JP3724747B2 - Non-contact level sensor - Google Patents

Description

  The present invention relates to a non-contact type liquid level sensor, and more specifically, a rotating shaft having a magnet fixed to an outer peripheral surface is supported by a pair of support holes excellent in coaxiality, thereby improving the durability of the bearing portion. In addition, the present invention relates to a non-contact type liquid level sensor that improves detection accuracy.

  Conventionally, for example, a non-contact type liquid level sensor that is mounted on a vehicle fuel tank or the like and detects a storage amount of liquid such as fuel has an annular magnet that rotates according to the movement of the float in the frame. It is arranged. The Hall element, which is a magnetoelectric conversion element, is arranged on the same plane as the annular magnet and at the center of the magnet. The Hall element detects changes in magnetic flux density caused by the rotating magnet and converts it into an electrical signal. To do. Thus, there is disclosed one that detects the liquid level (see, for example, Patent Document 1).

Further, a magnet holder to which a magnet is fixed by a holding means formed on the surface of the frame is rotatably held, a pair of cores facing the magnet, and a hole provided in a gap portion of the core Some devices are arranged in a frame to detect a change in magnetic flux density due to rotation of a magnet (see, for example, Patent Document 2).
JP 2002-206959 A (page 4-5, FIG. 1) Japanese Patent Laid-Open No. 2002-206945 (page 3-4, FIG. 1) The non-contact type liquid level sensor disclosed in Patent Documents 1 and 2 has a Hall element arranged in the same plane as the magnet (Patent) Reference 1), or a magnet holder that is rotatably held by a holding means formed on the surface of the frame (Patent Document 2) to reduce the thickness and cost of the non-contact type liquid level sensor. It is.

  As another conventional technique, the cover is welded to the housing by laser welding, vibration welding, etc., and the electronic parts are liquid-tightly sealed, and the performance of the non-contact type liquid level sensor is maintained with high accuracy over a long period of time. There are also known things to do.

  That is, as shown in FIG. 16, the conventional non-contact type liquid level sensor 1 is disposed such that the synthetic resin housing 2 is fixed in the vehicle fuel tank 3. A fuel pump 19 is disposed in the vehicle fuel tank 3, and foreign matter mixed in the fuel 17 such as gasoline is filtered by a filter 7 disposed at the suction port of the fuel pump 19 and supplied to an engine or the like. It has become.

  A rotating shaft 4 is rotatably disposed in a magnet housing portion 2 a formed in the housing 2, and a sintered magnet 5 is fitted on the outer peripheral surface of the rotating shaft 4, and the sintered magnet 5 is bonded or bonded. It is fixed to the rotating shaft 4 by means such as engagement. The sintered magnet 5 is, for example, a ferrite magnet or the like that is magnetized into an annular shape and fired and then magnetized in the radial direction.

  A synthetic resin magnet housing cover 14 is fixed to the opening of the magnet housing 2a. One end of the rotating shaft 4 is inserted into the support hole 14a provided in the magnet housing portion cover 14 and is rotatably supported.

  The other end of the float arm 6 whose one end is fixed to the float 8 is fitted into the hole of the rotating shaft 4 and fixed. When the float 8 moves up and down with the level displacement of the liquid level 15 in the vehicle fuel tank 3, the movement is transmitted to the rotating shaft 4 through the float arm 6, thereby rotating the rotating shaft 4. ing.

  The pair of substantially semicircular stators 9 are disposed so as to face the outer peripheral surface of the sintered magnet 5 so as to form a substantially circle. The stator 9 is fixed to the housing 2 by means such as insert molding and bonding to the housing 2 or fitting a pin integrally formed in the housing 2 into a positioning hole provided in the stator 9 and heat-clamping the pin. ing.

  Two gaps having a phase difference of 180 ° are formed between the end faces of the pair of stators 9. For example, a magnetoelectric conversion element 11 such as a Hall element or a Hall IC is sandwiched between the pair of stators 9. Are arranged as follows. The lead wire 11 a of the magnetoelectric conversion element 11 is electrically connected to the terminal 13.

  When the float 8 moves up and down with the displacement of the liquid level 15, the rotating shaft 4 rotates together with the sintered magnet 5. When the magnetic flux density passing through the magnetoelectric conversion element 11 changes with the rotation of the sintered magnet 5, the magnetoelectric conversion element 11 detects this, converts it into an electrical signal, and outputs it to the terminal 13. Yes.

  As shown in FIG. 16, the terminal 13 is for transmitting an electric signal detected by the magnetoelectric transducer 11 to the outside of the non-contact type liquid level sensor 1, and is one end 13a of a conductive metal plate. Is a vertically long flat plate-like member that is bent at a right angle and formed into an L-shape. The terminal 13 is disposed through the wall 2b of the housing 2 from the inside to the outside, and an intermediate portion thereof is embedded in the wall 2b and insert-molded.

  The intermediate portion of the terminal 13 has a plurality of V grooves 13b formed on the surface. Insert molding of the terminal 13 into the housing 2 is performed by applying the seal coating agent 18 to the intermediate portion including the V-groove 13b and then performing insert molding, whereby the intermediate portion of the terminal 13 is embedded in the wall 2b of the housing 2. . As a result, the seal coat agent 18 comes into close contact with the wall 2 b of the housing 2, and a sealing effect between the terminal 13 and the housing 2 is obtained.

  A cover 13 made of synthetic resin is welded by laser welding or the like, and one end 13a of the plurality of terminals 13 disposed in the liquid tightly sealed sensor chamber 2c has a magnetoelectric conversion element 11, a resistor and a capacitor (not shown). ) And the like are soldered and electrically connected to form part of the detection circuit. A potting agent 10 is applied to the soldering parts such as the magnetoelectric conversion element 11, the resistor, and the capacitor after soldering to reduce the force acting on the soldering part due to vibrations caused by the running of the vehicle. It comes to protect.

  A synthetic resin magnet housing cover 14 is fixed to the opening of the magnet housing 2a formed in the housing 2 by welding, engagement, or the like. The shaft portion of the rotary shaft 4 is fitted into the support hole 14a provided in the magnet housing portion cover 14 and the support hole 2d formed in the housing 2, and is supported rotatably.

  Since the magnet housing portion cover 14 and the housing 2 with which the shaft portion of the rotary shaft 4 is fitted are formed separately from each other and then fixed by welding, engagement, etc., the magnet housing portion cover 14 is supported. There is a possibility that the hole 14a and the support hole 2d of the housing 2 are fixed in a state where the shaft centers are shifted. If the shaft centers of the support hole 14a and the support hole 2d are deviated, the sintered magnet 5 rotates eccentrically, which adversely affects detection accuracy.

  Further, the deviation of the shaft core not only causes uneven wear of the bearing portion, but also may cause damage to the bearing portion due to an excessive force acting on the support hole 14a and the support hole 2d. Furthermore, there is a possibility that the fixing (welding, engagement) between the housing 2 and the magnet housing portion cover 14 will be incomplete, the bearing strength may be insufficient, and the bearing portion may be damaged due to vibration or the like associated with running of the vehicle. there were.

  The present invention has been made in view of the above-described problems, and its object is to improve the strength of the bearing portion and to support the rotation shaft so that it can be smoothly rotated without eccentricity, thereby improving the durability of the bearing portion. An object of the present invention is to provide a non-contact type liquid level sensor having excellent detection accuracy.

1) The non-contact type liquid level sensor of the present invention has one end attached to a housing provided with a pair of support holes having the same axis and a float that moves up and down in accordance with the displacement of the liquid level to be measured. A float arm whose other end is inserted into one support hole and rotatably fitted in the other support hole, and is fixed to the float arm in the housing, and the float arm as the float moves up and down A rotating shaft that rotates together with the rotating shaft , a magnet that is fixed to the outer peripheral surface of the rotating shaft and rotates together with the rotating shaft , a pair of stators that are arranged to face the outer peripheral surface of the magnet, and a rotation of the magnet. a non-contact type liquid level sensor having a magneto-electric transducer for converting a change in magnetic flux density in said stator caused by the movement of the detected and electrical signals, the float ah Are small diameter portion smaller in diameter than the center hole of the rotary shaft to the tip of the other end forming, characterized in that the large diameter portion to be press-fitted into the central hole in succession to the small diameter portion is formed.

  According to the non-contact type liquid level sensor having the above-described configuration, the pair of support holes for rotatably supporting the rotation shaft are formed integrally on the same component (housing). There is no risk of occurrence, and molding can be performed with high concentricity. Therefore, the magnet rotates smoothly without being eccentric, and a stable detection output can be obtained. In addition, uneven wear and damage of the bearing portion due to the misalignment of the pair of support holes can be eliminated. Further, since the pair of support holes are formed on the same component (housing), the bearing strength is strong and the bearing portion is not damaged even if an external force acts on the bearing portion. In addition, a small-diameter portion that fits into the support hole of the housing is provided at the tip of the float arm, and a large-diameter portion that is continuously fixed to the rotary shaft is formed in the small-diameter portion. When inserting the float arm, the small-diameter portion of the float arm can be inserted without coming into contact with the central hole of the rotating shaft, and the small-diameter portion and the central hole are not damaged by the insertion of the float arm. Therefore, the small-diameter portion can be smoothly fitted into the support hole of the housing to prevent backlash and eccentricity. The large-diameter portion of the float arm can be securely fixed by being press-fitted into the central hole of the rotating shaft without any damage.

2) The non-contact type liquid level sensor of the present invention is the non-contact type liquid level sensor according to 1), wherein the housing is formed with a magnet containing part for containing the magnet and the rotating shaft, A magnet housing cover that inserts an overhang portion formed to project in the direction between the inner side wall of the magnet housing portion and the side surface of the rotating shaft to limit the axial clearance of the rotating shaft. It is attached to the opening of the.

  According to the non-contact type liquid level sensor having the above-described configuration, the protruding portion provided on the magnet housing portion cover is inserted between the inner side wall of the magnet housing portion and the side surface of the rotating shaft so that the axial clearance of the rotating shaft is reduced. Since the restriction is made, the axial movement (thrust backlash) of the rotating shaft (magnet) can be suppressed, and thereby the output of the magnetoelectric conversion element can be stabilized.

  3) The non-contact type liquid level sensor of the present invention is the non-contact type liquid level sensor according to 1) or 2), wherein the float arm has a flange formed in the middle of the one end side, and the flange The one end of the float arm is press-fitted into the rotating shaft by pressing the float arm in the axial direction with a press-fitting rod.

  According to the non-contact type liquid level sensor having the above-described configuration, a flange is formed in the middle of the float arm, and a press-fitting rod is provided in the flange to press the float arm in the axial direction to press-fit into the rotating shaft. Since it did in this way, only the force of an axial direction can be made to act on a float arm, and it can press-fit straight to a rotating shaft, without making a float arm incline. Therefore, at the time of press-fitting, an excessive force is not applied to the bearing portion to cause damage. Furthermore, the rotation shaft (magnet) is not attached to the float arm in an inclined manner, and the detection output can be prevented from fluctuating due to meandering rotation of the rotation shaft, thereby improving detection accuracy.

  According to the non-contact type liquid level sensor of the present invention, the pair of support holes for rotatably supporting the rotation shaft are formed integrally on the same component (housing), so that the shaft core is displaced. There is no risk of occurrence, and molding can be performed with high concentricity. Therefore, the magnet rotates smoothly without being eccentric, and a stable detection output can be obtained. In addition, uneven wear and damage of the bearing portion due to the misalignment of the pair of support holes can be eliminated. Further, since the pair of support holes are formed on the same component (housing), the bearing strength is strong and the bearing portion is not damaged even if an external force acts on the bearing portion. In addition, a small-diameter portion that fits into the support hole is provided at the tip of the float arm, and a large-diameter portion that is continuously fixed to the rotating shaft is formed in the small-diameter portion, so that the float arm is inserted into the central hole of the rotating shaft. In this case, the small-diameter portion of the float arm can be inserted without contacting the central hole of the rotating shaft, and the small-diameter portion and the central hole are not damaged by the insertion of the float arm. Therefore, the small-diameter portion can be smoothly fitted into the support hole of the housing to prevent backlash and eccentricity. The large-diameter portion of the float arm can be securely fixed by being press-fitted into the central hole of the rotating shaft without any damage.

  Further, according to the non-contact type liquid level sensor of the present invention, the overhanging portion provided on the magnet housing portion cover is inserted between the inner side wall of the magnet housing portion and the side surface of the rotating shaft so that the axial direction of the rotating shaft Since the gap is limited, the axial movement of the rotating shaft (magnet) can be suppressed, and thereby the output of the magnetoelectric transducer can be stabilized.

  Further, according to the non-contact type liquid level sensor of the present invention, a flange portion is formed in the middle of the float arm, and a press-fit rod is provided in the flange portion so as to press the float arm in the axial direction so as to be a rotating shaft. Since the press-fitting is performed, only the axial force is applied to the float arm, so that the float arm can be press-fitted straight without tilting. Therefore, an excessive force is not applied to the bearing portion during press-fitting to cause damage. Furthermore, the rotation shaft (magnet) is not attached to the float arm in an inclined manner, and the detection output can be prevented from fluctuating due to meandering rotation of the rotation shaft, thereby improving detection accuracy.

  Hereinafter, an embodiment in which a non-contact type liquid level sensor according to the present invention is mounted on a vehicle fuel tank will be described in detail with reference to FIGS. FIG. 1 is a plan view of a non-contact type liquid level sensor according to an embodiment of the present invention, and is a plan view showing a terminal assembly inserted by removing the front side of the housing for easy understanding. 2 is a longitudinal sectional view taken along the line II-II in FIG. 1, FIG. 3 is a plan view of the terminal assembly, FIG. 4 is a rear perspective view of the housing, FIG. 5 is a front perspective view of the housing, and FIG. It is a top view of a liquid level sensor.

  FIG. 7 is a longitudinal sectional view showing a state in which the terminal is pressed by the movable pin to prevent the terminal from being deformed during insert molding of the terminal assembly, and (a) is a state in which the terminal is deformed by the injection pressure without the movable pin. (B) is a longitudinal sectional view showing a state where the terminal is held and pressed by the movable pin, and (c) is a longitudinal sectional view showing a state of the housing after molding. FIG. 8 is a longitudinal sectional view of a main part showing a state where a float arm is press-fitted into a rotating shaft arranged in the magnet housing portion, and FIG. 9 is a perspective view of the magnet housing portion cover.

  As shown in FIGS. 1 and 2, a non-contact type liquid level sensor 20 according to an embodiment of the present invention has a terminal assembly 30 insert-molded in a housing 21 and a terminal assembly except for an external connection portion 26g. Most of 30 is embedded in the synthetic resin of the housing 21.

  As shown in FIG. 3, the terminal assembly 30 includes terminals 26A, 26B, and 26C, a magnetoelectric transducer 25, a resistor 28, a capacitor 29, and a pair of stators 24 that are assembled together. The terminals 26A, 26B, and 26C constitute part of an electric circuit, and are for transmitting an electric signal detected by the magnetoelectric transducer 25 to the outside, and are formed by pressing a conductive metal plate. Three terminals 26A, 26B, and 26C having different shapes are made into one set.

  The upper ends of the respective terminals 26A, 26B, and 26C are formed so as to be connected to the belt-like carrier 26d. The belt-like carrier 26d is cut along a cutting line CL after the terminals 26A, 26B, and 26C are insert-molded in the housing 21. Thus, the terminals 26A, 26B, and 26C are separated from each other and function as independent terminals. The upper ends of the respective terminals 26A, 26B, and 26C after the strip-shaped carrier 26d is cut serve as external connection portions 26g.

  A plurality of V-grooves 26f are formed in the longitudinal direction of the terminals 26A, 26B, and 26C in the vicinity of the external connection portion 26g of the terminals 26A, 26B, and 26C and in the seal portion 26e embedded in the housing 21 when insert-molded in the housing 21. It is formed in the direction perpendicular to. The insert molding of the terminal assembly 30 (terminals 26A, 26B, 26C) is performed after the seal coat agent 18 is applied to the seal portion 26e including the V-groove 26f. As a result, the terminals 26A, 26B, 26C and the housing 21 are securely sealed.

  The pair of stators 24 formed in a substantially quadrant plate shape by a magnetic body is arranged so as to form a substantially semicircle in the longitudinal direction (vertical direction in FIG. 3) of the terminal 26B, and four caulking pins It is crimped by 31 and fixed to the terminal 26B. As a result, the pair of stators 24 are disposed so as to face the outer peripheral surface of the sintered magnet 23 and surround the lateral surface thereof by approximately 180 ° when the non-contact type liquid level sensor 20 is assembled (FIG. 1). reference).

  Examples of the magnetic body constituting each stator 24 include silicon steel plate, iron, martensitic stainless steel, and the like. The fixing of the pair of stators 24 to the terminal 26B is not limited as long as it can be firmly fixed, such as welding.

  In the gap G formed between the end faces of the pair of stators 24, for example, a magnetoelectric conversion element 25 such as a Hall element or a Hall IC is disposed between the pair of stators 24. The lead wire 25a of the magnetoelectric conversion element 25 is spot-welded to the terminals 26B and 26C and is electrically connected.

  The terminal 26B is provided with two element holding portions 26g and 26h formed by being bent into a substantially U-shape and projecting sideways. The main body of the resistor 28 and the capacitor 29 are arranged and positioned so as to be sandwiched between the substantially U-shaped element holding portions 26g and 26h. Since the resistor 28 and the capacitor 29 are arranged at predetermined positions simply by holding the main body part between the element holding parts 26g and 26h, not only the assembly is easy, but also the resistor 28 and the capacitor 29 are misplaced. It can be surely prevented. The heights of the element holding portions 26g and 26h are substantially the same as the heights of the main body portions of the resistor 28 and the capacitor 29. The lead wires 28a and 29a of the resistor 28 and the capacitor 29 are spot-welded and electrically connected to the terminals 26A and 26B and the terminals 26B and 26C, respectively. That is, an electric circuit is formed by the terminals 26A, 26B, and 26C, the magnetoelectric transducer 25, the resistor 28, and the capacitor 29. The fact that the lead wires 25a, 28a, and 29a of the magnetoelectric conversion element 25, the resistor 28, and the capacitor 29 are spot-welded to the terminals 26A, 26B, and 26C can be firmly fixed as compared with soldering, and solder, flux, and solder washing This is because environmentally friendly substances such as chemicals are not used and the environment can be considered.

  As shown in FIGS. 1, 2, 4, and 5, the terminal assembly 30 assembled as described above is applied with the seal coating agent 18 on the seal portion 26 e including the V grooves 26 f of the terminals 26 A, 26 B, and 26 C. After that, the housing 21 is formed by insert molding with a synthetic resin such as polyacetal. As a result, most of the terminal assembly 30 except the external connection portion 26 g is embedded in the housing 21.

  By insert molding, the terminals 26A, 26B, 26C, the magnetoelectric transducer 25, the resistor 28, the capacitor 29, and the pair of stators 24 are more securely fixed by the synthetic resin constituting the housing 21, and their relative positions are fixed. The relationship does not change. The injection pressure of the synthetic resin acts on the stator 24, the magnetoelectric conversion element 25, the resistor 28, and the capacitor 29 at the time of insert molding. The stator 24 is fixed by being crimped to the terminal 26B by a crimping pin 31. 25 is sandwiched between a pair of stators 24, and the body portions of the resistor 28 and the capacitor 29 are sandwiched and positioned by element holding portions 26g and 26h formed in a substantially U-shape, respectively. Since the wires 28a and 29a are spot-welded to the terminals 26A, 26B and 26C and are firmly fixed, they are not affected by the movement of their positions due to the injection pressure of the synthetic resin.

  The terminal assembly 30 is embedded in the synthetic resin except for the external connection portion 26g, and the seal coat agent 18 is applied to the seal portion 26e in the vicinity of the external connection portion 26g connected to the outside so that the space between the terminal assembly 30 and the housing 21 is not increased. Since the terminal assembly 30 is sealed, the terminal assembly 30 is reliably shut off from the outside to prevent liquid leakage and the like, and the electric circuit is protected from fuel and the like.

  The terminal assembly 30 needs to be insert-molded in a state where only the belt-like carrier 26d is held by a molding die (not shown) in order to embed all the portions except the external connection portion 26g in the housing 21. There is. As shown to Fig.7 (a), since the front-end | tip of terminal 26A, 26B, 26C is free, there exists a possibility of deform | transforming with the injection pressure of a synthetic resin. This deformation causes damage to the electronic components (resistor 28, capacitor 29) fixed to the terminals 26A, 26B, and 26C, or causes relative displacement between the pair of stators 24 and the sintered magnet 23. There is a possibility that the detection accuracy is lowered.

  In order to prevent this, as shown in FIG. 7B, movable pins 32 are provided in the molding die, and both sides of the terminals 26A, 26B, and 26C are indicated by hatched portions 33 in FIG. The synthetic resin is press-fitted into the molding die while holding it with the. Then, during the synthetic resin molding cycle, the movable pin 32 is retracted in the direction of arrow E, and finally the portion held by the movable pin 32 is also embedded in the synthetic resin (FIG. 7C). It is desirable to prevent deformation of the terminals 26A, 26B, and 26C due to molding.

As shown in FIGS. 1, 4, and 5, the housing 21 has a substantially semicircular magnet housing portion 21 a that is provided with an opening 21 b on the side so as to face the inner peripheral surfaces of the pair of stators 24. Is formed. On both side walls 21c of the magnet housing portion 21a, through holes 21d and 21e as support holes are formed on the same axis. Since the two through holes 21d and 21e are molded simultaneously, there is no misalignment and the molding is performed with high accuracy. Further, as shown in FIGS. 5 and 6, arm rotation restricting ribs 21f and 21g extending in the radial direction with respect to the through hole 21d are projected on one side surface of the housing 21, and the through hole will be described later. When the float arm 22 fitted to 21d and 21e rotates, the float arm 22 comes into contact therewith and the rotation angle of the float arm 22 is restricted to a predetermined angle, for example, 70 ° or 100 °.

  As shown in FIG. 8, a rotating shaft 36 supported by the float arm 22 is rotatably disposed in the magnet housing portion 21a, and a ring-shaped sintered magnet 23 is provided on the outer peripheral surface of the rotating shaft 36. Is fitted. The sintered magnet 23 is, for example, a ferrite magnet or the like that is magnetized in an annular shape and fired and then magnetized in the radial direction, and is fixed to the rotary shaft 36 by press-fitting, bonding, or the like.

  As shown in FIGS. 6 and 8, the other end of the float arm 22 whose one end is fixed to the float 38 has a tip 22 a smaller in diameter than the center hole 36 a of the rotation shaft 36. After the rotating shaft 36 is inserted into the magnet accommodating portion 21a from the opening 21b, the other end of the float arm 22 is inserted into one through hole 21d of the magnet accommodating portion 21a and the central hole 36a of the rotating shaft 36 to further reduce the diameter. Is inserted into the other through hole 21e of the magnet housing portion 21a. At this time, the large diameter portion 22 b formed following the small diameter tip portion 22 a is press-fitted into the center hole 36 a of the rotation shaft 36. As a result, the float arm 22 to which the rotary shaft 36 is fixed is rotatably supported by both the through holes 21d and 21e. The tip 22a of the float arm 22 has a smaller diameter than the center hole 36a of the rotating shaft 36. Therefore, when the float arm 22 is inserted into the center hole 36a of the rotating shaft 36, the tip 22a and the center hole 36a Is avoided, and the tip 22a of the float arm 22 is not damaged. Further, the central hole 36a of the rotating shaft 36 is not scraped by the tip 22a and is not damaged. Therefore, the small-diameter tip 22a can be smoothly fitted into the through hole 21e to prevent backlash and eccentricity. The large-diameter portion 22b of the float arm 22 is press-fitted into the center hole 36a of the rotating shaft 36 with a predetermined pressure and is securely fixed.

  As shown in FIGS. 1 and 9, the opening 21b of the magnet housing portion 21a is covered with a magnet housing portion cover 34 made of synthetic resin. That is, by engaging the claw 34a formed on the magnet housing portion cover 34 with the locking hole formed on the housing 21, the magnet housing portion cover 34 is assembled to the housing 21, and the foreign matter into the magnet housing portion 21a. Intrusion is prevented.

  The operation of this embodiment will be described.

  As shown in FIGS. 1 and 6, the non-contact type liquid level sensor 20 is disposed in a storage tank such as a fuel tank of an automobile, and the liquid level of gasoline or the like stored in the storage tank is determined. When displaced, the float 38 moves up and down to rotate the rotating shaft 36 together with the sintered magnet 23. When the magnetic flux density passing through the magnetoelectric conversion element 25 changes with the rotation of the sintered magnet 23, the magnetoelectric conversion element 25 detects this and converts it into an electrical signal, via the terminals 26A, 26B, and 26C. Output to the outside.

  The non-contact type liquid level sensor 20 disposed in the vehicle fuel tank is exposed to a liquid having swelling properties such as gasoline and used under severe conditions such as a large temperature change and vibration.

  The terminal assembly 30 insert-molded in the housing 21 is embedded in the synthetic resin except for the external connection portion 26g, and a seal coat agent 18 is applied to the seal portion 26e in the vicinity of the external connection portion 26g. Since there is a seal between the seal 21 and the plastic resin, there is no sealing failure caused by molding sink marks of the synthetic resin or poor welding of the cover, and the electric circuit is directly affected by swelling or the like caused by gasoline or the like. There is no. Therefore, the inside of the non-contact type liquid level sensor 20 is reliably sealed, and the non-contact type liquid level sensor 20 can be operated stably and accurately over a long period of time.

  Since the magnetoelectric conversion element 25, the electronic components (resistor 28, capacitor 29), the pair of stators 24 and the terminals 26A, 26B, 26C, etc. are embedded and fixed in the synthetic resin of the housing 21, they are not contacted as the vehicle travels. Even if the liquid level sensor 20 vibrates, the relative position of each component does not change and operates reliably without being affected by vibration. In addition to embedding by insert molding, the stator 24 is further crimped and fixed to the terminal 26B by a crimping pin 31, and the magnetoelectric transducer 25 is sandwiched between a pair of stators 24, and electronic components (resistor 28, capacitor 29). Since the main body is positioned by being sandwiched between element holding portions 26g and 26h each having a substantially U-shape, the electric circuit is not only affected by the injection pressure of the synthetic resin during insert molding, but also with traveling. It is not affected by vibration.

  Further, since the pair of stators 24 and the magnetoelectric transducer 25 are fixed on the same terminal 26B, the use environment temperature changes, the housing 21 expands and contracts, or the non-contact liquid level sensor 20 vibrates. Even if is added, the relative position between the pair of stators 24 and the magnetoelectric transducer 25 does not change. Therefore, the output of the non-contact type liquid level sensor 20 does not change, and the detection accuracy is maintained with high accuracy.

  As shown in FIG. 6, the float 38 moves up and down with the displacement of the liquid level of gasoline or the like stored in the storage tank. However, when the storage tank is full, the float arm 22 is moved to the arm rotation restricting rib 21f. When the storage tank is empty, the float arm 22 contacts the arm rotation restricting rib 21g. Thereby, the rotation range of the float arm 22 is regulated within a predetermined angle, for example, 70 ° or 100 °, and a stable output can be obtained.

  Next, a modification of the float arm will be described with reference to FIGS. FIG. 10 is a longitudinal sectional view showing a state in which a float arm having a conventional shape is press-fitted into a rotary shaft arranged in a magnet housing portion, and FIG. 11 is a diagram showing a press-fitting device in which the float arm of this embodiment is press-fitted into a rotary shaft arranged in a magnet housing portion. FIG. 12 is a side view of the float arm press-fitting device of this embodiment.

  As shown in FIG. 10, since the tip of the conventional float arm 22 is bent at a right angle, when the float arm 22 is pressed in the direction of the arrow K in order to press fit the rotary shaft 36, the float arm 22 is moved to the arrow L. It is press-fitted in a state inclined in the direction. Therefore, when the float arm 22 is press-fitted, the through holes 21d and 21e of the housing 21 are damaged, and the float arm 22 is pressed into the rotary shaft 36 in a tilted state, which not only obstructs smooth rotation but also causes the firing. The relative position of the binding magnet 23 and the magnetoelectric conversion element 25 is not stable, and the output of the magnetoelectric conversion element 25 may be affected.

  As shown in FIG. 11, the float arm 40 of the present embodiment is different from the conventional float arm 22 in that a flange 40 a is formed in the vicinity of the bent portion. The press fitting of the float arm 40 to the rotating shaft 36 is performed using a press fitting device 41.

  As shown in FIG. 12, the press-fitting device 41 includes a fixing jig 42 that fixes the housing 21 at a predetermined location, and a press-fitting rod 43. The fixing jig 42 is provided with a receiving jig 44 that slides in the horizontal direction and supports the lower surface of the rotating shaft 36 disposed in the magnet housing portion 21a (see FIG. 11). When the operation lever 45 is operated, the press-fitting rod 43 moves in the vertical direction in FIG. 12 by the action of a rack and a pinion (not shown). A groove 43 a that can accommodate a bent portion of the float arm 40 is formed at the tip of the press-fit rod 43.

  For press-fitting the float arm 40 into the rotating shaft 36, the housing 21 is disposed at a predetermined position of the fixing jig 42, and the rotating shaft 36 is inserted into the magnet housing portion 21a. After the receiving jig 44 is slid to support the lower surface of the rotary shaft 36, the operation lever 45 is operated to lower the press-fitting rod 43. The bent portion of the float arm 40 is accommodated in the groove 43a, and the tip of the press-fit rod 43 abuts against the flange portion 40a of the float arm 40 to press the float arm 40 straight in the axial direction. As a result, the float arm 40 is press-fitted into the rotating shaft 36 without tilting and with high positional accuracy, and smooth rotation of the rotating shaft 36 is ensured.

  The other portions are the same as those of the non-contact type liquid level sensor 20 of the embodiment shown in FIGS. 1 to 9, and therefore the same portions are denoted by the same reference numerals or the corresponding reference numerals and the description thereof is simplified or omitted. .

  Next, modified examples of the rotating shaft will be described with reference to FIGS. FIG. 13 is a longitudinal sectional view of a rotating shaft supported by a float arm and rotatably disposed in the magnet housing portion, FIG. 14 is a perspective view of the magnet housing portion cover, and FIG. 15 is a view showing that the rotating shaft is incorporated in the magnet housing portion. It is a longitudinal cross-sectional view which shows a procedure.

  In this modification, the shapes of the rotary shaft 50 and the magnet housing portion cover 51 are mainly different from those of the embodiment shown in FIGS. As shown in FIG. 13, the rotating shaft 50 of the modified example is a cylindrical member having a sintered magnet 23 fitted on the outer peripheral surface, and a through hole 50 b is formed at the center and the center of one side surface is formed. A shaft portion 50a is provided so as to protrude. The shaft portion 50a is fitted in one through hole 21e of the housing 21 and is rotatably arranged. The float arm 22 inserted through the through hole 21 d of the housing 21 is press-fitted into the through hole 50 b of the rotating shaft 50. Thus, the rotating shaft 50 is disposed in the magnet housing portion 21a so as to be rotatable by the float arm 22 inserted through the shaft portion 50a and the through hole 21d of the housing 21.

  As shown in FIG. 14, the magnet housing part cover 51 has a shape in which a bifurcated projecting part 51a is provided on the magnet housing part cover 34 shown in FIG.

  As shown in FIG. 15, the procedure for assembling the rotating shaft 50 into the magnet housing portion 21a is performed after the rotating shaft 50 is inserted in the direction of arrow M from the opening 21b of the magnet housing portion 21a (FIG. 15 (a)). Then, the rotary shaft 50 is moved in the direction of the arrow N, and the shaft portion 50a is fitted into the through hole 21e of the housing 21 (FIG. 15B). Next, one end of the float arm 22 is inserted through the through hole 21d of the housing 21 in the direction of arrow O, and press-fitted into the through hole 50b of the rotating shaft 50 for a predetermined length (FIG. 15C). Finally, the magnet housing portion cover 51 is attached to the housing 21 while the overhanging portion 51a is inserted between the inner side wall of the magnet housing portion 21a and the rotating shaft 50 (in the direction of arrow P), and the opening 21b of the magnet housing portion 21a is installed. Is closed (FIG. 15 (d)).

  According to this modification, the axial gap of the rotating shaft 50 can be adjusted by the thickness of the overhanging portion 51a, and the position of the rotating shaft 50 (sintered magnet 23) can be stabilized to improve detection accuracy. it can. In addition, the press-fitting length of the float arm 22 can be increased, the inclination of the float arm 22 can be prevented, and the float arm 22 can be securely fixed to the rotating shaft 50. In addition, it is possible to prevent foreign matter from entering the magnet housing portion 21a by mounting the magnet housing portion cover 51.

  The other portions are the same as those of the non-contact type liquid level sensor 20 of the embodiment shown in FIGS. 1 to 9, and therefore the same portions are denoted by the same reference numerals or the corresponding reference numerals and the description thereof is simplified or omitted. .

  Note that the present invention is not limited to the above-described embodiments and modifications, and modifications, improvements, and the like can be made as appropriate. In addition, the material, shape, dimension, numerical value, form, number, location, and the like of each component in the above-described embodiments and modifications 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 of the present invention is applicable not only to the vehicle fuel tank as described above but also to detection of the liquid level of various liquid storage tanks.

It is a top view of the non-contact-type liquid level sensor of one embodiment of the present invention. It is the II-II arrow longitudinal cross-sectional view in FIG. It is a top view of the terminal assembly in FIG. It is a back surface side perspective view of the housing in FIG. It is a surface side perspective view of the housing in FIG. It is a top view of the non-contact-type liquid level sensor in FIG. It is a longitudinal cross-sectional view which shows the state which presses a terminal with a movable pin at the time of insert molding of a terminal assembly, and prevents a deformation | transformation of a terminal, (a) is a longitudinal cross-sectional view which shows the state which a terminal deform | transforms with injection pressure, (b) is FIG. 6 is a longitudinal sectional view showing a state where the terminal is held and pressed by a movable pin, and FIG. 5C is a longitudinal sectional view showing a state of the housing after molding. It is a principal part longitudinal cross-sectional view which shows the state by which the float arm was press-fitted in the rotating shaft arrange | positioned in a magnet accommodating part. It is a perspective view of a magnet accommodating part cover. It is a longitudinal cross-sectional view which shows the state which press-fits the float arm to the rotating shaft arrange | positioned in the magnet accommodating part. It is a longitudinal cross-sectional view which shows the state which press-fits the float arm to the rotating shaft arrange | positioned in the magnet accommodating part by the press-fitting apparatus. It is a side view of the press fit apparatus of a float arm. It is a longitudinal cross-sectional view of the rotating shaft supported by the float arm and rotatably disposed in the magnet housing portion. It is a perspective view of a magnet accommodating part cover. It is a longitudinal cross-sectional view which shows the procedure in which a rotating shaft is integrated in a magnet accommodating part. It is a longitudinal cross-sectional view of the non-contact-type liquid level sensor arrange | positioned in the conventional fuel tank.

Explanation of symbols

20 Non-contact type liquid level sensor 21 Housing 21a Magnet housing portion 21b Opening port 21c Side wall 21d, 21e Through hole (support hole)
22, 40 Float arm 23 Magnet 24 Pair of stators 25 Magnetoelectric conversion element 36, 50 Rotating shaft 40a Hook 43 Push-in rod 50a Shaft 51 Magnet housing cover 51a Overhang

Claims (3)

One end is attached to a housing provided with a pair of support holes having the same axis, and a float that moves up and down according to the displacement of the liquid level to be measured, the other end is inserted into one support hole, and the other A float arm that is rotatably fitted in a support hole, a rotary shaft that is fixed to the float arm in the housing and that rotates together with the float arm as the float moves up and down, and an outer peripheral surface of the rotary shaft A magnet that rotates with the rotating shaft, a pair of stators arranged so as to face the outer peripheral surface of the magnet, and a change in magnetic flux density in the stator that occurs as the magnet rotates. A non-contact liquid level sensor provided with a magnetoelectric transducer for detecting and converting into an electrical signal,
A small-diameter portion having a smaller diameter than the central hole of the rotating shaft is formed at the tip of the other end of the float arm, and a large-diameter portion that is press-fitted into the central hole is formed continuously from the small-diameter portion. Non-contact type liquid level sensor.
The housing is formed with a magnet housing portion for housing the magnet and the rotating shaft, and a projecting portion formed by projecting laterally is formed between an inner side wall of the magnet housing portion and a side surface of the rotating shaft. 2. The non-contact type liquid level sensor according to claim 1, wherein a magnet housing part cover that is inserted into the magnet housing and limits an axial clearance of the rotating shaft is attached to an opening of the magnet housing part. The float arm has a flange formed in the middle of the one end side, and presses the float arm in the axial direction by placing a press-fitting rod on the flange, so that the one end of the float arm is moved to the rotating shaft. The non-contact type liquid level sensor according to claim 1, wherein the liquid level sensor is press-fitted into the non-contact type liquid level sensor.

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