JP2011141146A - Liquid level detector and manufacturing method the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid level detector which can prevent deformation of a wiring member such as a lead and a break in the wiring member such as the lead and its manufacturing method. <P>SOLUTION: The liquid level detector 1 includes: a float arm 3 having a float 2 which operates following the displacement of a liquid level; a magnet 5 which turns along with the operation of the float arm 3; and a detection element 6 for detecting a magnetic change in the magnet 5. The liquid level detector 1 further includes: a holder member 7 having a first arrangement part 7a for arranging the detection element 6 and a second arrangement part 7b for arranging an electric connection member 11 which is electrically connected with the detection element 6; a first case element 8 covering the holder member 7; and a second case element 9 covering the first case element 8. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a liquid level detection device that detects the level of a liquid such as various fuels in a tank and a method for manufacturing the same.

  A conventional liquid level detection device rotates a float arm having a float that moves up and down in accordance with the liquid level at one end, a magnet that rotates with the operation of the float arm, and the other end of the float arm. A housing that is movably supported, a detection element such as a magnetoelectric conversion element that is provided in the housing and detects a change in magnetism of the magnet, a circuit board that holds the detection element, and a filling that protects the circuit board An agent, a magnetic shield member provided so as to surround the circuit board and the magnet, and the magnetic shield member and the housing. The intrusion of the fuel and the like into the space for housing the detection element and the circuit board is performed. The thing provided with sealing materials, such as O-ring to prevent, is proposed (for example, refer patent document 1).

  The liquid level detection device requires the filler and the sealing material to protect the detection element from touching the fuel and the like, resulting in a large number of parts, poor assembly, There was a problem that the cost increased.

  Therefore, in order to protect the detection element, reduce the number of parts, improve the assemblability, and further reduce the cost, the detection element is first housed and fixed in the casing, and then the entire casing. There has been proposed a liquid level detecting device that is set in a body mold and insert-molded (see, for example, Patent Document 2).

JP 2007-322222 A JP 2007-183241 A

  By the way, the liquid level detection device inserts the detection element into a hole provided in the casing, and connects each lead of the detection element to a terminal provided in the casing by caulking or fusing, etc. Then, this casing is set in the body mold and insert molded. The resin forming the body is injected into the mold at a high pressure. Therefore, the lead and the terminal may be deformed by the pressure of the resin, or the connection portion between the lead and the terminal may be broken.

  Accordingly, the present invention pays attention to the above-mentioned problems, and provides a liquid level detection device capable of preventing deformation of a wiring member such as a lead and division of the wiring member such as the lead, and a manufacturing method thereof. Objective.

  The liquid level detection device of the present invention includes a float arm provided with a float that operates following displacement of the liquid level, a magnet that rotates in accordance with the operation of the float arm, and a detection element that detects a magnetic change of the magnet. In the liquid level detection apparatus, the holder member includes a first disposition portion for disposing the detection element and a second disposition portion for disposing an electrical connection member electrically connected to the detection element. And a first case body that covers the holder member, and a second case body that covers the first case body.

  A portion of the first case body that corresponds to the detection element is housed and a shield case that is covered with the second case body is provided.

  Further, the first arrangement portion of the holder member is exposed.

  In addition, an arm holder for holding the magnet and the float arm is rotatably supported by the first arrangement portion.

  Further, the manufacturing method of the liquid level detection device of the present invention includes a float arm provided with a float that operates following the displacement of the liquid level, a magnet that rotates in accordance with the operation of the float arm, and a magnetic change of the magnet. In a manufacturing method of a liquid level detection device comprising a detection element for detection, a first arrangement part is provided, wherein a first arrangement part for arranging the detection element is provided and an electrical connection member electrically connected to the detection element is arranged. The detecting element and the electrical connecting member are arranged on a holder member having two arranging portions, a first case body that covers the holder member is formed, and a second case body that covers the first case body is formed It is.

  Further, the holder member is disposed in a mold for forming the first case body, and the pressure for injecting the resin for forming the first case body into the mold is set to a low pressure.

  The present invention can provide a liquid level detection device capable of preventing the deformation of a wiring member such as a lead and the division of the wiring member such as the lead, and a manufacturing method thereof.

Sectional drawing of the liquid level detection apparatus of 1st Embodiment of this invention. Sectional drawing of the components which comprise the liquid level detection apparatus of the embodiment. Sectional drawing of the components which comprise the liquid level detection apparatus of the embodiment. Sectional drawing of the components which comprise the liquid level detection apparatus of the embodiment. Sectional drawing of the liquid level detection apparatus of 2nd Embodiment of this invention.

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

  The liquid level detection device 1 of the present invention includes a float 2, a float arm 3, an arm holder 4, a magnet 5, a detection element 6, a holder member 7, a first case body 8, and a second case body 9. It is equipped with. In addition, 10 is a shield case, 11 is an electrical connection member, and 12 is a frame cover.

  The float 2 floats on the liquid level of liquid such as liquid fuel, and follows the displacement of the liquid level. In this embodiment, the float 2 is made of a metal that is not easily corroded, such as stainless steel. In addition, the material of the float 2 is not limited to this embodiment, You may form with a synthetic resin.

  The float arm 3 is made of a nonmagnetic metal, holds the float 2 at one end, and is attached to the arm holder 4 at the other end.

  The arm holder 4 is made of synthetic resin and holds the float arm 3 and the magnet 5.

  The arm holder 4 includes a cylindrical portion 4a, and a magnet 5 is provided inside the cylindrical portion 4a. The arm holder 4 holds the float arm 3 by an arm holding portion 4c.

  In addition, a cylindrical portion 4b is provided at the center of the arm holder 4, and a bearing 4d including a concave portion that rotatably supports a later-described support shaft portion of the second case body 9 is provided on the cylindrical portion 4b. The arm holder 4 is rotatably supported by the second case body 9.

  A frame cover 12 is disposed on the left side of the arm holder 4 in FIG. 1 and is fixed to the second case body 9. The frame cover 12 holds the arm holder 4 in a retaining state and functions as a bearing that pivotally supports the cylindrical portion 4 b of the arm holder 4.

  The magnet 5 is annular and is magnetized with two poles, and is integrally formed by means such as insert molding simultaneously with the molding of the arm holder 4. The magnet 5 is disposed so as to face the outer periphery of a cylindrical portion described later of the second case body 9 and is disposed so as to surround the detection element 6. The magnet 5 rotates with the operation of the float arm 3.

  The detection element 6 is composed of, for example, a magnetoelectric conversion element such as a Hall element, and detects a change in magnetism accompanying the rotation of the magnet 5 and outputs a detection signal. The detection element 6 may be a detection element such as an MR element. The detection element 6 is disposed on the holder member 7, and the lead 6 a is electrically connected to the electrical connection member 11. The lead 6a and the electrical connection member 11 are connected by welding.

  The holder member 7 is made of a synthetic resin, for example, a synthetic resin such as polybutylene terephthalate (PBT). The holder member 7 includes a first arrangement portion 7 a that holds the detection element 6, a second arrangement portion 7 b that holds the electrical connection member 11, and a third arrangement portion 7 c that holds the electronic component 13. .

  The 1st arrangement | positioning part 7a is cup shape, and accommodates the detection element 6 inside this cup shape. The 2nd arrangement | positioning part 7b consists of a pin or wall part which pinches | interposes the electrical connection member 11 from both sides, and hold | maintains the electrical connection member 11. FIG. The 3rd arrangement | positioning part 7c is a cup shape, and accommodates the electronic component 13 in the inside of this cup shape.

  The electronic component 13 is, for example, a capacitor or a diode, and is intended to reduce input / output noise of the detection element 6. The electronic component 13 includes a lead 13 a and is electrically connected to the lead 6 a of the detection element 6. The lead 13a and the lead 6a are connected by welding.

  The first case body 8 is made of a synthetic resin injected at a low injection pressure of about 3 megapascals (MPa), for example, a polyester-based synthetic resin, and includes a detection element 6, a holder member 7, and an electrical connection member 11. And a part of the electronic component 13 are covered. The detection element 6, the holder member 7, a part of the electrical connection member 11 and the electronic component 13 are covered by forming the first case body 8 by insert molding.

  The second case body 9 is made of an oil-resistant synthetic resin that hardly swells with gasoline or alcohol, for example, a synthetic resin such as PBT or polyacetal (POM), and covers the first case body 8 and the shield case 10.

  The second case body 9 includes a cylindrical portion 9a. The cylindrical portion 9a includes a support shaft portion 9a1 that rotatably supports the arm holder 4.

  The thermal expansion coefficients of the first case body 8 and the second case body 9 are approximate and prevent peeling due to a temperature change.

  The shield case 10 protects the detection element 6 from an external magnetic field, and is made of, for example, an iron-nickel alloy and has a cup shape having a cylindrical portion 10a and a bottom portion 10b. A part of the cylindrical portion 10 a is provided with a notch portion 8 c for drawing the first case body 8 out of the shield case 10.

  The shield case 10 is covered with the second case body 9 in a state where the first case body 8 is housed in a recess formed by the cylindrical portion 10a and the bottom portion 10b. The shield case 10 is formed so as to accommodate a portion corresponding to the detection element 6 of the first case body 8. The shield case 10 can block the influence of magnetism from the outside of the liquid level detection device 1 and obtain a highly accurate detection output.

  By covering the shield case 10 with the second case body 9, deformation of the shield case 10 can be prevented. By preventing the deformation of the shield case 10, it is possible to prevent a change in magnetic characteristics. Furthermore, corrosion of the shield case 10 can be prevented. This is particularly effective when the fuel contains alcohol.

  In this embodiment, the electrical connection member 11 is a lead wire, and is composed of a conductor 11a having good conductivity such as copper and an insulating film 11b covering the conductor 11a. The conductor 11 a of the lead wire 11 is electrically connected to the lead 6 a of the detection element 6.

  Next, the manufacturing method of the liquid level detection apparatus 1 of this embodiment is demonstrated using FIGS.

  First, the detection element 6, the electronic component 13 and the lead wire 11 are attached to the holder member 7, the lead 6 a of the detection element 6 and the conductor 11 a of the lead wire 11 are electrically connected, and further the detection element 6 The lead 6a and the lead 13a of the electronic component 13 are electrically connected. (See FIG. 2).

  Second, the holder member 7 to which the detection element 6, the electronic component 13, and the lead wire 11 are attached is installed in a mold for forming the first case body 8, thereby forming the first case body 8. (See FIG. 3). When the first case body 8 is formed by insert molding, the resin forming the first case body 8 is injected into the mold at a low injection pressure of about 3 MPa, whereby the lead 6a of the detection element 6 is obtained. It is possible to prevent the electrical connection between the lead 11 and the conductor 11a of the lead wire 11 and the electrical connection between the lead 6a of the detection element 6 and the lead 13a of the electronic component 13. Further, the deformation of the lead 6a of the detection element 6 and the lead 13a of the electronic component 13 can be suppressed.

  Third, the first case body 8 shown in FIG. 3 is placed in a mold for molding the second case body 9, and the resin forming the second case body 9 is injected into the mold at an injection pressure of 100 to 150 MPa. The second case body 9 is formed by insert molding. (See FIG. 4). Thereafter, when the arm holder 4 including the float 2 and the float arm 3 is installed in the second case body 9 and the frame cover 12 is fixed to the second case body 9, the liquid level detection device 1 is completed.

  With the configuration described above, it is possible to provide the liquid level detection device 1 and its manufacturing method capable of preventing the deformation of the wiring member such as the lead 6a and the separation of the lead 6a and the electrical connection member 11. .

  In the present embodiment, the lead wire is used as the electrical connection member. However, the present invention is not limited to this embodiment. For example, a metal rod-shaped terminal may be used.

  Next, a second embodiment of the present invention will be described with reference to FIG. In addition, the same code | symbol is attached | subjected to the same and equivalent part as 1st Embodiment, and the detailed description is abbreviate | omitted.

  In the first embodiment of the present invention, the holder member 7 is covered with a first case body 8 and a second case body 9. Similarly, the portion of the first arrangement portion 7 a where the detection element 6 is arranged is also covered with the first case body 8 and the second case body 9. Therefore, the detection element 6 is surrounded by the first disposition portion 7a, the first case body 8, and the second case body 9 of the holder member 7, so that the diameter of the cylindrical portion 9a of the second case body 9 is increased. turn into. In particular, when the detection element 6 is arranged to be displaced from the central axis of the cylindrical portion 9a (the rotation center of the arm holder 4), the cylindrical shape is larger than when the detection element 6 is arranged on the central axis of the cylindrical portion 9a. The diameter of the part 9a becomes large.

  The size of the magnet 5 or the like is determined according to the size of the cylindrical portion 9a that houses the detection element 6, and as a result, the size of the liquid level detection device 1 is substantially determined.

  Therefore, in order to reduce the diameter of the cylindrical portion 9 a that houses the detection element 6, in the second embodiment, the first arrangement portion 17 a of the holder member 7 is formed by the first case body 8 and the second case body 9. Exposed without covering. In this embodiment, the 1st arrangement | positioning part 17a serves as the cylindrical part 9a of the 2nd case body 9 as described in 1st Embodiment. In this embodiment as well, as in the first embodiment, the first arrangement portion 17a is provided with a support shaft portion 17b that supports the arm holder 4 so as to be rotatable. Supports movable.

  Moreover, in this embodiment, when forming the 2nd case body 9 by forming the holder member 7 and the 2nd case body 9 with the same material, for example, PBT, the holder member 7 and the 2nd case body 9 is melted, and the holder member 7 and the second case body 9 are bonded. Therefore, it is possible to prevent fuel or the like from entering the second case body 9 from the adhesion portion between the holder member 7 and the second case body 9.

  With the configuration described above, the diameter of the first disposition portion 17a that is a cylindrical portion that houses the detection element 6 can be reduced, and the magnet 5 can be reduced in size, and thus the liquid level detection device 1 can be reduced in size. Can be

  In each embodiment of the present invention, in order to rotatably support the arm holder 4, the columnar portion 9a and the first disposing portion 17a are provided with the support shaft portions 9a1 and 17b, respectively. For example, the arm holder 4 may be rotatably supported by the columnar portion 9a or the first disposing portion 17a that also serves as the columnar portion.

  INDUSTRIAL APPLICABILITY The present invention can be used for a liquid level detection device that detects the liquid level of various liquids in a tank and a manufacturing method thereof.

DESCRIPTION OF SYMBOLS 1 Liquid level detection apparatus 2 Float 3 Float arm 4 Arm holder 5 Magnet 6 Detection element 6a Lead 7 Holder member 7a First arrangement part 7b Second arrangement part 8 First case body 9 Second case body 10 Shield case 11 Electricity Connecting member

Claims (6)

  In a liquid level detection apparatus comprising: a float arm having a float that operates following the displacement of the liquid level; a magnet that rotates in accordance with the operation of the float arm; and a detection element that detects a magnetic change of the magnet. A holder member that includes a first disposing portion that disposes the detecting element and includes a second disposing portion that disposes an electrical connection member that is electrically connected to the detecting element; and a first member that covers the holder member. A liquid level detection apparatus comprising: a case body; and a second case body that covers the first case body.   2. The liquid level detection device according to claim 1, further comprising a shield case that houses a portion corresponding to the detection element of the first case body and is covered with the second case body.   The liquid level detection device according to claim 1, wherein the first arrangement portion of the holder member is exposed.   The liquid level detection device according to claim 3, wherein an arm holder that holds the magnet and the float arm is rotatably supported by the first arrangement portion.   A liquid level detection apparatus comprising: a float arm including a float that operates following a displacement of a liquid level; a magnet that rotates in accordance with the operation of the float arm; and a detection element that detects a magnetic change of the magnet. In the manufacturing method, the detecting element and the holder are provided with a first disposing part for disposing the detecting element and a second disposing part for disposing an electrical connecting member electrically connected to the detecting element. A method of manufacturing a liquid level detecting device, comprising: arranging an electrical connection member; forming a first case body that covers the holder member; and forming a second case body that covers the first case body. The said holder member is arrange | positioned in the metal mold | die which forms the said 1st case body, The pressure which inject | emits the resin which forms the said 1st case body in the said metal mold | die was made into the low pressure | voltage. The manufacturing method of the liquid level detection apparatus of description.

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