7 and the terminal 8 are electrically connected to each other, the Hall element 7 and the terminal 8 are integrally insert-molded when the body 5 is resin-molded.

  As shown in FIG. 2, the body 5 includes a shaft portion 51, and the shaft holder 51 rotatably holds the magnet holder 4. In the vicinity of the tip of the shaft portion 51, a ring-shaped groove 52 is provided concentrically with the shaft portion 51. After the shaft portion 51 is fitted into the hole portion 41 of the magnet holder 4, a retaining ring 54 is attached to the groove 52. This restricts the movement of the magnet holder 4 in the direction away from the body 5 (the left direction indicated by the arrow in FIG. 2).

  That is, the shaft portion 51 of the body 5 is inserted into the hole 41 of the magnet holder 4 so that the magnet holder 4 is brought into contact with the body 5, and then the retaining ring 54 is mounted in the groove 52 of the shaft portion 51. Thereby, the magnet holder 4 is hold | maintained so that rotation with respect to the body 5 is possible.

  After inserting the arm 3 into the through hole 43, the arm 3 is rotated around the through hole 43, and the arm 3 is pushed into the locking portion 42 from the left side indicated by the arrow in FIG. As a result, the locking portion 42 is elastically deformed to hold and fix the arm 3, and thereby the arm 3 is fixed to the magnet holder 4.

  As shown in FIG. 5A, the stopper 53 formed on the body 5 is provided so that the position of the float 2 corresponds to the lowest and highest positions. Each stopper 53 is formed by integral molding with the body 5 and is provided so that the end of the arm 3 opposite to the float 2, that is, the portion protruding from the through hole 43 of the arm 3, as shown in FIG. 2. It is done.

  Accordingly, when the float 2 moves up and down as shown in FIG. 5A, the magnet holder 4 rotates about the rotation axis Z by an angle θ. That is, the rotation range of the magnet holder 4 (that is, the float 2 and the arm 3) in the fuel level gauge 1 according to the first embodiment of the present invention is the rotation angle θ. The rotation angle θ is set to 180 degrees so that the float 2 can move up and down at the maximum, but may be less than that.

  Here, when the axis center of the float 2 is positioned at the same height as the rotation axis Z that is the axis center of the rotation axis, that is, when the axis center of the float 2 is positioned on the X axis in FIG. The rotation angle θ is zero degrees, the clockwise rotation is the positive rotation angle, the counterclockwise rotation is the negative rotation angle, and the distance between the rotation axis Z and the axis center of the float 2 is R. Further, the level L of the liquid level 91 is such that the zero position is a position where the rotation angle θ is zero degree, the upper side is a positive level, and the lower side is a negative level.

  As a result, the level L of the liquid level 91 is expressed by the following sine wave equation (1), and the relationship of the level L of the liquid level 91 to the rotation angle θ is shown in FIG.

L = R · SINθ (1)
The Hall element 7 and the magnet 6 are configured to have an arrangement relationship shown in FIG. 5B when the rotation angle θ of the float 2 is −90 degrees, zero degrees, and +90 degrees, respectively. Thus, the Hall element 7 outputs the maximum voltage V12 when the rotation angle θ of the float 2 is +90 degrees, outputs the minimum voltage V11 when the rotation angle θ of the float 2 is −90 degrees, and those when the rotation angle θ is zero degrees. The intermediate voltage value (V11 + V12) / 2 is output.

  As described above, the Hall element 7 generates a Hall voltage proportional to the magnetic flux density of the magnetic field that passes through the Hall element 7. Therefore, the output voltage V1 of the Hall element 7 is expressed by the following sine wave equation (2), and FIG. 6B shows the relationship of the voltage V1 output from the Hall element 7 with respect to the rotation angle θ.

V1 = (1/2). (V12−V11) .SINθ + (V11 + V12) / 2 (2)
The electric circuit configuration of the fuel level gauge 1 according to the present embodiment described above will be described with reference to FIG.

  The control device 22 constituted by a microcomputer or the like is always supplied with electric power from the battery 40, the ignition switch 30 is connected so as to detect its operation position (off position, on position), and the fuel level gauge 1 outputs its output. The voltage V1 is connected to allow input.

  That is, the terminal 8 of the fuel level gauge 1 protrudes outward from the end of the body 5 in FIG. 2 and is connected to a connector (not shown) of an external wire harness (not shown). This external wire harness is connected to a wire harness (not shown) outside the fuel tank 10, and the wire harness outside the fuel tank 10 is connected to the control device 22. A fuel gauge 21 is connected to the control device 22.

  The control device 22 includes output adjusting means 22a that adjusts the output voltage V1 from the fuel level gauge 1 to the adjustment voltage V2, and driving means 22c that drives the fuel gauge 21 in accordance with the adjusted adjustment voltage V2. The output adjustment unit 22a includes a memory 22b including an electrically rewritable nonvolatile memory or a backup RAM (random access memory) that stores conversion data for adjusting the output voltage V1 to the adjustment voltage V2 as a map. .

  The relationship between the output voltage V1 of the Hall element 7 and the adjustment voltage V2 with respect to the level L of the liquid level 91 is shown in FIG.

  The fuel level gauge 1 and the output adjustment means 22 a of the control device 22 constitute a liquid level detection device, and the fuel gauge 21 and the control device 22 constitute a combination meter 20.

  Next, the operation of the fuel level gauge 1 according to the first embodiment of the present invention will be described.

  FIG. 8 is a table for explaining the contents of the data table showing the conversion relationship between the output voltages V1 and V2 stored in the memory 22b.

  When the ignition switch 30 is turned on, in FIG. 7, the control device 22 detects it and starts operation, and applies a voltage to the Hall element 7 of the fuel level gauge 1 to operate it.

  On the other hand, the float 2 of the fuel level gauge 1 floats on the liquid level 91 of the fuel 9 in the fuel tank 10, and the arm 3 holds the magnet holder 4 with respect to the body 5 in accordance with the level L of the liquid level 91. It is in a state rotated to an angle θ.

  That is, the rotation angle θ of the magnet holder 4 with respect to the body 5 can be determined from the level L of the liquid level 91 from the sine wave equation (1) shown in FIG.

  Further, the Hall element 7 and the magnet 6 are configured so as to have the arrangement relationship shown in FIG. Therefore, the Hall element 7 outputs a voltage V1 corresponding to the rotation angle θ from the sine wave equation (2) shown in FIG.

  The expressions (1) and (2) have the same period and phase. For this reason, the relationship of the voltage V1 output from the Hall element 7 to the level L of the liquid level 91 can be expressed by the following simple equation (3), which is shown in FIG. 6 (c). Shown in

V1 = (1 / (2R)). (V12−V11) .L + (V11 + V12) / 2 (3)
The output adjustment means 22a of the control device 22 adjusts the output voltage V1 linear with respect to the level L of the liquid level 91 to the adjustment voltage V2 shown in FIG. .

  However, the output characteristic of the fuel level gauge 1, that is, the voltage output from the Hall element 7 with respect to the level L of the liquid level 91 due to the variation in the output characteristics of the Hall element 7 and the variation in assembly of the Hall element 7 to the fuel tank 10. Variations occur in the relationship of V1.

  In the prior art, in FIG. 6B, when the rotation angle θ is zero degree, the configuration of outputting (V11 + V12) / 2 is not taken. That is, the rotation angle θ is shifted by the phase θ1 between the sine wave of Expression (1) and the sine wave of Expression (2). For this reason, the relationship between the voltage V1 output from the Hall element 7 and the rotation angle θ is a sine wave obtained by substituting (θ−θ1) for θ in Equation (2), and the Hall element 7 with respect to the level L of the liquid level 91. Unlike the simple expression (3) in which the relationship between the voltage V1 output from the output is linear, the relationship is complicated.

  As a result, in the calculation based on the above linear approximation, the variation in the characteristics of the Hall element 7 and the variation in the output characteristics due to the variation in the assembly of the Hall element 7 with respect to the fuel tank 10 are adjusted linearly with respect to the level L of the liquid level 91. It is difficult to adjust to the voltage V2. For this reason, the detection accuracy of a liquid level detection apparatus falls.

  On the other hand, in the fuel level gauge 1 according to the first embodiment of the present invention, the deviation of the phase θ1 can be eliminated, so that the output voltage V1 of the Hall element 7 is expressed by a simple equation (3) that is linear. . For this reason, since the variation in the output characteristics can be adjusted to the linear adjustment voltage V2 much more easily than in the prior art, the detection accuracy of the fuel level gauge 1 can be easily improved. .

  Specifically, as shown in FIG. 8, the output adjusting means 22a of the control device 22 outputs an output V11 when the rotation angle θ of the float 2 is −90 degrees and an output V12 when the rotation angle θ of the float 2 is +90 degrees. Then, the data is taken into the memory 22b of the output adjusting means 22a, and the converted data in the memory 22b is adapted to each case (V1). That is, those values are set to V21 and V22 of the predetermined adjustment voltage V2, and the intermediate voltage V2X corresponding to the intermediate voltage V1X is obtained by function conversion, and a data table is created and stored in the memory 22b.

  The output adjustment means 22a adjusts the output voltage V1 to the adjustment voltage V2 using the adapted conversion data (data table) of the memory 22b.

  For this reason, even if the output voltage V1 generated by the fuel level gauge 1 (Hall element 7) varies, the output adjusting means 22a of the control device 22 adjusts the output voltage V1 so that it becomes the adjusted voltage V2. Thereby, since there is no variation in the adjustment voltage V2, there is no variation in the detection value. As a result, the detection of the liquid level detection device constituted by the fuel level gauge 1 and the output adjustment means 22a of the control device 22 is performed. It is possible to reduce variation in values and improve the detection accuracy.

  Since the driving means 22c of the control device 22 drives the fuel gauge 21 based on the adjustment voltage V2, the fuel gauge 21 can display the level L of the liquid level 91 with high accuracy.

  The range of the rotation angle θ of the float 2 is not limited to the above case, and may be between −60 degrees and +80 degrees, for example. In this case, the Hall element 7 has an intermediate voltage value between an output value when the rotation angle θ of the float 2 is zero and an output value when the rotation angle θ of the float 2 is −60 degrees and an output value when the rotation angle θ of the float 2 is +60 degrees. The Hall element 7 and the magnet 6 are configured to output.

  That is, the Hall element 7 has the axis of the float 2 at the reference position (the position where the rotation angle θ of the float 2 is zero degrees) located at the same height as the rotation axis Z that is the axis center of the rotation axis. Each output value when the center is located at an equal distance in the vertical direction from the reference position (for example, an output value where the rotation angle θ of the float 2 is −60 degrees and an output value where the rotation angle θ of the float 2 is +60 degrees) Output intermediate values. Thus, the Hall element 7 and the magnet 6 are configured.

  Further, the number of the locking portions 42 need not be limited to two, and may be one or three or more.

(Second Embodiment)
FIG. 9A is a front view of a fuel level gauge 1 that is a liquid level detection device according to a second embodiment of the present invention, and FIG. 9B is a cross-sectional view taken along line IXB-IXB in FIG. FIG.

  FIG. 10 is a cross-sectional view taken along line XX in FIG.

  FIG. 11 is a schematic diagram for explaining the rotation angle θ and the level L of the liquid surface 91.

  In the fuel level gauge 1 which is the liquid level detection device according to the second embodiment of the present invention, unlike the first embodiment, the float 2 moves in the direction of the rotation axis Z, instead of the arrow in FIG. Move up and down as indicated by.

  Specifically, a first float guide 56 and a second float guide 57, which are guide portions for guiding the float 2 in the vertical direction, are newly provided. As shown in FIG. Fit guide grooves 2 a are provided on both side surfaces of the float 2. Further, the float 2 is formed in a quadrangular prism shape instead of a cylindrical shape so that it can be easily guided by the float guides 56 and 57.

  In addition to the locking portion 42, an arm guide 42 a is integrally formed on the magnet holder 4. The dimension between the inner diameter D2 of the locking portion 42 and the arm guide 42a is formed to be equal to or slightly larger than the outer diameter D1 of the arm 3.

  After the arm 3 is attached to the locking portion 42 and both the float guides 56 and 57 are fitted into the guide groove 2a of the float 2, both ends of the second float guide 57 are inserted into the first guide hole 55a and the second guide hole 58. And it fixes to the body 5 by adhesion | attachment, ultrasonic welding, etc. In addition, the attachment method with respect to the latching | locking part 42 of the arm 3 is the same as 1st Embodiment.

  The first float guide 56 and the guide base 55 are formed integrally with the body 5, and the second float guide 57 is formed separately from the body 5. The first guide hole 55 a is provided in the guide base 55, and the second guide hole 58 is provided in the main body portion of the body 5.

  The mounting structure between the magnet holder 4 and the body 5 and the arrangement of the magnet 6, the hall element 7 and the terminal 8 are the same as those in the first embodiment as shown in FIG. .

  Here, when the axis center of the float 2 is positioned at the same height as the rotation axis Z that is the axis center of the rotation axis, that is, when the axis center of the float 2 is positioned on the X axis in FIG. θ is zero degrees, clockwise is a positive rotation angle, counterclockwise is a negative rotation angle, and R is the distance between the rotation axis Z and the axis center of the float 2 located at the lower limit (or upper limit). Further, the level L of the liquid level 91 is such that the zero position is the position where the rotation angle θ is zero degree, the upper level (the upper direction indicated by the arrow in the figure) is a positive level, and the lower position is the lower level. Negative level.

  The Hall element 7 and the magnet 6 are configured as shown in FIG. 5B at a position where the rotation angle θ is zero degrees.

  With the above configuration, when the float 2 moves up and down while being guided by the float guides 56 and 57, the arm 3 is guided to move by the locking portion 42 and the arm guide 42a. Thereby, the vertical motion of the float 2 is converted into a rotational motion around the rotational axis Z of the magnet holder 4 by the arm 3.

  Since the float 2 moves up and down, space can be saved by the distance (X1-X2) as compared with the case where the float 2 rotates (indicated by reference numeral 2A in FIG. 11), but the rotation angle θ is equal to the phase θ2. Just shift. In addition, since the phase θ2 changes in accordance with the rotation angle θ, the relationship of the voltage V1 output from the Hall element 7 with respect to the rotation angle θ is more complicated than Expression (2).

  However, also in this embodiment, since the Hall element 7 and the magnet 6 are configured as shown in FIG. 5B at a position where the rotation angle θ is zero, the deviation of the phase θ1 shown in FIG. 6B can be removed. . Therefore, the output voltage V1 can be adjusted relatively easily to the adjustment voltage V2 that is linear with respect to the level L of the liquid level 91 by the output adjustment means 22a of the control device 22.

  As described above, in the present invention, the Hall element 7 has the float 2 at the reference position (rotation angle θ is zero degree) at the same height as the rotation axis Z that is the axis center of the rotation axis. Outputs an intermediate value between output values (for example, an output value with a rotation angle θ of −60 degrees and an output value with a rotation angle θ of +60 degrees) when the axis center is located at an equal distance in the vertical direction from the reference position. . As long as this requirement is satisfied, various modifications are possible without being limited to the above-described examples.

  Further, the output adjusting means 22 a may be disposed in the vicinity of the Hall element 7 or may be incorporated in the Hall element 7.

  Further, the number of magnets 6 need not be limited to one cylindrical magnet, and may be two or three.

  Further, the material of the magnet 6 may be another material such as a rare earth magnet instead of the ferrite magnet.

  Further, instead of the Hall element 7, other magnetic detection elements such as a magnetoresistive element may be used as the magnetic detection element.

  In addition, the liquid level detection device according to the present invention needs to include a float that floats on the liquid level of the liquid to be measured. However, the method for detecting the rotation angle of the holder is not limited to the above-described example. The modification of this can be considered.

  Further, the liquid level detection device according to the present invention is not limited to the fuel level gauge 1 for automobiles, but may be applied to other liquid level detection devices. Further, the liquid as the liquid level detection target is not limited to the fuel, and may be water, lubricating oil, various chemicals, or the like.

FIG. 1 is a front view of a fuel level gauge 1 which is a liquid level detection device according to a first embodiment of the present invention. 2 is a cross-sectional view taken along line II-II in FIG. 3 is a cross-sectional view taken along line III-III in FIG. FIG. 4 is a schematic diagram for explaining the magnetic flux distribution of the magnet 6 constituting a part of the rotation angle detector provided in the fuel level gauge 1 shown in FIG. FIG. 5A is a schematic diagram for explaining the rotation angle θ and the level L of the liquid surface 91, and FIG. 5B shows the positional relationship between the Hall element 7 and the magnet 6 that are magnetoelectric conversion elements with respect to the rotation angle θ. FIG. FIG. 6A is a characteristic diagram showing the relationship of the level L of the liquid level 91 with respect to the rotation angle θ, and FIG. 6B shows the relationship of the voltage V1 output from the Hall element 7 with respect to the rotation angle θ. FIG. 6C is a characteristic diagram showing the relationship between the output voltage V1 of the Hall element 7 and the adjustment voltage V2 with respect to the level L of the liquid level 91. FIG. FIG. 7 is a circuit configuration diagram for explaining an electrical circuit configuration of the fuel level gauge 1 which is the liquid level detection device according to the first embodiment of the present invention. FIG. 8 is a table for explaining the contents of the data table showing the conversion relationship between the output voltages V1 and V2 stored in the memory 22b. FIG. 9A is a front view of a fuel level gauge 1 that is a liquid level detection device according to a second embodiment of the present invention, and FIG. 9B is a cross-sectional view taken along line IXB-IXB in FIG. FIG. FIG. 10 is a cross-sectional view taken along line XX in FIG. FIG. 11 is a schematic diagram for explaining the rotation angle θ and the level L of the liquid surface 91.

Explanation of symbols

1 Fuel level gauge (Liquid level detector)
2 Float 2a Guide groove 3 Arm 4 Magnet holder 41 Hole 42 Locking portion 42a Arm guide 43 Through hole 5 Body 51 Shaft 52 Groove 53 Stopper 54 Retaining ring 55 Guide base 55a First guide hole 56 First float guide (guide) Part)
57 Second float guide (guide section)
58 Second guide hole 6 Magnet (rotation angle detector)
7 Hall element (rotation angle detector, magnetoelectric transducer)
71 Lead 8 Terminal 9 Fuel (Liquid)
91 Liquid level 10 Fuel tank
20 Combination meter 21 Fuel gauge 22 Control device 22a Output adjusting means 22b Memory 22c Driving means 30 Ignition switch 40 Battery Z Rotating shaft (Rotating shaft center)
D1 Outer diameter D2 Inner diameter W Opening dimension θ Rotation angle

Claims (7)

A float that floats on the liquid level in the reservoir;
An arm that is attached to the float and converts the vertical movement of the float according to the liquid level level of the liquid level into a rotational movement around a rotation axis;
A rotation angle detector that outputs an output value related to the position of the liquid level by detecting the rotation angle of the arm;
The rotation angle detector is configured such that when the float shaft center is positioned at the same height as the shaft center of the rotation shaft, the float shaft center is located at an equal distance in the vertical direction from the reference position. A liquid level detection apparatus configured to output a substantially intermediate value of each output value.   The liquid level detection device according to claim 1, further comprising a guide unit that linearly moves and guides the vertical movement of the float.   The liquid level according to claim 1 or 2, further comprising output adjusting means for adjusting an output value of the rotation angle detector to a predetermined output characteristic corresponding to a position of the float in a vertical movement direction. Detection device.   The liquid level according to claim 3, wherein the output adjusting means adjusts the output value of the rotation angle detector so as to have a linear characteristic with respect to a position of the float in a vertical movement direction. Detection device.   The liquid level detection device according to claim 3 or 4, wherein the output adjusting means is disposed in the rotation angle detector. The rotational angle detector includes a magnet that rotates in conjunction with the rotational motion of the arm, and a magnetoelectric conversion element that is fixed so as to cross the magnetic flux of the magnet and not to rotate.
The rotation angle of the arm is detected by measuring a magnetic flux density of the magnet that intersects the magnetoelectric conversion element by the magnetoelectric conversion element. The liquid level detection device according to item. A float that floats on the liquid level in the liquid storage tank, an arm that is attached to the float and that converts the vertical movement of the float into a rotational motion around a rotational axis, and a rotational angle detector that detects the rotational angle of the arm The rotation angle detector is at a reference position where the float is located at the same height as the rotation axis, and is approximately an intermediate value of each output value when the float is located at an equal distance in the vertical direction from the reference position. An output adjustment method for a liquid level detection device configured to output
An output adjustment method for a liquid level detection device, wherein an output value of the rotation angle detector is adjusted to a predetermined output characteristic corresponding to a position of the float in a vertical movement direction.

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