JP6790789B2 - Liquid level detector - Google Patents

Description

The present invention relates to a liquid level detecting device that detects a liquid level using magnetism.

As a liquid level detection device, for example, there is one disclosed in Patent Document 1.

The liquid level detection device as shown in Patent Document 1 includes a rotating portion that rotates according to the displacement of the float due to the fluctuation of the liquid level, a magnet that is fixed to the rotating portion and rotates together with the rotating portion, and the above. It is provided with a sensor that detects a change in magnetic force due to the rotational movement of a magnet, a plurality of terminals that electrically connect the sensor to the outside, and a lid that covers the connection between the terminal and the wire. Even if the fuel flows into the terminal, the elution (electrolytic corrosion) of the metal ions is suppressed due to the long metal ion flow path between the terminals.

Japanese Unexamined Patent Publication No. 2011-185616

However, in such a liquid level detection device, since the tubular portion surrounding the terminal is hollow and large with respect to the terminal, there is a risk that metal ions may elute from the entire surface of the terminal when the inside of the tubular portion is immersed in the liquid. there were.

Therefore, an object of the present invention is to focus on the above-mentioned problems and to provide a liquid level detection device capable of suppressing the generation and progress of electrolytic corrosion.

The liquid level detection device F of the present invention
A holder 2 that rotates according to the displacement of the float 6 due to fluctuations in the liquid level,
A magnet 2a fixed to the holder 2 and rotating together with the holder 2
A magnetic detection unit 3 that detects a change in magnetic force due to the rotational movement of the magnet 2a, and
The first resin body 11 that holds the magnetic detection unit 3 and
A second resin body 12 that covers the magnetic detection unit 3 and the first resin body 11 and
With
A fixing member 5 for fixing the second resin body 12 and
The connection terminal 5d built into the fixing member 5 and
A terminal 1a that is electrically connected to the end portion 5d2 of the connection terminal 5d and whose surface other than the contact surface 1a2 that abuts the end portion 5d2 is covered by a groove portion 12c that protrudes from the second resin body 12.
It is characterized by being equipped with.

With the above configuration, it is an object of the present invention to provide a liquid level detection device capable of achieving the desired object and suppressing the generation and progression of electrolytic corrosion.

The figure which shows one Embodiment of this invention. A cross-sectional view taken along the line AA of FIG. The figure which shows the 1st resin body of the same embodiment. The figure which shows the 2nd resin body of the same embodiment. The figure which shows the mounting member of the same embodiment. FIG. 5 shows a main body attached. BB sectional view of FIG. The figure which removed the mounting member from FIG.

Hereinafter, an 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.

As shown in FIGS. 1 and 2, the liquid level detection device F is mainly composed of a main body (resin body) 1, a holder 2, a magnetic detection unit 3, a cover 4, and a fixing member 5. There is.

The main body 1 includes a first rotation support portion 1b in which the holder 2 is rotatably supported. The first rotation support portion 1b is integrally formed with the second resin body 12. The first rotation support portion 1b has a cylindrical shape and projects toward the holder 2. The cylindrical first rotation support portion 1b has a sliding surface having a circular cross-sectional shape in the direction perpendicular to the rotation axis direction of the holder 2. In the main body 1 on the rotation axis of the first rotation support portion 1b, the magnetic detection surface of the package (magnetic detection element package) 3a containing the magnetic detection element is perpendicular to the rotation axis direction of the holder 2. It is arranged so that it faces the direction. Hereinafter, the case where the first rotation support portion 1b has a cylindrical shape will be described, but the first rotation support portion 1b may have an arbitrary shape, for example, a concave shape, as long as the holder 2 can be pivotally supported.

Further, the main body 1 is composed of a first resin body 11 and a second resin body 12. A positioning boss 1c and a hook (engagement portion) 1d for determining a position to be attached to the main body fixing portion 5a of the fixing member 5 are provided on the back surface (opposite to the side where the holder 2 is provided) of the main body portion 1. Both the positioning boss 1c and the hook 1d are integrally formed with the second resin body 12.

In the main body 1, a plurality of terminals 1a are insert-formed into the first resin body 11 by primary molding, and the magnetic detection unit 3 is resistance welded or soldered to the insert-molded terminals 1a, and the first resin body 11 is further formed. Secondary molding is performed with the second resin body 12.

As shown in FIG. 3, the first resin body 11 is made of a resin material such as polyacetal (hereinafter referred to as POM), and a plurality of terminals 1a are incorporated by molding. A magnetic detection element package 3a constituting the magnetic detection unit 3 and an electronic component (capacitor or resistor for noise absorption) 3b are mounted on a portion of the terminal 1a exposed from the first resin body 11. In the present embodiment, the magnetic detection element package 3a and the electronic component 3b are connected by a lead 3c, and the lead 3d is electrically connected to the terminal 1a by a method such as laser welding.

Hereinafter, the surface on which the magnetic detection unit 3 and the like are mounted will be referred to as the front surface 11a of the first resin body 11, and the back surface side will be referred to as the back surface 11b. The front surface 12a and the back surface 12b of the second resin body 12 are surfaces that cover the front surface 11a and the back surface 11b of the first resin body 11, respectively.

The first resin body 11 in which the magnetic detection unit 3 is 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, to form the main body portion 1. The first resin body 11 is covered with the second resin body 12 together with the magnetic detection unit 3. The first resin body 11 is hermetically sealed by the second resin body 12 together with the magnetic detection unit 3 in a state where the end portion 1a1 of the terminal 1a is exposed.

The first resin body 11 projects outward from the first resin body 11 and includes ribs (protrusions) 11e having a triangular cross section all around. The protruding tip portion of the rib 11e is melted by the heat during molding of the second resin body 12, so that the first resin body 11 and the second resin body 12 are integrally formed to form a watertight structure, and the first resin body 11 is formed. Prevents fuel from entering the gap between the resin body 12 and the second resin body 12.

As shown in FIG. 4, the second resin body 12 includes a groove portion 12c and a slit portion 12d. The surface (the surface in the same direction as the surface on which the magnetic detection unit 3 and the like are mounted) and both side surfaces of the plurality of terminals 1a exposed from the first resin body 11 are covered with the groove portions 12c, respectively. A slit portion 12d is provided between the different groove portions 12c. In the case of three terminals, three groove portions 12c and two slit portions 12d are provided. The back surface of the end portion 1a1 of the terminal 1a (the surface in the same direction as the back surface 12b of the second resin body 12) is a contact surface 1a2 that electrically connects to the connection terminal 5d described later.

As shown in FIG. 2, the holder 2 is made of a resin material such as POM, and the magnet 2a is fixed by insert molding and rotates together with the holder 2. A part of the magnet 2a is exposed from the holder 2.

The magnet 2a is made of, for example, a neodymium-ferrite material, and its shape is a cylindrical shape centered on the rotation axis of the holder 2. The magnetism of the magnet 2a is two-pole magnetization in this embodiment.

The holder 2 rotates in response to the displacement of the float 6 due to the fluctuation of the liquid level, and the float arm 7 for transmitting the displacement of the float 6 is fixed to the holder 2.

The holder 2 is provided with a holding portion 2b4 for holding the magnet 2a.

The holding portion 2b4 has a cylindrical shape, the lower side thereof is narrowed so as to be smaller than the outer shape of the magnet 2a, and the holding portion 2b4 is provided with a first hole 2b5 in which the magnet 2a is exposed.

Further, the holder 2 is provided with a first rotating portion 2b2.

The first rotating portion 2b2 is provided on the lower side of the holding portion 2b4. The first rotating portion 2b2 has a cylindrical shape, and the first rotating portion 2b2 is provided with a first hole 2b5. In the first rotating portion 2b2, a part of the inner peripheral surface of the cylindrical first hole 2b5 slides on the cylindrical outer peripheral sliding surface of the first rotating support portion 1b of the main body portion 1. It serves as a receiving surface and rotatably supports the holder 2.

Further, the holder 2 is provided with a second rotating portion 2b3.

The second rotating portion 2b3 has a cylindrical shape. The second rotating portion 2b3 is located above the first rotating portion 2b2 with the magnet 2a sandwiched in the rotation axis direction of the magnet 2a. The central axes of the first rotating portion 2b2 and the second rotating portion 2b3 are on the same axis, and the rotating axis of the magnet 2a is also located on the same axis. The outer periphery of the second rotating portion 2b3 having a circular cross-sectional shape in the direction perpendicular to the rotation axis direction of the magnet 2a is a sliding surface.

When the first rotating portion 2b2 is fitted to the first rotating support portion 1b of the main body portion 1, the holder 2 is arranged so that the magnet 2a of the holder 2 faces the magnetic detection surface of the magnetic detection element. The change in the magnetic pole of the magnet 2a due to the rotational operation of the holder 2 can be detected by the magnetic detection element. Further, the slidability of the holder 2 is improved by forming the main body 1 and the holder 2 with the same resin material.

As shown in FIG. 3, the magnetic detection unit 3 is composed of, for example, a magnetic detection element package 3a such as a Hall IC, an electronic component 3b, and leads 3c and 3d, and the magnetic force changes with the rotational operation of the magnet 2a. Is to be detected. The magnetic detection element package 3a includes electrodes 3a1. The electrode 3a1 is a plate-like body protruding from the side surface of the magnetic detection element package 3a, and the thickness in the vertical direction is thinner than the thickness of the magnetic detection element package 3a. The magnetic detection unit 3 is supplied with power and transmits a detection signal by the terminal 1a.

The magnetic detection unit 3 is positioned on the terminal 1a by a jig (not shown), and the electrode 3a1 and the lead 3d are electrically fixed to the terminal 1a by laser welding or resistance welding. The magnetic detection unit 3 is built in the main body unit 1.

As shown in FIGS. 1 and 2, the cover 4 is made of a resin material such as POM. The cover 4 is fixed to the main body 1 to prevent 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.

The cover 4 has a base portion 4b, a top plate portion 4c, and first and second wall portions 4d and 4e, and has a cassotte shape.

The second rotation support portion 4a is provided on the top plate portion 4c. The second rotation support portion 4a has a cylindrical shape, and its inner peripheral surface is a sliding receiving surface that slides with a sliding surface on the outer periphery of the second rotation portion 2b3. The second rotation support portion 4a rotatably supports the second rotation portion 2b3.

In the base portion 4b, the cover 4 is not in contact with the main body portion 1, but is fixed to a portion of the main body portion 1 (not shown). The base portion 4b and the main body portion 1 are fixed by appropriate means such as laser welding.

The top plate portion 4c has a disk shape of a flat plate, and a second rotation support portion 4a is provided at the center of the top plate portion 4c.

The first and second wall portions 4d and 4e are divided and have an arc shape when the liquid level detection device F is visually recognized from above. The float arm 8 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 8. Is playing. Although the lower end of the first wall portion 4d is not shown, it is fixed to the main body portion 1 by appropriate means such as laser welding.

As shown in FIGS. 5 and 6, the fixing member 5 is mainly composed of a main body fixing portion 5a, a brim portion 5b, and a connector portion 5c.

The main body fixing portion 5a fixes the main body portion 1 by a hook 1d provided on the main body portion 1.

In the brim portion 5b, the main body fixing portion 5a and the connector portion 5c are integrally formed. The liquid level detection device F is attached to and fixed to a fuel tank (not shown) by the brim portion 5b.

The connector portion 5c is arranged outside the fuel tank and is for electrically connecting to an external device (not shown).

The connection terminal 5d is bent at a substantially right angle and is insert-molded into the brim portion 5b and the connector portion 5c. The end on the connector portion 5c side is the end portion 5d1, and the end portion on the main body fixing portion 5a side is the end portion 5d2.

The main body 1 uses the slit portion 12d provided in the main body 1 and the second protruding portion 5f provided in the fixing member 5 as guides, and the contact surface 1a2 of the end 1a1 of the terminal 1a exposed from the groove 12c. After the contact surface 5d3 of the end portion 5d2 is brought into contact with the fixing member 5, the contact surface 5d3 is fixed to the fixing member 5 by the hook 1d and supported by the first protruding portion 5e provided on the fixing member 5.

At this time, as shown in FIGS. 7 and 8, the end portion 1a1 is covered with the groove portion 12c in three directions (surfaces 1a3, 1a4, 1a5) other than the contact surface 1a2 by insert molding. Further, since the contact surface 1a2 is covered with the contact surface 5d3 of the connection terminal 5d, the area where the terminal 1a comes into contact with the fuel can be minimized. Therefore, the amount of metal ions eluted through the fuel can be reduced, and electrolytic corrosion is unlikely to occur.

Further, by providing the second protruding portion 5f between the groove portions 12c, the electrical distance between the end portions 1a1 of the adjacent terminals 1a can be lengthened, and the progress of electrolytic corrosion can be suppressed.

Further, by arranging the terminals 1a used for signal output in the center, the potential difference between the adjacent terminals 1a can be reduced, and the progress of electrolytic corrosion can be suppressed. For example, by applying 5V and 0V to the two power supply lines and arranging the signal lines between them, the potential difference between the terminals can be reduced, and the power supply lines having the largest potential difference can be arranged apart from each other.

Further, an inexpensive structure is preferable because the end portion 1a1 is made of phosphor bronze plated with tin and the connection terminal 5d is made of brass, which is less likely to cause electrolytic corrosion.

It goes without saying that the above description is an example of the present invention, and various modifications and modifications can be made without departing from the gist thereof.

For example, in the above-described embodiment, the case where the terminal 1a is plate-shaped has been illustrated, but the contact surface 1a2 may be flat and the shape is arbitrary.

In the above embodiment, the case where the number of terminals 1a is three is illustrated, but the number of terminals is arbitrary.

In the above embodiment, the case where the opening of the groove portion 12c is provided on the back surface side of the second resin body 12 is illustrated, but the same effect can be expected even if the opening portion is provided on the front surface side.

Further, in the above-described embodiment, the magnetic detection element package 3a and the electronic component 3b are connected by a lead 3c, but the magnetic detection element package 3a and the electronic component 3b are independent components. Is also good.

The present invention can be used in a liquid level detection device having a built-in magnetic detection element and covering it by resin molding.

1 Main body (resin body)
1a terminal 1a1 end 1a2 contact surface 1a3 surface 1a4 surface 1a5 surface 1b first rotation support part 1c boss part 1d hook 2 holder 2a magnet 2b2 first rotation part 2b3 second rotation part 2b4 holding part 2b5 first hole 3 Magnetic detection unit 3a Magnetic detection element package 3a1 Electrode 3b Electronic component 3c Lead 3d Lead 4 Cover 4a Second rotation support part 4b Base part 4c Top plate part 4d First wall part 4e Second wall part 5 Fixing member 5a Main body fixing part 5b Brim part 5c Connector part 5d Connection terminal 5d1 End part 5d2 End part 5d3 Contact surface 5e 1st protrusion 5f 2nd protrusion 6 Float 7 Float arm 11 1st resin body 11a Front surface 11b Back surface 11c Side surface 11d Side surface 11e Projection 12 2nd Resin body 12a Front surface 12b Back surface 12c Groove 12d Slit F Liquid level detector

Claims (1)

A holder that rotates according to the displacement of the float due to fluctuations in the liquid level,
A magnet fixed to the holder and rotating with the holder,
A magnetic detection unit that detects changes in magnetic force due to the rotational movement of the magnet,
The first resin body that holds the magnetic detection unit and
A second resin body that covers the magnetic detection unit and the first resin body,
In the liquid level detection device equipped with
A fixing member for fixing the second resin body and
The connection terminal built into the fixing member and
A terminal that is electrically connected to the end of the connection terminal and whose surface other than the contact surface that abuts the end is covered by a groove that protrudes from the second resin body.
A liquid level detection device characterized by being equipped with.

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