JP2006308393A - Liquid level detection apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a compact liquid level detection apparatus capable of highly accurately detecting the position of a liquid level over the entire area of the range of movement of a float. <P>SOLUTION: In the liquid level detection apparatus, the float 9 is connected to a driver 7 to rotate a driver 7 by vertical movements of the float 9, and the rotation of the driver 7 is transmitted to a magnet holder 4 via a gear part 71 and a gear part 41 to drive the magnet holder 4 and make the angle of rotation of the magnet holder 4 smaller than the angle of rotation of the driver 7. Since it is thereby possible to contain the angle of rotation of the magnet holder 4 corresponding to the entire distance of movement of the float 9 or the distance of its movement between when a tank is full and when the tank is empty within an appropriate range of angle detection characteristic to a magneto-resistive element 6, it is possible to highly accurately detect the position of a liquid level 12 over the entire area of the range of movement of the float 9 and implement a compact fuel level gauge 1. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a liquid level detection device for detecting a liquid level of a liquid contained in a container or the like, and in particular, a liquid having a float that floats on a liquid and that detects the liquid level based on the position of the float. The present invention relates to a surface detection device.

  This type of liquid level detection device is used, for example, as a liquid level detection device for monitoring the amount of fuel stored in a fuel tank of an automobile.

A conventional liquid level detection device has a permanent magnet that rotates by movement of a float, and a liquid level that has a configuration in which a magnetoelectric conversion element is arranged so as to cross the magnetic flux of the permanent magnet on a member that rotatably holds the permanent magnet There is a detection device. In this method, the permanent magnet is rotated by the movement of the float to change the magnetic flux density of the permanent magnet crossing the magnetoelectric conversion element, and the change in the magnetic flux density is detected as the change in the output signal from the magnetoelectric conversion element. That is, there is one that detects the liquid level position based on the output signal level of the magnetoelectric transducer (see Patent Document 1).
JP 2001-124617 A

  In the conventional liquid level detection device described above, the guide for moving and guiding the normal float in a straight line is arranged so that the float moves linearly in a direction perpendicular to the liquid level, and a permanent magnet is accommodated and held beside this guide. In addition, a rotating member connected to the float by an arm is disposed.

  On the other hand, in order to cope with the diversification of automobile styles, there is an increasing need for smaller liquid level detection devices.

  One of the techniques for reducing the size of the liquid level detection apparatus as described above is to shorten the distance between the rotary member containing the permanent magnet and the float. If the float movement range, that is, the distance between the float position when the fuel tank is empty and the float position when the fuel tank is full is constant, the float movement decreases as the distance between the rotating member containing the permanent magnet and the float is shortened. The rotation angle of the rotating member corresponding to the range is increased.

  On the other hand, the magnetoelectric conversion element has an angular range that can be detected with high accuracy. For this reason, if the rotation angle of the rotating member corresponding to the movement range of the float is larger than the detectable angle of the magnetoelectric transducer, the liquid surface position detection accuracy may be lowered in a part of the movement range of the float.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a more compact liquid level detection device that can detect the liquid level position with high accuracy over the entire range of movement of the float. is there.

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

  The liquid level detection device according to claim 1 of the present invention includes a magnet that moves in conjunction with the vertical movement of the liquid level, and a magnetoelectric conversion element that outputs an electric quantity according to the position of the magnet. In the liquid level detection device that detects the liquid level by the output of the magnetoelectric conversion element, the float that moves in conjunction with the vertical movement of the liquid level, the first rotating member that has a magnet, and rotates in conjunction with the movement of the float. And a second rotating member that transmits the rotation to the first rotating member, and a rotation angle of the first rotating member that reduces the rotation of the second rotating member and transmits the rotation to the first rotating member. And a speed reduction means for making it smaller than that.

  In the conventional liquid level detection device, if the distance between the rotary member containing the magnet and the float is shortened in order to reduce the size of the liquid level detection device, the float movement range, that is, when the fuel tank is full and empty The rotation angle of the magnet corresponding to the difference in the liquid level is increased.

  By the way, the magnetoelectric conversion element has an angle range that can be detected with high accuracy. That is, there exists an angle range in which the output signal level of the magnetoelectric transducer corresponding to the unit angle change amount is sufficiently large.

  For this reason, when the rotation angle of the magnet corresponding to the movement range of the float becomes larger than the detectable angle of the magnetoelectric conversion element, the liquid surface position detection accuracy may decrease in a part of the movement range of the float.

  In the liquid level detection device according to the first aspect of the present invention, the first rotation in which the rotation of the second rotation member is transmitted via the speed reduction means, not the second rotation member that rotates in conjunction with the movement of the float. The member is provided with a magnet, and the rotation angle of the first rotation member corresponding to the movement of the float is set to be smaller than the rotation angle of the second rotation member by the reduction means.

  Thereby, even if the rotation angle of the first rotating member corresponding to the movement of the float exceeds the detectable angle range of the magnetoelectric conversion element, the rotation angle of the second rotating member corresponding to the movement of the float, that is, the magnet is converted to the magnetoelectric conversion. Since it can be within the detectable range of the element, the liquid level can be detected with high accuracy over the entire range of movement of the float.

  Therefore, it is possible to provide a more compact liquid level detection device while making it possible to detect the liquid level position with high accuracy over the entire range of movement of the float.

  The liquid level detection device according to claim 2 of the present invention specifies a gear mechanism as the speed reduction means, and the liquid level detection device according to claim 3 has the gear mechanism of the first rotation member and the second rotation member. It is specified that each gear is provided on the outer periphery.

  With such a gear, the rotation of the second rotating member can be simply decelerated and transmitted to the first rotating member.

  The liquid level detection apparatus according to claim 4 of the present invention is characterized in that the outer peripheral shapes of the first rotating member and the second rotating member including the first gear and the second gear are elliptical.

  In a conventional liquid level detection device, generally, a so-called rotation angle detection function member composed of a magnet and a magnetoelectric conversion element is disposed at a substantially middle point in the movement range of the float.

  For this reason, the rotation angle of the magnet corresponding to the unit movement length of the float is the maximum near the position where the float is closest to the magnet, and decreases as the float moves away from the magnet. When it comes to the minimum. Further, the larger the rotation angle of the magnet corresponding to the unit movement length of the float, the higher the liquid level detection accuracy.

  By the way, when the liquid level is low, that is, when the float is in the vicinity of the space time position, higher accuracy is required.

  However, in the conventional liquid level detection device, as described above, the rotation angle of the magnet corresponding to the unit movement length of the float is the minimum near the spacetime position, so the highest detection accuracy is required. At this point, the detection accuracy will be reduced.

  On the other hand, in the liquid level detection device according to claim 4 of the present invention, the outer peripheral shapes of the first rotating member and the second rotating member including the first gear and the second gear are elliptical as described above. .

  That is, as the float position approaches the space-time position from the intermediate position, it is possible to gradually change the gear ratio at the meshing portion of the first gear and the second gear, and thus corresponds to the unit movement length of the float. The rotation angle of the magnet can be made uniform over the entire movement range of the float.

  Accordingly, it is possible to provide a liquid level detection device that can improve the liquid level detection accuracy when the float is in the vicinity of the space time position and can detect the liquid level with high accuracy over the entire range of movement of the float.

  Hereinafter, a case where the liquid level detection device according to the embodiment of the present invention is applied to a fuel level gauge that is mounted in a fuel tank of an automobile and detects the level of fuel will be described with reference to the drawings. In the drawings, the same components are denoted by the same reference numerals.

(First embodiment)
FIG. 1 is a front view of a fuel level gauge 1 as a liquid level detection device according to a first embodiment of the present invention. Each component of the fuel level gauge 1 in FIG. 1 shows a state in which the liquid level 12 of the fuel 11 is at the lowest level. Further, in FIG. 1, the float 9 and the arm 8 are indicated by broken lines when the fuel level 12 is at the highest level, that is, when the fuel is full, and when the fuel level 12 is at the intermediate position.

  FIG. 2 is a cross-sectional view of the fuel level gauge 1 according to the first embodiment of the present invention, and is a cross-sectional view taken along line II-II in FIG.

  1 and 2, the upper part of the figure is the upper part in the state where the fuel level gauge 1 is attached to the automobile.

  FIG. 3 is a partial cross-sectional view of the fuel level gauge 1 according to the first embodiment of the present invention, and is a cross-sectional view taken along line III-III in FIG.

  FIG. 4 is a front view of the magnet holder 4 of the fuel level gauge 1 according to the first embodiment of the present invention.

  FIG. 5 is a schematic diagram for explaining an angular alignment method of the magnet holder 4 and the driver 7 in the fuel level gauge 1 according to the first embodiment of the present invention.

  The fuel level gauge 1 shown in FIGS. 1 to 4 is used for detecting the fuel remaining amount in the fuel tank 13 by measuring the height H of the liquid level 12 of the fuel 11 in the fuel tank 13. . The fuel level gauge 1 is disposed at the lowest position on the bottom surface inside the fuel tank 13.

  The fuel level gauge 1 mainly includes a float guide 2, a sensor holder 3, a magnet holder 4, a magnet 5, a magnetoresistive element 6, an arm 8, a float 9, and the like.

  The fuel level gauge 1 according to the first embodiment of the present invention is fixed to a fuel pump module (not shown), that is, an object to which the fuel level gauge 1 is attached via a float guide 2. The fuel pump module (not shown) is an integrated fuel pump, a fuel filter, and the like for sending the fuel 11 in the fuel tank 13 to the engine, and is installed at the bottom of the fuel tank 13. .

  The float guide 2 includes a base 21 and a guide rail 22. The height dimension H1 (see FIG. 1) of the base 21 of the float guide 2 enables the fuel level gauge 1 according to the first embodiment of the present invention to be applied to various types of fuel tanks 13 having different liquid level levels when full. Therefore, the fuel tank 13 to which the fuel level gauge 1 can be applied is set lower than the height from the fuel level gauge 1 installation position to the upper surface of the fuel tank 13 in the fuel tank 13 having the lowest liquid level when full. Yes.

  The base 21 is made of, for example, a resin material. As shown in FIG. 1, the base 21 includes holding holes 21 a and 21 b for holding and fixing the guide rail 22. As shown in FIG. 2, the base 21 has a sensor holder 3 to be described later in close contact, and a support that serves as an attachment surface to a fuel pump module (not shown) that is an object to which the fuel level gauge 1 is attached. A surface 21c is formed. Further, as shown in FIG. 1, the base 21 is provided with two mounting holes 21h as fixing means. The mounting hole 21h is for screwing the float guide 2, that is, the fuel level gauge 1 to the fuel pump module (not shown) through them. As shown in FIG. 2, the base 21 is provided with a through hole 21 e through which a shaft portion 31 of the sensor holder 3 described later is inserted. Since two shaft portions 31 are provided in the sensor holder 3, two through holes 21e are also provided. As shown in FIG. 1, the base 21 is provided with a rail portion 21f for moving and guiding a float 9, which will be described later, linearly in the vertical direction in FIG. As shown in FIG. 1, the base 21 includes a stopper portion 21 g that regulates the lowest position of the float 9 described later.

  The guide rail 22 is formed in a shape as shown in FIG. 1, for example, by bending a stainless steel rod having a circular cross section at a predetermined position. That is, the guide rail 22 includes rail portions 22a and 22b that are linear portions that are parallel to each other and inserted into a guide groove 91 of the float 9 described later, and a stopper portion 22c that regulates the highest position of the float 9. The stopper portion 22c position A (see FIG. 1) is formed so as to correspond to the highest position of the liquid level of the fuel tank 13 to which the fuel level gauge 1 is applied, that is, the float position H2 at the full liquid level position. . The rail portion 22b is formed in such a shape that when the guide rail 22 is fixed to the base 21, it is smoothly connected to the rail portion 21f of the base 21, that is, the float 9 can move up and down smoothly. Both ends of the guide rail 22 are press-fitted and fixed in the holding holes 21 a and 21 b of the base 21.

  The magnet holder 4 as the first rotating member is formed in an annular shape from a resin material or the like, for example. As shown in FIG. 2, the magnet holder 4 has a built-in magnet 5 that is a magnet. The magnet holder 4 includes a hole portion 42 that is an annular center hole, and the hole portion 42 is rotatably fitted to a shaft portion 31 of the sensor holder 3 described later. That is, as shown in FIG. 2, a projection 43 is provided on the inner periphery of the hole 42 of the magnet holder 4, and this projection 43 is fitted in the groove 32 provided in the shaft 31 of the sensor holder 3. As a result, the magnet holder 4 is restricted from moving in the axial direction of the shaft portion 31 (the left-right direction in FIG. 2). When the magnet holder 4 rotates with respect to the sensor holder 3, the magnet 5 also rotates integrally with the magnet holder 4, that is, displaces with respect to the sensor holder 3. The magnet holder 4 is provided with a gear portion 41 which is a first gear constituting a gear mechanism as a speed reducing means on the outer periphery thereof. The gear portion 41 is formed of a spur gear, and is disposed coaxially with the hole 42 at the end of the magnet holder 4 opposite to the sensor holder 3. The gear part 41 is integrally formed when the magnet holder 4 is resin-molded.

  For example, an annular magnet 5 is arranged coaxially with the hole 42, or two fan-shaped magnets 5 are arranged symmetrically with respect to the hole 42. In either case, the magnetic flux formed by the magnet 5 is perpendicular to the axial direction of the shaft portion 31 of the sensor holder 3 and rotates around the shaft portion 31 in conjunction with the rotation of the magnet holder 4. Magnetic state is set.

  The magnet holder 4 is made, for example, by insert molding the magnet 5 during resin molding.

  A driver 7 that is a second rotating member that rotates in conjunction with the movement of the float 9 described later and transmits the rotation to the magnet holder 4 that is the first rotating member is adjacent to the magnet holder 4 as shown in FIG. Are arranged. The driver 7 is provided with a gear portion 71 that is a second gear constituting a gear mechanism as a speed reducing means on the outer periphery thereof. The driver 7 is disposed by meshing the gear portion 71 with the gear portion 41 of the magnet holder 4. The driver 7 is formed in an annular shape from, for example, a resin material. The driver 7 includes a hole portion 72 that is an annular center hole, and the hole portion 72 is rotatably fitted to a shaft portion 31 of a sensor holder 3 that is a main body member described later. That is, as shown in FIG. 2, a protrusion 73 is provided on the inner periphery of the hole 72 of the driver 7, and this protrusion 73 is fitted in the groove 32 provided in the shaft portion 31 of the sensor holder 3. As a result, the movement of the driver 7 in the axial direction of the shaft portion 31 (left and right direction in FIG. 2) is restricted. The gear portion 71 is a spur gear that can mesh with the gear portion 41 of the magnet holder 4, and is disposed coaxially with the hole 72 at the end of the driver 7 opposite to the sensor holder 3. That is, when the driver 7 rotates, the torque is transmitted to the magnet holder 4 via the gear part 71 and the gear part 41, and the magnet holder 4 rotates. The gear part 71 is integrally formed when the driver 7 is resin-molded.

  Here, in the fuel level gauge 1 according to the first embodiment of the present invention, Z41> Z71 between the number of teeth Z41 of the gear portion 41 of the magnet holder 4 and the number of teeth Z71 of the gear portion 71 of the driver 7. The relationship is established. Therefore, when the driver 7 rotates, the speed is reduced and transmitted to the magnet holder 4. That is, the gear portion 71 and the gear portion 41 form a reduction gear mechanism that is a reduction means. Thereby, the rotation angle of the magnet holder 4 is smaller than the rotation angle of the driver 7.

  An arm 8 described later is slidably coupled to the driver 7. That is, as shown in FIG. 1, the arm 8 is coupled so as to be slidable in a direction orthogonal to the axial direction of the hole 72 of the driver 7. The driver 7 is provided with two pairs of guide projections 74 that serve as guides when the arm 8 slides relative to the driver 7 with the hole 72 interposed therebetween as shown in FIG. The distance between the pair of guide protrusions 74 is slightly larger than the diameter of the arm 8. That is, the arm 8 is set so as to be able to slide smoothly and without tilting between the guide protrusions 74. As shown in FIG. 1, a cap 75 is attached to these guide protrusions 74 to prevent the arm 8 from being detached from the guide protrusions 74.

The sensor holder 3 is made of, for example, a resin material. As shown in FIG. 2, the sensor holder 3 includes two shaft portions 31. The sensor holder 3 rotatably holds the magnet holder 4 and the driver 7 by fitting the hole 42 of the magnet holder 4 and the hole 72 of the driver 7 to the outer periphery of each shaft portion 31. As shown in FIG. 2, the shaft portion 31 has a groove portion 32 that engages with a protrusion portion 43 formed in the hole portion 42 of the magnet holder 4 or a protrusion portion 73 formed in the hole portion 72 of the driver 7. Among the shaft portions 31 of the sensor holder 3 provided coaxially with the portion 31, the shaft portion 31 that rotatably holds the magnet holder 4 is a displacement member as shown in FIG. A magnetoresistive element 6 which is a magnetoelectric conversion element as a detecting means for detecting the displacement of the magnet 5 is provided. As shown in FIG. 2, the magnetoresistive element 6 is arranged with the overlapping length with the magnet 5 as long as possible in the axial direction of the shaft portion 31. As a result, the magnetic flux amount of the magnet 5 intersecting with the magnetoresistive element 6 is increased, the output voltage of the magnetoresistive element 6 is increased, the liquid level 12 detection accuracy of the fuel level gauge 1 is increased, and strong noise resistance is achieved. Can be provided.

  The sensor holder 3 includes a terminal 10 for connecting the magnetoresistive element 6 to an external electric circuit. In the fuel level gauge 1 according to the first embodiment of the present invention, the number of electrodes of the magnetoresistive element 6 is two, and correspondingly, two terminals 10 are provided as shown in FIG. . As shown in FIG. 1, an electric wire 10 a is connected to the terminal 10. The magnetoresistive element 6 is connected to an external electric circuit through each electric wire 10a, for example, a control circuit that receives the detection signal from the magnetoresistive element 6 and measures the position of the liquid surface 12 to calculate the remaining amount in the fuel tank 13. Has been.

  A method for manufacturing the sensor holder 3 will be briefly described. First, the terminal 10 is connected to the lead 61 of the magnetoresistive element 6 by fusing or caulking. Next, the magnetoresistive element 6 and the terminal 10 are set in a resin mold of the sensor holder 3 and insert molded. Finally, the electric wire 10a is connected to the terminal 10 by fusing or caulking, and the sensor holder 3 is completed.

  The sensor holder 3 includes a fixing claw 33 for fixing the sensor holder 3 to the float guide 2. Four fixed claws 33 are provided as shown in FIG. As shown in FIG. 3, the fixing claw 33 is inserted and locked in a locking hole 21 d provided in the base 21 of the float guide 2.

  The sensor holder 3 and the magnet holder 4 exhibit a so-called rotation angle detection function in a state in which the hole portion 42 of the magnet holder 4 and the hole portion 72 of the driver 7 are rotatably coupled to the shaft portions 31 of the sensor holder 3. It becomes possible.

  The float 9 is formed from a resin material or the like in a substantially rectangular parallelepiped shape. The float 9 is set to have an apparent specific gravity smaller than that of the fuel by foam molding or cavity molding so as to surely float on the liquid surface 12 of the fuel 11.

  As shown in FIG. 3, guide grooves 91 and 92 are provided on the surfaces of the float 9 that face the rail portions 22 a and 22 b of the guide rail 22, respectively. The float 9 is mounted on the guide rail 22 by fitting the guide groove 91 with the rail portion 22a of the guide rail 22 and fitting the guide groove 92 with the rail portion 22a of the guide rail 22 or the rail portion 21f of the base 21. ing. The shapes of the guide grooves 91 and 92 are slightly larger than the shapes of the rail portions 22a and 22b and the rail portion 21f. That is, the float 9 is set so that it can move linearly smoothly along the rail portions 22a and 22b and the rail portion 21f in the guide rail 22.

  As shown in FIG. 3, the float 9 is provided with a through hole 93 penetrating in the horizontal direction. As shown in FIG. 3, an end portion of an arm 8 to be described later is inserted into the through hole 93. The diameter dimension of the through hole 93 is set slightly larger than the diameter dimension of the arm 8. As a result, when the float 9 moves in the vertical direction in accordance with the position fluctuation of the liquid level 12 in the fuel tank 13, the arm 8 rotates with respect to the float 9.

  The arm 8 is formed in a substantially L shape from a metal rod-like member having a circular cross section, for example. As shown in FIG. 3, one end of the arm 8 is rotatably engaged with the through hole 93 of the float 9. On the other hand, the other end of the arm 8 is slidably engaged with a hole formed by the guide projection 74 and the cap 75 of the driver 7 as shown in FIG. By connecting the driver 7 and the float 9 via the arm 8 in this way, when the float 9 moves up and down in accordance with the vertical movement of the liquid level, the arm 8 slides relative to the driver 7 and at the same time, the driver 7 is rotated. The rotation of the driver 7 is transmitted to the magnet holder 4 via the gear portion 71 and the gear portion 41, and the magnet holder 4 rotates at a rotational speed determined by the number of teeth Z71 of the gear portion 71 and the number of teeth Z41 of the gear portion 41. To do. That is, the arm 8 functions to convert the vertical movement of the float 9 into the rotational movement of the magnet holder 4.

  In order to make the float 9 follow the fluctuation of the liquid level 12 of the fuel 11 and improve the detection accuracy of the fuel level gauge 1, it is necessary to increase the buoyancy acting on the float 9. Its weight acts to increase the weight of the float 9. Therefore, it is desirable to make the arm 8 as light as possible, and it is made of, for example, a light metal such as aluminum or a pipe material thereof.

  Next, the assembly method of the fuel level gauge 1 according to the first embodiment of the present invention will be described in order.

  In addition, the sensor holder 3 and the magnet holder 4 are already completed before the process demonstrated below. That is, the sensor holder 3 contains a magnetoresistive element 6 and the magnet holder 4 contains a magnet 5.

  First, the float guide 2 is assembled. That is, both ends of the guide rail 22 are press-fitted and fixed into the holding holes 21 a and 21 b of the base 21 while the guide grooves 91 and 92 of the float 9 are fitted and inserted into the rail portions 22 a and 22 b of the guide rail 22, respectively.

  Next, the sensor holder 3 is fixed to the float guide 2. That is, while the shaft portion 31 of the sensor holder 3 is inserted into the through hole 21 e of the base 21, the four locking claws 33 of the sensor holder 3 are inserted and locked into the corresponding locking holes 21 d of the base 21.

  Next, the magnet holder 4 and the driver 7 are attached to the sensor holder 3. That is, the hole portion 42 of the magnet holder 4 is fitted to the shaft portion 31 of the sensor holder 3 protruding from the base 21, and is further pushed rightward in FIG. Engage with the groove 32. Accordingly, the magnet holder 4 is restricted from moving in the axial direction of the shaft portion 31 (left and right direction in FIG. 2), and the magnet holder 4 is rotatably held by the sensor holder 3. Subsequently, while meshing the gear portion 71 with the gear portion 41, the hole portion 72 of the driver 7 is fitted into the shaft portion 31 of the sensor holder 3 protruding from the base 21, and further pushed in the right direction in FIG. The protrusion 73 of the driver 7 is engaged with the groove 32 of the sensor holder 3. Accordingly, the driver 7 is restricted from moving in the axial direction of the shaft portion 31 (left-right direction in FIG. 2), and the driver 7 is rotatably held by the sensor holder 3.

  Next, the arm 8 is attached. That is, one end of the arm 8 is inserted into the through hole 93 of the float 9, the other end of the arm 8 is fitted between the pair of guide protrusions 74 of the driver 7, and the cap 75 is attached from above. As a result, the arm 8 is slidably held by the driver 7.

  This completes the assembly of the fuel level gauge 1 according to the first embodiment of the present invention.

  The completed fuel level gauge 1 is fixed to a fuel pump module (not shown) by screwing through a mounting hole 21h provided in the float guide 2. The fuel level gauge 1 is installed in the fuel tank 13 by installing a fuel pump module (not shown) at the bottom of the fuel tank 13.

  Next, the operation of the fuel level gauge 1 according to the first embodiment of the present invention, that is, the liquid level detection operation in the fuel tank 13 will be described.

  When the float 9 moves in the vertical direction in FIG. 1 according to the fluctuation of the height of the liquid level 12 of the fuel 11, the arm 8 rotates with respect to the driver 7 and simultaneously rotates the driver 7. At this time, the distance from the through hole 93 of the float 9 to the center of the hole 72 of the driver 7 changes as the float 9 moves up and down. However, since the arm 8 is slidably held by the driver 7, the arm 8 linearly moves with respect to the driver 7 by the amount of variation in the distance from the through hole 93 to the center of the hole 72 of the driver 7. Thereby, the fluctuation | variation of the above-mentioned distance is absorbed, and the driver 7 can be smoothly rotated in conjunction with the vertical movement of the float 9. The rotation of the driver 7 is transmitted to the magnet holder 4 via the gear portion 71 and the gear portion 41, and the magnet holder 4 rotates at a rotational speed determined by the number of teeth Z71 of the gear portion 71 and the number of teeth Z41 of the gear portion 41. To do.

  When the magnet 5 rotates in conjunction with the rotation of the arm 8, the magnetic flux density across the magnetoresistive element 6 changes and the output voltage of the magnetoresistive element 6 changes. The position of the float 9, that is, the liquid level 12 position H in the fuel tank 13 is recognized based on the output voltage of the magnetoresistive element 6, and the residual fuel amount in the fuel tank 13 is calculated based on the liquid level 12 position H. Is done.

  Next, the feature of the fuel level gauge 1 according to the first embodiment of the present invention, that is, the driver 7 is added, and the vertical movement of the float 9 is converted into the rotational motion of the magnet holder 4 via the gear portion 71 and the gear portion 41. The operational effects of the configuration will be described.

  In the conventional liquid level detection device, in order to reduce the size of the liquid level detection device, if the distance between the rotary member containing the permanent magnet and the float, ie, the length L in FIG. That is, the rotation angle of the permanent magnet corresponding to the difference between the liquid level positions when the fuel tank is full and empty is increased.

  Further, the magnetoelectric conversion element has an angular range that can be detected with high accuracy. That is, there exists an appropriate detection angle range in which the output signal level of the magnetoelectric conversion element corresponding to the unit angle change amount is sufficiently large. At an angle exceeding the proper detection angle range, the angle detection accuracy is lowered.

  Therefore, in the liquid level detection device, when the rotation angle of the permanent magnet corresponding to the float movement range is larger than the proper detection angle range of the magnetoelectric transducer, the liquid level position detection accuracy decreases in a part of the float movement range. there is a possibility.

  On the other hand, in the fuel level gauge 1 according to the first embodiment of the present invention, the float 9 is directly connected to the driver 7 instead of the magnet holder 4, and the driver 7 is rotated by the vertical movement of the float 9. Is transmitted to the magnet holder 4 through the gear portion 71 and the gear portion 41 to rotate the magnet holder 4, and a relationship of Z41> Z71 is established between the gear portion 71 of the driver 7 and the number of teeth Z71. I am letting. Thereby, the rotation angle of the magnet holder 4 is made smaller than the rotation angle of the driver 7. In other words, the rotation angle of the magnet holder 4 corresponding to the entire movement range of the float 9, that is, the movement distance from the liquid level 12 position when full to the liquid level 12 position when empty is greater than the rotation angle of the driver 7. It is small.

  That is, in the fuel level gauge 1 according to the first embodiment of the present invention, the magnet corresponding to the entire moving range of the float 9, that is, the moving distance from the liquid level 12 position when full to the liquid level 12 position when empty. The number of teeth Z41 of the gear portion 41 of the magnet holder 4 and the number of teeth Z71 of the gear portion 71 of the driver 7 are determined so that the rotation angle of the holder 4 falls within the above-described proper detection angle range unique to the magnetoresistive element 6. ing.

  Accordingly, it is possible to realize the fuel level gauge 1 that is smaller in size and that has a particularly small length dimension L in FIG. 1 while being able to detect the position of the liquid level 12 with high accuracy over the entire movement range of the float 9. .

  In the fuel level gauge 1 according to the first embodiment of the present invention, when the fuel level gauge 1 is assembled, for example, the float 9 and the liquid level 12 of the fuel 11 are at the lowest position as shown in FIG. When the fuel tank 13 is in the empty position, the magnetic flux direction of the magnet 5 is set to a predetermined direction, and the output signal of the magnetoresistive element 6 at this time needs to be a predetermined value. Therefore, it is necessary to set the angular positional relationship between the driver 7 and the magnet holder 4 to a predetermined relationship when the fuel level gauge 1 is assembled.

  Therefore, in the fuel level gauge 1 according to the first embodiment of the present invention, so-called alignment marks are provided on the gear portion 41 of the magnet holder 4 and the gear portion 71 of the driver 7. By assembling the fuel level gauge 1 so that the alignment marks (X and Y) of the respective teeth have a relationship as shown in FIG. 5, the angular positional relationship between the driver 7 and the magnet holder 4 described above. Are set to a predetermined relationship.

(Second Embodiment)
FIG. 6 shows a front view of the fuel level gauge 1 according to the second embodiment of the present invention.

  The fuel level gauge 1 according to the second embodiment of the present invention is different from the fuel level gauge 1 according to the first embodiment of the present invention in the shape of the magnet holder 4 and the driver 7, that is, the specifications of the gear portion 41 and the gear portion 71. It has changed.

  In the fuel level gauge 1 according to the second embodiment of the present invention, the shapes of the magnet holder 4 and the driver 7 are elliptical, and the corresponding shapes of the gear part 41 and the gear part 71 are also elliptical as shown in FIG. It has a shape. In this case, the pitch circle shape of each gear part 41 and 71 is also an ellipse, and the pitch ellipse is formed.

  When the pitch ellipse diameters at the meshing points of the gear part 41 and the gear part 71 are R41 and R71, the speed ratio K of the magnet holder 4 to the driver 7 is K = R71 / R41. In the fuel level gauge 1 according to the second embodiment of the present invention, the speed ratio K <1 in the entire linear movement range of the float 9, that is, the rotation angle of the magnet holder 4 is always the driver 7 regardless of the position of the float 9. It is smaller than the rotation angle.

  However, since the shape of the gear part 41 and the gear part 71 is elliptical, the speed ratio K of the magnet holder 4 to the driver 7 varies depending on the float 9 position. In the fuel level gauge 1 according to the second embodiment of the present invention, the speed ratio K is the maximum when the float 9 is at the lowest position (when the fuel tank 13 is empty) as shown in FIG. As 9 becomes a higher position, the speed ratio K decreases. The speed ratio K is minimized when the float 9 position is near the intermediate position, and increases as the float 9 position becomes a higher position. That is, the speed ratio K changes nonlinearly over the entire movement range of the float 9, and as a result, the rotation angle of the magnet holder 4 corresponding to the unit movement length of the float 9 is substantially uniform over the entire movement range of the float 9. It becomes. In other words, the output signal of the magnetoresistive element 6 changes linearly over the entire movement range of the float 9.

  In the case of the fuel level gauge 1 according to the first embodiment of the present invention described above, since the gear portion 41 and the gear portion 71 are circular, the speed ratio K of the magnet holder 4 to the driver 7 is constant regardless of the position of the float 9. Value. For this reason, the rotation angle of the magnet holder 4 corresponding to the unit movement length of the float 9 becomes maximum near the position where the float 9 is closest to the magnet holder 4, and decreases as the float 9 moves away from the magnet holder 4. When 9 is in the full tank position or the space time position, it is minimum. That is, the rotation angle of the magnet holder 4 corresponding to the unit movement length of the float 9 changes nonlinearly over the entire movement range of the float 9. In other words, the output signal of the magnetoresistive element 6 changes nonlinearly over the entire movement range of the float 9.

  On the other hand, in the fuel level gauge 1 according to the second embodiment of the present invention, the shape of the gear portion 41 and the gear portion 71 is elliptical, and as described above, over the entire movement range of the float 9, The output signal of the magnetoresistive element 6 can be changed linearly.

  Thereby, the liquid level detection accuracy when the float 9 is in the vicinity of the space time position can be improved, and the liquid level can be detected with high accuracy over the entire moving range of the float 9.

  In the fuel level gauge 1 according to the first embodiment and the second embodiment of the present invention described above, the magnetoresistive element 6 is used as the detecting means, but it is not necessary to be limited to the magnetoresistive element 6. Other types of magnetic detection elements may be used. For example, a Hall element or a magnetic diode may be used.

  Further, in the fuel level gauge 1 according to the first and second embodiments of the present invention described above, the fixing to the attachment target member is performed by screw tightening, but it is not necessary to be limited to the screw. For example, a structure in which a locking claw provided in the target member is engaged with a locking hole provided in the float guide 2 may be adopted.

  Further, in the fuel level gauge 1 according to the first embodiment and the second embodiment of the present invention, the float 9 is moved up and down linearly while being held by the linear float guide 2, but this is not limitative. Instead, the float guide 2 may be eliminated, and the float 9 may be moved up and down in an arc shape.

  Further, the speed reduction means is not limited to the gear mechanism. Furthermore, it is good also as a structure which interposes one or more gearwheels between a 1st rotation member and a 2nd rotation member.

  In the fuel level gauge 1 according to the first embodiment and the second embodiment of the present invention described above, the member to be attached is a fuel pump module (not shown), but it is necessary to limit the member to the fuel pump module. It may be attached directly in the fuel tank 13.

  Further, in the first and second embodiments of the present invention described above, the case where the liquid level detection device is applied to the fuel level gauge 1 for an automobile has been described as an example. The present invention is not limited to the fuel level gauge 1 and may be applied to a liquid level detection device incorporated in various consumer 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.

1 is a front view of a fuel level gauge 1 according to a first embodiment of the present invention. It is sectional drawing of the fuel level gauge 1 by 1st Embodiment of this invention, and is the II-II sectional view taken on the line in FIG. It is a fragmentary sectional view of the fuel level gauge 1 by 1st Embodiment of this invention, and is the III-III sectional view taken on the line in FIG. It is a front view of the magnet holder 4 of the fuel level gauge 1 by 1st Embodiment of this invention. It is a schematic diagram explaining the angle alignment method of the magnet holder 4 and the driver 7 in the fuel level gauge 1 by 1st Embodiment of this invention. It is a front view of the fuel level gauge 1 by 2nd Embodiment of this invention.

Explanation of symbols

1 Fuel level gauge (Liquid level detector)
2 Float guide 21 Base 21a Holding hole 21b Holding hole 21c Support surface 21d Locking hole 21e Through hole 21f Rail part 21g Stopper part 21h Mounting hole 22 Guide rail 22a Rail part 22b Rail part 22c Stopper part 3 Sensor holder 31 Shaft part 32 Groove part 33 Locking claw 4 Magnet holder (first rotating member)
41 Gear part (reduction means, gear mechanism, first gear)
42 hole 43 protrusion 5 magnet (magnet)
6 Hall element (magnetoresistance element)
7 Idler (second rotating member)
71 Gear part (reduction means, gear mechanism, second gear)
72 hole portion 73 protrusion portion 74 guide protrusion 75 cap 8 arm 9 float 91 guide groove 92 guide groove 93 through hole 10 terminal 10a electric wire 11 fuel 12 liquid surface 13 fuel tank A stopper position H liquid surface position H1 height dimension H2 full tank Float position K Speed ratio L Length dimension R41 Pitch ellipse radius R71 Pitch ellipse radius Z41 Number of teeth Z71 Number of teeth

Claims (4)

A magnet that moves in conjunction with the vertical movement of the liquid level;
It has a magnetoelectric conversion element that outputs an amount of electricity according to the position of this magnet,
In the liquid level detection device that detects the liquid level by the output of the magnetoelectric conversion element,
A float that moves in conjunction with the vertical movement of the liquid level;
A first rotating member having the magnet;
A second rotating member that rotates in conjunction with the movement of the float and transmits the rotation to the first rotating member;
Decelerating means for decelerating the rotation of the second rotating member and transmitting it to the first rotating member so that the rotation angle of the first rotating member is smaller than the rotation angle of the second rotating member. A liquid level detection device characterized by the above.   The liquid level detection device according to claim 1, wherein the speed reduction unit is a gear mechanism.   The gear mechanism is configured by a first gear provided on the outer periphery of the first rotating member and a second gear provided on the outer periphery of the second rotating member. The liquid level detection apparatus described in 1.   The liquid level detection device according to claim 3, wherein an outer peripheral shape of the first rotating member and an outer peripheral shape of the second rotating member are elliptical.

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