JPH11237274A - Level sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a level sensor by which a level can be detected without a contact, which does not generate an error even after a long-term use and whose reliability is high. SOLUTION: In a sensor, a level is detected in such a way that the movement of a float arm 10 to which a float 11 is attached is detected on the basis of a change in the output of a magnetoelectric conversion element 8. In this case, a detecting body A as a magnetic body is attached to the shaft part 10a of the float arm 10, the detecting body A is magnetized by a magnet 7, the detecting body A is constituted in such a way that the distance between itself and the magnetoelectric conversion element 8 is changed according to its angle of deflection, and the movement of the detecting body A is detected by the electromagnetic conversion element 8.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid level sensor, and more particularly, to a float type liquid level sensor which detects the movement of a detection object by a magneto-electric conversion element in a non-contact manner.

[0002]

2. Description of the Related Art FIG. 5 shows a liquid level sensor used in a conventional gasoline tank or the like. A float 11 is attached to one end of the float arm 10, and a holder 20 is attached to the other end. This holder 20
Is rotatably supported by a frame 22 via a shaft 21. A sliding contact 23 is attached to the tip of the holder 20, and the sliding contact 23 comes into sliding contact with a resistance plate 24 attached to the frame 22.

When the float 11 moves up and down due to fluctuations in the liquid level, the sliding contact 23 turns left and right, and the resistance value of the resistance plate 24 changes. It is designed to detect.

[0004]

Since the liquid amount sensor having the above-described structure uses a detection method based on the contact between the sliding contact 23 and the resistance plate 24, a detection error due to the contact resistance between the two is likely to occur. And the deterioration of durability due to sliding wear, generation of sliding noise, or sliding contact 2
There is a problem that the manufacturing process management such as adjustment of the contact pressure between the resistor 3 and the resistance plate 24 becomes complicated.

The present invention has been made in view of the above points, and has as its object to provide a highly reliable liquid level sensor capable of detecting a liquid level without contact and having no error even when used for a long time. And

[0006]

In order to achieve the above object, according to the first aspect of the present invention, there is provided a liquid level control apparatus for detecting a movement of a float arm to which a float is attached by detecting a change in an output of a magnetoelectric conversion element. A sensor, a magnetic detection body attached to the shaft of the float arm,
A magnet arranged in a non-contact manner with respect to the detection body to magnetize the detection body, and a magnetoelectric conversion element for detecting a movement of the detection body, wherein the detection body is provided with the magnetoelectric conversion element in accordance with a deflection angle thereof. And the distance between them is changed.

Therefore, according to the first aspect of the present invention, when the float moves up and down due to the fluctuation of the liquid level, the detecting body rotates via the float arm, and the distance between the detecting body and the magnetoelectric conversion element changes. The liquid level is detected by detecting a change in magnetic force due to the change in the distance with the magneto-electric conversion element. Therefore, the movement of the float arm can be detected in a non-contact manner, and the phenomenon of increase in contact resistance and generation of sliding noise is eliminated, and a high-quality liquid sensor with high accuracy and durability can be obtained.

According to a second aspect of the present invention, there is provided the liquid level sensor according to the first aspect, wherein the detecting body has a substantially fan-shaped front portion and a radius from the center of rotation on the outer periphery of the front portion. An outer peripheral surface portion formed so as to change linearly is formed of a magnetic plate, and the magnet and the magnetoelectric conversion element are mounted on a wiring board mounted in a case supporting a shaft portion of the float arm; And the detector is attached to the shaft so as to rotate around the magnet and the magnetoelectric conversion element.

Therefore, according to the second aspect of the present invention, the detector can be formed only by eccentrically processing a magnetic material such as an iron plate, and there is no need to process the magnet, so that the manufacture of the detector and the magnet is facilitated. .

[0010] Further, since the detection body is disposed so as to cover the wiring board and a case which contains the magnet and the magnetoelectric conversion element attached to the wiring board, the detection body can be made compact as a whole, and can be miniaturized. it can.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. The same members or those having the same functions as those in FIG. 5 are denoted by the same reference numerals.

1 and 2, a bottomed cylindrical case 2 is attached to a fixed body 1 fixed to a liquid container (not shown) via screws 3. A boss 4 is formed at the center of the bottom of the case 2, and a tip 4 a of the boss 4 is formed.
Is fitted in the hole 1a of the fixed body 1. A packing 5 is provided between the case 2 and the fixed body 1 and between the boss 4 and the fixed body 1.

A wiring board 6 fitted on the outer periphery of the boss 4 is provided in the case 2. A bias magnet 7 for magnetizing a detection body A described later on the wiring board 6
Is attached, and a magnetoelectric conversion element 8 is attached below the magnet 7. Terminal 1 on wiring board 6
5 are provided.

The shaft portion 10a of the float arm 10 is rotatably inserted into the boss 4. Float arm 1
A float 11 is attached to the other end of the zero. A disc-shaped holder 12 is attached to the tip of the shaft portion 10 a of the float arm 10.
Is attached.

The detector A has a ferromagnetic body (see FIG. 1) including a substantially fan-shaped front portion 13 having an arc-shaped inner peripheral edge 13a and an outer peripheral edge 13b, and an outer peripheral surface portion 14 formed along the outer peripheral edge 13b. For example, an iron plate), and the inner peripheral edge 13a is tightly fixed to the outer periphery of the holder 12. The center O of the circle of the outer peripheral edge 13b and the outer peripheral surface portion 14 is
a (the center of the holder 12, that is, the shaft 10a)
Of the inner peripheral edge 1
The distance between 3a and the outer peripheral surface 14 changes linearly around the shaft 10a.

The front surface portion 13 of the detector A is fixed to the outer periphery of the holder 12 and partially overlaps the wiring board 6 in a direction parallel to the shaft portion 10a so that the outer peripheral surface portion 13 is located on the outer periphery of the wiring board 6. Be placed. As a result, the detection body A is configured to cover the wiring board 6, the magnet 7, and the case 2 including the magnetoelectric conversion element 8, and the space corresponding to the radial direction of the case 2 occupied by the detection body A is reduced.

The detector A is magnetized by magnetism from the magnet 7 (the holder 12 and the case 2 are made of resin and is not affected by magnetism).
The output voltage value changes in response to a change in the magnetic force from the outer peripheral surface portion 14.

When the float 11 moves up and down due to fluctuations in the liquid level, the holder 12 rotates via the float arm 10 and the detector 13 fixed to the holder 12 rotates. Since the outer peripheral edge 13b of the detector 13 is eccentric, the distance between the outer peripheral surface portion 14 and the magnetoelectric conversion element 8 changes.

That is, as shown in FIG. 3, when the detection body A is at the position indicated by the solid line, the distance (gap) G1 between the magnetoelectric conversion element 8 and the outer peripheral surface portion 14 becomes maximum. The voltage becomes the minimum V1 (see FIG. 4), and when the detection object A is at the position indicated by the two-dot chain line, the magnetoelectric conversion element 8
The distance G2 between the magnetic field and the outer peripheral surface portion 14 becomes minimum, and at this time, the output voltage from the magnetoelectric conversion element 8 becomes the maximum V2. As described above, the change in the deflection angle of the detection body A causes the magnetoelectric conversion element 8 to move.
The position of the float 11, that is, the liquid level can be detected by detecting with the magnetoelectric conversion element 8 that the distance between the float 11 and the magnetic force on the magnetoelectric conversion element 8 changes.

As described above, in the liquid level sensor of the present embodiment, the magnetic body A is attached to the shaft portion 10a of the float arm 10, and the magnetoelectric conversion element 8 is provided in accordance with the deflection angle of the body A. And the output voltage of the magneto-electric conversion element 8 changes so that the movement of the float arm 10 can be detected in a non-contact manner, and the contact resistance increases and the sliding noise as in the prior art increases. Is eliminated, and a high-quality liquid quantity sensor with high accuracy and durability can be obtained.

Further, since the detection body A magnetized by the bias magnet 7 is detected by the magnetoelectric conversion element 8, the detection body A can be formed only by molding a magnetic body such as an iron plate. Since there is no need for processing, the manufacture of the detector A and the magnet 7 is facilitated. Further, since the detection body A is configured to cover the case 2 containing the wiring board 7, the magnet 7, and the magnetoelectric conversion element 8, the detection body A is compactly arranged and downsized. The detection circuit can also be provided in the space where it is located, which enables further miniaturization.

Furthermore, since the magnet 7 and the magneto-electric conversion element 8 are mounted on the wiring board 6 mounted on the case 2, the wiring board 6, the magnet 7 and the magneto-electric conversion element 8 are mounted.
Can be sealed in the case 2 and protected from liquid.

[0023]

As described in detail above, according to the first aspect of the present invention, the magnetic material attached to the shaft of the float arm is connected to the magnetoelectric conversion element in accordance with the deflection angle of the detection body. The distance is changed, and the change in magnetic force due to the change in distance is detected by the magneto-electric conversion element, so the movement of the float arm can be detected in a non-contact manner, increasing the contact resistance and generating sliding noise. Phenomenon is eliminated, accuracy is high,
A durable and high-quality liquid level sensor can be obtained.

According to the second aspect of the present invention, the detector has a fan-shaped front surface and an outer peripheral surface formed of a magnetic plate.
Since the detection body is covered with a case enclosing the wiring board and is rotated around the magnet and the magnetoelectric conversion element, in addition to the effect of the invention according to claim 1, only a ferromagnetic body such as an iron plate is formed. Detector can be formed with no need to process the magnet, making it easier to manufacture the detector, and since the detector is placed over the case, it is configured as a whole to be compact and compact. can do.

[Brief description of the drawings]

FIG. 1 is a front view showing an embodiment of a liquid level sensor of the present invention.

FIG. 2 is a sectional view taken along line II-II of FIG.

FIG. 3 is an operation explanatory diagram of the liquid level sensor of FIG. 1;

FIG. 4 is a graph showing a relationship between a deflection angle of a detection body of the liquid level sensor of FIG. 1 and an output voltage.

FIG. 5 is a front view of a conventional liquid level sensor.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Fixed plate 2 Case 6 Wiring board 7 Magnet 8 Magnetoelectric conversion element 10 Float arm 10a Shaft part 11 Float 13 Front part 14 Outer peripheral part A Detector

Claims (2)

[Claims] 1. A liquid level sensor for detecting movement of a float arm to which a float is attached by a change in output of a magnetoelectric conversion element, wherein detection of a magnetic body attached to a shaft of the float arm is performed. Body, a magnet arranged in a non-contact manner with respect to the detection body to magnetize the detection body, and a magnetoelectric conversion element for detecting the movement of the detection body, wherein the detection body is provided in accordance with the swing angle thereof. A liquid level sensor, wherein a distance between the sensor and the magnetoelectric conversion element is changed. 2. The detector according to claim 1, wherein a substantially fan-shaped front surface portion and an outer peripheral surface portion formed on an outer periphery of the front surface portion such that a radius from a rotation center changes linearly are formed of a magnetic plate. The magnet and the magneto-electric conversion element are mounted on a wiring board mounted in a case that supports the shaft portion of the float arm, and the detection body is mounted so as to cover the case and rotate around the magnet and the magneto-electric conversion element. 2. The liquid level sensor according to claim 1, wherein the liquid level sensor is attached to a shaft.