JP5621517B2 - Liquid level detector - Google Patents

Description

  The present invention relates to a liquid level detection device that detects the level of a liquid level stored in a container.

  2. Description of the Related Art Conventionally, a liquid level detection device that detects the height of a liquid level by detecting the rotation angle of a rotating body that rotates following the liquid level of a liquid stored in a container is known. For example, the liquid level detection device disclosed in Patent Document 1 includes a magnet holder as a rotating body that holds a magnet for forming a magnetic flux, and a main body having a shaft portion that rotatably supports the magnet holder. ing. In the liquid level detection device disclosed in Patent Document 1, a pair of magnets are arranged with the shaft portion of the main body portion interposed therebetween, and surround the shaft portion. A magnetoelectric conversion element for measuring the amount of magnetic flux formed by the pair of magnets is embedded in the shaft portion of the main body.

  In the liquid level detection device having the above configuration, the amount of magnetic flux penetrating the magnetoelectric conversion element varies depending on the rotation angle of the magnet holder. Therefore, the liquid level detection apparatus can detect the height of the liquid level stored in the container by detecting the rotation angle of the magnet holder by the magnetoelectric conversion element.

Japanese Patent No. 4093126

  By the way, in the liquid level detection device as described in Patent Document 1, the magnetic flux formed by the magnet arranged so as to surround the shaft portion in the liquid level detection device is released into the space surrounded by the magnet. , Penetrating the shaft. Here, in general, in the liquid level detection device as described in Patent Document 1, in order to smoothly rotate the magnet holder relative to the main body portion, the axial direction of the shaft portion is between the magnet holder and the main body portion. There is a play along. Therefore, the magnet holder can move along the axial direction of the shaft portion.

  When the magnet holder moves in the axial direction of the shaft portion due to this axial play, the magnetoelectric conversion element located inside the shaft portion is sandwiched between the pair of magnets, It will move away from the space where the magnetic flux is formed. Thereby, the magnetoelectric conversion element may be formed by a pair of magnets and may not be able to accurately detect the rotation angle of the magnet holder based on the amount of magnetic flux penetrating the magnetoelectric conversion element.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a liquid level detection device that can accurately detect the liquid level of the liquid based on the rotation angle of the rotating body. .

  In order to achieve the above object, according to the first aspect of the present invention, a rotating body that rotates following the liquid level of the liquid stored in the container, a main body fixed to the container, and a rotation protruding from the main body. A fixed body having a support shaft that rotatably supports the body, a magnet portion that rotates integrally with the rotary body while surrounding the support shaft, and forms a magnetic flux that penetrates the support shaft, and an element portion that is positioned inside the support shaft A detection circuit for detecting the rotation angle of the rotating body based on the amount of magnetic flux formed by the magnet portion and penetrating the element portion, and a pair of the support shaft on the inner peripheral side of the magnet portion with the support shaft interposed therebetween. A magnetic body portion that rotates integrally with the rotating body together with the magnet portion while sandwiching the magnet portion, extends from the inner peripheral side of the magnet portion to the element portion side along the axial direction of the support shaft, and passes the magnetic flux formed by the magnet portion. And a liquid level detecting device.

  According to the present invention, the magnetic flux formed by the magnet portion passes through the inside of the magnetic body portion arranged in a pair on the inner peripheral side of the magnet portion, and is released into the space sandwiched by these magnetic body portions. Thus, the support shaft is penetrated. These magnetic body portions extend from the inner peripheral side of the magnet portion to the element portion side along the axial direction of the support shaft. Therefore, even if the rotating body that is rotatably supported by the support shaft of the fixed body moves in the direction away from the support shaft along the axial direction, the element portion of the detection circuit located inside the support shaft is , It can stay in the space where the magnetic flux is sandwiched between the magnetic parts. Therefore, the detection circuit can accurately detect the rotation angle of the rotating body based on the amount of magnetic flux formed by the magnet portion and penetrating the element portion. Therefore, the liquid level detection device can accurately detect the liquid level height of the liquid stored in the container from the rotation angle of the rotating body that rotates following the liquid level of the liquid.

In the invention according to claim 2, the element portion is formed in a plate shape extending along the axial direction of the support shaft, and the magnetic body portion is formed on the support shaft more than the sensor portion of the element portion in the axial direction of the support shaft. It extends | stretches to the main-body part side, It is characterized by the above-mentioned.

In this invention, the magnetic body portion extends in the axial direction of the support shaft to the body portion side of the support shaft rather than the sensor portion of the plate-shaped element portion. Therefore, even when the rotating body moves along the axial direction of the support shaft in a direction away from the support shaft, most of the element portion is sandwiched between the magnetic body portions in the space where the magnetic flux exists. Can stay reliably. Accordingly, the detection circuit can accurately detect the rotation angle of the rotating body based on the amount of magnetic flux penetrating the element portion regardless of the position of the rotating body in the axial direction. Therefore, the liquid level detection device can accurately detect the liquid level height of the liquid stored in the container from the rotation angle of the rotating body.

  According to a third aspect of the present invention, the magnetic body portion includes a contact portion that contacts the magnet portion, and an extending portion that is positioned closer to the support shaft than the contact portion and sandwiches the element portion. To do.

  According to this invention, since the contact part of the magnetic body part is in contact with the magnet part, the magnetic flux formed by the magnet part reliably passes through the magnetic body part. In addition, in the magnetic part, the distance between the extending parts that are closer to the support shaft than the contact part is narrower than the distance between the contact parts. Therefore, the magnetic flux formed by the magnet portion reaches the other magnetic body portion from one magnetic body portion by mainly passing through the space sandwiched between the extending portions. Thereby, the density of the magnetic flux in the space sandwiched between the extending portions can be maintained high.

  Furthermore, even when the rotating body moves in a direction away from the support shaft due to the arrangement of the extending portions located across the element portion, the element portion can remain in the space sandwiched between the extending portions. As described above, the detection circuit can detect the rotation angle of the rotating body based on the amount of magnetic flux passing through the element portion in a space where a high magnetic flux density is maintained. Thereby, the detection of the liquid level based on the rotation angle of the rotating body becomes more accurate.

  According to a fourth aspect of the present invention, the magnetic part has a circular cross-sectional shape.

  According to the present invention, by using the magnetic part having a circular cross section, the space between the pair of magnetic parts becomes narrow in the circumferential direction of the support shaft. Thereby, the density of the magnetic flux in the space sandwiched between the magnetic parts is increased. Therefore, the detection circuit can detect the rotation angle of the rotating body based on the amount of magnetic flux penetrating the element portion in a space where a high magnetic flux density is maintained. Thereby, the detection of the liquid level based on the rotation angle of the rotating body becomes more accurate.

  The invention according to claim 5 is characterized in that the magnetic body portion has a plate shape that extends along the axial direction of the support shaft and curves along the circumferential direction of the support shaft.

  According to this invention, the magnetic flux that exists in the space sandwiched between the magnetic body portions due to the shape of the magnetic body portion that extends along the axial direction of the support shaft and curves along the circumferential direction of the support shaft. The density unevenness is suppressed. Therefore, even if the rotating body moves along the axial direction of the support shaft, the amount of magnetic flux penetrating the element portion is hardly changed. As described above, the detection circuit can accurately detect the rotation angle of the rotating body based on the amount of magnetic flux penetrating the element portion regardless of the position of the rotating body. Therefore, the detection of the liquid level based on the rotation angle of the rotator becomes more accurate.

1 is a front view of a fuel level gauge according to a first embodiment of the present invention. It is the II-II sectional view taken on the line of FIG. It is a figure for demonstrating the characteristic part of a fuel level gauge, Comprising: It is the enlarged view to which the area | region III of FIG. 1 was expanded. It is the IV-IV sectional view taken on the line of FIG. It is a figure for demonstrating the characteristic part of the fuel level gauge by 2nd embodiment of this invention. FIG. 6 is a cross-sectional view taken along line VI-VI in FIG. 5. It is a figure for demonstrating the characteristic part of the fuel level gauge by 3rd embodiment of this invention. It is the VIII-VIII sectional view taken on the line of FIG. It is a figure which shows the modification of FIG. It is a figure which shows another modification of FIG.

  Hereinafter, a plurality of embodiments of the present invention will be described with reference to the drawings. In addition, the overlapping description may be abbreviate | omitted by attaching | subjecting the same code | symbol to the corresponding component in each embodiment. When only a part of the configuration is described in each embodiment, the configuration of the other embodiment described above can be applied to the other part of the configuration. In addition, not only combinations of configurations explicitly described in the description of each embodiment, but also the configurations of a plurality of embodiments can be partially combined even if they are not explicitly specified unless there is a problem with the combination. .

(First embodiment)
Hereinafter, an example in which the liquid level detection device according to the first embodiment of the present invention is applied to a fuel level gauge 100 installed in a fuel tank 90 of a vehicle will be described. The fuel level gauge 100 detects the height of the liquid level 91a of the fuel 91 stored in the fuel tank 90, and outputs the detection result to an external measuring device such as a combination meter (not shown).

  1 and 2 are a front view and a sectional view taken along line II-II of the fuel level gauge 100. FIG. The fuel level gauge 100 is fixed to a fuel tank 90 which is a container together with the fuel pump module 93 by being attached to the wall surface of the fuel pump module 93. The method for attaching the fuel level gauge to the fuel tank is not limited to the above-described form. For example, the fuel level gauge may be directly fixed inside the fuel tank 90 via a stay or the like (not shown).

  First, the basic configuration of the fuel level gauge 100 will be described with reference to FIGS. 1 and 2. The fuel level gauge 100 is configured by combining a float 60, a float arm 50, a housing 20, a magnet holder 30, a detection circuit 40, a wiring 70, and the like.

  The float 60 is made of a material having a specific gravity smaller than that of the fuel 91, such as foamed ebonite. The float 60 can float on the liquid level 91 a of the fuel 91. The float 60 is formed in a thin rectangular parallelepiped shape so that the height of the liquid level 91a can be detected even when the remaining amount of the fuel 91 is very small. Further, a through hole 61 is formed in the float 60 so as to pass through the center of gravity of the float 60. The float 60 is not limited to the rectangular parallelepiped shape described above, and may be a columnar shape or the like.

  The float arm 50 is formed of a round bar-shaped core made of a metal material such as stainless steel. The float arm 50 is provided with a float holding part 53 and a stopper part 51. The float holding portion 53 is provided at an end portion on the float 60 side among both end portions of the float arm 50. The float holding portion 53 is formed by bending the float arm 50 about 90 degrees in the same direction as the rotation axis of the magnet holder 30. The float arm 50 holds the float 60 by inserting the float holding portion 53 into the through hole 61 of the float 60. The stopper 51 is provided at the end of the float arm 50 on the magnet holder 30 side. The stopper portion 51 is formed by bending the float arm 50 in the same direction as the rotation axis of the magnet holder 30 and about 90 degrees toward the housing 20.

  The housing 20 is made of polyphenylene sulfide (PPS) resin or the like that is not affected by an organic solvent such as the fuel 91 and does not decrease in strength even at high temperatures. The housing 20 includes a main body 23, a support shaft 21, and stopper walls 24a and 24b. The main body 23 is formed in a rectangular parallelepiped shape, and is fixed to the fuel tank 90 by being attached to the fuel pump module 93. The support shaft 21 protrudes in the horizontal direction from the central portion of the main body portion 23. The support shaft 21 has a cylindrical shape and supports the magnet holder 30 so as to be rotatable. The stopper walls 24a and 24b are provided on two wall portions facing each other in the horizontal direction while being attached to the wall surface of the fuel pump module 93. These stopper walls 24 a and 24 b are disposed at positions on the rotation path of the stopper portion 51 so as to come into contact with the stopper portion 51 of the float arm 50. One stopper wall 24a is for preventing the float 60 from coming into contact with the bottom surface 90b of the fuel tank 90. In the state where the remaining amount of the fuel 91 in the fuel tank 90 is very small (solid line in FIG. 1). The stopper portion 51 is provided in contact with the stopper portion 51. The other stopper wall 24b is for preventing the float 60 from contacting the ceiling surface 90a of the fuel tank 90, and the fuel tank 90 is filled with the maximum amount of fuel 91 (see FIG. 1). In the two-dot chain line), it is provided so as to come into contact with the stopper portion 51.

  The magnet holder 30 is formed in a cylindrical shape with, for example, polyacetal (POM) resin, which has good oil and solvent resistance and excellent mechanical properties. The magnet holder 30 has a bearing portion 33, a magnet 31, a flange portion 34, a stopper hole 35, and an arm locking portion 32.

  The bearing portion 33 is an inner peripheral wall of the magnet holder 30 and is fitted into the support shaft 21 of the housing 20. The magnet holder 30 is rotatably supported by the housing 20 by fitting the bearing portion 33 into the support shaft 21. In addition, since the inner diameter of the bearing portion 33 is slightly larger than the outer diameter of the support shaft 21, the magnet holder 30 can smoothly rotate relative to the housing 20.

  The magnet 31 is formed in a plate shape that curves along the cylindrical surface of the outer periphery of the support shaft 21, and the shape of the cross section perpendicular to the axial direction of the support shaft 21 forms a fan shape. The magnet 31 is accommodated in the magnet holder 30 and is fixed to the magnet holder 30 by a locking claw (not shown) for locking provided in the magnet holder 30. A pair of magnets 31 are arranged with the support shaft 21 of the housing 20 interposed therebetween, and surround the support shaft 21. The magnet 31 rotates relative to the housing 20 integrally with the magnet holder 30 while surrounding the support shaft 21. As the magnet 31, for example, a permanent magnet such as a ferrite magnet, a rare earth magnet, an alnico magnet, or a bonded magnet is used.

  The flange portion 34 is a bowl-shaped portion provided on the outer peripheral wall of the magnet holder 30. The stopper hole 35 is a hole formed in the flange portion 34 along the axial direction of the magnet holder 30. The arm locking portion 32 is a claw portion for locking the float arm 50, and extends from the axial end surface of the magnet holder 30 that contacts the float arm 50. The float arm 50 is fixed to the magnet holder 30 by locking the float arm 50 to the arm locking portion 32 in a state where the stopper portion 51 is inserted into the stopper hole 35.

  With the above configuration, the float arm 50 supported by the magnet holder 30 converts the vertical movement of the float 60 following the liquid level 91 a of the fuel 91 into a rotational motion and transmits it to the magnet holder 30. As a result, the magnet holder 30 rotates relative to the housing 20 following the liquid level 91 a of the fuel 91 stored in the fuel tank 90.

  The detection circuit 40 includes a magnetoelectric conversion element 42 and three terminals 41. The detection circuit 40 detects the rotation angle of the magnet 31 relative to the housing 20 based on the amount of magnetic flux formed by the magnet 31 and passing through the magnetoelectric conversion element 42 by using the magnetoelectric conversion element 42.

  The magnetoelectric conversion element 42 is embedded in the housing 20 by insert molding. The magnetoelectric conversion element 42 is located inside the support shaft 21 so as to be sandwiched between the magnets 31 housed inside the magnet holder 30. The magnetoelectric conversion element 42 has a plate shape extending along the axial direction of the support shaft 21. The magnetoelectric conversion element 42 includes three input / output units 42a serving as an input terminal, a ground terminal, and an output terminal. The magnetoelectric conversion element 42 is a Hall element, and a voltage proportional to the amount of magnetic flux passing through the magnetoelectric conversion element 42 is detected as a detection result when the sensor unit 42c receives an action of a magnetic field from the outside in a state where a voltage is applied. , Output from the output terminal of the input / output unit 42a.

  The three terminals 41 are formed of a highly conductive phosphor bronze plate or brass plate. Each terminal 41 has a plate shape extending along the vertical direction. Each terminal 41 is connected to each input / output part 42a of the magnetoelectric conversion element 42 by welding or the like at the lower end in the vertical direction among both ends in the extending direction. Further, of the both ends of each terminal 41, the end on the upper side in the vertical direction is exposed to the outside of the housing 20.

  Three wirings 70 are provided and are connected to the terminal 41 respectively. The detection result of the rotation angle of the magnet holder 30 by the magnetoelectric conversion element 42 is transmitted to a measuring device such as a combination meter outside the fuel tank 90 via the wiring 70.

  With the configuration described above, the fuel level gauge 100 outputs a voltage corresponding to the level of the liquid level 91 a of the fuel 91. Specifically, when the direction of the magnetic flux formed by the magnet 31 that rotates and displaces integrally with the magnet holder 30 is along the thickness direction of the magnetoelectric conversion element 42, the amount of magnetic flux penetrating the magnetoelectric conversion element 42 is maximized. Thereby, the voltage as the detection result output by the magnetoelectric conversion element 42 is maximized. When the magnet 31 rotates in a specific direction due to a change in the level of the liquid level 91a and the amount of magnetic flux penetrating the magnetoelectric conversion element 42 decreases, the voltage as the detection result output from the magnetoelectric conversion element 42 decreases. Furthermore, when the magnet 31 rotates in a specific direction and the plane direction of the magnetoelectric conversion element 42 and the direction of the magnetic flux are parallel, the amount of magnetic flux penetrating the magnetoelectric conversion element 42 is minimized and output from the magnetoelectric conversion element 42. The voltage as the detection result is the lowest.

  In the fuel level gauge 100 described so far, as shown in FIG. 3, a clearance C along the axial direction of the support shaft 21 is provided between the magnet holder 30 and the housing 20. The clearance C is for smoothly rotating the magnet holder 30 relative to the housing 20. However, because the clearance C is provided, the magnet holder 30 can move along the axial direction of the support shaft 21 by the size of the clearance C. In particular, when the magnet holder 30 is moved in the direction in which it is removed from the support shaft 21, the magnetoelectric conversion element 42 is moved away from the space sandwiched between the pair of magnets 31. Then, since the density of the magnetic flux in the vicinity of the magnetoelectric conversion element 42 decreases, the voltage as the detection result output from the magnetoelectric conversion element 42 greatly fluctuates.

  The iron core 80, which is a configuration for suppressing fluctuations in the detection results as described above and is a characteristic part of the fuel level gauge 100 according to the first embodiment, will be described in detail with reference to FIGS. In FIG. 3, the illustration of the configuration of the float arm 50, the arm locking portion 32, and the like is omitted.

  The iron core 80 is formed of a ferromagnetic material such as a steel material. A pair of iron cores 80 are arranged inside the magnet 31 with the support shaft 21 interposed therebetween. With this arrangement, the magnetic flux formed by the magnet 31 passes through the iron core 80. The iron core 80 is accommodated in the magnet holder 30 and fixed to the magnet holder 30. Thereby, the iron core 80 is integrated with the magnet holder 30 together with the magnet 31 with the support shaft 21 interposed therebetween, and rotates relative to the housing 20.

  The iron core 80 extends along the axial direction of the support shaft 21 from the inner peripheral side of the magnet 31 to the main body portion 23 side of the support shaft 21 and to the magnetoelectric conversion element 42 side. The iron core 80 has a circular cross section perpendicular to the axial direction, and is bent at the center. The iron core 80 has a contact portion 81 and an extending portion 83. Each contact portion 81 is in contact with each inner peripheral wall 31 a of each magnet 31. When each contact part 81 and the inner peripheral wall 31a of the magnet 31 contact, the magnetic flux formed by the magnet 31 surely passes through the iron core 80.

  The extending portion 83 extends from the contact portion 81 located on the inner peripheral side of the magnet 31 toward the magnetoelectric conversion element 42 side along the axial direction of the support shaft 21. The extending portion 83 extends from the sensor portion 42 c of the magnetoelectric conversion element 42 to the main body portion 23 side in the axial direction of the support shaft 21. The extending portion 83 of the first embodiment has a length L1 that is longer than the sensor portion 42c of the magnetoelectric transducer 42 in the axial direction of the support shaft 21 even when the clearance C between the housing 20 and the magnet holder 30 is maximized. Only extends to the main body 23 side.

  The extending portion 83 is closer to the support shaft 21 than the contact portion 81 due to the bending provided in the iron core 80. Therefore, the interval between the extending portions 83 is narrower than the interval between the contact portions 81. As a result, the magnetic flux formed by the magnet 31 and passing through the iron core 80 mainly passes through the space sandwiched between the extending portions 83 rather than the space sandwiched between the contact portions 81, so that one iron core 80 moves to the other. The iron core 80 is reached. As described above, the pair of iron cores 80 exhibits an effect of guiding the magnetic flux formed by the pair of magnets 31 toward the main body portion 23 along the axial direction of the support shaft 21.

  In the first embodiment described so far, the magnetic flux formed by the magnet 31 passes through the support shaft 21 by passing through the inside of the iron core 80 and being released into the space sandwiched between the iron cores 80. These iron cores 80 extend from the inner peripheral side of the magnet 31 along the axial direction of the support shaft 21 to the magnetoelectric conversion element 42 side along the axial direction of the support shaft 21. Therefore, even when the magnet holder 30 is moved in the direction away from the support shaft 21, the magnetoelectric conversion element 42 can remain in the space where the magnetic flux exists, which is sandwiched between the extending portions 83 of the iron core 80. Therefore, the fluctuation of the detection result by the magnetoelectric conversion element 42 due to the movement of the magnet holder 30 is suppressed. Thereby, the detection circuit 40 can accurately detect the rotation angle of the magnet holder 30 based on the amount of magnetic flux penetrating the magnetoelectric conversion element 42.

  In addition, in the first embodiment, the extending portion 83 of the iron core 80 is closer to the main body portion 23 than the sensor portion 42c of the plate-like magnetoelectric conversion element 42 regardless of the position of the magnet holder 30 in the axial direction of the support shaft 21. It extends to. Therefore, even when the magnet holder 30 is moved in the direction in which the magnet holder 30 is removed from the support shaft 21, the magnetoelectric conversion element 42 can reliably stay in the space where the magnetic flux exists, which is sandwiched between the extending portions 83. Thereby, regardless of the position of the magnet holder 30, the detection circuit 40 can accurately detect the rotation angle of the magnet holder 30 based on the amount of magnetic flux penetrating the magnetoelectric conversion element 42.

  In the first embodiment, the magnetic flux formed by the magnet 31 and passing through the iron core 80 reaches the other iron core 80 from one iron core 80 by mainly passing through a space sandwiched between the extending portions 83. By limiting the space through which the magnetic flux passes to the space sandwiched between the extending portions 83 among the space sandwiched between the contact portions 81 and the space sandwiched between the extending portions 83, the magnetic flux in the space between the extending portions 83 can be reduced. The density of can be kept high. In addition, even if the magnet holder 30 is moved in the direction of coming out of the support shaft 21 due to the arrangement of the extending portion 83 located with the magnetoelectric conversion element 42 interposed therebetween, the magnetoelectric conversion element 42 is interposed between the extending portions 83. Can stay in the confined space. As described above, the detection circuit 40 can detect the rotation angle of the rotating body based on the amount of magnetic flux penetrating the magnetoelectric conversion element 42 in a space where a high magnetic flux density is maintained. Thereby, the detection of the rotation angle of the magnet holder 30 by the detection circuit 40 becomes more accurate.

  In addition, in the first embodiment, the space sandwiched by the extending portions 83 is narrowed in the circumferential direction of the support shaft 21 by using the iron core 80 having a circular cross section. By narrowing the space sandwiched between the extending portions 83, the density of magnetic flux in the space increases. Therefore, the detection circuit 40 can detect the rotation angle of the magnet holder 30 based on the amount of magnetic flux passing through the magnetoelectric conversion element 42 in a space where a high magnetic flux density is maintained. Thereby, the detection of the rotation angle of the magnet holder 30 by the detection circuit 40 becomes more accurate.

  As described above, the fuel level gauge 100 according to the first embodiment is stored in the fuel tank 90 from the rotation angle of the magnet holder 30 that rotates following the liquid level 91a of the fuel 91, as shown in FIG. The height of the liquid level 91a of the fuel 91 can be accurately detected.

  In the first embodiment, the housing 20 corresponds to the “fixed body” recited in the claims, the magnet holder 30 corresponds to the “rotating body” recited in the claims, and the pair of magnets 31 includes The magnetoelectric conversion element 42 corresponds to the “element part” described in the claims, and the pair of iron cores 80 corresponds to the “magnetic body” described in the claims. The fuel tank 90 corresponds to the “container” described in the claims, the fuel 91 corresponds to the “liquid” described in the claims, and the fuel level gauge 100 corresponds to the claims. This corresponds to the “liquid level detection device”.

(Second embodiment)
The second embodiment of the present invention shown in FIGS. 5 and 6 is a modification of the first embodiment. The fuel level gauge 200 according to the second embodiment includes an iron core 280 corresponding to the iron core 80 (see FIG. 4 and the like) of the fuel level gauge 100 according to the first embodiment. Hereinafter, based on FIG.5 and FIG.6, the fuel level gauge 200 by 2nd embodiment is demonstrated in detail.

  The iron core 280 according to the second embodiment is different in shape from the iron core 80 according to the first embodiment (see FIG. 4 and the like). Each iron core 280 has a plate shape extending along the axial direction of the support shaft 21. In addition, each iron core 280 is curved along the circumferential direction of the support shaft 21, and the cross-sectional shape has a fan shape. The iron core 280 is formed of a ferromagnetic material like the iron core 80, and rotates relative to the housing 20 integrally with the magnet holder 230 together with the magnet 31 while sandwiching the support shaft 21.

  The iron core 280 includes a contact portion 281 and an extending portion 283 corresponding to the contact portion 81 and the extending portion 83 (see FIG. 4 and the like) of the iron core 80, respectively. Each contact portion 281 is curved along each inner peripheral wall 31a of each magnet 31, and is in contact with each inner peripheral wall 31a. When the contact portion 81 of the iron core 280 and the inner peripheral wall 31a of the magnet 31 are in close contact with each other over a wide area, the magnetic flux formed by the magnet 31 surely passes through the iron core 280.

  The extending portion 283 extends from the contact portion 281 toward the magnetoelectric conversion element 42 along the axial direction of the support shaft 21. The extending portion 283 of the second embodiment has a length L2 that is longer than the sensor portion 42c of the magnetoelectric transducer 42 in the axial direction of the support shaft 21 even when the clearance C between the housing 20 and the magnet holder 230 is maximized. Only extends to the main body 23 side. The extending portion 283 is closer to the support shaft 21 than the contact portion 281 due to the bending provided in the iron core 280. Thereby, the magnetic flux formed by the magnet 31 and passing through the iron core 280 reaches the other iron core 280 from one iron core 280 by mainly passing through the space sandwiched between the extending portions 283. As described above, the pair of iron cores 280 is configured so that the magnetic flux formed by the pair of magnets 31 is aligned along the axial direction of the support shaft 21 in the same manner as the iron core 80 according to the first embodiment (see FIG. 4 and the like). The effect | action induced | guided | derived to the part 23 side is exhibited.

  In addition, the extending portion 283 extends along the circumferential direction of the support shaft 21. Therefore, the area where the magnetic flux is emitted from the iron core 280 and the area where the magnetic flux enters the iron core 280 are enlarged in the radial direction of the support shaft 21. As a result, the density unevenness of the magnetic flux existing in the space between the extending portions 283 is suppressed.

  Even in the second embodiment described so far, when the magnet holder 230 moves in the direction of being removed from the support shaft 21, the magnetoelectric conversion element 42 can remain in the space sandwiched between the extending portions 283. As a result, the detection circuit 40 can accurately detect the rotation angle of the magnet holder 230 based on the amount of magnetic flux penetrating the magnetoelectric conversion element 42.

  In addition, in the second embodiment, since the density of the magnetic flux existing between the extending portions 283 is equalized, even if the magnet holder 230 moves in the axial direction along the support shaft 21, it penetrates the magnetoelectric conversion element 42. The amount of magnetic flux becomes difficult to change. As described above, the detection circuit 40 can more accurately detect the rotation angle of the magnet holder 230 based on the amount of magnetic flux penetrating the magnetoelectric conversion element 42 regardless of the position of the magnet holder 230.

  As described above, also in the fuel level gauge 200 according to the second embodiment, the height of the liquid level 91a (see FIG. 1) of the fuel 91 stored in the fuel tank 90 is accurately detected.

  In the second embodiment, the magnet holder 230 corresponds to the “rotary body” described in the claims, the pair of iron cores 280 corresponds to the “magnetic body portion” described in the claims, and the fuel level. The gauge 200 corresponds to a “liquid level detection device” described in the claims.

(Third embodiment)
The third embodiment of the present invention shown in FIGS. 7 and 8 is another modification of the first embodiment. The fuel level gauge 300 according to the third embodiment includes an iron core 380 corresponding to the iron core 80 (see FIG. 4 and the like) of the fuel level gauge 100 according to the first embodiment.

  The iron core 380 is not bent like the iron core 80 according to the first embodiment (see FIG. 4 and the like) and the iron core 280 according to the second embodiment, and has a quadrangular prism shape extending along the axial direction of the support shaft 21. Yes. The iron core 380 is made of a ferromagnetic material, similarly to the iron cores 80 and 280 of the above embodiment. The iron core 380 is fixed to the magnet holder 330 so as to be in contact with the inner peripheral wall 31a of the magnet 31. Thereby, the iron core 380 rotates relative to the housing 20 integrally with the magnet holder 330 together with the magnet 31 while sandwiching the support shaft 21.

  Of both ends of the iron core 380 in the extending direction, the end on the main body 23 side extends to the magnetoelectric conversion element 42 side rather than the sensor part 42c of the magnetoelectric conversion element 42. The iron core 380 of the third embodiment has a length L3 that is longer than the sensor portion 42c of the magnetoelectric conversion element 42 in the axial direction of the support shaft 21 even in a state where the clearance C between the housing 20 and the magnet holder 330 is maximized. It extends to the main body 23 side.

  Even in the third embodiment described so far, when the magnet holder 330 moves in the direction of being removed from the support shaft 21, the magnetoelectric conversion element 42 can remain in the space where the magnetic flux exists, which is sandwiched between the iron cores 380. Thereby, the detection circuit 40 can accurately detect the rotation angle of the magnet holder 330 based on the amount of magnetic flux penetrating the magnetoelectric conversion element 42. Accordingly, even in the fuel level gauge 300 according to the third embodiment, the height of the liquid level 91a of the fuel 91 stored in the fuel tank 90 (see FIG. 1) is accurately detected.

  In the third embodiment, the magnet holder 330 corresponds to the “rotary body” described in the claims, the pair of iron cores 380 corresponds to the “magnetic body portion” described in the claims, and the fuel level. The gauge 300 corresponds to the “liquid level detection device” described in the claims.

(Other embodiments)
Although a plurality of embodiments according to the present invention have been described above, the present invention is not construed as being limited to the above embodiments, and can be applied to various embodiments and combinations without departing from the gist of the present invention. can do.

  In the third embodiment, the iron core 380 is formed in a quadrangular prism shape. However, the shape of the iron core is not limited to the shape exemplified in the above embodiment. For example, as shown in FIG. 9, a cylindrical iron core 480 may be arranged on the inner peripheral side of the magnet 31 so as to contact the magnet 31. Alternatively, as shown in FIG. 10, the columnar iron core 580 having a fan-shaped cross section that curves along the circumferential direction of the support shaft 21 is in close contact with the inner peripheral wall 31 a of the magnet 31. You may arrange | position at the inner peripheral side. Thus, the configuration corresponding to the “magnetic part” described in the claims corresponds to the relative positional relationship between the magnet 31 and the magnetoelectric conversion element 42, the shape of the magnet 31 and the magnetoelectric conversion element 42, and the like. The optimum shape may be selected as appropriate.

  In the said embodiment, the iron core was formed with ferromagnetic materials, such as steel materials. However, as long as the magnetic flux formed by the magnet 31 passes and can guide the position of the magnetic flux, the structure corresponding to the “magnetic part” described in the claims is, for example, pure iron or the like The soft magnetic material may be used.

  In the above embodiment, the magnets 31 surround the support shaft 21 by being arranged in a pair so as to sandwich the support shaft 21. However, if the magnetic flux that penetrates the support shaft 21 can be formed, the magnet may have an annular shape that is arranged coaxially with the support shaft 21, for example. Alternatively, three or more magnets may be arranged so as to surround the support shaft 21.

  In the embodiment, the magnetoelectric conversion element 42 has a plate shape extending along the axial direction of the support shaft 21. However, the shape of the magnetoelectric conversion element 42 is not limited to a plate shape. For example, the magnetoelectric conversion element may have a columnar shape arranged coaxially with the support shaft 21. In addition, the “magnetic part” described in the claims is disposed so as to sandwich the magnetoelectric conversion element and straddle the magnetoelectric conversion element in the axial direction of the support shaft 21 regardless of the shape of the magnetoelectric conversion element. Is desirable.

  The present invention has been described based on a plurality of examples in which the present invention is applied to a fuel level gauge that detects the height of the liquid level 91a of the fuel 91 stored in the fuel tank 90 of the vehicle. It is not limited to the detection of the liquid level. The present invention may be applied to a liquid level detection system in a container such as other fluids mounted on a vehicle, such as brake fluid, engine cooling water, and engine oil. Furthermore, the present invention may be applied to a liquid level detection system in a container provided in various consumer devices and various transport machines, not limited to vehicles.

20 Housing (fixed body), 21 Support shaft, 23 Main body part, 24a, 24b Stopper wall, 30, 230, 330 Magnet holder (rotating body), 31 Magnet (magnet part), 31a Inner peripheral wall, 32 Arm locking part, 33 Bearing part, 34 Flange part, 35 Stopper hole, 40 Detection circuit, 41 Terminal, 42 Magnetoelectric conversion element (element part), 42a Input / output part, 42c Sensor part, 50 Float arm, 51 Stopper part, 53 Float holding part, 60 float, 61 through hole, 70 wiring, 80, 280, 380, 480, 580 iron core (magnetic part), 81,281 contact part, 83,283 extending part, 90 fuel tank (container), 90a ceiling surface, 90b Bottom surface, 91 Fuel (liquid), 91a Liquid surface, 93 Fuel pump module, 100, 200 300 fuel level gauge, C clearance

Claims (5)

A rotating body that rotates following the liquid level of the liquid stored in the container;
A main body fixed to the container, and a fixed body having a support shaft that protrudes from the main body and supports the rotating body rotatably,
A magnet portion that rotates integrally with the rotating body while surrounding the support shaft, and forms a magnetic flux penetrating the support shaft;
A detection circuit that has an element portion located inside the support shaft and detects a rotation angle of the rotating body based on a magnetic flux formed by the magnet portion and penetrating the element portion;
A pair of magnets are arranged on the inner peripheral side of the magnet part with the support shaft in between, and rotate together with the rotating body together with the magnet part while sandwiching the support shaft. A magnetic part that extends toward the element part along the direction and through which a magnetic flux formed by the magnet part passes;
A liquid level detection device comprising: The element portion has a plate shape extending along the axial direction of the support shaft,
The liquid level detection device according to claim 1, wherein the magnetic body portion extends in the axial direction of the support shaft to the main body portion side of the support shaft from the sensor portion of the element portion. The magnetic part is
A contact portion that contacts the magnet portion;
An extending portion positioned closer to the support shaft than the contact portion and sandwiching the element portion; and
The liquid level detection device according to claim 1, wherein:   The liquid level detection device according to claim 1, wherein the magnetic body portion has a circular cross section.   The said magnetic body part makes | forms the plate shape extended | stretched along the axial direction of the said support shaft, and curving along the circumferential direction of the said support shaft. Liquid level detection device.

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