JP2015141162A - Liquid level detector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid level detector allowing check for displacement of a magnet built in a holder.SOLUTION: A liquid level detector F comprises: a holder 2 that rotates on the basis of displacement of a float caused by fluctuation in the liquid level; a disk magnet 2a that is fixed on the holder 2 and rotates together with the holder 2; and a magnetic detection element 3 that detects a magnetic change caused by the rotation of the magnet 2a. The holder 2 has a hole 2c in which a part of the magnet 2a is exposed.

Description

  The present invention relates to a liquid level detection device that detects the level of a liquid such as fuel in a fuel tank.

  A conventional liquid level detection device is disclosed in Patent Document 1, for example. The liquid level detection device includes a holder that rotates according to the displacement of the float accompanying a change in the liquid level, a magnet that is fixed to the holder so as to rotate together with the holder 2, and a rotational operation of the magnet. And a magnetic detection element for detecting a change in magnetic force.

JP2013-242174A

  However, in this liquid level detection device, the magnet is displaced with respect to the normal position of the holder due to the molding pressure at the time of insert molding of the holder, and the output characteristics of the magnetic transducer element vary. There was a problem.

  Therefore, the present invention focuses on the above-mentioned problems and aims to provide a liquid level detection device that can confirm the displacement of a magnet built in a holder.

  The liquid level detection device of the present invention includes a holder that rotates in accordance with a displacement of a float accompanying a change in liquid level, a disk-shaped magnet that is fixed to the holder and rotates with the holder, and the rotation of the magnet In the liquid level detection device including a magnetic detection element that detects a magnetic force change accompanying an operation, a hole through which a part of the magnet is exposed is provided in the holder.

  With the above configuration, the present invention can achieve the intended purpose, and can provide a liquid level detection device that can confirm the displacement of the magnet built in the holder.

The top view of the liquid level detection apparatus of 1st Embodiment of this invention. Sectional drawing of the II-II line | wire in FIG. The top view of the holder of the embodiment. Sectional drawing of the IV-IV line in FIG. The perspective view of the magnet of the embodiment. Sectional drawing which shows the shaping | molding method of the holder of the embodiment. The top view of the holder of 2nd Embodiment of this invention. The top view of the holder of 3rd Embodiment of this invention. Sectional drawing of the holder of 4th Embodiment of this invention. The perspective view of the magnet of the embodiment.

  Hereinafter, a first embodiment of the present invention will be described with reference to the accompanying drawings.

  The liquid level detection device F of the present invention is installed in a fuel tank (not shown) that stores liquid fuel such as gasoline.

  The liquid level detection device F mainly includes a main body 1, a holder 2, a magnet 2 a, a magnetic detection element 3, and a cover 4.

  The main body 1 is composed of a first resin body 11 and a second resin body 12.

  The first resin body 11 is made of a resin material such as polyacetal (hereinafter referred to as POM), and incorporates a plurality of terminals 1a by primary molding. A magnetic detection element 3 and an electronic component (a noise absorbing capacitor or resistor) 5 are mounted on a portion of the terminal 1a exposed from the first resin body 11.

  The first resin body 11 in which the magnetic detection element 3 and the electronic component 5 are mounted on the terminal 1a is insert-molded by the second resin body 12 made of the same resin material as the first resin body 11, so that the main body 1 is formed. The The first resin body 11 is hermetically sealed by the second resin body 12 together with the terminal 1a, the magnetic detection element 3, and the electronic component 5.

  The main body portion 1 includes a first rotation support portion 1b on which the holder 2 is rotatably supported. The first rotation support portion 1 b is formed integrally with the second resin body 12. The 1st rotation support part 1b is carrying out the column shape, and protrudes in the holder 2 side provided with the magnet 2a. The columnar first rotation support portion 1b includes a sliding surface having a circular cross-sectional shape perpendicular to the rotation axis direction of the magnet 2a. In the main body 1 on the rotation axis of the first rotation support portion 1b, the magnetic detection surface 3a of the magnetic detection element 3 is disposed in a state of facing the magnet 2a.

  In addition, a positioning boss 1c is provided on the rear surface (opposite to the side where the holder 2 is provided) of the main body 1 to determine a position to be attached to, for example, a fuel pump or a mounting stay. And a hook 1d attached to a mounting stay or the like. Both the positioning boss 1c and the hook 1d are formed integrally with the second resin body 12.

  The manufacturing method of the main-body part 1 insert-molds the several terminal 1a connected mutually to the 1st resin body 11 by primary molding, divides the terminal 1a by press after insert molding, and magnetically detects this divided | segmented terminal 1a. The element 3 and the electronic component 5 are resistance welded or soldered, and the first resin body 11 is secondarily formed with the second resin body 12, and the main body 1 is completed by the manufacturing method described above.

  The holder 2 is made of a resin material such as POM, and the magnet 2a is fixed by insert molding. The holder 2 rotates together with the magnet 2a according to the displacement of the float accompanying the fluctuation of the liquid level.

  The magnet 2a is made of, for example, a neodymium-ferrite material, and the shape thereof is a disc shape with the rotation axis of the magnet 2a as the center, and in this embodiment, two poles are magnetized. Also, four protrusions 2a1 projecting outward are provided on the outer peripheral surface of the magnet 2a. The protrusion 2 a 1 is a detent that prevents the magnet 2 a from rotating with respect to the holder 2 when the magnet 2 a is built in the holder 2.

  The holder 2 includes a flange portion 2b, an arm attachment portion 2b1, a first rotating portion 2b2, a second rotating portion 2b3, and a hole 2c.

  The flange portion 2b has a disk shape and is formed so as to spread in the radial direction about the rotation axis of the holder 2 in a direction perpendicular to the rotation axis direction of the holder 2.

  An arm mounting portion 2b1 is provided on the upper surface (the upper surface in FIG. 2) of the flange portion 2b. The arm attachment portion 2b1 is for attaching a float arm 6 for transmitting the movement of a float (not shown) that operates in conjunction with the fluctuation of the liquid level to the holder 2.

  A holding portion 2b4 and a first rotating portion 2b2 for holding the magnet 2a are provided on the lower surface of the flange portion 2b.

  The holding portion 2b4 has a cylindrical shape, and its lower side is narrowed to be smaller than the outer shape of the magnet 2a, and includes a first hole 2b5 through which the magnet 2a is exposed.

  The first rotating part 2b2 is provided below the holding part 2b4. The first rotating part 2b2 has a cylindrical shape, and the hole of the first rotating part 2b2 communicates with the first hole 2b5 of the holding part 2b4. The first rotating portion 2b2 is a sliding receiving surface in which a part of the inner peripheral surface of the cylindrical hole 2b5 slides with the cylindrical outer peripheral sliding surface of the first rotating support portion 1b of the main body portion 1. Thus, the holder 2 is rotatably supported.

  In addition to the arm mounting portion 2b1, a second rotating portion 2b3 is provided on the upper surface of the flange portion 2b.

  The second rotating part 2b3 has a cylindrical shape and includes a second hole 2b6 through which the magnet 2a is exposed. The 2nd rotation part 2b3 is located above the 1st rotation part 2b2 on both sides of the magnet 2a in the rotation-axis direction of the magnet 2a. The central axes of the cylindrical first rotation part 2b2 and the second rotation part 2b3 are on the same axis, and the rotation axis of the magnet 2a is also located on the same axis. In the second rotating portion 2b3, the outer periphery having a circular cross-sectional shape perpendicular to the rotating shaft direction of the magnet 2a is a sliding surface.

  The holder 2 is arranged so that the magnet 2 a of the holder 2 faces the magnetic detection surface 3 a of the magnetic detection element 3 when the first rotation portion 2 b 2 is fitted to the first rotation support portion 1 b of the main body 1. Thus, the magnetic detection element 3 can detect a change in the magnetic pole of the magnet 2 a accompanying the rotation of the holder 2. Moreover, the slidability of the holder 2 is improved by comprising the main-body part 1 and the holder 2 with the same resin material.

  The holder 2 has a hole 2c through which a part of the magnet 2a is exposed. A part of the magnet 2a is visible through the hole 2c.

  In the present embodiment, four holes 2c are provided. This hole 2c exposes a part of the outer periphery of the magnet 2a. The four holes 2c are provided substantially evenly on the circumference of the magnet 2a. The shape of the hole 2c is a cylindrical recess, and the upper surface and part of the side surface of the magnet 2a are exposed.

  As shown in FIG. 6, the holder 2 is molded by placing a magnet 2a in the space formed by the upper mold 13 and the lower mold 14, and injecting the molten resin into the space to place the holder 2 in the space. Mold. When the magnet 2 a is disposed in the upper and lower molds 13 and 14, the magnet 2 a is moved by the four positioning pins 13 a provided on the upper mold 13 and the protrusions 14 a provided on the lower mold 14. Fixed inside. In FIG. 6, only two positioning pins 13a are shown, but there are two other pins 13a that are not shown. Moreover, the positioning pin 13a contacts the upper surface and side surface of the magnet 2a. Further, the protrusion 14a contacts the lower surface of the magnet 2a. The positioning pin 13a and the protrusion 14a suppress the movement of the magnet 2a in the direction of the rotation axis, and the positioning pin 13a suppresses the movement of the magnet 2a in the direction perpendicular to the rotation axis. Even if it receives, the magnet 2a does not move from a regular position.

  As described above, the hole 2c is formed by the positioning pin 13a at the time of molding the holder 2, and the magnet 2a can be suppressed by the upper and lower molds 13 and 14, thereby suppressing the positional deviation of the magnet 2a in the vertical and horizontal directions. It is possible to suppress variations in the output characteristics of the detection element.

  The magnetic detection element 3 is made of, for example, a Hall IC, and detects a change in magnetic force accompanying the rotation operation of the magnet 2a. The magnetic detection element 3 is electrically fixed to the terminal 1a by laser welding or resistance welding. In addition, the magnetic detection element 3 is supplied with power and transmitted with a detection signal by a lead wire 7 electrically connected to the terminal 1a.

  The cover 4 is made of a resin material such as POM. The cover 4 is fixed to the main body 1 and prevents the holder 2 from falling off. The cover 4 includes a second rotation support portion 4a, a base portion 4b, a top plate portion 4c, and first and second wall portions 4d and 4e.

  As shown in FIG. 2, the cover 4 has a shape in which a handle is inverted up and down with a base portion 4 b, a top plate portion 4 c, and first and second wall portions 4 d and 4 e.

  The 2nd rotation support part 4a is provided in the top-plate part 4c so that it may protrude below in FIG. The second rotation support portion 4a has a cylindrical shape, and an inner peripheral surface thereof is a sliding receiving surface that slides with a sliding surface on the outer periphery of the second rotation portion 2b3. The 2nd rotation support part 4a supports the 2nd rotation part 2b3 so that rotation is possible.

  The base 4 b has a flat plate shape, is fixed to the main body 1, and fixes the cover 4 to the main body 1. The base 4b and the main body 1 are fixed by appropriate means such as laser welding.

  The top plate portion 4c has a flat disk shape, and as shown in FIG. 1, when the liquid level detection device F is viewed from the upper surface, the upper and lower portions in FIG. 1 are cut out. A second rotation support portion 4a is provided in the middle of the top plate portion 4c.

  The first and second wall portions 4d and 4e are divided, and when the liquid level detection device F is viewed from the upper side, each of the wall portions 4d and 4e has an arc shape. The float arm 6 is exposed from the portion where the first and second wall portions 4d and 4e are divided, and the first and second wall portions 4d and 4e function as a stopper that regulates the rotation range of the float arm 6. Plays. Note that a fixed piece 4d1 is provided at the lower end of the first wall portion 4d (the portion in contact with the main body portion 1). Similarly to the base portion 4b, the fixed piece 4d1 is also formed by an appropriate means such as laser welding. 1 is fixed.

  As described above, it is possible to provide a liquid level detection device that can confirm the deviation of the magnet 2a after the holder 2 is molded.

  The above description exemplifies the present invention, and it goes without saying that various changes and modifications can be made without departing from the scope of the invention.

  As another embodiment, in the second embodiment shown in FIG. 7, three holes 22c are provided. This hole 22c exposes a part of the outer periphery of the magnet 2a. The three holes 22c are provided substantially evenly on the circumference of the magnet 2a. The shape of the hole 22c is a cylindrical recess, and the upper surface and part of the side surface of the magnet 2a are exposed. Also in this embodiment, the liquid level detection apparatus which enabled confirmation of the shift | offset | difference of the magnet 2a after the shaping | molding of the holder 2 can be provided similarly to 1st Embodiment.

  As still another embodiment, in the third embodiment shown in FIG. 8, two holes 32c are provided. This hole 32c exposes a part of the outer periphery of the magnet 2a. The shape of the two holes 32c is an arc shape along the outer peripheral portion of the magnet 2a. The upper surface and part of the side surface of the magnet 2a are exposed from the hole 32c. Also in this embodiment, the liquid level detection apparatus which enabled confirmation of the shift | offset | difference of the magnet 2a after the shaping | molding of the holder 2 can be provided similarly to 1st Embodiment.

  As still another embodiment, in the fourth embodiment shown in FIGS. 9 and 10, the hole from which a part of the magnet 42a is exposed is the second hole 2b6 formed in the second rotating portion 2b3. In the present embodiment, a recess 42a2 facing the hole 2b6 is provided at the center of the magnet 42a. The recess 42a2 is a cylindrical recess. A mold positioning pin (not shown) is inserted into the recess 42a2 to determine the position of the magnet 42a. Reference numeral 42a1 denotes a protrusion for stopping rotation. Also in the present embodiment, a liquid level detection device capable of confirming the displacement of the magnet 42a after molding of the holder 2 can be provided as in the first embodiment. Further, the position of the magnet 42a is determined accurately by determining the position by the recess 42a2 provided in the magnet 42a, and the positioning pin for determining the position of the magnet 42a is common to the portion for forming the hole 2b6 of the holder 2 As a result, the shape of the mold for molding the holder 2 is not complicated, and the increase in cost can be suppressed.

  In addition, the shape of the recessed part 42a2 of the magnet 42a of 4th Embodiment is not limited to a cylindrical shape, Arbitrary shapes may be sufficient. In addition, the diameter of the recess 42a2 of the magnet 42a of the fourth embodiment is equivalent to the hole 2b6 of the holder 2, but is not limited to this embodiment, and the diameter of the recess 42a2 may be smaller than the hole 2b6. Good.

  The present invention is applicable to a liquid level detection device that detects the liquid level of various liquids in a fuel tank.

F liquid level detection device 1 main body 1a terminal unit 1b first rotation support 1c positioning boss 1d hook 2 holder 2a magnet 2a1 protrusion 2b flange 2b1 arm attachment 2b2 first rotation 2b3 second rotation 2b4 holding Part 2b5 1st hole 2b6 2nd hole 2c, 22c, 32c hole 3 Magnetic detection element 3a Magnetic detection surface 4 Cover 4a 2nd rotation support part 4b Base part 4c Top plate part 4d 1st wall part 4e 2nd wall part 5 Electron Parts 6 Float arm 7 Lead wire 11 First resin body 12 Second resin body 13 Upper mold 13a Positioning pin 14 Lower mold 42a Magnet 42a2 Recess

Claims (4)

A holder that rotates according to the displacement of the float accompanying a change in the liquid level, a disk-shaped magnet that is fixed to the holder and rotates with the holder, and a magnet that detects a change in magnetic force associated with the rotating operation of the magnet. A liquid level detection apparatus comprising a detection element, wherein the holder is provided with a hole through which a part of the magnet is exposed. The liquid level detection apparatus according to claim 1, wherein one hole is provided, and a concave portion that faces the hole is provided at a center of the magnet. 2. The liquid level detection according to claim 1, wherein two holes through which a part of the outer peripheral portion of the magnet is exposed are provided, and the shape of the two holes is an arc shape along the outer peripheral portion of the magnet. apparatus. 2. The liquid level according to claim 1, wherein at least three or more holes from which a part of the outer peripheral portion of the magnet is exposed are provided, and the three or more holes are provided substantially evenly on the circumference of the magnet. Detection device.

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