JP2010164543A - Liquid level sensor and assembly method therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a structure withstanding an impact generated when a float comes into collision. <P>SOLUTION: A frame 2 has stopper parts 41, 42 on two spots provided on the fringe of a circular groove 24 into which a rotating member 3 is inserted, for regulating a rotation range of a projection part 35 projecting from the outer circumferential surface of the rotating member. An inclined plane 42b erected to a rotationally moving direction is formed on one stopper part on which the projection part abuts on the first place, when the rotating member is assembled into the circular groove of the frame, and the projection part is put into an engaged state by being moved rotationally up to the rotation range, and a pawl part 36 to be climbed over by deforming elastically the inclined plane of one stopper part is formed on the projection part. While the projection part is positioned in the rotation range, when the pawl part abuts on one stopper part 42, a highest position state of the liquid level is detected, and when an inelastic part on the base end side of the pawl part abuts on the other stopper part 41, a lowest position state of the liquid level is detected. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a liquid level sensor that detects the height of a liquid level, and more particularly to a liquid level sensor that detects the height of a liquid level by the vertical movement of a float floating on the liquid level.

  This type of liquid level sensor is used, for example, as a level sensor for monitoring the level of a liquid level in a fuel tank of an automobile. This liquid level sensor has a float attached to a rotating member to which a ring-shaped magnet is fixed via an arm, a frame that rotatably supports the rotating member within a predetermined rotation range, and a magnet that faces the magnet. A liquid level sensor that is embedded in a frame and includes a Hall element that detects a rotational phase of a magnet by a change in magnetic flux density is widely known (for example, see Patent Document 1).

  According to this configuration, when the float moves up and down in conjunction with the liquid level, the magnet of the rotating member rotates, and the magnetic flux density of the magnetic lines of force passing through the Hall element changes. Here, the Hall element generates a Hall voltage proportional to the magnetic flux density when a magnetic field is applied from the outside while a voltage is applied. Therefore, by detecting this Hall voltage, the rotational phase of the magnet, that is, the liquid The surface level is detected.

JP 2006-208212 A

  By the way, according to Patent Document 1, the other end of the arm whose one end is fixed to the float is held by the locking portion provided in the rotating member, and the tip portion thereof is inserted into the locking groove of the frame. Yes. The locking groove is formed in an arc shape in a direction in which the distal end portion of the arm moves by the rotation of the rotating member, and restricts the rotation range of the rotating member. Thereby, when the rotating member rotates and the tip of the arm contacts the end of the locking groove, the rotating member stops rotating.

  As in Patent Document 1, a liquid level sensor that detects the liquid level by converting the vertical movement of a float into a rotational movement of a rotary member is usually suspended from the rotary member to the lowest position via an arm. In this state, that is, in a state where the liquid level shows the lowest level, it is inserted into an empty fuel tank and manually attached to a predetermined position in the tank.

  However, since the space in the fuel tank is narrow and dark, for example, an operator may accidentally make the float suspended from the frame collide with the bottom surface or side surface of the fuel tank. Here, the movement of the float is normally regulated so as to move in a set direction from the state suspended from the lowest position. For this reason, when the float moves (rises) due to the impact at the time of the collision, the impact is absorbed by the movement of the float, so that the impact transmitted to the frame side is reduced. However, when an impact is applied in a direction in which the float cannot be moved due to shaking, the impact force is directly transmitted to the frame, and the end of the arm strongly presses the end of the locking groove, which may damage the frame. In particular, in the structure of Patent Document 1, since the tip of the arm is a metal rod, when the arm strongly presses the end of the locking groove, the arm is bent or the end of the resin locking groove is deformed. There is a risk of doing so.

  Moreover, in patent document 1, as a structure which supports a rotation member, by inserting the hole of the center of a rotation member in the front-end | tip part of the axial part by the side of a flame | frame, and attaching a snap ring to the front end side of a shaft part, rotation member Adopts a structure that regulates the movement in the direction away from the frame. However, such a structure cannot be considered as an impact when the float collides with the bottom of the fuel tank, and may cause a great damage due to the impact at the time of the collision.

  On the other hand, in such a liquid level sensor, it is necessary to measure the Hall voltage output from the Hall element corresponding to the upper limit and the lower limit of the liquid level detection at the time of assembly. Therefore, in Patent Document 1, the Hall voltage is detected in a state in which the rotating member is rotated and a part of the arm is in contact with the locking groove on the frame side, that is, in a state in which the rotation is restricted, and this detected value is detected in the frame. Writing to be stored in a memory (for example, EPROM) embedded in the memory is performed.

  Here, in Patent Document 1, a locking groove serving as a stopper for the rotating member is formed on the frame side, and the arm is brought into contact with the locking groove to restrict the rotation of the rotating member. When writing, it is necessary to attach an arm to the rotating member. However, since the liquid level sensor has many variations and the shape of the arm varies depending on the model number of the liquid level sensor, for example, a dedicated jig for writing must be prepared every time the arm shape is renewed. However, there is a problem that the manufacturing cost becomes high.

  In view of the above problems, a first object of the present invention is to provide a liquid level sensor having a structure capable of withstanding an impact when a float collides.

  It is a second object of the present invention to provide a method for assembling a liquid level sensor that can simplify the assembling work regardless of the shape of the arm.

  In order to solve the first problem, the present invention provides a cylindrical rotating member on which a ring-shaped magnet is coaxially fixed, a frame that rotatably supports the rotating member, and a frame facing the magnet. A liquid level sensor configured to rotate a rotating member by a vertical movement of a float floating on a liquid surface, and a magnetic detection element that detects a rotation phase of a magnet by a change in magnetic flux density. The frame includes a circular groove into which the rotating member is inserted, and two stopper portions that are provided on the periphery of the circular groove and restrict the rotation range of the protrusion protruding from the outer peripheral surface of the rotating member. When the rotating member is assembled into the circular groove of the frame and then the protruding portion is rotated to the rotation range to be in the engaged state, the first stopper portion with which the protruding portion first contacts stands in the rotational movement direction. An inclined surface is formed, and the protrusion is formed with a claw portion that elastically deforms and climbs over the inclined surface of the one stopper portion, and the claw portion is in the state where the protrusion is positioned in the rotation range. When contacting the stopper, the highest level of the liquid level is detected, and when the inelastic part on the base end side of the claw is in contact with another stopper, the lowest level of the liquid level is detected. It is a feature.

  According to such a configuration, in a state where the rotating member is assembled in the circular groove of the frame, the rotating member can be easily formed into the circular groove of the frame by rotating until the claw portion of the protrusion gets over the inclined surface of the one stopper. Can be engaged. In this engaged state, the rotation range of the protrusion is restricted by two stoppers, and the lowest and lowest levels of the liquid level can be detected by the protrusions coming into contact with each stopper. . According to the present invention, since the rotation range of the rotating member is regulated by using the protrusion (claw portion) for locking the rotating member, the stopper portion of the frame can be reduced. Therefore, the liquid level sensor can be made compact.

  Here, for example, when the liquid level swings and the float rises, the highest level of the liquid level may be temporarily detected. In this case, the protrusion of the rotating member contacts the stopper. Impact due to contact is relatively small. On the other hand, for example, when a liquid level sensor is installed in an empty fuel tank, if the float collides with the bottom surface of the fuel tank or the like in the lowest level of the liquid level, the protrusion of the rotating member comes into strong contact with the stopper. Sometimes. Therefore, in the present invention, the detection of the highest level of the liquid level is made by detecting a claw part having a weak strength against one stopper part, and the detection of the lowest level of the liquid level that is likely to be overloaded. In addition, the detection is performed when the non-elastic portion on the base end side of the strong claw portion comes into contact with another stopper portion. Thereby, for example, even if the float collides with the bottom surface when the liquid level sensor is inserted into the fuel tank, it is possible to prevent the rotating member and the frame from being damaged.

  In this case, the rotating member has a plurality of notches formed by a plurality of locking projections projecting from the outer peripheral surface on the tip end side in the axial direction from the projecting portion by cutting out from the outer peripheral surface of the circular groove of the frame. The protrusion can be configured to be engaged with the frame by rotating and moving to the rotation range in a state where the protrusion is fitted in the groove.

  According to such a configuration, since the plurality of locking projections are locked on the frame side, the movement of the rotating member in the direction away from the frame can be firmly restricted with a simple structure, and the direction in which the rotating member leaves Even if a force acts on the locking structure, damage to the locking structure can be prevented.

  In addition, the rotation range can be adjusted by the length of the claw portion in the rotation direction in which the claw portion comes into contact with one stopper portion when the projection portion is positioned in the rotation range. According to this, a rotation range can be easily adjusted by preparing several rotating members from which the length of a nail | claw part differs.

  Further, it is assumed that the rotating member has a mirror mirror symmetry with respect to a plane including the axis of the rotating member in a state where the protrusion is positioned in the rotation range. According to this, the rotation direction of the holder can be reversed by exchanging two rotating members having a mirror-symmetrical relationship and assembling to the frame, so it can be easily applied to products having different float deflection directions. It becomes possible to apply.

  Moreover, in order to solve said 2nd subject, this invention is an assembly method of assembling the liquid level sensor of this invention of the above-mentioned description, Comprising: 1st assembling | attaching a rotating member to a flame | frame is made into an engagement state. A second step of storing the detection value of the magnetic detection element at a position where the rotation member engaged with the frame is restricted by the stopper portion in a memory attached to the frame; And a third step of attaching an arm for transmitting the vertical movement to the rotating member to the rotating member.

  In the liquid level sensor according to the present invention, since the rotation of the rotating member is restricted by the protrusion of the rotating member coming into contact with the stopper formed on the frame, the rotating member rotates regardless of the shape of the arm. Range is regulated. Therefore, when such a liquid level sensor is used, the detection value of the magnetic detection element at the position where the rotation of the rotating member is restricted is stored in the memory before the arm is attached to the rotating member attached to the frame. . In this way, the process up to the second process stored in the memory can be made common regardless of the shape of the arm, so that the assembling process can be simplified. Further, since it is not necessary to produce a dedicated jig for storing in the memory in accordance with the shape of the arm, the manufacturing cost can be reduced.

  According to the present invention, it is possible to prevent the liquid level sensor from being damaged even when the float collides with the bottom surface or the like when the liquid level sensor is installed in the fuel tank.

  Furthermore, according to the present invention, the assembling work can be simplified regardless of the shape of the arm.

It is a disassembled perspective view of the liquid level sensor of this embodiment. It is a disassembled perspective view which shows the state which looked at the liquid level sensor of FIG. 1 from the back surface side. It is the top view (a) and right view (b) of the flame | frame used for the liquid level sensor of FIG. FIG. 2 is a left sectional view of a frame used in the liquid level sensor in FIG. 1. It is the left view (a) and right view (b) of the holder used for the liquid level sensor of FIG. It is a figure explaining the rotation range of a holder when a holder is attached to the flame | frame used for the liquid level sensor of FIG. It is a figure explaining the change of the rotation range when the length of a nail | claw part is switched in the state which locked the holder to the flame | frame of FIG. It is a top view when the holder from which a rotation direction differs in the flame | frame of FIG. 1 is latched.

  Hereinafter, an embodiment of a liquid level sensor to which the present invention is applied will be described with reference to the drawings.

  FIG. 1 is an exploded perspective view of an embodiment of a liquid level sensor to which the present invention is applied. FIG. 2 is an exploded perspective view showing a state in which the liquid level sensor of FIG. 1 is viewed from the back side. 3A is a plan view of a frame used in the liquid level sensor of FIG. 1, and FIG. 3B is a right side view. FIG. 4 is a left sectional view of a frame used in the liquid level sensor of FIG. 5A is a left side view of a holder used in the liquid level sensor of FIG. 1, and FIG. 5B is a right side view. 6A and 6B are diagrams for explaining the rotation range of the holder when the holder is locked to the frame of FIG. 1. FIG. 6A shows the lowest level of the liquid level, and FIG. 6B shows the highest level of the liquid level. Represents. FIG. 7 is a diagram for explaining the change of the rotation range when the length of the claw portion is switched in a state where the holder is locked to the frame of FIG. FIG. 8 is a plan view when holders having different rotation directions are respectively engaged with the frame of FIG.

  The liquid level sensor of the present embodiment detects, for example, the level of fuel in a fuel tank of an automobile, and the liquid level sensor of the present embodiment is attached to a predetermined position in the fuel tank. .

  As shown in FIGS. 1 and 2, the liquid level sensor 1 includes a frame 2, a holder 3 serving as a rotating member, and a magnet 4 fixed to the holder 3. The frame 2 is made of a resin material, and is formed in a flat, substantially rectangular parallelepiped shape having the liquid level height of the arrow A (FIG. 1) as a longitudinal direction. The frame 2 includes a base frame 21 and a support frame 23 provided on the base frame 21 with a space 22 interposed therebetween. The support frame 23 is disposed substantially in parallel on the base frame 21, and both end portions thereof are connected to and supported by the base frame 21. A holder hole 24 is provided at the center of the support frame 23, and a plurality of (three in the illustrated example) cuts 25 a to 25 c are provided at equal intervals in the circumferential direction.

  A first stopper 41 and a second stopper 42 are provided at an interval on a surface 23 a along the periphery of the holder hole 24 of the support frame 23. The first stopper 41 and the second stopper 42 have vertical surfaces 41a and 42a that rise vertically from the surface 23a, and inclined surfaces 41b and 42b.

  A cylindrical support shaft 26 protruding from the base frame 21 is provided in the center of the holder hole 24 so as to protrude from the surface 23 a coaxially with the holder hole 24. A Hall element 27 is embedded in the support shaft 26 as a magnetic detection element (FIG. 4). The hall element 27 is electrically connected to a circuit board 28 embedded in the base frame 21. In addition to the Hall element 27, a memory (not shown) is electrically connected to the circuit board 28. As will be described later, the memory is for storing a detected value of the Hall voltage output from the Hall element 27 at a position where the rotation of the holder 3 is restricted. For example, an EPROM capable of writing and erasing is used. . The base frame 21 is provided with two connector portions 29 from which terminals (not shown) of the circuit board 28 protrude and a protective wall 30 that protects a float arm to be described later.

  The holder 3 is made of a resin material, is formed in a cup shape in which one cylindrical opening is closed, and an inner cylinder 33 is coaxially and integrally provided inside the closing surface of the outer cylinder 32. A plurality (three in the illustrated example) of protrusions 34 a to 34 c are provided at equal intervals in the circumferential direction on the outer peripheral surface of the opening periphery of the outer cylinder 32, and these protrusions 34 correspond to the positions of the notches 25, It is formed in a size that can be inserted into the notch 25. Further, a plate-like regulating member 35 extending in the tangential direction from the outer peripheral surface is provided on the outer peripheral surface of the outer periphery of the closed surface of the outer cylinder 32. When viewed from the axial direction of the holder 3, the restricting member 35 is disposed at a position that does not overlap the protrusion 34, and a claw portion 36 that elastically deforms in the axial direction of the holder 3 folds the restricting member 35 at the tip side. It is extended to. A protrusion bulging toward the opening side of the holder 3 is provided at the tip of the claw part 36, and an inclined surface 37 that is inclined toward the opening side is formed on the protrusion.

  A ring-shaped magnet 4 is inserted into the gap between the outer cylinder 32 and the inner cylinder 33 of the holder 3. As shown in FIG. 2, a projecting portion 4 a that protrudes outward is provided on the outer periphery of the magnet 4, and the inner periphery of the outer cylinder 32 of the holder 3 is engaged with the projecting portion 4 a of the magnet 4. An engagement groove 38 is provided. By positioning the protrusion 4 a of the magnet 4 in the engagement groove 38, the magnet 4 is positioned in the circumferential direction with respect to the holder 3.

  As shown in FIG. 2, the holder 3 has a plate-like hook extending in the axial direction from the inside of the closed surface of the outer cylinder 32 in a recess formed by partially cutting the inner periphery of the outer cylinder 32. Two 39 are provided. The hook 39 is formed so as to be elastically deformed in the radial direction of the holder 3, and a claw protruding toward the inner cylinder 33 is formed on the tip side.

  The holder 3 is provided with a fixing portion 50 for fixing one end of the float arm 5. In the illustrated example, one end of the float arm 5 is inserted, and the fixing portion 50 includes two through holes 51 and 52, a guide groove 53 that guides the float arm 5, and an engagement portion that engages and holds the float arm 5. 54. The float 6 is attached to the other end of the float arm 5 by a retaining member 6a without coming off.

  The float 6 is made of, for example, a substantially rectangular parallelepiped made of synthetic resin so as to float on the liquid surface of the liquid (for example, fuel). The float arm 5 is formed of a round bar made of metal such as stainless steel which is a non-magnetic material. In the illustrated example, the float arm 5 is bent at a right angle in a predetermined direction at three locations near both ends and approximately in the center, and is formed so that the holder 3 is rotated by the vertical movement of the float 6. Thereby, the restriction range of the vertical movement of the float 6, that is, the rotation restriction range of the holder 3 with respect to the frame 2, the F point indicating the fuel in the highest state, that is, the full state (FULL), the lowest state, That is, it is set to be performed between the point E indicating the empty state (EMPTY).

  Next, the operation when assembling the liquid level sensor 1 configured as described above will be described.

  First, the magnet 4 is fitted into the holder 3 and fixed. The magnet 4 is fitted into the holder 3 in a state in which the protruding portion 4 a protruding from the outer peripheral surface is aligned with the engaging groove 38 of the outer cylinder 32. At this time, the hook 39 is elastically deformed by the insertion of the magnet 4 and is spread outward, and returns to the original state when the magnet 4 reaches the back. Thus, the magnet 4 is held coaxially by the holder 3 without coming out of the holder 3 in the axial direction at a position where the tip is in contact with the inside of the sealing surface of the holder 3. Moreover, since the protrusion 5a is latched by the engagement groove 38, the magnet 5 does not cause a positional deviation in the rotation direction.

  Subsequently, the holder 3 to which the magnet 4 is fitted is assembled in the frame 2. Here, in order to mount the inner cylinder 33 on the support shaft 26, the protrusions 34 a to 34 c of the holder 3 are made to correspond to the notches 25 a to 25 c of the frame 2, respectively, and the holder 3 is inserted into the holder hole 24 of the frame 2 to the back. . At this time, the holder 3 is inserted at a position where the tip 36 a of the claw portion 36 of the regulating member 35 is advanced more clockwise than the second stopper 42. In this state, the inclined surface 37 of the claw portion 36 is disposed so as to face the inclined surface 42 b of the second stopper 42.

  After the holder 3 is assembled in this manner, the holder 3 is rotated counterclockwise until the claw portion 36 is elastically deformed and the claw portion 36 gets over the second stopper 42. At this time, it is possible to prevent the holders 3 from coming out of the frame 2 due to the projections 34 being caught on the edge of the holder hole 24. As a result, the holder 3 is engaged with the frame 2 and is supported to freely rotate around the support shaft 26. The rotation range of the holder 3 is such that the tip 36a of the claw portion 36 of the regulating member 35 abuts against the flat surface 42a of the second stopper 42, and the base end 36b of the claw portion 36 of the regulating member 35 is the flat surface 41a of the first stopper 41. Is set to a predetermined range up to the position where it hits, that is, a rotation restriction range.

  In order to smoothly rotate the holder 3, the opening end surface 3 a of the inner cylinder 33 protrudes in the axial direction from the opening end surface 4 a of the outer cylinder 32 so that the opening end surface 3 a of the holder 3 does not contact the base frame 21. Is formed. The axial length of the support shaft 26 is shorter than the axial length of the inner cylinder 33.

  By the way, the liquid level sensor 1 assembled in this way is usually in a state where the float 6 is suspended from the holder 3 via the float arm 5, that is, in a state where the liquid level shows the lowest level. It is inserted into an empty fuel tank and manually attached to a predetermined position in the tank.

  However, since the space in the fuel tank is narrow and dark, an operator may accidentally collide the float 6 suspended from the frame 2 with the bottom or side surface of the fuel tank. In this case, when an impact force is applied in the direction in which the float 6 rotates, the impact force is released by the rotation of the float 6, and the impact force transmitted to the frame 2 side becomes small. However, when an impact force is applied in a direction in which the float 6 does not rotate, the float 6 is already in a state where the liquid level is at the lowest level. For this reason, the float 6 does not rotate, and the force is directly transmitted to the frame 2 side, so that the impact is large. When receiving such a large impact, the frame 2, the holder 3, and the float arm 5 may be damaged.

  In the present embodiment, when the tip 36a of the claw portion 36, which is an elastic structure having a relatively weak strength, abuts against the flat surface 42a of the second stopper 42, the highest level of the liquid level is detected and the relatively strong non-strength is detected. When the base end 36b of the claw portion 36, which is an elastic structure, comes into contact with the flat surface 41a of the first stopper 41, the lowest level state of the liquid level is detected. That is, the holder 3 engaged with the frame 2 has a rotational phase in which the float 6 is at the lowest position due to the action of gravity in the empty fuel tank, that is, as shown in FIG. The base end 36b of the claw portion 36 of the holder 3 comes into contact with the flat surface 41a of the first stopper 41 (point E), and the lowest level state of the liquid level is detected. On the other hand, when the liquid level rises due to refueling or rocking of the liquid level while the float 6 is floating on the liquid level in the fuel tank, the holder 3 rotates clockwise, as shown in FIG. Furthermore, the tip 36a of the claw portion 36 of the regulating member 35 comes into contact with the flat surface 42a of the second stopper 42 (point F), and the highest level of the liquid level is detected.

  In this embodiment, a stopper structure with high strength is adopted on the point E side where overload is applied, and a claw structure which can be elastically deformed and hinged is adopted on the point F side where low load is applied. . For this reason, even when the float 6 collides against the bottom surface or the side surface when the liquid level sensor 1 is installed in the fuel tank, the stopper structure having high strength on the point E side does not cause deformation such as bending. Since the rotation of the holder 3 can be restrained, the holder 3 and the frame 2 can be prevented from being damaged.

  Moreover, according to this embodiment, since the rotation range of the holder 3 is regulated using the nail | claw part 36 for making the holder 3 latch with the frame 2, the stopper of the frame 2 can be made small. The liquid level sensor 1 can be downsized.

  Further, according to the present embodiment, the holder 3 is rotated with respect to the frame 2 by rotating the holder 3 in a state where the three protrusions 34 a to 34 c of the holder 3 are assembled to correspond to the notches 25 a to 25 c of the frame 2. Even if a force is applied in a direction in which the holder 3 moves away from the frame 2, the holder 3 can be firmly held by the three protrusions 34 a to 34 c.

  In the present embodiment, since the float 3 is inserted into the holder 3 and fixed after the holder 3 is assembled to the frame 2 after being rotated, the float arm 5 is assembled last. It is possible to suppress bulkiness during product transfer.

  Further, in the present embodiment, the rotation range of the float 2 is set such that the tip 36 a of the claw portion 36 of the regulating member 35 contacts the flat surface 42 a of the second stopper 42, and the base end 36 b of the claw portion 36 is the first stopper 41. Although it is set as a range up to a position corresponding to the flat surface 41a, this rotation range can be adjusted by appropriately changing the length of the claw portion 36 of the regulating member 35, for example. That is, as shown in FIG. 7, the circumferential direction until the tip 36 a of the claw 36 hits the flat surface 42 a of the second stopper 42 by shortening the length of the claw 36 extending in the rotation direction of the holder 3. Therefore, for example, the rotation range 60 ° of (b) can be increased to the rotation range 80 ° of (a). Thus, by preparing the holder 3 having a part of the restriction member 35 having a different length, the rotation range of the float 6 can be appropriately changed using the common frame 2.

  In the present embodiment, an example in which the holder 3 is rotated clockwise (arrow a) in the direction in which the tip 36a of the claw portion 36 contacts the second stopper 42, that is, as shown in FIG. 6) However, instead of this, the holder 3 may be formed to rotate counterclockwise (arrow b) as shown in FIG. 8B. These holders 3 are in a state in which the shape of the holder 3 around the rotation axis is mirror-symmetric with respect to a plane including this axis in a state in which the claw portion 36 is located in the rotation restriction range between both stoppers. By replacing the holders having a mirror-symmetrical relationship in this way, the rotation direction of the holder 3, that is, the rotation direction from the point E to the point F can be reversed, and the fuel tank having a different deflection direction of the float 6. It is possible to easily apply to the above.

  By the way, when assembling the liquid level sensor 1 of the present embodiment, the Hall element at a position where the rotation of the holder 3 is restricted in a state in which the holder 3 to which the magnet 4 is attached is assembled and engaged with the frame 2. 27 detection values are written in the memory, and then the float arm 5 is attached to the holder 3. Specifically, the position where the tip 36a of the claw portion 36 of the regulating member 35 abuts on the flat surface 42a of the second stopper 42 (point F) and the base end 36b of the claw portion 36 of the regulating member 35 are the first stopper 41. The Hall voltage output from the Hall element 27 is detected at a position where it abuts on the flat surface 41a (point E), and the detected value is written in the memory. Thus, the upper limit and the lower limit of the liquid level detection can be defined by writing the detected value of the Hall voltage in a state in which the rotation of the holder 3 is restricted to the memory. When the writing to the memory is completed, the float arm 5 that matches the product number of the liquid level sensor 1 is assembled to the holder 3.

  According to the assembling method of the present embodiment, it is possible to share and automate the process until it is stored in the memory regardless of the shape of the float arm 5. As a result, the assembling work can be simplified, and the inventory can be reduced by the first-in first-out operation by sharing the parts. Moreover, when performing the assembly | attachment operation | work of the float arm 5 to the holder 3 by a manual operation etc., since it can work collectively in the area where labor costs are cheap, for example, it can aim at reduction of manufacturing cost. Further, since the holder 3 is assembled to the frame 2 and the float arm 5 is not attached, it can be transported in a compact manner, so that the transportation cost can be reduced.

DESCRIPTION OF SYMBOLS 1 Liquid level sensor 2 Frame 3 Holder 4 Magnet 5 Float arm 6 Float 21 Base frame 22 Space 23 Support frame 24 Holder hole 25 Cut 26 Support shaft 27 Hall element 32 Outer cylinder 33 Inner cylinder 33 Projection 35 Restriction member 36 Claw part 36a Front end 36b Base end 37 Inclined surface 41 First stopper 42 Second stopper 50 Fixed portion

Claims (5)

A cylindrical rotating member on which a ring-shaped magnet is fixed coaxially, a frame that rotatably supports the rotating member, and fixed to the frame so as to face the magnet. A liquid level sensor configured to rotate the rotating member by a vertical movement of a float that floats on a liquid surface, and a magnetic detection element that detects by change.
The frame includes a circular groove into which the rotating member is inserted, and two stopper portions that are provided at a peripheral edge of the circular groove and restrict a rotation range of a protruding portion that protrudes from the outer peripheral surface of the rotating member. Have
When the rotating member is assembled into the circular groove of the frame and then the protruding portion is rotated to the rotation range to be in an engaged state, the one protruding portion first contacts the protruding portion. An inclined surface rising in the rotational movement direction is formed, and the protrusion is formed with a claw portion that elastically deforms and climbs over the inclined surface of the one stopper portion,
When the claw portion comes into contact with the one stopper portion in a state where the projection portion is located in the rotation range, the highest level state of the liquid surface is detected and the inelasticity of the base end side of the claw portion is detected. A liquid level sensor that detects the lowest level of the liquid level when the portion abuts against the other stopper.   The rotating member has a plurality of notches formed by a plurality of locking protrusions protruding from the outer peripheral surface on the tip end side in the axial direction from the protrusions by cutting outward from the outer peripheral surface of the circular groove of the frame. 2. The liquid level sensor according to claim 1, wherein in a state where the protrusion is inserted into the groove and assembled, the protrusion is rotated to the rotation range to be engaged with the frame. 3.   The rotation range is adjusted by a length of the claw portion in a rotation direction in which the claw portion comes into contact with the one stopper portion when the protrusion is positioned in the rotation range. 2. The liquid level sensor according to 2.   4. The rotating member has one of mirror symmetry with respect to a plane including the axis of the rotating member in a state where the protrusion is positioned in the rotation range. 5. The liquid level sensor according to any one of the above. An assembly method for assembling the liquid level sensor according to claim 1,
A first step of assembling the rotating member to the frame;
A second step of storing a detection value of the magnetic detection element in a position where the rotation member engaged with the frame is restricted in rotation by the stopper portion in a memory attached to the frame;
And a third step of attaching to the rotating member an arm for transmitting the vertical movement of the float to the rotating member after storing in the memory.

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