JP2005010093A - Liquid level detector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid level detector capable of reducing the number of part items and the assembling man-hour. <P>SOLUTION: This liquid level detector is provided with a first projection part 54 provided at the tip of a minor diameter part 53 of a shank 51 to be protruded to the radial circumferential side of the minor diameter part 53, a second projection part 42 provided at the end part on the first projection 54 of the shank 51 of the inner wall of a hole part 51 so that the first projection part 54 can be passed in the axial direction, and a stopper 55 provided on a body 5 and allowed to abut on the end part opposite to the float 3 of an arm 3 to regulate the rotating range around the shank 51 of a magnet holder 4. When the magnet holder 4 is at least within the rotating range regulated by the stopper 55, the liquid level detector is constituted so that the second projection part 52 abuts on the first projection part 54 to regulate the movement of the magnet holder 4 to the direction of leaving the body 5. Accordingly, since a dropping-out preventive flange which is provided in a conventional liquid level detector can be dispensed with to eliminate its mounting work, a liquid level gauge 1 capable of reducing the number of part items and the assembling man-hour can be realized. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a liquid level detection device for measuring the liquid level of a liquid stored in a container, and more particularly to a non-contact type liquid level detection device using a magnetoelectric conversion element.
[0002]
[Prior art]
This type of liquid level detection device is used, for example, as a liquid level detection device for monitoring the amount of fuel stored in a fuel tank of an automobile.
[0003]
In this type of liquid level detection device, a float that floats on a liquid whose liquid level is to be measured, a magnet holder that holds a magnet and includes a hole, and a float and a magnet holder are connected to move the float up and down. An arm that converts the rotational movement of the magnet holder, a shaft portion, a body portion that fits the shaft portion into the hole portion and rotatably holds the magnet holder around the shaft portion, and a magnetic flux of the magnet And a magneto-electric conversion element fixed to the main body so as to intersect, and the magnetic flux density of the magnet intersecting the magneto-electric conversion element is detected by the magneto-electric conversion element to detect the rotation angle of the magnet holder, that is, the liquid level. For example, see Patent Document 1).
[0004]
[Patent Document 1]
Japanese Patent Application Laid-Open No. 2002-206959
[Problems to be solved by the invention]
In the above-described conventional liquid level detection device, the magnet holder is attached to the main body portion in order to prevent the magnet holder from moving from the main body portion in the axial direction of the shaft portion. That is, after the hole portion of the magnet holder is fitted into the shaft portion of the main body portion, the prevention flange is attached to the main body portion.
[0006]
For this reason, there is a problem that the number of parts of the liquid level detection device increases and the number of assembling steps increases.
[0007]
The present invention has been made in view of the above points, and an object thereof is to provide a liquid level detection device capable of reducing the number of parts and the number of assembly steps.
[0008]
[Means for Solving the Problems]
The present invention employs the following technical means to achieve the above object.
[0009]
According to a first aspect of the present invention, there is provided a liquid level detection apparatus, comprising: a float that floats on a liquid that is a liquid level measurement target; a magnet holder that holds a magnet and includes a hole; An arm that converts the vertical movement of the float into a rotational movement of the magnet holder, and a main body portion that has a shaft portion, fits the shaft portion into the hole portion, and rotatably holds the magnet holder around the shaft portion. And a magnetoelectric conversion element fixed to the main body so as to cross the magnetic flux of the magnet, and the magnetic flux density of the magnet crossing the magnetoelectric conversion element is detected by the magnetoelectric conversion element, and the magnet holder is rotated based on the detection signal A liquid level detecting device for detecting an angle, that is, a liquid level, wherein a shaft portion includes a large diameter portion fitted into a hole portion, and a small diameter portion formed coaxially with the large diameter portion at a tip of the large diameter portion. , The first protrusion is provided at the tip of the diameter portion so as to extend in the radial direction of the small diameter portion on a part of the outer periphery of the small diameter portion, and has a hole at the tip end side end of the shaft portion of the inner wall of the hole portion. The second protrusion provided to extend in the radial direction of the portion, and a stopper provided on the main body to contact the end of the arm opposite to the float to regulate the rotation range around the shaft portion of the magnet holder The contour line in the axial direction of the shaft part of the first protrusion part is included in the axial direction contour line of the large diameter part, and the second protrusion part provided on the inner wall of the hole part is the first protrusion of the shaft part The portion is formed in a shape that allows passage, and when the magnet holder is at least in the rotation range, the second protrusion is in contact with the first protrusion and the movement of the magnet holder in the direction away from the main body is restricted. did.
[0010]
With the configuration as described above, the contour shape of the opening of the magnet holder opposite to the main body portion is formed by the arc that is the contour line of the hole portion and the contour line of the second protrusion. In other words, the hole is partially closed. Further, the contour shape of the opening is formed such that the first protrusion of the shaft can pass through in a state where the hole of the magnet holder is fitted to the large diameter portion of the shaft.
[0011]
Therefore, in the assembling step of the liquid level detection device according to claim 1 of the present invention, the magnet holder without the arm is attached to the first protrusion portion of the shaft portion and the opening portion on the opposite side to the main body portion of the hole portion. After passing through and mounting on the main body, the magnet holder is rotated left or right so that the first protrusion of the shaft is brought into contact with the second protrusion of the hole of the magnet holder. Prevention becomes possible.
[0012]
This eliminates the need for the escape prevention flange provided in the conventional liquid level detection device, that is, eliminates the need for attaching the prevention flange, thereby realizing a liquid level detection device that can reduce the number of parts and assembly man-hours.
[0013]
Further, after the arm is attached to the main body before mounting the magnet holder, that is, the magnet holder alone, the magnet holder is prevented from coming off from the main body at least when it is in the rotation range as the liquid level detecting device. . In other words, it is possible to perform an electrical characteristic confirmation operation or a detection signal adjustment operation of the liquid level detection device with the arm not attached. Therefore, since the work can be performed in a state where the arm is not attached, that is, in a state where the physique is small, it is possible to improve the workability of the electrical characteristic confirmation work or detection signal adjustment work of the liquid level detection device.
[0014]
In the liquid level detection device according to the second aspect of the present invention, the magnet holder is provided with a locking portion having a groove, and the arm is held and fixed in the groove by the elastic force of the locking portion.
[0015]
In this case, the attachment of the arm to the magnet holder is completed by inserting the arm into the groove of the locking portion while elastically deforming the locking portion. As a result, the arm can be easily and reliably fixed to the locking portion, so that the arm can be easily attached to the magnet holder.
[0016]
In the liquid level detection device according to the third aspect of the present invention, the locking portion has an opening and a holding portion, and the cross-sectional shape orthogonal to the axial direction of the holding portion is rectangular or circular, and the width dimension or the inner diameter dimension thereof. Is set smaller than the outer diameter dimension of the arm, and the width dimension orthogonal to the axial direction of the opening is set smaller than the width dimension or inner diameter dimension of the holding portion.
[0017]
Thereby, when attaching an arm to a latching | locking part, since a latching | locking part can be reliably elastically deformed, an arm can be reliably fixed to a latching | locking part. Further, after the arm is attached to the locking portion, the elastic force due to the elastic deformation of the locking portion continues to act on the arm, so that the arm can be prevented from coming off from the locking portion in the process of using the liquid level detection device. .
[0018]
In the liquid level detection device according to the fourth aspect of the present invention, the magnet holder is provided with a through hole parallel to the hole, and the arm is fitted into the through hole.
[0019]
In this case, since the arm is held by both the locking portion and the through hole of the magnet holder, the positional relationship between the arm and the magnet holder can be accurately maintained. Therefore, variation in detection characteristics between products of the liquid level detection device can be reduced.
[0020]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, a case where the liquid level detection device according to the embodiment of the present invention is applied to a fuel level gauge that is mounted in a fuel tank of an automobile and detects the level of fuel will be described with reference to the drawings. In the drawings, the same components are denoted by the same reference numerals.
FIG. 1 is a front view of a fuel level gauge 1 which is a liquid level detection device according to an embodiment of the present invention, and shows a state in which a liquid level 91 of fuel 9 is at the lowest level. In FIG. 1, for ease of understanding, a part of the arm 3 is not shown by being broken.
[0021]
2 is a cross-sectional view of the fuel level gauge 1 according to an embodiment of the present invention, and is a cross-sectional view taken along the line II-II of FIG.
[0022]
FIG. 3 is a partial cross-sectional view of the fuel level gauge 1 according to the embodiment of the present invention, and is a cross-sectional view taken along the line III-III of FIG.
[0023]
FIG. 4 is a schematic diagram for explaining the magnetic flux distribution of the magnet 6 in the fuel level gauge 1 according to the embodiment of the present invention.
[0024]
1 and 2, the upper part of the figure is the upper part in the state where the fuel level gauge 1 is attached to the automobile.
[0025]
1 and 2 show the state where the fuel level 91 is at the lowest level, that is, when the fuel tank (not shown) is almost empty.
[0026]
In FIG. 1, the liquid level 91, the float 2, and the arm 2 when the fuel liquid level 91 is at the highest level, that is, when the tank is full, are indicated by broken lines. Accordingly, when the position of the liquid level 91 of the fuel 9 changes from the highest level to the lowest level, and the float 2 moves up and down as shown in FIG. 1, the magnet holder 4 rotates by the angle θ. That is, the rotation range of the magnet holder 4 in the fuel level gauge 1 according to the embodiment of the present invention is the angle θ.
[0027]
The fuel level gauge 1 is fixed in a fuel tank (not shown) for storing fuel 9 which is liquid, and detects the level 91 of the liquid level.
[0028]
The float 2 is made of resin or the like, and has an apparent specific gravity so that it floats on the liquid level 91 of the fuel.
[0029]
The arm 3 is formed of a metal rod, for example, and connects the float 2 and the magnet holder 4. That is, as shown in FIG. 1, the float 2 is fixed to one end of the arm 3, and the other end of the arm 3 is fixed to the magnet holder 4. When the float 2 moves up and down as the liquid level 91 fluctuates, this movement is transmitted to the magnet holder 4 by the arm 3 and converted into a rotational movement of the magnet holder 4.
[0030]
The magnet holder 4 is made of resin or the like, and as shown in FIG. 2, incorporates a magnet 6 and is rotatably engaged with a body 5 which is a main body portion to be described later. As shown in FIG. 2, the magnet holder 4 includes a hole portion 41 for rotatably engaging the body 5, a locking portion 43 for holding and fixing the arm 3, and a through hole 47.
[0031]
Below, the structure of the magnet holder 4 is demonstrated.
[0032]
The magnet 6 is made of, for example, a ferrite magnet or the like, and in the fuel level gauge 1 according to the embodiment of the present invention, a cylindrical one is used and is arranged concentrically with the hole 41. Furthermore, as shown in FIG. 4, the magnet 6 is two-pole magnetized on its inner peripheral surface. Therefore, the magnetic flux M of the magnet 6 flows in the radial direction of the hole 41. In the fuel level gauge 1 according to the embodiment of the present invention, the magnet 6 is integrally insert-molded when the magnet holder 4 is molded with resin.
[0033]
As shown in FIG. 2, the hole 41 is formed as a through hole. When the hole 41 is rotatably fitted to the shaft 51 of the body 5, specifically, the large diameter portion 52, the magnet holder 4 rotates about the center of the shaft 51 of the body 5 as the rotation axis. Further, as shown in FIGS. 1 and 2, the tip end side end portion of the shaft portion 51 of the inner wall of the hole portion 41, that is, the left end portion in FIG. 2, extends in the radial direction of the hole portion 41. Two provided second protrusions 42 are formed. The two second protrusions 42 are formed on the inner wall of the hole 41 at intervals of 180 degrees, that is, facing each other. Further, the shape of the second protrusion 42 is formed so that the first protrusion 54 provided at the tip of the shaft 51 of the body 5 which is a main body, which will be described later, can pass, that is, can pass in the axial direction of FIG. Has been. In other words, the hole 41 is formed so that the first protrusion 54 can pass through the opening of the hole 41 on the second protrusion 42 side. Further, the second projecting portion 42 comes in contact with the first projecting portion 54 at the tip of the shaft portion 51 of the body 5 described later in the axial direction, so that the magnet holder 4 moves away from the body 5 (left side in FIG. 2). Is restricted from moving.
[0034]
In the fuel level gauge 1 according to the embodiment of the present invention, as shown in FIGS. 1 and 2, two locking portions 43 are arranged on the end surface of the magnet holder 4 opposite to the body 5. The locking portion 43 includes a groove 44 for holding and fixing the arm 3. As shown in FIG. 3, the groove 44 includes an opening 45 and a holding portion 46. Note that FIG. 3 shows the arm 3 in an unmounted state, and the arm 3 is indicated by a one-dot chain line. The holding portion 46 is formed in a circular shape as shown in FIG. 3 with a cross-sectional shape orthogonal to the axial direction, that is, the direction perpendicular to the paper surface of FIG. 3, and its diameter dimension D2 is larger than the diameter dimension D1 of the arm 3. It is formed small. The opening 45 is formed such that a width dimension W orthogonal to the axial direction, that is, the direction perpendicular to the paper surface of FIG. 3, is smaller than the diameter dimension D2 of the holding part 46, as shown in FIG. When the arm 3 is mounted in the groove 44 of the locking portion 43, when the arm 3 is pushed into the groove 44 of the locking portion 43 from the left side in FIG. 3, the locking portion 43 is elastically deformed, and the holding portion 46. The arm 3 is held and fixed. At this time, the locking portion 43 is in an elastically deformed state, and the arm 3 is held by the elastic force of the locking portion 43. Further, the two locking portions 43 are arranged so that the central axes of the holding portions 46 coincide with each other. The through hole 47 is formed in parallel with the hole 41 of the magnet holder 4 as shown in FIGS. The diameter dimension of the through hole 47 is the same as the diameter dimension D1 of the arm 3 or slightly smaller than the diameter dimension D1. In other words, the size of both is such that when the arm 3 is attached to the magnet holder 4 in the assembly process of the fuel level gauge 1, the arm 3 can be easily inserted into the through hole 47 by hand, and the arm 3 after being inserted into the through hole 47. Is an interference fit that can be rotated by hand. Further, as shown in FIG. 1, the through hole 47 is arranged so that its central axis intersects with the central axis of the holding portion 46 of the both locking portions 43.
[0035]
The body 5 that is the main body is made of, for example, resin. As shown in FIG. 2, the body 5 includes a shaft portion 51, and the shaft portion 51 rotatably holds the magnet holder 4. The body 5 includes a hall element 7 which is a magnetoelectric conversion element for detecting the rotation angle of the magnet holder 4 and includes a terminal 8 for electrically connecting the hall element 7 to the outside. The body 5 also includes a stopper 55 for restricting the rotation range of the magnet holder 4. The fuel level gauge 1 according to an embodiment of the present invention is fixed to a fuel tank (not shown) via a body 5.
[0036]
Below, the structure of the body 5 is demonstrated.
[0037]
The shaft portion 51 is formed by integral molding with the body 5. As shown in FIG. 2, the shaft portion 51 has a large-diameter portion 52 that is rotatably fitted to the hole portion 41 of the magnet holder 4, and a large-diameter portion at the tip of the large-diameter portion 52 (left end portion in FIG. 2). A small diameter portion 53 formed coaxially with 52, and a tip of the small diameter portion 53 (left end portion in FIG. 2) extends to a part of the outer periphery of the small diameter portion 53 in the radial direction of the small diameter portion 53 (vertical direction in FIG. 2). It is comprised from the 1st projection part 54 provided so that it might take out.
[0038]
As shown in FIG. 1, the first protrusions 54 are formed on the outer periphery of the small-diameter portion 53 at intervals of 180 degrees, that is, facing each other. Further, the contour shape of the first protrusion 54 in the axial direction of the shaft portion 51 (perpendicular to the plane of FIG. 1) is the contour shape of the shaft portion 51, that is, the contour shape of the large diameter portion 52, as shown in FIG. Is included. That is, the arc portion of the first protrusion 54 is an arc having the same diameter as or smaller than that of the large diameter portion 52. Thus, when the magnet holder 4 is engaged with the body 5 during the assembly work of the fuel level gauge 1, the first protrusion 54 can pass through the hole 41 of the magnet holder 4.
[0039]
Moreover, the width dimension W of the 1st projection part 54 is the same as the diameter dimension D3 of the small diameter part 53, or less than it, as shown in FIG. Moreover, the length dimension L1 of the small diameter part 53 is set sufficiently larger than the length dimension L2 of the hole 41 of the magnet holder 4 as shown in FIG. Also, the length dimension L3 is set slightly larger than the thickness dimension L4 of the second protrusion 42 of the hole 41 as shown in FIG. That is, the length dimension L3 and the length dimension L4 are set so that the magnet holder 4 can be rotated smoothly and the axial gap between the body 5 and the magnet holder 4, that is, L3-L4 is as small as possible. Thereby, the magnet holder 4 can be easily engaged with the body 5 during the assembly work of the fuel level gauge 1.
[0040]
As shown in FIG. 2, the Hall element 7 that is a magnetoelectric conversion element is disposed in the shaft portion 51. On the other hand, the magnet 6 fixed to the magnet holder 4 is disposed concentrically with the shaft portion 51 on the outer peripheral side of the shaft portion 51. For this reason, the Hall element 7 always intersects the magnetic flux M of the magnet 6 as shown in FIG.
[0041]
Here, the operation of the Hall element 7 will be briefly described.
[0042]
The Hall element 7 is made of a semiconductor, and generates a Hall voltage proportional to the magnetic flux density passing through the Hall element 7 when a magnetic field is applied from the outside while a voltage is applied to the Hall element 7. That is, when the Hall element 7 and the magnetic flux M are orthogonal to each other, the density of magnetic flux passing through the Hall element 7 is maximized and the Hall voltage is maximized. When the Hall element 7 and the magnetic flux M are parallel, the magnetic flux density passing through the Hall element 7 is minimized and the Hall voltage is minimized.
[0043]
In the fuel level gauge 1 according to the embodiment of the present invention, when the magnet holder 4 rotates due to the fluctuation of the liquid level 91, the crossing angle between the Hall element 7 and the magnetic flux M of the magnet 6 changes. Changes the Hall voltage, which is the output voltage of Therefore, by detecting this Hall voltage, the rotation angle of the magnet holder 4, that is, the liquid level 91 level can be measured.
[0044]
The terminal 8 is made of a conductive metal, and one end thereof is electrically connected to the lead 71 of the Hall element 7 as shown in FIG. This connection is, for example, by caulking or fusing. On the other hand, the other end of the terminal 8 protrudes outward from the body 5 and is connected to a connector (not shown) of an external wire harness (not shown). In the fuel level gauge 1 according to the embodiment of the present invention, the Hall element 7 and the terminal 8 are integrally formed by insert molding when the body 5 is resin-molded.
[0045]
In the fuel level gauge 1 according to the embodiment of the present invention, the stopper 55 that restricts the rotation range of the magnet holder 4 corresponds to each of the highest and lowest positions of the liquid level 91 as shown in FIG. Two are provided. Each stopper 55 is formed by integral molding with the body 5 and comes into contact with an end portion of the arm 3 opposite to the float 2, that is, a portion protruding from the through hole 47 of the arm 3 as shown in FIG. 2. Is provided. In other words, when the magnet holder 4 is assembled to the body with the arm 3 not attached to the magnet holder 4, the magnet holder 4 can freely rotate without contacting the stopper 55.
[0046]
Next, regarding the assembly method of the fuel level gauge 1 according to the embodiment of the present invention, in particular, the hole 41 of the magnet holder 4 and the shaft of the body 5 which are the characteristics of the fuel level gauge 1 according to the embodiment of the present invention. The operation and effect of the unit 51 will be mainly described.
[0047]
By this time, the magnet holder 4 and the body 5 have been assembled. Further, the assembly of the float 2 to the arm 3 is completed.
[0048]
First, the magnet holder 4 is assembled to the body 5. At this time, the shaft portion 51 of the body 5 is fitted into the hole 41 of the magnet holder 4 and the magnet holder 4 is inserted in the right direction of FIG. Then, the first projecting portion 54 of the shaft portion 51 is caused to protrude from the hole portion 41 through the space between the opposing second projecting portions 42 of the magnet holder 4.
[0049]
Next, the magnet holder 4 is rotated around the shaft portion 51 to shift the phases of the second protrusion 42 of the magnet holder 4 and the first protrusion 54 of the body 5. In other words, the first protrusion 54 has an angular relationship that makes it impossible to pass between the opposing second protrusions 42 of the magnet holder 4. Thereby, the 2nd protrusion part 42 of the magnet holder 4 contact | abuts to the 1st protrusion part 54 of the body 5, and the movement to the direction (left direction of FIG. 2) which the magnet holder 4 leaves | separates is controlled. That is, the magnet holder 4 is prevented from falling off the body 5.
[0050]
Here, in the fuel level gauge 1 according to an embodiment of the present invention, the phase of the second protrusion 42 of the magnet holder 4 and the first protrusion 54 of the body 5 is such that the magnet holder 4 is at least in the operating rotation range, that is, When the rotation angle θ is within the range shown in FIG. 1, the second protrusion 42 is always in contact with the first protrusion 54, and the axial movement of the magnet holder 4 is restricted.
[0051]
By adopting such a configuration, it is possible to eliminate the escape prevention flange provided in the conventional liquid level detection device. That is, it is possible to eliminate the work for attaching the prevention flange. Therefore, the fuel level gauge 1 that can reduce the number of parts and the number of assembly steps can be realized.
[0052]
Next, in this state, it is set in a dedicated adjustment device (not shown), and the magnet holder 4 is rotated to check and adjust the output voltage of the Hall element 7. In this case, for example, a pin (not shown) of the adjusting device is inserted into the through hole 47 of the magnet holder 4 to rotate the magnet holder 4, and this pin is protruded from the through hole 47 and brought into contact with the stopper 55. Thus, even when the arm 3 is not attached, the same operation as that in the attached state can be performed. Since this operation is performed with the arm 3 not attached to the magnet holder 4, the adjustment operation can be easily performed and the size of the adjustment device can be reduced.
[0053]
Next, the arm 3 is attached to the magnet holder 4. At this time, first, the tip of the arm 3 is fitted into the through hole 47, and then the arm 3 is rotated in the groove 44 of the locking portion 43 while the arm 3 is rotated with the through hole 47 as a fulcrum. Push in so that it fits completely into the holding part 46.
[0054]
This completes the assembly of the fuel level gauge 1 according to one embodiment of the present invention.
[0055]
FIG. 5 shows a partial cross-sectional view of a modified example of the fuel level gauge 1 according to one embodiment of the present invention. FIG. 5 corresponds to a sectional view taken along line III-III in FIG.
[0056]
In this modification, the shape of the locking portion 43 is changed as shown in FIG. In this modification, when attaching the arm 3 to the magnet holder 4, the arm 3 is moved from the top to the bottom in FIG. 4 and inserted into the holding portion 46 of the locking portion 43.
[0057]
In the fuel level gauge 1 according to the embodiment of the present invention described above, the two second projecting portions 42 of the magnet holder 4 are provided to face each other by 180 degrees, and the first projecting portion 54 of the body 5 is provided. The number of the second protrusions 42 and the first protrusions 54 is not limited to the example of the above-described embodiment, but the fuel level gauge 1 When the magnet holder 4 is in the operating rotation range at the time of operation, the second protrusion 42 is always in contact with the first protrusion 54, and the axial movement of the magnet holder 4 can be restricted. Or it is good also as three or more and it is good also as angular relations other than 180 degree | times.
[0058]
Further, in the fuel level gauge 1 according to the embodiment of the present invention described above, the number of the locking portions 43 is two, but the number is not limited to two, and may be one or three or more. .
[0059]
In the fuel level gauge 1 according to the embodiment of the present invention described above, the material of the magnet 6 is a ferrite magnet, but other materials such as a rare earth magnet or a bond magnet may be used.
[0060]
In the fuel level gauge 1 according to the embodiment of the present invention described above, the Hall element 7 is used as the magnetic detection element. However, other magnetic detection elements such as a magnetoresistive element or a magnetic diode are used. It may be used.
[0061]
Moreover, although one Embodiment of this invention demonstrated above demonstrated the case where the liquid level detection apparatus was applied to the fuel level gauge 1 for motor vehicles as an example, the use is not restricted to the fuel level gauge 1 for motor vehicles, You may apply to other liquid level detection apparatuses. Further, the liquid as the liquid level detection target is not limited to the fuel, and may be water, lubricating oil, various chemicals, or the like.
[Brief description of the drawings]
FIG. 1 is a front view of a fuel level gauge 1 according to an embodiment of the present invention, showing a state where a liquid level 91 is at the lowest level.
2 is a cross-sectional view of a fuel level gauge 1 according to an embodiment of the present invention, and is a cross-sectional view taken along line II-II in FIG.
FIG. 3 is a partial cross-sectional view of a fuel level gauge 1 according to an embodiment of the present invention, and is a cross-sectional view taken along line III-III in FIG.
FIG. 4 is a schematic diagram illustrating a magnetic flux distribution of a magnet 6 in a fuel level gauge 1 according to an embodiment of the present invention.
FIG. 5 shows a partial cross-sectional view of a modified example of the fuel level gauge 1 according to one embodiment of the present invention.
[Explanation of symbols]
1 Fuel level gauge (Liquid level detector)
2 Float 3 Arm 4 Magnet holder 41 Hole portion 42 Second protrusion 43 Locking portion 44 Groove 45 Opening portion 46 Holding portion 47 Through hole 5 Body (main body portion)
51 Shaft 52 Large Diameter 53 Small Diameter 54 First Projection 55 Stopper 6 Magnet 7 Hall Element (Magnetoelectric Conversion Element)
71 Lead 8 Terminal 9 Fuel (liquid)
91 Liquid level D1 Diameter dimension D2 Diameter dimension D3 Diameter dimension L1 Length dimension L2 Length dimension L3 Length dimension L4 Thickness dimension W Width dimension θ Rotation angle

Claims (4)

A float floating in the liquid whose liquid level is to be measured;
A magnet holder that holds a magnet and has a hole;
An arm that connects the float and the magnet holder to convert the vertical movement of the float into a rotational motion of the magnet holder;
A main body portion having a shaft portion, fitting the shaft portion into the hole portion, and holding the magnet holder so as to be rotatable around the shaft portion;
A magnetoelectric conversion element fixed to the main body so as to intersect the magnetic flux of the magnet,
A liquid level detection device that detects a magnetic flux density of the magnet that intersects the magnetoelectric conversion element by the magnetoelectric conversion element, and detects a rotation angle of the magnet holder, that is, the liquid level based on the detection signal,
The shaft portion includes a large-diameter portion that fits into the hole portion, a small-diameter portion that is formed coaxially with the large-diameter portion at the tip of the large-diameter portion, and an outer periphery of the small-diameter portion at the tip of the small-diameter portion. A first protrusion provided to extend in the radial direction of the small diameter portion in a part of
A second protrusion provided to extend in the radial direction of the hole at the end of the shaft on the inner end of the hole;
A stopper provided on the main body portion and in contact with an end of the arm opposite to the float to regulate a rotation range around the shaft portion of the magnet holder;
The contour line in the axial direction of the shaft portion of the first protrusion is included in the axial contour line of the large diameter portion,
The second protrusion provided on the inner wall of the hole is formed in a shape through which the first protrusion of the shaft can pass,
The liquid is characterized in that when the magnet holder is at least in the rotation range, the second protrusion is in contact with the first protrusion and movement of the magnet holder in a direction away from the main body is restricted. Surface detection device. The magnet holder is provided with a locking portion having a groove,
The liquid level detection device according to claim 1, wherein the arm is held and fixed in the groove by an elastic force of the locking portion. The groove has an opening and a holding portion, a cross-sectional shape perpendicular to the axial direction of the holding portion is rectangular or circular, and the width or inner diameter thereof is set smaller than the outer diameter of the arm, and The liquid level detection device according to claim 2, wherein a width dimension orthogonal to the axial direction of the opening is set smaller than a width dimension or an inner diameter dimension of the holding portion. The magnet holder is provided with a through hole parallel to the hole,
The liquid level detection device according to claim 2, wherein the arm is fitted into the through hole.

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