JP2003004508A - Liquid level sensor - Google Patents

Abstract

To provide a liquid level sensor that achieves durability, rotational stability, and cost reduction. A counterbored hole 4a2 is provided in a convex bearing portion 4a on an arm holder 4 side, and a concave bearing portion 2a on a frame 2 side is provided.
Is provided with a cylindrical bearing extension 2a2 that is rotatably fitted in the counterbore 4a2, thereby extending the bearing length without extending the thickness a of the liquid level sensor. Further, by providing the locking piece 4a4 for fixing the magnet 5a using the counterbore 4a2, durability and rotational stability are improved, and conventional insert molding is not required. Furthermore, it can prevent shipping with the magnet 5a half-fitted.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid surface level sensor having a float arm that rotates according to the liquid surface level, and more particularly to a liquid surface level sensor that improves durability and achieves downsizing and cost reduction. Regarding the level sensor.

[0002]

2. Description of the Related Art Conventionally, there has been known a liquid level sensor having a rod-shaped float arm having a float attached at its tip, which float moves up and down according to the liquid level of fuel in a tank. FIG. 6 is a plan view showing an example of this type of liquid level sensor, and FIG. 7 is a sectional view taken along the line AA of the liquid level sensor shown in FIG.

As shown in FIG. 6, a liquid level sensor 91 of this type includes a frame 92 made of resin, a float arm 3 made of metal, an arm holder 94 made of resin, an electric circuit 5,
And a float 6 having buoyancy with respect to the liquid to be measured. In the liquid level sensor 91,
The float arm 3 to which the float 6 that moves up and down according to the fluctuation of the liquid level of the liquid to be measured is attached rotates within the rotation angle range θ.

As shown in FIG. 7, the frame 92 is equipped with an electric circuit 5 for detecting the liquid level, for example, a hall element 5c described later. The frame 92 is provided with an electronic device housing portion 92b that is open to the upper side. In the electronic device housing portion 92b, a hall element 5c as a magnetoelectric conversion element that detects a magnetic force from the ring-shaped magnet 5a and converts the magnetic force into an electric signal, and the hall element 5c.
A wiring board 5d on which the above components are mounted is housed. The wiring board 5d is connected to an output terminal 5e for guiding the electric signal output from the Hall element 5c to the outside. The electronic device housing portion 92b is filled with a molding material (not shown). The electric signal corresponds to the rotation angle of the float arm 3, that is, the liquid level. Further, a ring-shaped core 5b as a magnetism collecting member is also attached to the frame 92. However, a part of the core 5b is provided with a gap for sandwiching the Hall element 5c.

The frame 92 is made up of the float arm 3
It has a cylindrical convex bearing portion 92a that is used at the time of mounting. A shaft hole 92a1 into which the rotary shaft of the float arm 3 is inserted is formed in the center of the convex bearing 92a.

The float arm 3 is in the shape of a single metal rod, and comprises a rotating shaft portion which serves as a fulcrum of rotation, and a rotating portion which is bent at a right angle to the rotating shaft portion. A cylindrical float 6 made of a material having buoyancy with respect to the liquid to be measured is attached to the tip of the rotating portion of the float arm 3.

The arm holder 94 holds the float arm 3 by a claw-shaped arm holding portion 94b, and is attached to the frame 92 to rotate the held float arm 3 with the rotary shaft portion as a fulcrum. Let Further, the arm holder 94 is used for the frame 9
It has a cylindrical concave bearing portion 94a corresponding to the second convex bearing portion 92a. A shaft hole 94 into which the rotary shaft portion of the float arm 3 is inserted is also provided in the center of the concave bearing portion 94a.
a1 is formed. The ring-shaped magnet 5a is provided around the outer surface of the concave bearing portion 94a. The convex bearing portion 92a and the concave bearing portion 94a are rotatably fitted to each other.

When the liquid level sensor 91 is assembled,
First, the convex bearing portion 92a and the concave bearing portion 94a are fitted to each other, and the arm holder 94 is attached to the frame 92. Then, after inserting the rotary shaft portion of the float arm 3 into the shaft holes 92a1 and 94a1, the float arm 3
The pivoting part of is pressed into the arm holding part 94b. As a result, the float arm 3 can rotate together with the arm holder 94 and does not fall off from the frame 92. In addition, the convex bearing portion 92a and the concave bearing portion 94a
Due to the fitting, the rotation of the float arm 3 is also stabilized.

A liquid level sensor 91 having such a structure
Is attached to a tank (not shown) that stores a liquid to be measured such as gasoline. Then, when the float 6 moves up and down due to the fluctuation of the liquid level, the float arm 3
Rotates about the rotation shaft as a fulcrum within a predetermined angle range θ. The rotation within this angle range θ changes the magnetic force from the magnet 5a detected by the Hall element 5c, and an electric signal indicating the liquid level based on this change is output terminal 5e.
Taken from.

[0010]

By the way, as shown in FIG. 7, when the thickness of the sensor is a, the length of the bearing portion is b, and the length of the detection portion is c, this corresponds to the length b. Since the bearing portion is a portion that always rotates, the longer the bearing, the better the durability and rotation stability. However, the thickness a of the sensor cannot be increased in the upward direction of this bearing portion from the viewpoint of the size and shape of the tank. On the other hand, it is difficult to extend in the downward direction because the detection section is located below the bearing section. That is, it has been considered that the length b of the bearing portion is difficult to extend under the above-mentioned thickness limitation of the sensor.

Further, in the detection section, the magnet 5a used as a detection element is attached to the side surface of the concave bearing section 94a by insert molding. However, in the insert molding, the manufacturing cost is increased due to factors such as requiring skill to adjust the molding pressure, man-hours required, the molding cost is high, and the material of the concave bearing portion 94a is limited because heat is generated during the molding. There was a problem of doing.

Therefore, in view of the above situation, the present invention improves the shapes of the concave bearing portion and the convex bearing portion,
The above two problems are solved. That is, the present invention provides a liquid level sensor that extends the bearing portion without changing the outer shape of the sensor, facilitates attachment of a magnet, and has durability, rotational stability, and cost reduction. It is an issue.

[0013]

As shown in FIG. 1, a liquid level sensor according to claim 1, which has been made to solve the above-mentioned problems, has a float 6 having a buoyant force with respect to the liquid to be measured at its tip. A rod-shaped float arm 3 attached to one end, a frame 2 having an electric circuit for detecting the liquid level of the liquid to be measured based on the rotation of the float arm 3, and the float arm 3 In addition, the arm holder 4 assembled to the frame 2 for rotating the float arm 3 and the cylindrical concave bearings provided on the frame 2 and the arm holder 4, respectively, rotatably fitted to each other. The portion 2a and the convex bearing portion 4a, the counterbore hole 4a2 having a cylindrical inner wall surface provided in the convex bearing portion 4a, and the counterbore hole 4a2.
A cylindrical bearing extension 2a2 that rotatably fits into the shaft, and shaft holes 2a1 and 4a1 that are provided in the bearing extension 2a2 and the counterbore hole 4a2 and into which the other end of the float arm 3 is inserted. And the other end of the float arm 3 is inserted into the shaft holes 2a1 and 4a1 of the bearing extension 2a2 and the counterbore hole 4a2 which are rotatably fitted, and the float arm 3 is inserted into the arm holder 4 Is held in.

According to the first aspect of the present invention, the convex bearing portion 4a on the arm holder 4 side is provided with the counterbore hole 4a2, and the concave bearing portion 2a on the frame 2 side is rotatably fitted in the counterbore hole 4a2. A cylindrical bearing extension 2a2 is provided. Thereby, the bearing length can be extended without extending the thickness of the liquid level sensor.

A liquid level sensor according to a second aspect of the present invention, which has been made to solve the above-mentioned problems, is the same as the liquid level sensor according to the first aspect, as shown in FIGS. From the outer surface thereof to the counterbore 4a2.
Is provided with a pair of flexible locking pieces 4a4 formed by notches, and the liquid level level locked by the pair of locking pieces 4a4 is provided on the outer surface of the convex bearing portion 4a. It is characterized in that a ring-shaped magnet 5a used for detection of is provided around.

According to the second aspect of the present invention, the convex bearing portion 4a is provided with a locking piece 4a4 formed by cutting from the outer surface to the countersunk hole 4a2. Then, with this locking piece 4a4, the magnet 5 as a detection element
a is fixed. That is, using the counterbore hole 4a2 provided in the convex bearing portion 4a for durability and rotational stability,
A locking piece 4a4 for fixing the magnet 5a is provided.

A liquid level sensor according to a third aspect of the present invention, which has been made to solve the above-mentioned problems, is the same as the liquid level sensor according to the second aspect, as shown in FIGS. A rib 4a3, which abuts on the inner surface of the magnet 5a and prevents rattling, is extended on the outer surface of the.

According to the third aspect of the present invention, the rib 5a3, which abuts the inner surface of the magnet 5a and prevents rattling, extends on the outer surface of the convex bearing portion 4a.
a is stably fixed to the convex bearing portion 4a, and the detection accuracy is also improved.

The liquid level sensor according to claim 4 made to solve the above-mentioned problems, as shown in FIGS. 3 and 4, is the liquid level sensor according to claim 3, wherein one of the magnets 5a is provided. A linear groove portion 5f extending from the inside to the outside is formed on the bottom surface, and the disk-shaped base portion 4c of the arm holder 4 serving as the base of the convex bearing portion 4a corresponds to the groove portion 5f. A linear protrusion 4d1 extending outward from the outer side surface of the convex bearing 4a is extended.

According to the fourth aspect of the invention, in the base portion 4c of the convex bearing portion 4a to which the magnet 5a is attached, the protrusion portion 4d corresponding to the groove portion 5f formed on the bottom surface of the magnet 5a.
1 is provided, the mistake of the mounting surface of the magnet 5a is prevented, and after the mounting, the magnet 5a has the convex bearing portion 4a.
Prevents rotation around.

In order to solve the above-mentioned problems, a liquid level sensor according to a fifth aspect of the present invention has, as shown in FIG. 1, a float 6 having buoyancy with respect to the liquid to be measured attached to one end thereof. A rod-shaped float arm 3, and a frame 2 carrying an electric circuit for detecting the liquid level of the liquid to be measured based on the rotation of the float arm 3.
An arm holder 4 that holds the float arm 3 and that is assembled to the frame 2 to rotate the float arm 3 is provided on each of the frame 2 and the arm holder 4, and is rotatably fitted to each other. The cylindrical concave bearing portion 2a and the convex bearing portion 4a, and a pair of flexible locking pieces 4a4 linearly extending upward formed by using the outer side surface of the convex bearing portion 4a. And a ring-shaped magnet 5a used for detecting the liquid surface level locked by the pair of locking pieces 4a4, and provided at the center of the concave bearing portion 2a and the convex bearing portion 4a, respectively. , Shaft holes 2a1 and 4a1 into which the other end of the float arm 3 is inserted, and the shaft holes 2a of the concave bearing portion 2a and the convex bearing portion 4a that are rotatably fitted.
The other end of the float arm 3 is inserted through 1, 4a1,
The float arm 3 is held by the arm holder 4.

According to the fifth aspect of the invention, the locking piece 4a4 is provided by utilizing the outer side surface of the convex bearing portion 4a. The locking piece 4a4 fixes the magnet 5a as the detection element. As a result, durability and rotation stability are improved, and the conventional insert molding becomes unnecessary.

[0023]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. First, the structure of the liquid level sensor according to the present invention, particularly the extended structure of the bearing portion, and the operation will be described with reference to FIGS. 1 and 2. FIG. 1 is a sectional view showing an embodiment of a liquid level sensor of the present invention. FIG. 2 is a sectional view showing a divided state of the liquid level sensor of FIG. The sectional direction of FIG. 1 is similar to that of FIG. The plan view of the liquid level sensor shown in FIG. 1 is the same as that shown in FIG. 6 and is omitted here.

A liquid level sensor 1 shown in FIG. 1 is attached to, for example, a fuel tank of a vehicle, and has a resin frame 2, a metal float arm 3, a resin arm holder 4, an electric circuit 5, And a float 6 having buoyancy with respect to the liquid to be measured.

In this liquid level sensor 1, FIG.
Similarly to the above, the float arm 3 to which the float 6 that moves up and down according to the fluctuation of the liquid level of the liquid to be measured is attached at one end rotates within the above-described rotation angle range θ.

Since the float arm 3, the electric circuit 5 and the float 6 are the same as those shown in FIG. 7, duplicate description will be omitted here. Reference numerals given in this FIG. 1 indicate the same components as those in FIG.

As shown in FIGS. 1 and 2, the frame 2
Is an electric circuit 5 for detecting the liquid level, for example,
The Hall element 5c described later is mounted. The frame 2 is formed with an electronic device housing portion 2b that is open to the upper side. In the electronic device housing portion 2b, a Hall element 5c as a magnetoelectric conversion element that detects the magnetic force from the ring-shaped magnet 5a and converts the magnetic force into an electric signal, and the Hall element 5c.
A wiring board 5d on which parts such as c are mounted is housed. The wiring board 5d is connected to an output terminal 5e for guiding the electric signal output from the Hall element 5c to the outside. The electronic device housing portion 2b is filled with a molding material (not shown). The electric signal corresponds to the rotation angle of the float arm 3, that is, the liquid level. Further, a ring-shaped core 5b as a magnetism collecting member is also attached to the frame 92. However, a part of the core 5b is provided with a gap for sandwiching the Hall element 5c. The process up to this point is the same as the liquid level sensor shown in FIG. 7.

Further, a cylindrical concave bearing portion 2a having a shape corresponding to a convex bearing portion 4a of the arm holder 4 described later is formed on the lower surface of the frame 2. For more information,
A cylindrical bearing extension 2a2 having a height of about b1 is formed at the center of the concave bearing 2a. A shaft hole 2a1 into which the rotary shaft portion of the arm 3 is inserted is provided at the center of the bearing extension portion 2a2.

The arm holder 4 holds the float arm 3 by a claw-shaped arm holding portion 4b, and is attached to the frame 2 and rotates the held float arm 3 with the rotary shaft portion as a fulcrum. Let The arm holder 4 includes a concave bearing portion 2 a of the frame 2.
It has a cylindrical convex bearing portion 4a corresponding to. Specifically, the height of the convex bearing portion 4a is about b at the center.
A counterbore hole 4a2 having one cylindrical inner wall surface is formed. The bearing extension 2a is provided in the counterbore 4a2.
2 are rotatably fitted. That is, the bearing extension 2a
As the 2 and the counterbore hole 4a2 are fitted, the concave bearing portion 2a and the convex bearing portion 4a are rotatably fitted. A shaft hole 4a1 into which the rotary shaft portion of the arm 3 is inserted is also provided in the center of the countersunk hole 4a2.

The convex bearing portion 4a of the arm holder 4
The ring-shaped magnet 5a is provided around the outer surface of the. The mounting structure of the magnet 5a to the convex bearing portion 4a becomes clear in FIGS. 3 and 4.

As shown in FIG. 2, in the liquid level sensor 1, first, a frame 2, which is a main body, a float arm 3 having a float 6 attached to one end, and an arm holder 4 are separately formed. When assembling the liquid level sensor 1, first, the convex bearing portion 4a of the arm holder 4 is
The magnet 5a and the like are attached to the bearing extension portion 2a2.
Next, the concave bearing portion 2a and the convex bearing portion 4a are rotatably fitted by fitting the bearing extension portion 2a2 and the counterbore hole 4a2. After that, the arm holder 4 is attached to the frame 2
Attached to. Then, after inserting the rotating shaft portion of the float arm 3 into the shaft holes 2a1 and 4a1, the rotating portion of the float arm 3 is press-fitted into the arm holding portion 4b. As a result, the float arm 3 is rotatable together with the arm holder 4 and integrated so as not to fall off the frame 2.

The liquid level sensor 1 having such a structure is
It is attached to a gasoline tank (not shown) that stores a liquid to be measured such as gasoline. When the float 6 moves up and down due to the change in the liquid level, the float arm 3 rotates within the predetermined angle range θ with the rotary shaft portion as a fulcrum. The rotation within this angle range θ changes the magnetic force from the magnet 5a detected by the Hall element 5c, and an electric signal indicating the liquid level based on this change is output terminal 5e.
Taken from.

Thus, the convex bearing portion 4a on the arm holder 4 side is provided with the counterbore hole 4a2, and the concave bearing portion 2a on the frame 2 side is a cylindrical bearing extension which is rotatably fitted in the counterbore hole 4a2. By providing the portion 2a2, the bearing length can be extended as shown by b1 in FIG. 1 without extending the thickness a of the liquid level sensor. As a result,
Durability and rotation stability are improved. If the bearing length is the same as the conventional one, the thickness of the liquid level sensor can be greatly reduced. That is, downsizing is possible.

Next, the structures of the arm holder 4 and the magnet 5a described above will be described with reference to FIGS. FIG. 3 (A) is a perspective view showing the arm holder with a magnet attached, and FIG. 3 (B) is an exploded perspective view of FIG. 3 (A). 4 (A) is a plan view of the arm holder with a magnet attached, and FIG. 4 (B) is an enlarged view of the Z portion of FIG. 4 (A).

As shown in FIG. 3A, the disc portion 4d formed on the disc-shaped base portion 4c of the arm holder 4 includes:
The ring-shaped magnet 5a is inserted into and mounted on the convex bearing portion 4a. The inner surface of the magnet 5a contacts the ribs 4a3 of the convex bearing 4a, and is further fixed to the arm holder 4 by a pair of locking pieces 4a4. Further, the groove 5f formed on one bottom surface of the magnet 5a has a protrusion 4d1 formed on the disk portion 4d of the arm holder 4.
And the magnet 5a is fixed so as not to rotate.

Further, as shown in FIG. 3B, the counterbore hole 4
The convex bearing portion 4a in which a2 is opened extends upward from the disc portion 4d. The convex bearing portion 4a is provided with a pair of flexible locking pieces 4a4 formed by cutting from the outer surface to the countersunk hole 4a2. In addition, on the side surface of the convex bearing portion 4a,
A plurality of ribs 4 contacting the inner side surface of the ring-shaped magnet 5a
a3 is formed. Further, the circular disc portion 4d of the arm holder 4 has a shape corresponding to the groove portion 5f of the magnet 5a, and has a linear protrusion portion 4 extending outward from the outer surface of the convex bearing portion 4a.
d1 is extended. The above-mentioned claw-shaped arm holding portion 4b is provided on the upper arm portion of the arm holder 4.

As described above, the counterbore hole 4a2 provided in the convex bearing portion 4a is used for durability and rotational stability,
A flexible engaging piece 4a4 is easily provided by making a notch in the countersunk hole 4a2 from the outer surface of the convex bearing portion 4a. Therefore, durability and rotation stability are improved, and insert molding as in the past is not necessary, and the effect of reducing manufacturing cost is added. Further, since the base portion 4c is provided with the protrusion 4d1 corresponding to the groove 5f formed on the bottom surface of the magnet 5a, it is possible to prevent a mistake in the mounting surface of the magnet 5a during the mounting and to prevent the magnet 5a from being mounted after the mounting. Prevents rotation around the convex bearing portion 4a. As a result, a liquid level sensor with higher detection accuracy can be obtained.

As shown in FIGS. 4 (A) and 4 (B), the magnet 5a mounted on the convex bearing portion 4a has its inner side surface contacting the plurality of ribs 4a3 of the convex bearing portion 4a. There is. The ribs 4a3 are linearly extended in parallel with the height direction of the convex bearing portion 4a at a height where the ribs 4a3 come into contact with the inner surface of the magnet 5a from the outer surface of the bearing portion 4a. This rib 4a
3 contacts the inner side surface of the ring-shaped magnet 5a to fix the magnet 5a without rattling. Especially, this rib 4a3
In order to uniformly fix the magnets 5a to the convex bearing portion 4a, four magnets are provided on the outer periphery of the convex bearing portion 4a so as to be offset by 90 degrees. Thereby, the magnet 5a is stably fixed to the convex bearing portion 4a, and the detection accuracy is improved.

Further, as shown in FIG. 5 (A), the magnet 5a
If is completely fitted in the convex bearing portion 4a, the diameter X of the counterbore hole 4a2 is larger than the diameter Y of the bearing extension portion 2a2, so that they can be fitted rotatably. That is, the arm holder 4 is attached to the frame 2. On the other hand, when the magnet 5a is not completely attached to the convex bearing portion 4a, each locking piece 4a4 remains bent inward, so that the diameter X1 of the counterbore hole 4a2 is equal to the bearing extension portion 2a.
The diameter is smaller than the diameter Y of 2 and the bearing extension 2a2 cannot be fitted in the counterbore 4a2. That is, the arm holder 4 cannot be assembled to the frame 2. As a result, it is possible to prevent the magnet 5a from being shipped in a state of being half fitted.

As described above, according to the liquid level sensor of this embodiment, the counterbore hole 4a2 and the corresponding bearing extension 2a2 prevent the bearing length from increasing without increasing the thickness of the liquid level sensor. Only can be extended. Further, by utilizing the countersunk hole 4a2, the locking piece 4a4 for fixing the magnet 5a is provided, and the conventional insert molding becomes unnecessary. Further, the magnet 5a is prevented from being shipped in a state of being half fitted. As a result, there is provided a liquid level sensor that achieves cost reduction, size reduction, quality improvement, and durability improvement.

[0041]

As described above, according to the invention described in claim 1, the convex bearing portion 4a on the arm holder 4 side is provided with the counterbore hole 4a2, and the concave bearing portion 2a on the frame 2 side is provided with the counterbore hole. By providing the cylindrical bearing extension 2a2 that is rotatably fitted to the 4a2, the bearing length can be extended without extending the thickness of the liquid level sensor. As a result, durability and rotation stability are improved. If the bearing length is the same as the conventional one, the thickness of the liquid level sensor can be greatly reduced. That is, downsizing is possible.

According to the second aspect of the invention, the counterbore hole 4a provided in the convex bearing portion 4a for durability and rotational stability.
2 is used to provide the locking piece 4a4 for fixing the magnet 5a. As a result, durability and rotation stability are improved, insert molding as in the past is not required, and the effect of reducing manufacturing cost is added. Further, when the magnet 5a is not completely fitted, as shown in FIG. 5A, the arm holder 4 cannot be assembled to the frame 2, so that the magnet 5a is shipped in a semi-fitted state. Can be prevented.

According to the third aspect of the present invention, the rib 5a3, which abuts against the inner surface of the magnet 5a and prevents rattling, is provided on the outer surface of the convex bearing portion 4a.
The effect that a is stably fixed to the convex bearing portion 4a and the detection accuracy is improved is also added to the above effect.

According to the fourth aspect of the invention, in the base portion 4c of the convex bearing portion 4a to which the magnet 5a is attached, the protrusion portion 4d corresponding to the groove portion 5f formed on the bottom surface of the magnet 5a.
1 is provided, the mistake of the mounting surface of the magnet 5a is prevented, and after the mounting, the magnet 5a has the convex bearing portion 4a.
Prevents rotation around. As a result, a liquid level sensor with higher detection accuracy can be obtained.

According to the fifth aspect of the invention, the locking piece 4a for fixing the magnet 5a by utilizing the outer side surface of the convex bearing portion 4a.
By providing No. 4, durability and rotation stability are improved, and insert molding as in the past is not necessary, and the manufacturing cost is reduced. Further, when the magnet 5a is not completely fitted, as shown in FIG. 5A, the arm holder 4 cannot be assembled to the frame 2, so that the magnet 5a is shipped in a semi-fitted state. Can be prevented.

[Brief description of drawings]

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

FIG. 2 is a sectional view showing a divided state of the liquid level sensor of FIG.

FIG. 3 (A) is a perspective view showing an arm holder with a magnet attached. 3 (B) is shown in FIG.
It is an exploded perspective view of (A).

FIG. 4 (A) is a plan view of the arm holder with a magnet attached. FIG. 4 (B) is an enlarged view of the Z portion of FIG. 4 (A).

FIG. 5 (A) is an explanatory view showing a state where the magnet 5a is completely fitted. FIG. 5B is an explanatory diagram showing a state where the magnet 5a is not completely fitted.

FIG. 6 is a plan view showing an example of this type of liquid level sensor.

7 is a cross-sectional view of the liquid level sensor shown in FIG. 6 taken along the line AA.

[Explanation of symbols]

1 Liquid level sensor 2 frames 2a concave bearing 2a1 rotating shaft hole 2a2 bearing extension 3 float arms 4 arm holder 4a Convex bearing part 4a1 rotating shaft hole 4a2 counterbore hole 4b Arm holding part 5a magnet 6 floats

Claims (5)

[Claims] 1. A rod-shaped float arm having a float having buoyancy with respect to the liquid to be measured attached to one end, and a liquid level of the liquid to be measured based on the rotation of the float arm. And a frame on which the electric circuit is mounted, an arm holder that holds the float arm and is assembled to the frame to rotate the float arm, and a frame and an arm holder that are respectively provided and are rotatable relative to each other. A cylindrical concave bearing portion and a convex bearing portion that are fitted to each other, a counterbore hole having a cylindrical inner wall surface provided in the convex bearing portion, and a cylindrical shape that is rotatably fitted to the counterbore hole. Of the bearing extension and a shaft hole through which the other end of the float arm is inserted, which is provided in each of the bearing extension and the counterbore hole, and is rotatable. The other end of the float arm to the respective shaft holes of fitted the bearing extension and the countersunk hole has is inserted, the liquid level sensor the float arm is characterized in that it is held in the arm holder. 2. The liquid level sensor according to claim 1, wherein the convex bearing portion is provided with a pair of flexible locking pieces formed by a cut extending from an outer surface of the convex bearing portion to the counterbore hole. A ring-shaped magnet used for detecting the liquid surface level locked by the pair of locking pieces is provided around the outer surface of the convex bearing portion. Surface level sensor. 3. The liquid level sensor according to claim 2, wherein a rib that abuts on an inner surface of the magnet to prevent rattling is extended on an outer surface of the convex bearing portion. Liquid level sensor to be. 4. The liquid level sensor according to claim 3, wherein one bottom surface of the magnet is formed with a linear groove portion from the inside to the outside, and the arm serves as a base of the convex bearing portion. The liquid level sensor, wherein a linear protrusion that extends outward from the outer surface of the convex bearing portion, which corresponds to the groove, is provided on the disk-shaped base of the holder. 5. A rod-shaped float arm having a float having a buoyant force with respect to the liquid to be measured attached to one end, and a liquid level of the liquid to be measured based on the rotation of the float arm. And a frame on which the electric circuit is mounted, an arm holder that holds the float arm and is assembled to the frame to rotate the float arm, and a frame and an arm holder that are respectively provided and are rotatable relative to each other. A cylindrical concave bearing portion and a convex bearing portion that are fitted to each other, and a pair of flexible locking pieces that extend linearly upward and are formed by using the outer surface of the convex bearing portion. A ring-shaped magnet used for detecting the liquid surface level locked by the pair of locking pieces, and provided in the center of the concave bearing portion and the convex bearing portion, respectively. The other end of the float arm is inserted therethrough, and the other end of the float arm is inserted through the respective shaft holes of the concave bearing portion and the convex bearing portion that are rotatably fitted. Is
A liquid level sensor, wherein the float arm is held by the arm holder.