JP4905192B2 - Liquid level detection device and manufacturing method thereof - Google Patents

Description

  The present invention relates to a liquid level detecting device for detecting a liquid level of a liquid contained in a container and a method for manufacturing the same, and more particularly, to a liquid level position of a fuel that is mounted in a fuel tank of an automobile or the like. It is suitable for application to a liquid level detection device for detection.

  As a conventional liquid level detection device of this type, for example, a magnet is fixed in a rotating member that rotates when a vertical movement of a float that floats on the liquid surface is transmitted through an arm, and the rotating member is rotatably held. There exists a thing of the structure which has arrange | positioned the Hall element which is a magnetoelectric conversion element in a member (refer patent document 1).

  In this conventional liquid level detection device, the magnetoelectric conversion element is connected to an external electric circuit through an electric conductor having one end connected to the electrode of the magnetoelectric conversion element in the main body and the other end exposed to the outside of the main body. Electrically connected. In order to prevent liquid from entering the main body through the gap between the main body and the electric conductor, a rubber material is disposed so as to be in close contact with the entire circumference of the electric conductor in the main body. The electric conductor and the rubber material are insert-molded at predetermined positions in the main body when the main body is molded with a resin material.

  Further, as another example of the conventional liquid level detection device, a resin bush fitted to an electric conductor in a resin body, and the electric conductor interposed between the resin bush and the electric conductor and by the resin bush. In contrast, there is one having a seal structure composed of an elastic bush to which a compressive stress is applied (see Patent Document 1).

Also in this case, the electric conductor, the resin bush, and the elastic bush are insert-molded at predetermined positions in the main body when the main body is molded with a resin material.
Japanese Patent Laid-Open No. 2005-10047 Japanese Utility Model Publication No. 1-124676

  In the above-described liquid level detection device described in Patent Document 1, when the electric conductor and the rubber material are insert-molded into the resin material, the rubber material is deformed by the heat and pressure of the molten resin, and the electric conductor and It may be difficult to ensure the seal between the main body portions. Further, in the liquid level detection device described in Patent Document 2 described above, the elastic bushing is protected by the resin bushing and its deformation is restricted, but since the molten resin directly touches the elastic bushing, the rubber material is also deformed, There is a possibility that it is difficult to secure a seal between the electric conductor and the main body.

  The present invention has been made in view of such a problem, and an object of the present invention is to provide a liquid level detection device capable of suppressing the rubber material from being deformed and the sealing performance between the electric conductor and the main body from being deteriorated in the manufacturing process. And a method for manufacturing the same.

  The present invention employs the following technical means to achieve the above object.

  According to a first aspect of the present invention, there is provided the liquid level detecting device, wherein the rotating member, a fixing member made of a resin material that rotatably holds the rotating member, a float floating in the liquid, and a float fixed to one end side An arm whose other end is fixed to the rotating member and converts the vertical movement of the float caused by the vertical movement of the liquid level into the rotational movement of the rotating member; a magnetoelectric conversion element housed in the fixing member so that the displacement of the magnet can be detected; A liquid level detecting device comprising an electric conductor having one end connected to an electrode of a magnetoelectric conversion element and the other end extending to the outside of the fixing member so as to be connectable to an external electric circuit in the fixing member. A sheath member fitted in the electric conductor, and an elastic bushing interposed between the sheath member and the electric conductor and applying a compressive stress to the electric conductor by the sheath member, the elastic bushing being in the axial direction of the electric conductor In It is characterized in that it comprises an annular recess which is concave with respect to the annular and fixing member of the electrical conductor and substantially coaxially at the opposite end with a member.

  In the step of insert molding by setting the sheath member fitted with the electrical conductor and the elastic bushing in the molding die of the fixing member, the molten resin injected into the mold cavity reaches the elastic bushing, The elastic bush is pressed under the pressure of the molten resin. At this time, in the annular recess of the elastic bush, the force due to the pressure of the molten resin acts to widen the annular recess. That is, the elastic bushing is pressed against the electric conductor on the inner peripheral side of the annular recess, and at the same time, the elastic bushing is pressed against the sheath member on the outer peripheral side of the annular recess. Therefore, in the insert molding process, when the elastic bushing receives the pressure of the molten resin, the surface pressure between the elastic bush and the electric conductor and the surface pressure between the elastic bush and the sheath member become higher, and the seal between the elastic bush and the electric conductor becomes higher. And sealability between the elastic bushing and the sheath member are improved. As a result, as in the case of a conventional liquid level detection device, the deformation of the elastic bush becomes non-uniform due to the molten resin directly contacting the elastic bush during insert molding, and the elastic bush and the electrical conductor, and between the elastic bush and the sheath member. It is possible to prevent a problem that good airtightness cannot be maintained.

  As described above, it is possible to provide a liquid level detection device capable of suppressing the rubber material from being deformed in the manufacturing process and reducing the sealing performance between the electric conductor and the main body.

  In this case, as in the liquid level detection device according to claim 2 of the present invention, if the axial cross-sectional shape of the annular recess is substantially V-shaped or semicircular, the invention according to claim 1 is achieved. The effect, that is, the effect of further increasing the surface pressure between the elastic bush and the electric conductor and the surface pressure between the elastic bush and the sheath member can be obtained with certainty.

  The liquid level detection apparatus according to claim 3 of the present invention is characterized in that an annular protrusion is formed on the outer periphery of the sheath member within the fixed member.

  In such a configuration, the molten resin injected into the mold cavity is inserted into the sheath in the step of insert molding by setting the elastic bushing and the lid member in the molding die of the fixing member while fitting the electric conductor. The entire outer surface of the member, that is, the outer surface of the annular protrusion provided on the outer periphery of the sheath member is in close contact. Thereby, the contact area of a fixing member and a sheath member becomes large, and the coupling force of a fixing member and a sheath member can be raised. In addition, in the unlikely event that a gap is generated between the sheath member and the fixing member after the insert molding, this gap can be a path for liquid to enter from the outside of the fixing member, but the protrusion provided on the outer periphery of the sheath member Therefore, this path is bent and the total length is increased. Therefore, even if the liquid enters, the intrusion stops due to the pressure loss of the pipe resistance of this path, and it is possible to prevent the liquid from entering the depth of the fixed member, for example, to the place where the magnetoelectric conversion element is present.

  In this case, as in the liquid level detection device according to claim 4 of the present invention, if the sheath member is formed of a resin material, the annular member provided in the sheath member in the step of insert molding the sheath member into the fixed member. When the projections of the sheath member are wrapped in the molten resin, the projections of the sheath member have a surface area larger than the volume thereof, so that the temperature of the projection is higher than the other portions of the sheath member. Weld. That is, in the annular protrusion, the sheath member and the fixing member are completely welded. Therefore, even when the liquid level detection device is immersed in the liquid in the usage state of the liquid level detection device, the liquid is prevented from entering through the boundary portion between the sheath member and the fixing member and reaching the magnetoelectric conversion element. be able to.

  A manufacturing method of a liquid level detection device according to claim 5 of the present invention is the manufacturing method of the liquid level detection device according to any one of claims 1 to 3, wherein a sheath member is provided on the electric conductor. A first step of fitting an elastic bush between the electric conductor and the sheath member; and a second step of insert molding the sheath member and the electric conductor after the first step to form a fixing member. It is said.

  By performing the above-described steps in this order, a method for manufacturing a liquid level detection device capable of suppressing the rubber material from being deformed in the manufacturing process and reducing the sealing performance between the electric conductor and the main body is provided. be able to.

  Hereinafter, a case where the liquid level detection device according to the embodiment of the present invention is applied to a fuel level gauge 1 that is mounted in a fuel tank of an automobile and detects the level of fuel will be described with reference to the drawings. In addition, the same code | symbol is attached | subjected to the same component in each figure.

  The fuel level gauge 1 is disposed and fixed in the fuel tank 14, for example, in the fuel tank 14. The fuel level gauge 1 is a fuel pump for sending the fuel 13 to the outside of the fuel tank 14, for example, an engine (not shown). (Not shown).

  Below, the structure of the fuel level gauge 1 is demonstrated.

  The magnet holder 2 that is a rotating member is formed of, for example, a resin material. A magnet 6 is fixed to the magnet holder 2 as shown in FIG. The magnet holder 2 is rotatably held by a body 3 which is a main body portion to be described later. Thereby, when the magnet holder 2 rotates with respect to the body 3, the magnet 6 also rotates integrally with the magnet holder 2, that is, displaces with respect to the body 3.

  Further, as shown in FIG. 1, the arm 5 is fixed to the magnet holder 2. The arm 5 is made of a metal material, for example, a stainless steel round bar. As shown in FIG. 1, a float 4 to be described later is fixed to one end side of the arm 5, and the other end side of the arm 5 is fixed to the magnet holder 2. Since the float 4 is set so as to float on the fuel 13 that is a liquid, the arm 5 functions to convert the vertical movement of the float 4 due to the vertical movement of the liquid surface 13 a into the rotational movement of the magnet holder 2. As shown in FIG. 2, the end of the arm 5 on the side opposite to the float 4 is bent at a substantially right angle toward the body 3 to form a stopper 5a. The stopper 5a is formed in parallel with the rotation axis of the magnet holder 2, that is, the center axis of the hole 2a described later. The stopper portion 5 a functions to fix the arm 5 to the magnet holder 2 by fitting into the fixing hole 2 c of the magnet holder 2. At the same time, the stopper 5a comes into contact with a stopper 3d formed on the body 3 described later, as shown in FIG. Thereby, the rotation angle range of the magnet holder 2 is regulated.

  The float 4 is formed in a hollow three-dimensional shape from a resin material or the like, and has an apparent specific gravity so as to surely float on the liquid level 13a of the fuel when attached to the arm 5. When the float 4 moves up and down in accordance with the change in the position of the liquid level 13 a, this movement is transmitted to the magnet holder 2 by the arm 5, and the magnet holder 2 rotates with respect to the body 3.

  As shown in FIG. 2, the magnet holder 2 includes a hole portion 2 a that is rotatably fitted to a shaft portion 3 a of a body 3 described later. The magnet holder 2 is moved in the axial direction (left and right direction in FIG. 2) at the end opposite to the body 3 (left side in FIG. 2) in the axial direction of the hole 2a when the magnet holder 2 is assembled to the body 3. A restricting portion 2b that restricts the above is provided. Further, as shown in FIG. 2, the magnet holder 2 is provided with a fixing hole 2 c that fits with a stopper 5 a provided on the arm 5. As shown in FIG. 2, the fixing hole 2 c is formed in parallel with the hole 2 a of the magnet holder 2. The diameter dimension of the fixing hole 2 c is formed to be the same as or slightly smaller than the diameter dimension of the arm 5. That is, the size of the two is such that when the arm 5 is attached to the magnet holder 2 in the assembly process of the fuel level gauge 1, the arm 5 can be easily inserted into the fixing hole 2c by an operator and inserted into the fixing hole 2c. The rear arm 5 is an interference fit that can be rotated by hand.

  As shown in FIG. 2, the magnet holder 2 is provided with a fixing portion 2 d for holding the arm 5. As shown in FIGS. 1 and 2, two fixing portions 2 d are arranged on the end surface of the magnet holder 2 opposite to the body 3. As shown in FIG. 3, the fixing portion 2 d includes a holding portion 2 e that is in close contact with the arm 5, and an opening 2 f that serves as an entrance to the fixing portion 2 d when the arm 5 is attached. In FIG. 3, the fixing portion 2 d shows a shape when the arm 5 is not attached, and the arm 5 is indicated by a one-dot chain line. As shown in FIG. 3, the holding portion 2 e is formed in a circular shape, as shown in FIG. 3, and the diameter dimension d <b> 1 is larger than the diameter dimension D <b> 1 of the arm 5. It is formed small. As shown in FIG. 3, the opening 2f has a width W that is smaller than the diameter d1 of the holding portion 2e. When the arm 5 is mounted in the groove 24a of the fixed portion 2d, when the arm 5 is pushed into the groove 24a of the fixed portion 2d from the left side of FIG. 3, the fixed portion 2d is elastically deformed and the arm 5 is moved to the holding portion 2e. Is fixed. At this time, the fixing portion 2d is in an elastically deformed state, and the arm 5 is held by the elastic force of the fixing portion 2d. Further, the two fixing portions 2d are arranged with the central axes of the respective holding portions 2e aligned. Furthermore, the common central axis of both the holding parts 2e is arranged so as to intersect with the central axis of the fixing hole 2c fitted to the stopper 5a provided on the arm 5.

  Since the magnet holder 2 is configured as described above, the arm 5 can be easily and reliably attached to the magnet holder 2.

  A magnet 6 that is a permanent magnet as a displacement member is fixed to the magnet holder 2. The magnet 6 is made of, for example, a ferrite magnet or the like, and in the fuel level gauge 1 according to the embodiment of the present invention, a cylindrical type is used, and is disposed concentrically with the hole 2a as shown in FIG. . Further, the magnet 6 is two-pole magnetized as shown in FIG. The magnetic flux M of the magnet 6 is distributed as shown in FIG. 4, and the magnetic flux on the inner peripheral side of the magnet 6 flows in the radial direction of the hole 2a. Further, in the fuel level gauge 1 according to one embodiment of the present invention, the magnet 6 is insert-molded integrally in the magnet holder 2 when the magnet holder 2 is resin-molded.

  The body 3 that is a fixing member is formed of a resin material. As shown in FIG. 2, the body 3 includes a shaft portion 3a, and the hole portion 2a of the magnet holder 2 is fitted to the outer periphery of the shaft portion 3a, so that the magnet holder 2 is rotatably held. . As shown in FIG. 2, a small-diameter portion 3b having a diameter smaller than that of the shaft portion 3a is extended on the distal end side of the shaft portion 3a that is fitted to the hole portion 2a of the magnet holder 2. As shown in FIG. 2, a groove 3c is provided in the small diameter portion 3b. As shown in FIG. 2, a snap ring 15 is attached to the groove 3c. When the restricting portion 2b of the magnet holder 2 comes into contact with the snap ring 15, the movement of the magnet holder 2 in the direction away from the body 3 (movement toward the left side in FIG. 2) is restricted. As shown in FIG. 1, the body 3 includes a pair of stoppers 3 d for restricting the rotation angle range of the magnet holder 2.

  In the shaft portion 3a of the body 3, as shown in FIG. 2, a Hall IC 7 serving as a magnetoelectric conversion element serving as detection means for detecting the displacement of the magnet 6 serving as a displacement member is incorporated. The Hall IC 7 is held in the body 3 by insert molding the body 3 during resin molding. As shown in FIG. 2, the Hall IC 7 is arranged so that the overlapping length with the magnet 6 is as long as possible inside the magnet 6 and in the axial direction of the shaft portion 3a. Thereby, the magnetic flux M amount of the magnet 6 intersecting with the Hall IC 7 can be increased, the output voltage of the Hall IC 7 can be increased, and the liquid level 13a detection accuracy can be increased. The Hall IC 7 includes a lead 7a for electrically connecting the Hall IC 7 to the outside. The Hall IC 7 used in the fuel level gauge 1 according to the embodiment of the present invention includes three leads 7a.

  Here, the operation of the Hall IC 7 will be briefly described.

  The Hall IC 7 is made of a semiconductor, and generates a Hall voltage proportional to the magnetic flux density passing through the Hall IC 7 when a magnetic field is applied from the outside while a voltage is applied to the Hall IC 7. That is, when the Hall IC 7 and the magnetic flux M are orthogonal, the magnetic flux density passing through the Hall IC 7 is maximized and the Hall voltage is maximized. When the Hall IC 7 and the magnetic flux M are parallel, the magnetic flux density passing through the Hall IC 7 is minimized and the Hall voltage is minimized.

  In the fuel level gauge 1 according to the embodiment of the present invention, when the magnet holder 2 rotates due to the fluctuation of the liquid level 13a, the crossing angle between the Hall IC 7 and the magnetic flux M of the magnet 6 changes, and accordingly, the output of the Hall IC 7 The Hall voltage, which is a voltage, changes. Therefore, the rotation angle of the magnet holder 2, that is, the position of the liquid surface 13a can be measured by detecting the Hall voltage.

  The three leads 7a of the Hall IC 7 are each electrically connected to the terminal 8 as shown in FIG. The terminal 8 is made of a conductive material such as a copper-based metal. Both are connected and fixed by caulking or fusing. The opposite end portion of each terminal 8 connected to the lead 7 a is electrically connected to an electric wire 9 that is an electric conductor, and is connected to an external electric circuit via the electric wire 9. That is, as shown in FIG. 2, one end of the electric wire 9 is conductively connected to the lead 7 a of the Hall element 7 via the terminal 8, and the other end extends outside the body 3. As the electric wire 9, one formed by covering the outer periphery of a conductor such as a copper wire with an insulating coating film made of resin, rubber or the like is used. At the joint between the electric wire 9 and the terminal 8, the conductor of the electric wire 9 and the terminal 8 are connected and fixed by caulking or fusing, and a part of the terminal 8 sandwiches the insulating coating film of the electric wire 9. . As shown in FIG. 2, the electric wire 9 is fitted and held in a sleeve 10 that is a sheath member in the body 3.

  The sleeve 10 is formed in a substantially bottomed cylindrical shape from a resin material. As shown in FIG. 2, the sleeve 10 includes a bottom portion 10c and a cylindrical portion 10a formed subsequent to the bottom portion 10c. Further, on the outer periphery of the sleeve 10, a ring portion 10b which is an annular protrusion extending over the entire periphery is provided. In the fuel level gauge 1 according to the embodiment of the present invention, three ring portions 10 b are provided at substantially equal intervals in the axial direction of the sleeve 10. As shown in FIG. 2, the sleeve 10 is fitted to the electric wire 9 at the bottom 10 c. In a state where the electric wire 9 is fitted to the sleeve 10, the terminal 8, that is, the Hall element 7 is positioned on the cylindrical portion 10 a side of the sleeve 10 as shown in FIG. 2. In other words, the sleeve 10 is disposed in the body 3 such that the cylindrical portion 10 a is on the Hall element 7 side and the bottom portion 10 c is on the opposite side of the Hall element 7, that is, toward the outside of the body 3.

  A rubber bush 11 that is an elastic bush is disposed in the cylindrical portion 10a. The rubber bush 11 is formed in a substantially cylindrical shape, and its cylindrical hole portion is fitted to the electric wire 9 and its outer peripheral portion is fitted to the cylindrical portion 10 a of the sleeve 10. In the state of the rubber bush 11 alone, that is, the state before being attached to the sleeve 10, the inner diameter dimension of the cylindrical hole portion is the same as or slightly smaller than the outer diameter dimension of the electric wire 9, and the outer diameter dimension is the inner diameter dimension of the cylindrical portion 10 a of the sleeve 10. It is set larger. For this reason, when the electric wire 9 is fitted to the rubber bush 11 and the rubber bush 11 is fitted to the cylindrical portion 10a of the sleeve 10, the rubber bush 11 is elastically deformed to be in a compressed state. Acts on the sleeve 10. That is, the surface pressure at the contact portion between the rubber bush 11 and the electric wire 9 and the surface pressure at the contact portion between the rubber bush 11 and the sleeve 10 are increased. Thereby, the airtightness between the rubber bushing 11 and the electric wire 9 and the airtightness between the rubber bushing 11 and the sleeve 10 are maintained high. An annular groove 11a, which is an annular recess, is formed at the end of the rubber bush 11 opposite to the bottom 10c of the sleeve 10, that is, the open end of the cylindrical portion 10a of the sleeve 10. As shown in FIG. 3, the annular groove portion 11 a has a substantially inverted V-shaped cross section. The annular groove portion 11 a is formed coaxially with the through hole 11 b formed in the rubber bush 11 for allowing the electric wire 9 to pass therethrough. Therefore, when the electric wire 9 is fitted to the rubber bush 11 and the rubber bush 11 is fitted to the cylindrical portion 10 a of the sleeve 10, the annular groove portion 11 a is in a coaxial relationship with the electric wire 9.

  The sleeve 10 is disposed with respect to the body 3 such that the cylindrical portion 10 a is on the Hall element 7 side and the bottom portion 10 c is on the opposite side of the Hall element 7, that is, toward the outside of the body 3. As shown in FIG. 2, a part of the bottom portion 10 c of the sleeve 10 is exposed to the outside of the body 3, and the electric wire 9 extends to the outside of the sleeve 10.

  Next, a method for manufacturing the fuel level gauge 1 according to one embodiment of the present invention, particularly a method for manufacturing the body 3 that is a feature of the fuel level gauge 1 according to one embodiment of the present invention will be described.

  First, each of the three leads 7a of the Hall element 7 is connected to one end of the terminal 8 by caulking or fusing.

  Next, the other end of the terminal 8 is connected to one end of the conductor of the electric wire 9 by caulking or fusing. At this time, a part of the terminal 8 is plastically deformed to sandwich the insulating coating film of the electric wire 9.

  Next, the rubber bush 11 and the sleeve 10 are fitted to the electric wire 9 in this order from the other end side. At this time, it arrange | positions so that the annular groove part 11a of the rubber bush 11 may exist on the opposite side to the bottom part 10c of the sleeve 10, ie, it may become a positional relationship as shown in FIG.

  Next, the sleeve 10 is set at a predetermined position with respect to the electric wire 9, that is, a position as shown in FIG. 2, and then the rubber bush 11 is fitted into the cylindrical portion 10 a of the sleeve 10. At this time, the rubber bush 11 is brought into contact with the bottom 10 c of the sleeve 10.

  Next, a sub-assembly (hereinafter simply referred to as a sub-assembly) composed of the Hall element 7, the terminal 8, the electric wire 9, the sleeve 10, and the rubber bush 11 integrated through the above-described steps is molded into the body 3 resin. Set in a mold for insert molding. Here, the resin material forming the body 3 is the same as the resin material used for the sleeve 10.

  In this insert molding process, the molten resin injected into the mold for molding the body 3 resin is in close contact with the outer surface of the sleeve 10 and the rubber bush. At this time, the force in the direction indicated by the arrow in FIG. 3 acts on the molten resin side end portion of the rubber bush 11, specifically, on the annular groove portion 11 a of the rubber bush 11 due to the injection pressure of the molten resin. Further, when the outer surface of the ring portion 10b of the sleeve 10 is covered with the molten resin, the ring portion 10b has a large surface area compared to its volume due to the protrusion shape, so that the temperature rises quickly due to the heat of the molten resin. Then, the surface of the ring portion 10b is melted and fused and integrated with the injected resin. That is, in the completed body 3, the sleeve 10 and the body 3 are integrated by melting at the ring portion 10b, and there is no gap between them.

  Thus, the body 3 is completed.

  Next, the operation and effect of the fuel level gauge 1 configured as described above according to the embodiment of the present invention, particularly the operation and effect of the configuration of the lead-out portion of the electric wire 9 from the body 3 will be described.

  When manufacturing the fuel level gauge 1 according to the embodiment of the present invention, as described above, in the step of insert molding by setting the subassembly in the body 3 resin molding die, Specifically, a force in a direction indicated by an arrow in FIG. 3 acts on the annular groove portion 11a of the rubber bush 11 by the injection pressure of the molten resin. As shown in FIG. 3, this force acts in a direction substantially perpendicular to the wall surface of the annular groove 11 a and a direction toward the bottom 10 c of the rubber bush 11 sleeve 10. Under these forces, the rubber bushing 11 is pressed against the electric wire 9 and the cylindrical portion 10 a of the sleeve 10. Thereby, in the vicinity of the annular groove 11a of the rubber bush 11, the surface pressure of the contact portion between the rubber bush 11 and the electric wire 9 and the surface pressure of the contact portion between the rubber bush 11 and the sleeve 10 are larger than before the insert molding step. Here, the annular groove portion 11a, the electric wire 9 and the cylindrical portion 10a of the sleeve 10 are in a coaxial positional relationship. For this reason, although the surface pressure of the contact part of the rubber bush 11 and the electric wire 9 in the vicinity of the annular groove 11a of the rubber bush 11 and the surface pressure of the contact part of the rubber bush 11 and the sleeve 10 are increased as compared with those before the insert molding, the rubber bush 11 The size is uniform in the circumferential direction. That is, the surface pressure distribution in the circumferential direction of the rubber bush 11 is uniform. Thereby, the airtightness between the rubber bushing 11 and the electric wire 9 and the airtightness between the rubber bushing 11 and the sleeve 10 are maintained high without being lowered. Therefore, as in the case of the conventional liquid level detection device, the deformation of the elastic bush becomes non-uniform due to the molten resin coming into direct contact with the elastic bush at the time of insert molding, and between the elastic bush and the electric conductor and between the elastic bush and the sheath member. Therefore, it is possible to prevent the problem that the favorable airtightness cannot be maintained.

  Also on the outer peripheral side of the sleeve 10, the surface of the ring portion 10 b is melted by the heat of the injected resin and fused and integrated with the injected resin, so that the airtightness between the sleeve 10 and the body 3 is maintained well. .

  Next, a modification of the fuel level gauge 1 according to an embodiment of the present invention will be described.

  In this modification, the cross-sectional shape of the annular recess of the rubber bush 11 is changed with respect to the fuel level gauge 1 according to the embodiment of the present invention. In other words, the annular recess is changed from an annular groove 11a having an inverted V-shaped cross section in the fuel level gauge 1 according to the embodiment of the present invention to an annular groove 11c having a substantially semicircular cross section as shown in FIG. .

  Also in this modification, in the step of insert molding by setting the subassembly in the body 3 resin molding die, the molten resin side end portion of the rubber bush 11, that is, the annular groove portion 11c, due to the molten resin injection pressure, In FIG. 6, a force in the direction indicated by the arrow acts. As shown in FIG. 6, this force acts in a direction substantially perpendicular to the wall surface of the annular groove 11c. Under these forces, the rubber bushing 11 is pressed against the electric wire 9 and the cylindrical portion 10 a of the sleeve 10. Thereby, in the vicinity of the annular groove portion 11c of the rubber bush 11, as in the case of the fuel level gauge 1 according to the embodiment of the present invention, the contact pressure between the rubber bush 11 and the electric wire 9, and the rubber bush 11 and the sleeve 10 The surface pressure of the contact portion becomes larger than that before the insert molding process. Here, the annular groove portion 11c, the electric wire 9 and the cylindrical portion 10a of the sleeve 10 are in a coaxial positional relationship. For this reason, although the surface pressure of the contact part of the rubber bush 11 and the electric wire 9 in the vicinity of the annular groove 11c of the rubber bush 11 and the surface pressure of the contact part of the rubber bush 11 and the sleeve 10 are increased from those before the insert molding, the rubber bush 11 The size is uniform in the circumferential direction. That is, the surface pressure distribution in the circumferential direction of the rubber bush 11 is uniform. Thereby, the airtightness between the rubber bushing 11 and the electric wire 9 and the airtightness between the rubber bushing 11 and the sleeve 10 are maintained high without being lowered.

  From the above, the fuel level gauge that can maintain the airtightness between the rubber bushing 11 and the electric wire 9 and the airtightness between the rubber bushing 11 and the sleeve 10 by the modification of the fuel level gauge 1 according to the embodiment of the present invention. 1 can be provided.

  In the fuel level gauge 1 according to one embodiment of the present invention described above, the cross-sectional shape of the annular recess is an inverted V shape, and in the fuel level gauge 1 according to the modification, the cross-sectional shape of the annular recess is a substantially semicircular shape. However, the cross-sectional shape of the annular recess is not limited to these shapes, and a force that presses the rubber bush 11 against the electric wire 9 and the cylindrical portion 10a of the sleeve 10 acts upon receiving the pressure of the injected resin. Any other shape may be used as long as it is a simple shape. For example, a trapezoidal shape that opens in a C shape toward the body 3 may be used.

  In the fuel level gauge 1 according to the embodiment and the modification of the present invention described above, the Hall IC 7 is used as the magnetoelectric conversion element serving as the detecting means. However, the present invention is not limited to this, and other types of magnetoelectric elements are used. A conversion element such as an MRE element (magnetoresistive element) or a magnetic diode may be used.

  Further, in the fuel level gauge 1 according to the embodiment and the modification of the present invention described above, the number of the ring portions 10b provided in the casing 10 is three, but one or more may be provided.

  In the fuel level gauge 1 according to one embodiment of the present invention described above, the material of the terminal 8 is a copper-based metal, but other metal materials may be used.

  In the fuel level gauge 1 according to the embodiment of the present invention described above, the material of the magnet 6 is a ferrite magnet. However, other materials such as a rare earth magnet, an alnico magnet, or a bond magnet may be used.

  Further, in the fuel level gauge 1 according to the embodiment of the present invention described above, the number of terminals 8 for connection to an external electric circuit is three, but it is not necessary to limit to three. What is necessary is just to set according to the number of electrodes with which the magnetoelectric conversion element used is equipped.

  Further, in the embodiment of the present invention described above, the case where the liquid level detecting device is applied to the fuel level gauge 1 for an automobile has been described as an example. However, the use thereof needs to be limited to the fuel level gauge 1 for an automobile. There is no. You may apply for the detection of the liquid level in containers, such as other liquids mounted in a motor vehicle, for example, brake fluid, engine cooling water. Furthermore, the present invention is not limited to automobiles, and may be applied for detecting a liquid level in a liquid container provided in various consumer devices.

It is a front view of fuel level gauge 1 by one embodiment of the present invention. It is the II-II sectional view taken on the line in FIG. It is the III section enlarged view in FIG. It is the IV-IV sectional view taken on the line in FIG. It is a schematic diagram explaining the magnetization state and magnetic flux distribution of the magnet 6 in the fuel level gauge 1 by one Embodiment of this invention. It is sectional drawing of the modification of the fuel level gauge 1 by one Embodiment of this invention.

Explanation of symbols

1 Fuel level gauge (Liquid level detector)
2 Magnet holder (rotating member)
2a hole 2b regulating part 2c fixing hole 2d fixing part 2e holding part 2f opening 3 body (fixing member)
3a Shaft portion 3b Small diameter portion 3c Groove portion 3d Stopper 4 Float 5 Arm 5a Stopper 6 Magnet 7 Hall element (magnetoelectric conversion element)
7a Lead 8 Terminal 9 Electric wire (electrical conductor)
10 Sleeve (sheath member)
10a Cylindrical part 10b Ring part (annular protrusion)
10c Bottom 11 Rubber bushing (elastic bushing)
11a Annular groove (annular recess)
11c Annular groove (annular recess)
13 Fuel (liquid)
13a Liquid level 14 Fuel tank 15 Snap ring C Center axis D1 Diameter dimension d1 Diameter dimension M Magnetic flux W Width dimension

Claims (5)

A rotating member;
A fixing member made of a resin material that rotatably holds the rotating member;
A float floating in a liquid,
An arm that has the float fixed to one end and the other end fixed to the rotating member, and converts the vertical movement of the float caused by the vertical movement of the liquid surface into rotational movement of the rotating member;
A magnetoelectric transducer housed in the fixed member so as to detect displacement of the magnet ;
In the fixing member, a liquid level detection device comprising: one end connected to the electrode of the magnetoelectric conversion element and the other end extending to the outside of the fixing member so as to be connectable to an external electric circuit; ,
A sheath member fitted to the electric conductor in the fixing member;
An elastic bushing interposed between the sheath member and the electrical conductor and acting on the electrical conductor by the sheath member;
The elastic bushing is provided with an annular recess that is substantially coaxial with the electrical conductor and concave with respect to the fixing member at the end opposite to the sheath member in the axial direction of the electrical conductor. Detection device.   The liquid level detection device according to claim 1, wherein an axial sectional shape of the annular recess is substantially V-shaped or semicircular. The liquid level detection device according to claim 1, wherein an annular protrusion is formed on an outer periphery of the sheath member within the fixed member.   The liquid level detection device according to claim 1, wherein the sheath member is formed of a resin material. A method for manufacturing a liquid level detection device according to any one of claims 1 to 4,
A first step of fitting the sheath member to the electrical conductor and mounting the elastic bushing between the electrical conductor and the sheath member;
And a second step of forming the fixing member by insert-molding the sheath member and the electric conductor in which the first step has been completed.

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