JP2012247274A - Liquid level detection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid level detection device in which an output error of a detecting element due to positional deviation of an arm holder is reduced.SOLUTION: A liquid level detection device 100 comprises: a float arm 20 in which a float to be floated at a liquid level is attached to one end, and to be displaced according to the fluctuation of the liquid level; an arm holder 30 for holding the other end of the float arm 20, and rotating around a predetermined rotating shaft according to the displacement of the float arm; a case body 55 for storing the arm holder 30 in a rotatable manner; a magnet 40; and a magnetic detecting element 51 for detecting magnetic alternation according to the displacement of the magnet 40. The arm holder 30 has a main body 31 for holding the magnet 40 so that the magnet 40 is displaced according to the rotation of the arm holder 30, and an extending part 32 extending from the main body 31. The case body 55 has a guide part for guiding a tip end 33 of the extending part 32 to regulate the inclination of the arm holder 30 with respect to the rotating shaft.

Description

  The present invention relates to a liquid level detection device.

  For example, a non-contact type liquid level detection device using a magnetoelectric conversion element is known as a liquid level detection device that detects the liquid level and amount of various liquids (fuel, etc.) in a tank provided in a vehicle (such as an automobile). ing.

  The non-contact type liquid level detection device disclosed in Patent Document 1 includes a float arm that holds a float, an arm holder that holds a magnet, a support shaft that rotatably supports the arm holder, and a detection element. And a second case body having a cylindrical portion formed therein, and the amount of various liquids in the tank is detected by detecting the magnetic change of the magnet by the detection element.

JP 2010-230537 A

  The liquid level detection device according to Patent Document 1 supports the arm holder in a pivotable manner by the support shaft portion of the second case body that is inserted into the bearing of the arm holder, but in the radial direction, the arm holder is not supported. In this liquid level detection device, the arm holder is the shaft of the support shaft part because the structure is only restricted by the support shaft part and the hole (bearing part) of the cover part fixed to the second case body. It tends to be displaced obliquely with respect to the direction. For this reason, there has been a problem that the output error of the detection element due to the positional deviation of the arm holder becomes large due to the behavior of the arm holder other than in the circumferential direction.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a liquid level detection device that suppresses an output error of a detection element due to a positional deviation of an arm holder.

In order to achieve the above object, a liquid level detection device according to the present invention includes:
A float that floats on the liquid surface is attached to one end, and a float arm that displaces as the liquid level fluctuates;
An arm holder that holds the other end of the float arm and rotates around a predetermined rotation axis with the displacement of the float arm;
A storage portion for rotatably storing the arm holder;
A magnet, and a magnetic detection element that detects a change in magnetism of the magnet due to displacement of the magnet,
The arm holder has a holding portion that holds the magnet so that the magnet is displaced with the rotation of the arm holder, and an extending portion that extends from the holding portion,
The storage portion has a guide portion that guides a tip portion of the extending portion and restricts the arm holder from being inclined with respect to the rotation shaft.
It is characterized by that.

  ADVANTAGE OF THE INVENTION According to this invention, the liquid level detection apparatus which suppressed the output error of the detection element by the position shift of an arm holder can be provided.

It is a perspective view of the liquid level detection apparatus which concerns on one Embodiment of this invention. It is a top view of the liquid level detection apparatus which concerns on one Embodiment of this invention. (A) is the sectional view on the AA line of FIG. 2 of the liquid level detection apparatus concerning 1st Embodiment, (b) is a top view of the arm holder which concerns on 1st Embodiment. In the liquid level detection device shown in FIG. 3A, it is a diagram in which members other than the case body are omitted, and is a view for explaining the case body according to the first embodiment. (A) is the sectional view on the AA line of FIG. 2 of the liquid level detection apparatus concerning 2nd Embodiment, (b) is a top view of the arm holder which concerns on 2nd Embodiment. In the liquid level detection device shown in FIG. 5A, it is a diagram in which members other than the case body are omitted, and is a view for explaining the case body according to the second embodiment. It is a figure for demonstrating the upper case which concerns on the modification of 2nd Embodiment in which the control member was formed. (A)-(d) is a figure for demonstrating the front-end | tip part and guide part which concern on a modification, and is an enlarged view of the location corresponded to the B section shown to Fig.5 (a). (A), (b) is the sectional view on the AA line of FIG. 2 of the liquid level detection apparatus which concerns on a modification.

  A liquid level detection device according to an embodiment of the present invention will be described with reference to the drawings.

(First embodiment)
As shown in FIGS. 1 to 3, the liquid level detection device 100 according to the first embodiment includes a float 10, a float arm 20, an arm holder 30, a magnet 40, and a device main body 50.

  The float 10 is formed in a substantially bowl shape from a metal material that hardly corrodes, such as stainless steel. The float 10 receives buoyancy from the liquid whose liquid level is to be measured, floats on the liquid surface, and is displaced as the liquid level changes. The float 10 may be formed from a synthetic resin.

  The float arm 20 is formed in a wire shape from, for example, a nonmagnetic metal, and the float 10 is attached to one end thereof. The other end is held by the arm holder 30.

  The arm holder 30 shown in FIGS. 3A and 3B is a member that is formed of, for example, synthetic resin and holds the float arm 20. The arm holder 30 includes a substantially cylindrical main body 31 and an extension 32 (an example of a first portion) extending from the main body 31.

A through hole 31a through which a cylindrical member 551c described later is passed is formed at the center of the main body 31. The arm holder 30 rotates about the cylindrical axis of the cylindrical member 551c passing through the through hole 31a. In the liquid level detection apparatus 100 according to the present embodiment, the columnar axis of the columnar member 551c is an ideal rotation axis of the arm holder 30, and the more the arm holder 30 is tilted with respect to this rotation axis, the more magnetic detection is performed. An output error of the element occurs. The opening diameter of the through hole 31a is slightly larger than the diameter of the columnar member 551c.
As shown in FIG. 3A, a magnet holding portion 31 b having a substantially U-shaped cross section for holding the magnet 40 is formed on the inner side surface portion of the main body portion 31. The main body 31 surrounds a magnetism detection element 51 (described later) around the rotation axis by the magnet holding part 31 b and holds the magnet 40 so as to be displaced with the rotation of the arm holder 30.
As shown in FIG. 3B, an arm holding portion 31 c that holds the float arm 20 is provided on the upper surface of the main body portion 31. Here, “upper” refers to a direction in which a cylindrical member 551c described later extends (a direction in which the tip of the cylindrical member 551c faces), and the opposite direction is referred to as “lower” (FIGS. 3A and 4). Etc.) The same shall apply hereinafter. In FIG. 3A, the float arm 20 and the arm holding portion 31c are omitted.

  The extending portion 32 is a rod-like member that extends substantially perpendicularly to the axial direction of the columnar member 551 c located at the rotation center of the arm holder 30. There are a plurality of extending portions 32 (four in FIG. 3B), and they are arranged so that the angles between them are equal (90 ° in FIG. 3B). By arranging in this way, the thrust load applied to the arm holder 30 can be evenly distributed to each of the extending portions 32, which contributes to stable rotation of the arm holder 30.

  The distal end portion 33 of the extending portion 32 is formed in a spherical shape and slides on a guide portion 60 described later.

  A magnet 40 shown in FIG. 3A is an annular (ring-shaped) ferrite magnet, for example, and is magnetized to an even number of poles (for example, two poles) in the radial direction. The magnet 40 is held by the magnet holding portion 31b of the arm holder 30 simultaneously with the molding of the arm holder 30, for example, by insert molding. The magnet 40 held in this manner rotates (displaces) together with the arm holder 30 as the float 10 is operated (that is, as the float arm 20 is displaced). The magnet 40 is disposed so as to surround a portion where a magnetic detection element 51 of a columnar member 551c to be described later is embedded. Hereinafter, the hole in the annular magnet 40 is referred to as a through hole 41. The diameter of the through hole 41 is substantially equal to the diameter of the through hole 31 a of the arm holder 30.

  The apparatus main body 50 includes a magnetic detection element 51, a circuit board 52, a first lead wire 53, a second lead wire 54, and a case body 55 (an example of a storage unit).

  The magnetic detection element 51 is composed of a magnetoelectric conversion element such as a Hall element, detects a change in magnetism accompanying the rotation of the magnet 40, and outputs a detection signal to an external device (not shown) such as an ECU (Electronic Control Unit). To do. The magnetic change indicated by the detection signal corresponds to the change in the liquid level, whereby the liquid level detection device 100 can detect the position of the liquid level in cooperation with the external device. The magnetic detection element 51 is embedded in a cylindrical member 551c described later.

  The circuit board 52 includes a hard board such as a glass epoxy resin and an electronic circuit (not shown) formed by electronic components or the like mounted on the board.

  The first lead wire 53 is interposed between the magnetic detection element 51 and the circuit board 52 and electrically connects the magnetic detection element 51 and an electronic circuit included in the circuit board 52.

  The second lead wire 54 shown in FIGS. 1 and 2 is interposed between the circuit board 52 and the external device, and electrically connects the electronic circuit included in the circuit board 52 and the external device.

  By the first lead wire 53 and the second lead wire 54, the magnetic detection element 51 and the external device are conductively connected. By being conductively connected in this way, the magnetic detection element 51 can output a detection signal to an external device.

  The case body 55 is made of, for example, a polyester-based synthetic resin, and accommodates the arm holder 30 in a rotatable manner. The case body 55 includes a lower case 551 and an upper case 552.

The lower case 551 covers the magnetic detection element 51, the circuit board 52, the first lead wire 53, and a part of the second lead wire 54. By forming the lower case 551 by insert molding, the magnetic detection element 51, the circuit board 52, the first lead wire, and a part of the second lead wire are covered. In addition, the lower case 551 does not need to be comprised with a single member, and may be comprised by the aggregate | assembly of a some member.
As shown in FIG. 4, the lower case 551 has a first recess 551a, a second recess 551b, and a columnar member 551c.

  The 1st recessed part 551a is the space part formed in the column shape.

  The 2nd recessed part 551b is a space part formed in the truncated cone shape located on the 1st recessed part 551a and expanding upwards.

  The columnar member 551c is a columnar member that extends upward from the bottom surface of the first recess 551a through the center of the first recess 551a and the second recess 551b. The magnetic detection element 51 is embedded in the cylindrical member 551c. In a state after the liquid level detection device 100 is assembled, the cylindrical member 551c has through holes 31a, 41, and 552b (the through holes 552b will be described later) provided in the arm holder 30, the magnet 40, and the upper case 552, respectively. For example, as shown in FIG. 3, the upper end portion is exposed slightly above the upper case 552. A method for assembling the liquid level detection device 100 will be described later.

The upper case 552 is a lid-like member that covers at least a part of the lower case 551 (for example, a portion that houses the arm holder 30 as shown in FIG. 3) from above. For example, both have engaging portions (not shown) corresponding to each other, and thereby the upper case 552 can be fixed to the lower case 551.
As shown in FIG. 4, the upper case 552 has a third recess 552a and a through hole 552b.

The 3rd recessed part 552a is a space part located in the lower surface side of the upper case 552, and was formed in the truncated cone shape extended toward the downward direction. The third recessed portion 552a is formed in the same shape as the second recessed portion 551b formed in the lower case 551, and the bottom surfaces of the third recessed portion 552a and the second recessed portion 551b having a truncated cone shape exactly coincide with each other. That is, the third recess 552a is plane-symmetric with respect to the contact surfaces of the second recess 551b, the upper case 552, and the lower case 551.
4 indicate the boundary between the first recess 551a and the second recess 551b and the boundary between the second recess 551b and the third recess 552a.

As shown in FIG. 4, the end portion 33 of the extension portion 32 of the arm holder 30 is inside the portion of the case body 55 that corresponds to the side peripheral portions of the second concave portion 551b and the third concave portion 552a. It functions as a guide portion 60 that is a groove portion that enters and restricts the arm holder 30 from being inclined with respect to the rotation axis. The guide part 60 guides the tip part 33 so that the arm holder 30 rotates around an ideal rotation axis.
The guide 60 is formed in a V-shaped cross section that opens toward the inside of the apparatus main body 50. The guide portion 60 according to the present embodiment is a V-shaped groove formed by rotating such a V-shaped groove 360 ° around the column axis of the columnar member 551c.

  Thus, in this embodiment, the guide part 60 is formed so as to straddle the upper case 552 and the lower case 551.

  The through hole 552b is a hole formed upward from the bottom surface of the third recess 552a.

The liquid level detection device 100 configured as described above is assembled, for example, as in the following 1) to 3).
1) First, the arm holder 30 is placed on the lower case 551 in a state where the cylindrical member 551c of the lower case 551 is passed through the through hole 31a of the arm holder 30. Here, the lower case 551 is formed by insert molding so as to cover the magnetic detection element 51, the circuit board 52, the first lead wire 53, and a part of the second lead wire 54. The float arm 20 and the magnet 40 are held. Therefore, the cylindrical member 551c is in a state where the through hole 41 of the magnet 40 is also penetrated.
2) Next, the upper case 552 is mounted on the lower case 551 on which the arm holder 30 is placed so as to cover the upper case 552 from above. In this state, the float arm 20 held by the arm holder 30 protrudes from the apparatus main body 50 through a rectangular hole (not shown) provided on the side surface of the case body 55. The rectangular hole has a length that does not hinder the movement of the float arm 20 (movability in the rotation direction of the arm holder 30) so that the short side is slightly larger than the diameter of the float arm 20. Formed.
3) Then, the float 10 is attached to the float arm 20 protruding from the apparatus main body 50.

  As shown in FIG. 3A, when the assembled liquid level detection device 100 is maintained in a state in which the columnar member 551c is directed upward, a spherical tip portion of the extending portion 32 of the arm holder 30 is provided. 33 abuts a part of the lower case 551 corresponding to the side periphery of the truncated conical second recess 551b. In this manner, the arm holder 30 is placed on the lower case 551. On the other hand, a very slight clearance is provided between the upper side of the tip portion 33 and the portion of the upper case 552 corresponding to the side periphery of the truncated conical third recess 552a. It does not contact 552.

  Conversely, assuming that the columnar member 551c is kept downward (the liquid level detection device 100 is in the opposite state to that of FIG. 3), the tip 33 is partially frustoconical in the upper case 552. 3 abuts on the portion corresponding to the side circumference of the recess 552a. On the other hand, the distal end portion 33 does not come into contact with a portion of the lower case 551 corresponding to the truncated conical second recess 551b.

  In the liquid level detection device 100, the arm holder 30 and the case body 55 (the lower case 551 and the upper case 552) are in the above relationship, so that the arm holder 30 is in the thrust direction (axial direction) and the radial direction. In both directions (the axial direction and the vertical direction), there is very little play, and it is possible to rotate while reducing the burden of frictional force from the case body 55. The arm holder 30 can be smoothly rotated, but is regulated in both directions with a very small clearance.

  Moreover, since the front-end | tip part 33 is formed in spherical shape and the guide part 60 is a V-shaped groove, the front-end | tip part 33 contacts the guide part 60 partially, and the burden of frictional force is reduced, Slide. By forming the distal end portion 33 and the guide portion 60 in this way, the arm holder 30 can rotate smoothly. Note that the V-shaped angle in the V-shaped groove of the guide portion 60 may be appropriately determined in consideration of the load applied to the arm holder 30 by propagating through the float arm 20.

Further, when a force other than the rotation direction is applied to the arm holder 30 and the axis serving as the center of rotation of the arm holder 30 is inclined with respect to the column axis of the column member 551c of the lower case 551, for example, four tips Of the portions 33, two adjacent tip portions 33 abut against the lower case 551, and the remaining two tip portions 33 abut against the upper case 552, so that the arm holder 30 is inclined with respect to the rotation axis. Can be well regulated. Thus, the guide part 60 controls that the arm holder 30 inclines with respect to a rotating shaft.
As described above, the apparatus main body 50 rotatably supports the arm holder 30 with the guide portion 60.

  The liquid level detection device 100 according to the first embodiment can regulate the arm holder 30 in various directions as described above while allowing the arm holder 30 to rotate smoothly. Therefore, behavior other than the rotation (rotation) direction of the arm holder 30 can be satisfactorily suppressed (that is, positional deviation of the arm holder 30 can be suppressed). Therefore, according to the liquid level detection device 100, the output error of the magnetic detection element 51 due to the positional deviation of the arm holder 30 can be suppressed.

(Second Embodiment)
A liquid level detection apparatus 200 according to the second embodiment will be described with reference to FIGS. Below, it demonstrates centering on a different point from 1st Embodiment. In addition, about the structure which has the same shape and function as 1st Embodiment, the same code | symbol is attached | subjected and the description is abbreviate | omitted suitably.

  As shown in FIGS. 5A and 5B, the liquid level detection device 200 according to the second embodiment includes an arm holder 230 having an extending portion 232 different from that of the first embodiment.

  The extending portion 232 includes a first member 232a that is a rod-like member extending substantially perpendicular to the axial direction of the columnar member 551c, and a second member that is formed so as to hang downward from the end of the first member 232a. 232b (an example of the second portion). The distal end portion 33 of the second member 232b is formed in a spherical shape, and slides on a guide portion 260 described later.

  In the case body 55, a guide portion 260 is formed so as to correspond to the distal end portion 33 of the extending portion 232 formed to be bent peculiar to the present embodiment.

  Specifically, a groove is formed in the lower case 551 constituting the case body 55 so as to circularly surround a portion corresponding to the end portion of the bottom surface of the columnar first recess 551a, The portion 33 functions as a guide portion 260 that slides. The guide part 260 is a V-shaped groove having an upper opening as shown in FIG. In the second embodiment, the second recess 551b as in the first embodiment is not required in the lower case 551. Further, the upper case 552 does not need the third recess 552a as in the first embodiment.

In the liquid level detection device 200, the arm holder 230 is rotatable to the device main body 50 (the case body 55) when a part of the spherical tip portion 33 abuts on the guide portion 260 formed as described above. Supported. For example, as shown in FIG. 5A, if the liquid level detection device 200 is kept in a state in which the columnar member 551c is directed upward, when the guide portion 260 is a V-shaped groove, ideally 1 The spherical surface of each of the tip portions 33 is supported by contacting the guide portion 260 at two points.
As described above, the device main body 50 of the liquid level detection device 200 rotatably supports the arm holder 230 with the guide portion 260 formed in the lower case 551.

  In the liquid level detection device 200, the arm holder 230 and the case body 55 (lower case 551) are in the above relationship, whereby the arm holder 230 is regulated in the radial direction. Further, in the thrust direction, the V-shaped guide portion 260 can regulate the arm holder 230 to some extent if no force is applied only in the upward direction in the axial direction. For this reason, since the liquid level detection apparatus 200 according to the second embodiment can also suppress the behavior other than the rotation direction of the arm holder 230 (that is, the positional deviation of the arm holder 230 can be suppressed). The output error of the magnetic detection element 51 due to the positional deviation can be suppressed.

  In addition, as shown in FIG. 7, the behavior of the arm holder 230 in the thrust direction (axial direction) may be further regulated by providing the upper case 552 with a regulating member 552c that projects downward from the lower surface. For example, if the regulating member 552c is formed in a cylindrical shape and the liquid level detecting device 200 is kept in a state in which the columnar member 551c is directed upward, between the lower surface of the regulating member 552c and the upper surface of the arm holder 230, A slight clearance is provided.

  In addition, since the distal end portion 33 is formed in a spherical shape and the guide portion 260 is a V-shaped groove portion, the distal end portion 33 is in partial contact with the guide portion 260, and the burden of frictional force is reduced. Slide. By forming the tip 33 and the guide 260 in this way, the arm holder 230 can rotate smoothly. Note that the V-shaped angle in the V-shaped groove of the guide portion 260 may be appropriately determined in consideration of the load applied to the arm holder 230 by propagating through the float arm 20.

(Modification)
In the above description, the tip portion 33 is formed in a spherical shape and the guide portion 260 is a V-shaped groove. However, the shape is not limited thereto. As shown in FIG. 8A, a guide portion 260a configured by a square groove (in the figure, a trapezoidal shape) may be used.

  Further, as shown in FIG. 8B, a first wall portion 261 that is erected from a portion corresponding to the bottom surface of the first recess 551 a of the lower case 551 and is located closer to the axial center portion side than the distal end portion 33. The second wall portion 262 located on the outer peripheral side of the distal end portion 33 is configured by one or both of them, and the shape that regulates the distal end portion 33 can be said to be the guide portion 260b in a broad sense. Such a guide part 260b may be used. Although not shown, the first wall portion 261 and the second wall portion 262 are both annular when viewed from above (when viewed in plan).

  Further, as shown in FIG. 8C, the distal end portion of the extending portion 232 may be a distal end portion 33a configured in a hemispherical shape, an ellipsoidal shape, or the like instead of a perfect spherical shape. Further, the guide part is not limited to the V-shaped groove and the square groove, but may be a guide part 260c having a semicircular cross section.

  Furthermore, the guide part is not limited to a groove part such as a V-shaped groove or a square groove, but may be a guide part 260d configured by a convex part as shown in FIG. And the front-end | tip part of the extension part 232 may be the front-end | tip part 33b comprised from the recessed part corresponding to a convex part.

  Of course, such a modification of the tip portion and the guide portion can also be applied to the liquid level detection device 100 according to the first embodiment.

  Moreover, although the cylindrical member was formed in the lower case in the above, it is not restricted to this, You may form in an upper case.

  In the present invention, as shown in FIGS. 9A and 9B, the case body 55 does not have the column member 551 c, and the float arm 20 is inserted into the through holes 31 a provided in the arm holders 30 and 230. It can also be applied to the liquid level detecting devices 100 ′ and 200 ′ having a structure in which they are press-fitted into and fixed. In this case, a part of the float arm 20 (the portion press-fitted into the arm holders 30 and 230) serves as the central axis of rotation. Although not shown in the figure, the magnetic detection element 51 is disposed at a predetermined position of the case body 55 where the magnetic change of the magnet 40 can be detected, and the detection signal is sent to the circuit board 52 (FIG. 9A). ) (B) (not shown) to the external device.

  In such liquid level detection devices 100 ′ and 200 ′, for example, the lower case 551 may be formed with a bearing 551 d configured by a cylindrical recess or the like as illustrated. And you may hold | maintain the arm holders 30 and 230 rotatably with the guide parts 60 and 260 and this bearing 551d. The bearing 551d is formed with a diameter slightly larger than the diameter of the float arm 20.

  In addition, this invention is not limited by the above embodiment and drawing. Changes (including deletion of constituent elements) can be added to the embodiments and the drawings as appropriate without departing from the scope of the present invention.

DESCRIPTION OF SYMBOLS 100 ... Liquid level detection apparatus 10 ... Float 20 ... Float arm 30 ... Arm holder 31 ... Main-body part (31a ... Through-hole, 31b ... Magnet holding part, 31c ... Arm holding part)
32 ... extension part 33 ... tip part (33a, 33b ... tip part according to modification)
DESCRIPTION OF SYMBOLS 40 ... Magnet 41 ... Through-hole 50 ... Apparatus main body 51 ... Magnetic detection element 52 ... Circuit board 53 ... 1st lead wire 54 ... 2nd lead wire 55 ... Case body 551 ... Lower case (551a ... 1st recessed part, 551b ... 1st 2 recesses, 551c ... cylindrical member)
552 ... upper case (552a ... third recess, 552b ... through hole, 552c ... regulating member)
60 ... Guide part 200 ... Liquid level detection device 230 ... Arm holder 232 ... Extension part (232a ... 1st member, 232b ... 2nd member)
260 ... guide part (260a, 260b, 260c, 260d ... guide part according to modification)
261 ... 1st wall part 262 ... 2nd wall part 551d ... Bearing

Claims (5)

A float that floats on the liquid surface is attached to one end, and a float arm that displaces as the liquid level fluctuates;
An arm holder that holds the other end of the float arm and rotates around a predetermined rotation axis with the displacement of the float arm;
A storage portion for rotatably storing the arm holder;
A magnet, and a magnetic detection element that detects a change in magnetism of the magnet due to displacement of the magnet,
The arm holder has a holding portion that holds the magnet so that the magnet is displaced with the rotation of the arm holder, and an extending portion that extends from the holding portion,
The storage portion has a guide portion that guides a tip portion of the extending portion and restricts the arm holder from being inclined with respect to the rotation shaft.
A liquid level detection device characterized by that. The extending portion has a first portion extending in a radial direction of rotation of the arm holder,
The guide part guides a tip part of the first part;
The liquid level detection device according to claim 1, wherein: The extending portion has a second portion extending along the rotation axis,
The guide part guides a tip part of the second part;
The liquid level detection device according to claim 1, wherein: The guide portion is a groove portion that restricts the tip of the extension portion from entering the inside and the arm holder from being inclined with respect to the rotation axis.
The liquid level detection device according to claim 1, wherein the liquid level detection device is a liquid level detection device. The groove portion is a V-shaped groove or a square groove,
The distal end portion of the extending portion is a spherical member.
The liquid level detection device according to claim 4, wherein:

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