JP5142380B2 - Non-contact level sensor - Google Patents

Description

  The present invention relates to a non-contact type liquid level sensor, and more particularly to a non-contact type liquid level sensor that facilitates assembly.

  In the conventional contact type liquid level sensor, when the float moves up and down according to the displacement of the liquid level to be measured, the movable contact slides on the resistance plate, and the resistance value changes. Some have detected the liquid level by detecting. In this type of contact type liquid level sensor, the movable contact and the resistance plate may be oxidized. In this case, there is a problem in detection accuracy due to extremely large fluctuations in the detected resistance value or noise, and there is room for improvement.

  In recent years, a non-contact type liquid level sensor that converts a change in magnetic force into an electric signal by a magnetoelectric conversion element has been proposed as a liquid level sensor that improves the above-described problem (see, for example, Patent Document 1). . In this non-contact type liquid level sensor, the movement of the float that moves up and down in accordance with the change in the liquid level in the automobile fuel tank is transmitted to the float arm attached to the float. Further, the rotation transmitted to the float arm is transmitted to the holder, and the rotation amount (rotation angle) of the magnet provided in the holder is converted into an electrical signal corresponding to the liquid level by the magnetoelectric conversion element.

  As another conventional example of a non-contact type liquid level sensor, one shown in FIG. 7 has been proposed. In this non-contact type liquid level sensor, a terminal assembly is insert-molded in a synthetic resin frame 11, and most of the terminal assembly is embedded in the frame 11 except for a part. The terminal assembly is one in which each terminal for sensor power supply and sensor signal output, a magnetoelectric conversion element, a resistor, a capacitor and a stator are assembled together. Each terminal constitutes a part of an electric circuit and takes out an electric signal detected by the magnetoelectric transducer.

  Further, a substantially semicircular stator in which two magnetic plates such as silicon steel plate, iron, martensite stainless steel, etc. are combined is provided. Magnetoelectric conversion elements such as Hall elements and Hall ICs are interposed in the gap between the two magnetic plates, and the lead wires of the magnetoelectric conversion elements are electrically connected to the terminals by spot welding. Resistor and capacitor leads are also connected between the terminals by spot welding. The terminal assembly assembled in this way is insert-molded using a synthetic resin such as polyacetal to form the frame 11. The stator is provided at a magnet corresponding portion described later.

  The frame 11 is formed with a magnet storage portion 12 that opens to the side. A through-type support hole 13 is formed in the two opposite side walls of the magnet storage portion 12. These support holes 13 are on the same axis. A rotating body 14 is stored in the magnet storage unit 12. As shown in FIG. 8, the rotating body 14 includes a magnet holder 15 with a hook having a center hole 17 and a ring-shaped sintered magnet 16 fixed to the outer periphery of the magnet holder 15 by adhesion. ing. The sintered magnet 16 is two-pole magnetized in the circumferential direction.

  The float 19 moves up and down due to a change in the liquid level in the automobile fuel tank, and an end of a shaft portion 18 a of a float arm 18 bent in an L shape is attached to the float 19. The distal end portion 18 b of the float arm 18 is press-fitted into the center hole (center hole of the magnet holder 15) 17 of the rotating body 14 through one support hole 13 of the frame 11 and is supported by the other support hole 13.

  This prevents the rotating body from coming off from the tip end portion 18b of the float arm 18. A flange portion 20 is integrally provided on the distal end side 18 b of the float arm 18. Since the float arm 18 is bent in an L shape as described above, the flange portion 20 is used to apply the press-fitting load at the tip portion in the direction perpendicular to the frame 11 (arrow P direction). .

The rotating body 14 is housed in the magnet housing portion 12, and the tip of the float arm 18 is press-fitted from the outside of the frame 11 into the center hole 17 of the rotating body 14 through the support hole 13. Further, as shown in FIG. 8, for example, a sheet metal cover 21 is attached to the opening of the magnet storage portion 12. The cover 21 is integrally provided with a spring piece 21a at the upper and lower portions, and the spring piece 21a is elastically engaged with the inner peripheral surface of the opening in the mounted state of the cover 21. Thereby, the inside of the magnet storage part 18 is sealed.
JP 2004-37196 A

  However, in the non-contact type liquid level sensor, it is necessary to press the tip end of the float arm 18 in the vertical direction into the center hole of the rotating body 14 accommodated in the magnet accommodating portion 12 at the time of assembly. The non-contact type liquid level sensor is configured to fix the float arm 18 to the rotating body 14 by inserting the float arm 18 through the center hole of the rotating body 14. It is necessary to have a configuration in which the tip portion can be squeezed by a considerable force. In order for the center hole of the rotating body 14 to be inserted into the center hole against the frictional force generated by the force generated by squeezing the tip of the float arm 18, the tip of the float arm 18 is inserted in the vertical direction. Must be pressed with a strong force. For this reason, a flange 20 for press-fitting operation is integrally provided on the float arm 18 so that a strong pressure can be applied to the tip of the float arm 18, and the float 20 is used to float. In order to perform the press-fitting work of the arm 18, a press-fitting device and a press-fitting press for the collar unit 20 are required. As a result, there has been a problem that the assembly work of the non-contact type liquid level sensor is prolonged and the manufacturing cost is increased.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a non-contact type liquid level sensor that can easily assemble a cylindrical holder and a float arm to a frame at a low work cost. There is.

In order to achieve the above-described object, a non-contact type liquid level sensor according to the present invention is characterized by the following (1).
(1) A cylindrical holder to which a float arm is attached, and a frame that rotatably supports the cylindrical holder, and rotates according to the vertical movement of the liquid surface on which the float attached to the float arm floats. A non-contact type liquid level sensor that detects the level of the liquid level based on the amount of rotation of the cylindrical holder,
The frame includes a frame main body, a horizontal axis projecting horizontally on the outer surface of the frame main body to rotatably support the cylindrical holder, and a magnetoelectric conversion element housed therein; and A lower guide provided on the outer surface of the lower portion so as to form a first gap between the lower outer surface of the frame body located on the lower side and including a lower arc surface centered on the horizontal axis And an upper part centered on the horizontal axis so as to form a second gap between the upper part and the outer side surface of the upper part of the frame body located above the horizontal axis. An upper guide portion including an arc surface, and an arc hole centered on the horizontal axis that is drilled in the upper guide portion in a horizontal direction,
When the cylindrical holder is rotatably supported by the horizontal shaft, the inner peripheral surface faces the outer peripheral surface of the horizontal shaft, the outer peripheral surface faces the lower arc surface and the upper arc surface, and the horizontal axis A hollow cylindrical rotating body that contains an annular magnet with a shaft as an inside, and a third outer space between the lower guide portion and the upper guide portion so as to be inserted into the outer periphery of the rotating body. A pair of retaining portions, an arm end holding notch into which one end of the L-shaped float arm is inserted and one of the pair of retaining portions, and the L-shaped float arm An arm shaft holding portion provided on the bottom surface of the rotating body so as to detachably hold the shaft portion of
Of the pair of retaining portions respectively accommodated in the first gap and the second gap by rotation of the cylindrical holder, the arm end of one retaining portion facing the arc hole The distal end portion of the float arm having the shaft portion mounted on the arm shaft holding portion is inserted into the holding notch.

  According to the non-contact type liquid level sensor having the configuration (1), the arm end holding notch is configured to hold one side of the L-shaped float arm, and the other side is held by the arm shaft holding unit. The force with which the notch and the arm shaft holding part squeeze the float arm 33 may be small. For this reason, when mounting the float arm to the cylindrical holder, the force to fit the two sides of the float arm into the arm end holding notch and the arm shaft holding part can be reduced, and the float arm can be easily mounted to the cylindrical holder. can do. As a result, it is possible to reduce the assembly work time and cost of the non-contact type liquid level sensor.

  Further, by restricting the movement area of the float arm whose tip is held in the arm end holding notch by the arc hole of the frame, the pair of retaining pieces are placed in the third gap between the lower guide frame and the upper guide frame. Therefore, it is possible to reliably prevent the cylindrical holder from coming out of the frame.

  With the non-contact type liquid level sensor of the present invention, the cylindrical holder and the float arm can be easily assembled to the frame at a low work cost.

  The present invention has been briefly described above. The embodiments described below will be further clarified by referring to the drawings.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is an exploded perspective view showing a non-contact type liquid level sensor according to an embodiment of the present invention, and FIG. 2 is a cross-sectional view of the frame when the cylindrical holder is not attached, as viewed from II-II in FIG. 3 is a cross-sectional view of the frame when the cylindrical holder is mounted as viewed from II-II in FIG. 1, and FIG. 4 is a cylindrical holder in the non-contact type liquid level sensor according to the embodiment of the present invention. FIG. 5 is a front view of the frame when not mounted, FIG. 5 is a front view of the frame when the cylindrical holder is mounted in the non-contact liquid level sensor of the embodiment according to the present invention, and FIG. 6 is an embodiment according to the present invention. It is explanatory drawing which shows the assembly | attachment procedure of the cylindrical holder with respect to a flame | frame, and a float arm in the non-contact-type liquid level sensor.

  As shown in FIGS. 1 to 5, the non-contact liquid level sensor 30 of the present embodiment includes a frame 31, a cylindrical holder 32, and a float arm 33. Of these, the frame 31 is formed by injection molding synthetic resin, and has a large number of ribs (not shown) for reinforcement and attachment of parts. The frame 31 is fixed at a predetermined position in the fuel tank of the automobile. The one outer side surface (the right side surface in FIG. 2) of the frame 31 is horizontal so as to protrude in the horizontal direction from the one outer side surface of the frame body 31a located at the center of the frame 31 shown in FIGS. A shaft 34 is integrally formed with the frame 31.

  The horizontal shaft 34 has a bottomed hollow cylindrical shape with a predetermined height, and a magnetoelectric conversion element 36 is accommodated in the cylindrical hole 35. A sliding resin is used for the horizontal shaft 34, and the cylindrical holder 32 is supported on the horizontal shaft 34 so as to be smoothly rotated by a rotating body 59 of a cylindrical holder 32 (described later) fitted thereto. . As the magnetoelectric conversion element 36, a Hall element or a Hall IC is used. The lead wire 37 of the magnetoelectric conversion element 36 is connected to a terminal 38 partially embedded in the frame 31 by spot welding.

  For example, three terminals 38 are provided for power supply and signal output. An electric circuit element 39 such as a capacitor or a resistance element is connected between these terminals 38. The terminal 38 has an upper end protruding outside from the upper end of the frame 31, and this is a connection portion with an external lead terminal (not shown). The lower half of the terminal 38 is exposed from the outer surface of the frame body 31a on the side opposite to the installation side of the horizontal shaft 34.

  If this exposed surface side is exposed to moisture or dust or the like adheres to it, the quality of the terminal or electronic components connected to the terminal will be deteriorated. In order to prevent this quality deterioration, the cover 40 is mounted so as to cover the exposed portion. The cover 40 is formed of a synthetic resin made of the same material as or similar to the frame 31, and the peripheral edge can be thermally welded to the frame 31 as necessary. As a result, the space 41 including the exposed portion can be reliably sealed. When the cover 40 is configured to be detachable from the frame 31, it is possible to replace, repair, or inspect electronic components such as the resistors and capacitors in the space 41.

  On the outer surface of the frame body 31a and below the horizontal shaft 34, a lower guide portion 42 is integrally formed with the frame body 31a so as to be bridged with the frame body 31a. The lower guide portion 42 is coupled at two locations of the frame main body 31a and the coupling portions 43a and 43b, and forms a gap 43 penetrating in the vertical direction between the outer surface of the frame main body 31a to form a bridge shape. . In addition, a lower circular arc surface 44 having a predetermined radius centered on the horizontal axis 34 is formed on the upper portion of the lower guide portion 42. The lower guide portion 42 has a substantially horizontally long rectangle when the lower guide portion 42 is viewed from the front.

  Further, on the outer surface of the frame main body 31a and above the horizontal shaft 34, the upper guide portion 45 is integrally formed with the frame so as to be bridged to the frame main body 31a. The upper guide portion 45 is coupled at two locations of the frame main body 31a and the coupling portions 46a and 46b, and forms a bridge shape by forming a gap 46 penetrating in the vertical direction between the outer surface of the frame main body 31a. . The shape of the gap 46 penetrates in the vertical direction so as to penetrate in the vertical direction, as shown in FIG. An upper circular arc surface 47 centering on the horizontal axis 34 is formed at the lower portion of the upper guide portion 45. Further, the upper guide portion 45 is formed with an arc hole 48 that passes through the gap 46. Further, the upper guide portion 45 has a substantially horizontally long rectangle when the upper guide portion 45 is viewed from the front.

  The arc hole 48 has an arc shape with a predetermined radius centered on the horizontal axis 34 and has a symmetrical size. The shape of the arc hole 48 is a shape that restricts a later-described float arm 33 that moves in the arc hole 48 within an angle region of 90 degrees. The outer surface of the frame body 31a facing the arc hole 48 has a distal end portion 33b of the float arm 33 according to the rotation of the float arm 33 when the float arm 33 passes through the arc hole 48 as will be described later. A guide groove 31c (substantially the same locus as the circular arc hole 48) is formed. As described above, the frame 31 includes the frame main body 31a, the horizontal shaft 34, the lower guide portion 42, the upper guide portion 45, and the arc hole 48.

  On the other hand, at the center of the cylindrical holder 32, the inner peripheral surface faces the outer peripheral surface of the horizontal shaft 34, and the outer peripheral surface faces the lower arc surface 44 of the lower guide portion 42 and the upper arc surface 47 of the upper guide portion 45, respectively. A rotating body 59 on the bottomed hollow cylinder in which an annular magnet 57 centering on the horizontal shaft 34 is accommodated is located. When the cylindrical holder 32 is mounted on the frame 31, the outer periphery of the rotating body 59 can be inserted into the gap 49 between the lower guide portion 42 and the upper guide portion 45, and the gap 43 of the lower guide portion 42, A pair of retaining pieces 50 and 51, each of which can be fitted in the gap 46 of the upper guide portion 45, are provided so as to project. These retaining pieces 50 and 51 are arranged on the outer periphery of the rotating body 59 on a substantially straight line passing through the center of the rotating body 59. The retaining piece 50 has a hook shape when viewed from the direction in which the rotating body 59 is fitted to the horizontal shaft 34, and has a partially open arm end retaining notch 52 that retains an end of a float arm 33 to be described later. Is formed. Since the retaining piece 50 is formed in a hook shape and has elasticity, the attachment and detachment and holding of the tip of the float arm 33 are made easy and reliable.

  An arm shaft holding portion 53 for detachably mounting the shaft portion 33a of the float arm 33 is integrally provided on the bottom surface of the rotating body 59. The arm shaft holding portion 53 has a hook shape as shown in FIG. 1, and is formed so as to be positioned on a line connecting the centers of the arm shaft holding notches 54 and the retaining pieces 50 and 51 that form the hook shape. Yes. Since the arm shaft holding portion 53 is also elastic in the hook-like portion, the attachment and detachment and holding of the shaft portion of the float arm 33 are made easy and reliable.

  The inner surface of the rotating body 59 is formed by the ring-shaped wall 55. The ring-shaped wall 55 is a smooth surface having a diameter adapted to be rotatable with respect to the outer peripheral surface of the horizontal shaft 34. The edge of the ring wall 55 faces the ring guide groove 31b formed on the outside of the frame 31 so that the rotation of the ring wall 55 is not hindered.

  An annular ring-shaped notch 56 is formed between the ring wall 55 that is the inner surface of the rotating body 59 and the outer peripheral wall 32 a that is the outer surface of the rotating body 59. It is stored and faces a concentric position with respect to the horizontal shaft 34. As the magnet 57, for example, a ferrite magnet or the like magnetized with two magnetic poles of the S pole and the N pole in the circumferential direction after the magnetic powder is formed into a ring shape and fired is used. The magnet 57 is positioned so as to overlap with the magnetoelectric conversion element 36 in the horizontal axis 34 in the vertical direction, and the rotational position of the holder 32 by the magnetoelectric conversion element 36 can be detected with high sensitivity.

  The float arm 33 has, for example, an “L” shape, and a short-side tip portion 33b is refracted in a vertical direction with respect to the long-side shaft portion 33a. The shaft portion 33 a has a thickness (diameter) that can be fitted into the arm shaft holding notch 54 of the arm shaft holding portion 53. A float 58 that moves up and down with the displacement of the liquid level in the fuel tank is attached to the tip of the shaft portion 33a. On the other hand, the distal end portion 33 b of the float arm 33 has a thickness that can be fitted into the arm end holding cutout 52 of the retaining piece 50.

  A non-contact liquid level sensor is formed by assembling the frame 31, the cylindrical holder 32, and the float arm 33 as follows.

  First, as shown in FIG. 6A, the cylindrical holder 32 is cylindrical so that the pair of retaining pieces 50 and 51 are interposed in the gap 49 between the upper guide portion 45 and the lower guide portion 42 of the frame 31. The shape holder 32 is aligned with the gap 49. Further, the cylindrical holder 32 is inserted into the gap 49. Further, the cylindrical holder 32 is pressed so that the rotating body 59 of the cylindrical holder 32 is aligned with the center of the horizontal axis 34 of the frame 31.

  If the axis of the rotary body 59 of the cylindrical holder 32 and the axis of the horizontal axis 34 coincide, the cylindrical holder 32 can be pressed against the outer surface of the frame body 31a. By this pressing, the ring wall 55 of the cylindrical holder 32 fits smoothly into the outer peripheral surface of the horizontal shaft 34. Accordingly, the retaining pieces 50 and 51 are positioned so as to face the gap 46 of the upper guide portion 45 and the gap 43 of the lower guide portion 42, respectively.

  Therefore, as shown in FIG. 6B, the cylindrical holder 32 is rotated by 90 degrees in the arrow direction A, so that one retaining piece 50 enters the gap 43 and the other retaining piece. 51 is moved into the gap 46 respectively. As a result, the arm end holding cutout 52 of the retaining piece 50 faces the arc hole 48. As shown in FIG. 6B, when the cylindrical holder 32 is rotated 90 degrees, the pair of retaining pieces 50 and 51 are accommodated in the gaps 43 and 46, respectively. As long as the moving angle is maintained, the pair of retaining pieces 50, 51 and the upper guide portion 45 and the lower guide portion 42 cooperate to prevent the cylindrical holder 32 from coming out.

  Next, the tip 33 b of the float arm 33 is fitted through the arc hole 48 so as to penetrate the arm end holding notch 52 of the retaining piece 50. This fitting is easy because the arm end holding cutout 52 has a hook shape. The tip end portion 33 b of the float arm 33 is stably held by the elasticity of the hook portion of the arm end holding notch 52. When the distal end portion 33 b of the float arm 33 is fitted into the arm end holding cutout 52, the distal end portion 33 b of the float arm 33 is pivoted so that the shaft portion 33 a of the float arm 33 is inclined, and the arm shaft holding portion 53. Keep away from contact.

  Subsequently, the shaft portion 33a of the float arm 33 is rotated to the arm shaft holding notch 54 side with the tip 33b of the float arm 33 penetrating through the arm end holding notch 52 as an axis, and the arm shaft holding portion 53 The shaft portion 33 a of the float arm 33 is fitted into the arm shaft holding notch 54 from the opening side of the arm shaft holding notch 54. As a result, the shaft portion 33a is stably held in the arm shaft holding notch 54 as shown in FIG. As a result, the float arm 33 is securely fixed to the cylindrical holder 32 at two locations.

  As a result of fixing the tip 33b of the float arm 33 to the arm end holding notch 52 of the retaining piece 50 through the arc hole 48 and fixing the shaft portion 33a in the arm shaft retaining notch 54, the upper guide portion 45 is retained. It will be in the state narrowed by the piece 50 and the axial part 33a. In such a state, the rotation angle of the cylindrical holder 32 is restricted to a range in which the distal end portion 33b of the float arm 33 can move in the arc hole 48, so that the pair of retaining pieces 50, 51 are the lower guide portions. 42 and the upper guide part 45 do not face the gap 49. Therefore, the cylindrical holder 32 does not come out of the frame 31.

  On the other hand, the amount of rotation of the cylindrical holder 32 is detected by a magnetoelectric conversion element 36 installed in the horizontal shaft 34, and this detection output is transmitted to each terminal 38 via a lead wire 37. In this case, due to the smooth sliding contact between the cylindrical holder 32 and the horizontal shaft 34, the detection signal obtained from the magnetoelectric transducer 36 when the cylindrical holder 32 is rotated becomes highly accurate and stable. Electrical components (circuit elements) such as resistors and capacitors are connected between the terminals 38 as described above, and signal processing (for example, waveform shaping processing) by these circuit elements is performed to detect the detection signal. Is led to an external circuit connected to terminal 38.

  As described above, according to the non-contact type liquid level sensor of the embodiment of the present invention, one end of the L-shaped float arm 33 is held by the arm end holding notch 52 and the other side by the arm shaft holding portion 53. Since it is the structure to hold | maintain, the force which the arm end holding | maintenance notch 52 and the arm axis | shaft holding part 53 squeeze the float arm 33 may be small. Therefore, when the float arm 33 is mounted on the cylindrical holder 32, the force for fitting the two sides of the float arm 33 into the arm end holding notch 52 and the arm shaft holding portion 53 can be reduced, and the float arm 33 can be cylindrical. Can be easily attached to the cylindrical holder 32. As a result, it is possible to reduce the assembly work time and cost of the non-contact type liquid level sensor.

  Further, the arc region 48 of the frame 31 restricts the moving area of the float arm 33 in which the tip end portion 33b is held in the arm end holding notch 52 within a rotation range of 90 degrees of the cylindrical holder 32, for example. The retaining pieces 50 and 51 do not face the gap 49 between the lower guide portion 42 and the upper guide portion 45, so that the cylindrical holder 32 can be reliably prevented from coming out of the frame 31.

  When inspecting or repairing the magnet 57 or the like in the cylindrical holder 32 attached to the frame 31, the float arm 33 is separated from the arm shaft holding cutout 54 and the arm end holding cutout 50 of the cylindrical holder 32. The cylindrical holder 32 is rotated in the opposite direction. Thereby, the cylindrical holder 32 is easily separated from the frame 31, and the inspection and repair can be quickly performed.

  In addition, this invention is not limited to the above-mentioned embodiment, A deformation | transformation, improvement, etc. are possible suitably. In addition, the material, shape, dimension, numerical value, form, number, arrangement location, and the like of each component in the above-described embodiments are arbitrary and are not limited as long as the present invention can be achieved.

  Needless to say, the non-contact type liquid level sensor 30 of the present invention is not limited to the vehicle fuel tank as described above, but can be widely applied to the detection of the liquid level in various liquid storage tanks.

The disassembled perspective view which shows the non-contact-type liquid level sensor of embodiment which concerns on this invention A cross-sectional view of the frame when the cylindrical holder is not attached, as viewed from II-II in FIG. Cross-sectional view of the frame when the cylindrical holder is mounted, as viewed from II-II in FIG. The front view of the flame | frame at the time of cylindrical holder non-mounting in the non-contact-type liquid level sensor of embodiment which concerns on this invention The front view of the flame | frame at the time of cylindrical holder mounting | wearing in the non-contact-type liquid level sensor of embodiment which concerns on this invention Explanatory drawing which shows the assembly | attachment procedure of the cylindrical holder and the float arm with respect to a flame | frame in the non-contact-type liquid level sensor of embodiment which concerns on this invention. Exploded perspective view showing a conventional non-contact type liquid level sensor Explanatory drawing which shows the attachment method of the float arm with respect to the cylindrical holder in the conventional non-contact-type liquid level sensor

Explanation of symbols

30 Non-contact type liquid level sensor 31 Frame 31a Frame body 32 Cylindrical holder 33 Float arm
33a Shaft portion 33b Tip portion 34 Horizontal shaft 36 Magnetoelectric conversion element 37 Lead wire 38 Terminal 39 Circuit element 42 Lower guide portion 43 Gap 44 Lower arc surface 45 Upper guide portion 46 Gap 48 Arc hole 49 Gap 50, 51 Retaining piece 52 Arm End holding cutout 53 Arm shaft holding section 54 Arm shaft holding cutout 55 Ring wall 56 Ring cutout 57 Magnet 58 Float 59 Rotating body

Claims (1)

A cylindrical holder provided with a float arm; and a frame that rotatably supports the cylindrical holder, the cylindrical shape rotating according to a vertical movement of a liquid surface on which the float attached to the float arm floats A non-contact type liquid level sensor that detects the level of the liquid level based on the amount of rotation of the holder,
The frame includes a frame main body, a horizontal axis projecting horizontally on the outer surface of the frame main body to rotatably support the cylindrical holder, and a magnetoelectric conversion element housed therein; and A lower guide provided on the outer surface of the lower portion so as to form a first gap between the lower outer surface of the frame body located on the lower side and including a lower arc surface centered on the horizontal axis And an upper part centered on the horizontal axis so as to form a second gap between the upper part and the outer side surface of the upper part of the frame body located above the horizontal axis. An upper guide portion including an arc surface, and an arc hole centered on the horizontal axis that is drilled in the upper guide portion in a horizontal direction,
When the cylindrical holder is rotatably supported by the horizontal shaft, the inner peripheral surface faces the outer peripheral surface of the horizontal shaft, the outer peripheral surface faces the lower arc surface and the upper arc surface, and the horizontal axis A hollow cylindrical rotating body that contains an annular magnet with a shaft as an inside, and a third outer space between the lower guide portion and the upper guide portion so as to be inserted into the outer periphery of the rotating body. A pair of retaining portions, an arm end holding notch into which one end of the L-shaped float arm is inserted and one of the pair of retaining portions, and the L-shaped float arm An arm shaft holding portion provided on the bottom surface of the rotating body so as to detachably hold the shaft portion of
Of the pair of retaining portions respectively accommodated in the first gap and the second gap by rotation of the cylindrical holder, the arm end of one retaining portion facing the arc hole A non-contact type liquid level sensor, wherein a tip end portion of the float arm having a shaft portion mounted on the arm shaft holding portion is inserted into a holding notch.

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