JP2012233747A - Liquid level detection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid level detection device in which energization failure is suppressed by preventing generation of stress due to twist of an electric cord occurring at insert molding.SOLUTION: A liquid level detection device 1 includes: a float arm 3 having a float 2 that follows a change of the liquid level and is actuated thereby; a magnet 5 that rotates following the actuation of the float arm 3; a detection element 6 that detects a change in magnetism caused by the rotation of the magnet 5; an electrically connection member 11 to be electrically connected with the detection element 6; and a lead terminal 14 whose one end is connected with a lead 6b of the detection element 6, and whose another end is connected with the electrically connection member 11. A recess 14b is formed at the other end of the lead terminal 14 connected to the electrically connection member 11, and the electrically connection member 11 is arranged in the recess 14b and is welded and connected to the recess 14b.

Description

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

  In order to detect the level of a liquid such as fuel in an automobile tank, a non-contact type liquid level detection device using a magnetoelectric conversion element has been proposed.

  In this liquid level detection device, a magneto-electric conversion element, an electronic component and a pair of stators are fixed to a predetermined portion of a set of terminals to form a terminal assembly, and the terminal assembly is insert-molded into a housing, and the terminal assembly is made of a synthetic resin. (For example, patent document 1).

JP 2004-251780 A

  By the way, as for the said liquid level detection apparatus, the said terminal was provided with the external connection part, and the connector was required for the connection with an external apparatus. Providing the connector has led to an increase in cost. Therefore, it is possible to suppress an increase in cost by connecting a wiring cord directly to the terminal.

  As means for connecting the wiring cord to the terminal, there is means for connecting by welding.

  However, the connection between the conventional flat terminal and the wiring cord has a problem that the welding position is not easily determined at the time of welding, and the positional accuracy of the wiring cord with respect to the terminal is not obtained. Further, when the joined terminal and the wiring cord are insert-molded with a resin, the wiring cord is twisted, and there is a possibility that a conduction failure may occur due to excessive stress at a connection point with the terminal.

  Therefore, the present invention pays attention to the above-described problems, and an object of the present invention is to provide a liquid level detection device that prevents the occurrence of stress due to the twisting of an electric cord that occurs during insert molding and suppresses the occurrence of poor energization.

  The liquid level detection device of the present invention detects a float arm provided with a float that follows the displacement of the liquid level, a magnet that rotates in accordance with the operation of the float arm, and a magnetic change that accompanies the rotation of the magnet. In a liquid level detection device comprising a detection element that performs electrical connection with the detection element, the lead of the detection element is connected to one end side, and the electrical connection member is connected to the other end side. A lead terminal is provided, a recess is provided on the other end side of the lead terminal connected to the electrical connection member, the electrical connection member is disposed in the recess, and is connected to the recess by welding.

  Further, the concave portion is composed of one bottom surface, two side surfaces, and an abutting surface, the bottom surface and the two side surfaces abut against the side surface of the electrical connecting member, and the abutting surface is the electrical connecting member. The end portion of the electric connection member is provided to restrict the movement of the electric connection member in the longitudinal direction.

  The liquid level detection device of the present invention can provide a liquid level detection device that prevents the occurrence of stress due to the twisting of the electric cord that occurs during insert molding and suppresses the occurrence of poor energization.

Sectional drawing of the liquid level detection apparatus of 1st Embodiment of this invention. Sectional drawing of the AA line in FIG. Sectional drawing of the BB line in FIG. Sectional drawing of the CC line in FIG. The principal part expanded sectional view of the embodiment. The principal part expansion perspective view of the embodiment. The principal part expansion perspective view 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 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. And an electrical connection member 11, a lead terminal 14, a frame cover 12, and an electronic component 13. Reference numeral 10 denotes a shield case.

  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 holder member 7 is provided on the cylindrical portion 4b. The arm holder 4 is rotatably supported by the holder member 7.

  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 holder member 7 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 includes a main body 6a having a detection portion covered with a resin, and leads 6b extending from the main body 6a.

  The detection element 6 of this embodiment includes three leads 6b. The lead 6b is divided into a main body side 6b1 and a front end side 6b2 with the bent portion as a boundary, and the main body side 6b1 of the lead 6b faces the rotation axis direction of the magnet 5 together with the main body 6a of the detection element 6. The leading end side 6b2 of the lead 6b is bent in a direction perpendicular to the rotation axis direction of the magnet 5. The leading end side 6b2 of the plurality of leads 6b is different from the leading end side 6b2 of the adjacent lead 6b with respect to the rotation axis direction of the magnet 5. In the present embodiment, of the three leads 6 b, the leading end side 6 b 2 of the central lead 6 b and the leading end side 6 b 2 of the two leads 6 b on both sides are the central leads with respect to the rotation axis direction of the magnet 5. The front end side 6b2 of 6b is provided at a position farther from the magnet 5 than the front end side 6b2 of the two leads 6b on both sides.

  The detection element 6 is disposed on the holder member 7, and the lead 6 b of the detection element 6 is electrically connected to the lead portion 13 b and the lead terminal 14 of the electronic component 13. Connection of the lead portion 13b of the lead 6b of the detection element 6 and the lead terminal 14 is connected by welding. The detection element 6 may be a detection element such as an MR element.

  The holder member 7 is made of a synthetic resin, for example, a synthetic resin such as polybutylene terephthalate (PBT). The holder member 7 has a columnar portion 7a provided with a support shaft portion 7b that rotatably supports the arm holder 4. The holder member 7 includes a frame body 7c that is formed to extend in a direction perpendicular to the central axis of the cylindrical portion 7a.

  The columnar portion 7 a of the holder member 7 is provided with a first holding portion 7 d that is a concave portion that holds the main body 6 a of the detection element 6. Further, the frame body 7 c of the holder member 7 is provided with a second holding portion 7 e that contacts and holds the lead 6 b of the detection element 6. The second holding portion 7e is in contact with the distal end side 6b2 of each lead portion 6b of the detection element 6.

  In addition, the frame 7c of the holder member 7 includes a third holding portion 7f that holds the main body portion 13a of the electronic component 13, a fourth holding portion 7g that holds the lead portion 13b of the electronic component 13, and the electrical connection member 11. A fifth holding part 7h for holding and a sixth holding part 7i for holding the lead terminal 14 are provided.

  The third holding portion 7f of the holder member 7 regulates the movement and inclination of the magnet 5 of the main body portion 13a of the electronic component 13 in the rotation axis direction, and in the present embodiment, has a cup shape. The main body 13a of the electronic component 13 is accommodated in the cup shape. Note that the shape of the third holding portion 7f is not limited to the cup shape, and any shape that restricts the movement and inclination of the magnet 5 of the main body portion 13a of the electronic component 13 in the rotation axis direction may be used.

  The fourth holding portion 7g of the holder member 7 is in contact with and holds each lead portion 13b of the electronic component 13a. The fifth holding portion 7h of the holder member 7 is provided with a wall portion that abuts on the electrical connection member 11 and sandwiches the electrical connection member 11 from both sides, and holds the electrical connection member 11. The sixth holding portion 7 i of the holder member 7 is in contact with and held by the lead terminal 14.

  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 is disposed on both sides of the three leads 6b with respect to the distal end side 6b2 of the three leads 6b in which the detection elements 6 are arranged. The electronic component 13 includes a main body portion 13a and a lead portion 13b extending from the main body portion 13a.

  The electronic component 13 of this embodiment includes two lead portions 13b. The lead portion 13b is divided into a main body side 13b1 and a tip end side 13b2 with the bent portion as a boundary. The leading end side 13b2 of the lead portion 13b is bent in a direction perpendicular to the rotation axis direction of the magnet 5, and is bent in a direction perpendicular to the leading end side 6b2 of the lead 6b of the detection element 6. ing. The leading end side 13b2 of each of the plurality of lead portions 13b of the electronic component 13 is at a different position with respect to the rotation axis direction of the magnet 5. In the present embodiment, of the two lead portions 13 b, the leading end side 13 b 2 of one lead portion 13 b and the leading end side 13 b 2 of the other lead portion 13 b are one lead portion with respect to the rotation axis direction of the magnet 5. The leading end side 13b2 of 13b is provided at a position farther from the magnet 5 than the leading end side 13b2 of the other lead portion 13b.

  The lead part 13 b of the electronic component 13 is electrically connected to the lead 6 b of the detection element 6. The lead portion 13b is connected to the lead 6b by welding.

  The first case body 8 is made of a synthetic resin that can be molded at a low pressure, for example, a polyester-based synthetic resin. The detection element 6, a part of the holder member 7, a part of the electrical connection member 11, the electronic component 13, and the lead terminal 14 is covered by forming the first case body 8 by insert molding. A part of the cylindrical portion 7 a and the support shaft portion 7 b of the holder member 7 are exposed without being covered with the first case body 8.

  The second case body 9 is made of a synthetic resin, for example, a synthetic resin such as PBT or polyacetal (POM), and the first case body 8 except for a part of the columnar portion 7a and the support shaft portion 7b of the holder member 7. And the shield case 10 is covered.

  Since the holder member 7 and the second case body 9 are formed of the same material, for example, PBT, when the second case body 9 is formed, the holder member 7 and the second case body 9 are melted. 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.

  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 shields the detection element 6 from an external magnetic field, and is made of, for example, an iron-nickel alloy and has a cup shape including a cylindrical portion 10a and a bottom portion 10b. A part of the cylindrical portion 10 a includes a notch portion 10 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 shield case 10 from being deformed, it is possible to prevent changes 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 includes a conductor 11a and an insulating coating 11b made of an insulating synthetic resin or the like that covers the conductor 11a. The conductor 11a is a collection of a plurality of thin wires made of a metal having good conductivity such as copper, and the portions exposed from the insulating film 11b are collected so as not to be separated by solder or the like (not shown). In addition, the conductor 11a of the electrical connection member 11 may be configured by a single conductor. The conductor 11 a of the lead wire 11 is electrically connected to the lead terminal 14.

  The lead terminal 14 is made of a metal having conductivity, and electrically connects the lead 6b of the detection element 6 and the electrical connection member 11. The lead 6b of the detection element 6 and the conductor 11a of the electrical connection member 11 are connected to both ends of the lead terminal 14, respectively. At both ends of the lead terminal 14, a recess 14a for the lead 6b of the detection element 6 and a recess 14b for the conductor 11a of the electrical connecting member 11 are provided.

  The recesses 14a and 14b are formed by pressing or the like, and the recesses 14a and 14b are formed by one bottom surface 14a1 and 14b1, two side surfaces 14a2 and 14b2, and a protrusion located behind the recesses 14a and 14b. Four surfaces including the contact surfaces 14a3 and 14b3 are provided. Since the concave portions 14a and 14b of the lead terminal 14 are formed in an elongated rod-like member, wall portions 14a4 and 14b4 are provided on both sides of the concave portions 14a and 14b in order to form the side surfaces 14a2 and 14b2.

  Recesses 14a and 14b are detected at three points by contacting the side surfaces of the lead 6b of the detection element 6 and the conductor 11a of the electrical connecting member 11 on the three surfaces of the bottom surface 14a1 and 14b1 and the side surfaces 14a2 and 14b2. The lead 6b of the element 6 and the conductor 11a of the electrical connecting member 11 are supported. Further, the abutting surfaces 14a3 and 14b3 abut the lead 6b of the detection element 6 and the end of the conductor 11a of the electrical connection member 11, thereby restricting the longitudinal movement of the detection element 6 and the electrical connection member 11. can do. The lead 6b of the detection element 6 and the conductor 11a of the electrical connection member 11 are disposed in the recesses 14a and 14b, respectively, and are fixed to the recesses 14a and 14b by welding and electrically connected thereto.

  By providing the recesses 14a and 14b of the lead terminal 14, the lead 6b of the detection element 6 and the conductor 11a of the electrical connection member 11 can be held by the lead terminal 14, and the lead 6b of the detection element 6 generated during insert molding. Further, it is possible to prevent the occurrence of stress due to the twisting of the electrical connection member 11 and to suppress the occurrence of poor energization.

  In the present embodiment, of the three lead terminals 14, the lead terminals 14 on both sides are bent in a crank shape, and the lead 6 b is located at a different position with respect to the rotation axis direction of the magnet 5. This facilitates connection between the distal end side 6b2 and the three electrical connection members 11 aligned at the same position. The lead terminals 14 on both sides may be flat without being crank-shaped bent, and instead, the electrical connection member 11 may be arranged differently with respect to the rotation axis direction of the magnet 5.

  The electrical connection between the lead 6 b of the detection element 6, the electrical connection member 11, the lead portion 13 b of the electronic component 13 and the lead terminal 14 is performed by connecting the detection element 6, the electrical connection member 11, the electronic component 13 and the lead terminal to the holder member 7. 14 is arranged and welded to make an electrical connection.

  With the configuration as described above, it is possible to provide a liquid level detection device 1 that can prevent the occurrence of stress due to the twist of the lead 6b of the detection element 6 and the electrical connection member 11 that occur during insert molding, and can suppress the occurrence of poor conduction. Can do.

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

DESCRIPTION OF SYMBOLS 1 Liquid level detection apparatus 2 Float 3 Float arm 5 Magnet 6 Detection element 6b Lead 6b1 Lead (main body side)
6b2 Lead (tip side)
DESCRIPTION OF SYMBOLS 11 Electrical connection member 11a Conductor 11b Insulating film 14 Lead terminal 14a, 14b Recessed part 14a1, 14b1 Bottom surface 14a2, 14b2 Side surface 14a3, 14b3 Abutting surface 14a4, 14b4 Wall part

Claims (2)

A float arm having a float that operates following the displacement of the liquid surface, a magnet that rotates in accordance with the operation of the float arm, a detection element that detects a magnetic change associated with the rotation of the magnet, and the detection element An electrical connection member for electrical connection, wherein the electrical connection member is provided with a lead terminal connected to the lead of the detection element on one end side and connected to the electrical connection member on the other end side. A liquid level detecting device comprising: a concave portion provided on the other end side of the lead terminal connected to the concave portion; the electrical connection member disposed in the concave portion; and connected to the concave portion by welding. The recess is composed of one bottom surface, two side surfaces, and an abutment surface, the bottom surface and the two side surfaces abut against the side surface of the electrical connection member, and the abutment surface is an end of the electrical connection member The liquid level detection device according to claim 1, wherein the liquid level detection device is provided in contact with a portion to restrict movement of the electrical connection member in a longitudinal direction.

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