JP4867531B2 - Liquid level detector - Google Patents

Description

  The present invention relates to a liquid level detection device that detects a liquid level of a liquid contained in a container, and in particular, a liquid level detection that is mounted in a fuel tank of an automobile or the like and detects a liquid level position of the fuel. It is suitable for application to an apparatus.

  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 rotating member is provided with a through hole, while the fixed member is provided with a shaft portion, and the through hole and the shaft portion are rotatably fitted, The rotating member is rotatably held by the fixed member.
Japanese Patent Laid-Open No. 2005-9047

  In the conventional liquid level detection device described above, a minimum gap is formed in the fitting portion between the through hole of the rotating member and the shaft portion of the fixed member so that the rotating member can rotate around the shaft portion. Has been. Due to this gap, the central axis of the through hole may be inclined rather than parallel to the central axis of the shaft portion. That is, the rotating member may rotate around an axis orthogonal to the central axis of the shaft portion.

  As described above, when the central axis of the through hole of the rotating member is inclined with respect to the central axis of the shaft portion, the amount of magnetic flux passing through the magnetoelectric conversion element accommodated in the shaft portion is parallel to the shaft portion. It changes with respect to a certain time. For this reason, even if the angular position of the rotating member is the same, that is, the liquid surface position is the same, if the attitude of the rotating member with respect to the shaft portion changes, the output of the magnetoelectric transducer changes, and the liquid surface position is detected with high accuracy Can be difficult.

  Further, when the rotating member is inclined with respect to the shaft portion, the rotation surface of the arm attached to the rotating member is inclined from a state orthogonal to the central axis of the shaft portion. For this reason, the position of the float attached to the tip of the arm also moves from the normal state position. Since the float is located farthest from the center of the rotating member, the amount of movement associated with the inclination of the rotating member is large. Therefore, when the rotating member is inclined with respect to the shaft portion, the float moves and comes into contact with the inner wall of the fuel tank, thereby preventing the smooth rotation of the arm and making it difficult to detect the liquid level position with high accuracy. there is a possibility.

  The present invention has been made in view of such problems, and the object thereof is to suppress the tilting of the rotating member with respect to the shaft portion of the fixed member and to detect the liquid level position with high accuracy. Is to provide a simple liquid level detection device.

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

The liquid level detection apparatus according to claim 1 of the present invention includes a rotating member having a through hole, and a fixing member that has a shaft portion and that fits the through hole in the shaft portion and rotatably holds the rotating member. A float that floats on the liquid, an arm that has a float fixed to one end and the other end fixed to a rotating member, and converts the vertical movement of the float caused by the vertical movement of the liquid level into a rotational movement of the rotating member, and a rotating member a magnet fixed to rotate the rotating member integrally, a liquid level detecting device and a detectably magnetoelectric conversion element accommodated in the fixing member the displacement of the magnet in the through hole at the outer peripheral surface of the rotary member and the first restricting portion provided coaxially and annularly provided to the shaft portion and coaxially and annularly in the fixing member, contactable to made form the first regulating portion in the axial direction of the shaft portion The second restricting portion and the rotating member are assembled to the fixed member. In this state, the gap between the first restricting portion and the second restricting portion in the axial direction of the shaft portion is within the range in which the rotating member can be smoothly rotated by the fitting gap between the shaft portion of the fixed member and the through hole of the rotating member. Is set to be smaller than the displacement generated on the outer peripheral surface, and one of the first restricting portion and the second restricting portion is formed in an annular shape that is continuous over the entire circumference, of the first restricting portion and the second restricting portion. The other is characterized by being formed in a partially interrupted annular shape .

  First, in the conventional liquid level detection device, the rotating member can be inclined by the gap between the through hole of the rotating member and the shaft portion of the fixed member. That is, when the rotating member is in contact with the shaft portion at both ends of the through-hole, that is, when both the contacts are on the opposite side across the central axis of the shaft portion, the inclination of the rotating member with respect to the central axis is maximum. Become.

  In the above configuration, when the liquid level detecting device is in use, when the posture of the rotating member is changed so as to be inclined with respect to the axial direction of the shaft portion due to a gap between the through hole and the shaft portion, the rotating member The first restricting portion comes into contact with the second restricting portion of the fixing member, and the change in the posture of the rotating member is suppressed. Here, the 1st control part is provided in the outer peripheral surface of the rotation member. That is, it is provided on the outer peripheral side of the through hole. Therefore, the axial component of the shaft portion of the first restricting portion movement amount becomes large even if the inclination angle of the rotating member is very small, and even if the rotating member is slightly inclined, the first restricting portion is the first member of the fixed member. 2 Abuts against the restricting portion, whereby the change in the posture of the rotating member is immediately prevented. That is, even if the size of the gap between the through hole of the rotating member and the shaft portion of the fixing member is the same as that of the conventional liquid level detection device, the fixing member can be tilted at the maximum tiltable angle in the conventional liquid level detection device. At the time of inclining by a smaller angle, the first restricting portion comes into contact with the second restricting portion of the fixed member, and the change in posture of the rotating member is suppressed.

  As a result, the rotation member can be prevented from tilting with respect to the shaft portion of the fixed member, and the output fluctuation of the magnetoelectric conversion element at the same liquid surface position can be suppressed very slightly. A liquid level detection device capable of detection can be provided.

Furthermore, the first restricting portion is formed coaxially and annularly with the through hole, the second restricting portion is formed in the shaft portion and coaxially and annularly.

  Thereby, the inclination of the rotating member can be effectively suppressed regardless of the angular position around the shaft portion of the rotating member, in other words, regardless of the liquid level position.

  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.

  FIG. 1 is a front view of a fuel level gauge 1 that is a liquid level detection device according to an embodiment of the present invention, and shows a state where the fuel level gauge 1 is mounted in a fuel tank 11 that is a container. FIG. 1 shows a state in which the liquid level 10a of the fuel 10 is at the lowest level. Therefore, the float 4, the arm 5 and the magnet holder 2 of the fuel level gauge 1 are also in a corresponding posture. Further, in FIG. 1, the liquid level 10a of the fuel 10 is in the highest state, that is, the positions of the liquid level 10a, the float 4 and the arm 5 when the fuel is full are indicated by broken lines. In FIG. 1, a part of the arm 5 is omitted from the illustration for easy understanding.

  FIG. 2 is a cross-sectional view of the fuel level gauge 1 according to an embodiment of the present invention, and is a cross-sectional view taken along the line II-II in FIG.

  In FIGS. 1 and 2, the upper side of the figure is the upper side in the usage state of the fuel level gauge 1.

  The fuel level gauge 1 is disposed and fixed in the fuel tank 11, for example, in the fuel tank 11. The fuel level gauge 1 is a fuel pump for sending the fuel 10 to the outside of the fuel tank 11, 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 10 which 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 10 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 C of the hole 2a described later. The stopper 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 10 a of the fuel when attached to the arm 5. When the float 4 moves up and down according to the change in the position of the liquid level 10 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 2 a as a through hole that is rotatably fitted to a shaft 3 a of a body 3 to be 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 protrusion 2 d that is a holding portion for holding the arm 5. As shown in FIGS. 1 and 2, two fixing protrusions 2 d are arranged on the end surface of the magnet holder 2 opposite to the body 3. As shown in FIG. 3, the fixed protrusion 2 d includes a holding portion 2 e that is in close contact with the arm 5 and holds and fixes, and an opening 2 f that serves as an entrance to the fixed protrusion 2 d when the arm 5 is attached. In FIG. 3, the fixing protrusion 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 of the holding part 2 e is greater than the diameter dimension D <b> 1 of the arm 5. It is formed small. The opening 2f is formed such that the height dimension W is smaller than the diameter dimension d1 of the holding part 2e as shown in FIG. When the arm 5 is attached to the fixed protrusion 2d, when the arm 5 is pushed into the opening 2f of the fixed protrusion 2d from the left side of FIG. 3, the fixed protrusion 2d is elastically deformed, and the arm 5 is held by the holding part 2e. Fixed. At this time, the fixed protrusion 2d is in an elastically deformed state, and the arm 5 is held by the elastic force of the fixed protrusion 2d. Further, the two fixing protrusions 2d are arranged so that the central axes of the holding portions 2e coincide with each other. 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.

  In the magnet holder 2, the fixing hole 2c and the fixing protrusion 2d are configured as described above, so that the arm 5 can be easily and reliably attached to the magnet holder 2.

  A magnet 6 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.

  As shown in FIG. 2, the magnet holder 2 has a flange portion 2g as a first restricting portion formed on the outer peripheral surface thereof. The flange 2g is formed coaxially with the hole 2a and in an annular shape.

  The body 3 that is a fixing member is formed of a resin material. As shown in FIG. 2, the body 3 is provided with a shaft portion 3 a protruding in a cantilever manner. By fitting the shaft 3a and the hole 2a of the magnet holder 2, the body 3 holds the magnet holder 2 so as to be rotatable. 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 restricting portion 3c is provided at the tip of the small diameter portion 3b. Movement of the magnet holder 2 in the direction away from the body 3 (movement toward the left side in FIG. 2) by engaging the restriction portion 2b of the magnet holder 2 with the small diameter portion 3b and contacting the restriction portion 2b with the restriction portion 3c. Is regulated. 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. When the stopper 5a of the arm 5 fixed to the magnet holder 2 is brought into contact with the stopper 3d, the rotational movement of the magnet holder 2 is restricted.

  As shown in FIG. 2, the body 3 is provided with a guide portion 3 e as a second restricting portion. The guide portion 3e is formed coaxially and annularly with the shaft portion 3a so as to be able to contact the flange portion 2g of the magnet holder 2 in the axial direction of the shaft portion 3a. That is, when the magnet holder 2 is attached to the body 3, the guide portion 3e and the flange portion 2g of the magnet holder 2 are coaxially and are in a positional relationship facing each other in the axial direction of the shaft portion 3a. When the magnet holder 2 is mounted on the body 3, a gap S is necessarily formed between the guide portion 3e and the flange portion 2g as shown in FIG. The size of the gap S is a restriction portion by a fitting gap between the shaft portion 3a and the hole portion 2a within a range in which the guide portion 3e and the flange portion 2g are not reliably in contact with each other and smooth rotation of the magnet holder 2 is ensured. It is set smaller than the displacement generated in the 2g portion.

  As shown in FIG. 2, a hall element 7, which is a magnetic detection element for detecting the displacement of the magnet 6, is built in the shaft portion 3 a of the body 3. As shown in FIG. 2, the hall element 7 is housed in a casing 9 which will be described later, and is then fixed in the body 3 by insert molding. As shown in FIG. 2, the hall element 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 element 7 can be increased, the output voltage of the Hall element 7 can be increased, and the liquid level 10a detection accuracy can be increased. The Hall element 7 includes three leads 7a for electrically connecting the Hall element 7 to the outside.

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

  The Hall element 7 is made of a semiconductor, and generates a Hall voltage proportional to the magnetic flux density passing through the Hall element 7 when a magnetic field is applied from the outside while a voltage is applied to the Hall element 7. That is, when the Hall element 7 and the magnetic flux M are orthogonal to each other, the density of magnetic flux passing through the Hall element 7 is maximized and the Hall voltage is maximized. When the Hall element 7 and the magnetic flux M are parallel, the magnetic flux density passing through the Hall element 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 10a, the crossing angle between the Hall element 7 and the magnetic flux M of the magnet 6 changes. The Hall voltage, which is the output voltage of, changes. Therefore, by detecting this Hall voltage, the rotation angle of the magnet holder 2, that is, the position of the liquid surface 10a can be measured.

  In the fuel level gauge 1 according to the embodiment of the present invention, the Hall element 7 is fixed in the body 3 via a casing 9 as shown in FIG.

  The casing 9 is made of the same resin material as the body 3. The casing 9 is provided with a holding hole 9a, and the Hall element 7 is inserted and fixed in the holding hole 9a. The cross section of the holding hole 9a (the cross section in the direction perpendicular to the plane of FIG. 2) is substantially the same as the cross sectional shape of the Hall element 7. When the Hall element 7 is inserted into the holding hole 9a, the Hall element 7 is The holding hole 9a is in close contact with the wall surface, and there is almost no gap between them. A terminal 8 for connecting the hall element 7 to an external electric circuit is integrated with the casing 9 by insert molding.

  The terminal 8 is formed of a conductive material, for example, a copper-based metal. One end of the terminal 8 is connected to the lead 7a of the Hall element 7 so as to be conductive as shown in FIG. 2, and the other end is shown in FIG. In addition, it is exposed from the casing 9, that is, the body 3 for connection to an external electric circuit. The terminal 8 is arranged in the same number as the number of electrodes of the Hall element 7, that is, the leads 7a. In the fuel level gauge 1 according to the embodiment of the present invention, three terminals 8 are provided as shown in FIG.

  The Hall element 7 is inserted into the holding hole 9a of the casing 9, and is fixed to the body 3 by insert molding in a state where each lead 7a is connected to the corresponding terminal 8 by caulking, soldering, fusing or the like.

  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, the terminal 8 is set in a mold for casing 9 resin molding and insert molding is performed. As a result, the resin material forming the casing 9 and the terminal 8 are firmly coupled.

  Next, the hall element 7 is inserted into the holding hole 9 a of the casing 9. As shown in FIG. 2, the holding hole 9a is a bottomed blind hole, and the tip of the Hall element 7 is brought into close contact with the bottom surface of the holding hole 9a.

  Subsequently, each lead 7a of the Hall element 7 is connected to the corresponding terminal 8 so as to be conductive, for example, by fusing, soldering, or caulking.

Next, the casing 9 in which the above steps are completed is set in a mold for body 3 resin molding and insert molding is performed. In addition, the resin material used for shaping | molding of the casing 9 is used for body 3 shaping | molding.
Next, the magnet holder 2 is assembled to the body 3 by fitting the through hole 2a of the magnet holder 2 in which the magnet 6 is incorporated with the shaft portion 3a.

  Next, the arm 5 to which the float 4 is already fixed is attached to the magnet holder 2. First, the stopper 5a of the arm 5 is inserted into the fixing hole 2c of the magnet holder 2 until the arm 5 and the upper surface of the cover 4 are in contact with each other. Subsequently, the arm 5 is rotated around the stopper 5a so as to approach the opening 2f of the fixed protrusion 2d, and the arm 5 is fixed in the holding portion 2e of the fixed protrusion 2d.

  Thus, the manufacturing process of the fuel level gauge 1 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, that is, the operation and effect of the configuration including the flange portion 2g and the guide portion 3e will be described.

  First, in the conventional liquid level detection device, a radial gap is always formed between the through hole of the rotating member and the shaft portion of the fixed member in order to ensure smooth rotation of the rotating member. Since there is always a gap, the central axis of the through hole may be inclined rather than parallel to the central axis of the shaft portion. That is, the rotating member may rotate around an axis orthogonal to the central axis of the shaft portion. As described above, when the central axis of the through hole of the rotating member is inclined with respect to the central axis of the shaft portion, the amount of magnetic flux passing through the magnetoelectric conversion element accommodated in the shaft portion is parallel to the shaft portion. It changes with respect to a certain time. For this reason, even if the angular position of the rotating member is the same, that is, the liquid surface position is the same, if the attitude of the rotating member with respect to the shaft portion changes, the output of the magnetoelectric transducer changes, and the liquid surface position is detected with high accuracy. Can be difficult. Further, when the rotating member is inclined with respect to the shaft portion, the rotation surface of the arm attached to the rotating member is inclined from a state orthogonal to the central axis of the shaft portion. For this reason, the position of the float attached to the tip of the arm also moves from the normal state position. Since the float is located farthest from the center of the rotating member, the amount of movement associated with the inclination of the rotating member is large. Therefore, when the rotating member is inclined with respect to the shaft portion, the float moves and comes into contact with the inner wall of the fuel tank, thereby preventing the smooth rotation of the arm and making it difficult to detect the liquid level position with high accuracy. there is a possibility. In particular, when the rotating member and the fixed member are formed by resin molding, the nominal value of the gap is set large in consideration of dimensional variations during molding, etc., so that the liquid level position can be detected with high accuracy. It is likely to be difficult.

  On the other hand, according to the configuration of the fuel level gauge 1 according to the embodiment of the present invention, the flange portion 2g is provided on the outer peripheral surface of the magnet holder 2, and the magnet holder 2 is provided on the body 3 in the axial direction of the shaft portion 3a. A guide portion 3e is provided so as to be able to come into contact with the flange portion 2g. Further, the size of the gap S in the axial direction of the shaft portion 3a formed between the guide portion 3e and the flange portion 2g is set so that the guide portion 3e and the flange portion 2g are not in contact with each other smoothly. The displacement is set smaller than the displacement generated in the restricting portion 2g due to the fitting gap between the shaft portion 3a and the hole 2a within a range in which proper rotation is ensured.

  In such a configuration, when the magnet holder 2 rotates around an axis orthogonal to the central axis C of the shaft portion 3a due to the radial clearance between the through hole 2a and the shaft portion 3a, for example, an arrow in FIG. When rotating in the direction as indicated by, the flange portion 2g comes into contact with the guide portion 3e, thereby preventing the movement of the magnet holder 2. The flange portion 2g is formed on the outer peripheral surface of the magnet holder 2. That is, since the magnet holder 2 is formed at a position radially away from the central axis C of the magnet holder 2, the magnet holder 2 is only slightly rotated around an axis orthogonal to the central axis C of the shaft portion 3 a, so that the flange portion The gap S between 2g and the guide part 3e becomes 0, both come into contact with each other, and rotation in the direction orthogonal to the central axis C of the magnet holder 2 is suppressed. Thus, it is possible to provide the fuel level gauge 1 that can reliably prevent the magnet holder 2 from rotating in the direction orthogonal to the shaft portion 3a of the body 3 and can detect the liquid level position with high accuracy. it can.

  Further, according to the configuration of the fuel level gauge 1 according to the embodiment of the present invention, the flange portion 2g and the guide portion 3e are both formed in an annular shape, so that the angular position around the shaft portion 3a of the magnet holder 2 is determined. Regardless of the position of the liquid level 10, regardless of the position of the liquid level 10, it is possible to reliably suppress the magnet holder 2 from rotating in the direction orthogonal to the shaft portion 3a of the body 3 and detect the liquid level position with high accuracy. It is possible to provide a fuel level gauge 1 capable of

  In the fuel level gauge 1 according to the embodiment of the present invention described above, the flange portion 2g and the guide portion 3e are both formed in an annular shape that is continuous over the entire circumference. It is not necessary to limit the part 3e to such a shape, and the part 3e may be partially interrupted.

  Further, in the fuel level gauge 1 according to the embodiment of the present invention described above, the Hall element 7 is used as the magnetoelectric conversion element serving as the detection means, but the present invention is not limited to this, and other types of magnetoelectric conversion elements. For example, an MRE element (magnetoresistive element) or a magnetic diode may be used.

  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 and an alnico magnet may be used. Moreover, the magnet 6 may be formed only from a metal, or may be formed as a bonded magnet obtained by mixing and molding metal powder and resin.

  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 be limited to three and is necessary. It may be increased or decreased accordingly.

  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-III 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.

Explanation of symbols

1 Fuel level gauge (Liquid level detector)
2 Magnet holder (rotating member)
2a Hole (through hole)
2b restricting portion 2c fixing hole 2d fixing protrusion 2e holding portion 2f opening 2g flange portion (first restricting portion)
3 Body (fixing member)
3a Shaft portion 3b Small diameter portion 3c Restriction portion 3d Stopper 3e Guide portion (second restriction portion)
4 Float 5 Arm 5a Stopper 6 Magnet 7 Hall element (Magnetoelectric conversion element)
7a lead 8 terminal 9 casing 9a holding hole 10 fuel (liquid)
10a Liquid level 11 Fuel tank C Central axis D1 Diameter dimension d1 Diameter dimension M Magnetic flux S Gap W Height dimension

Claims (1)

A rotating member having a through hole;
A fixing member having a shaft portion and fitting the through hole in the shaft portion to hold the rotating member rotatably;
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 magnet fixed to the rotating member and rotating integrally with the rotating member;
A liquid level detection device comprising a magnetoelectric conversion element housed in the fixed member so as to detect displacement of the magnet,
A first restricting portion provided coaxially and annularly with the through hole on the outer peripheral surface of the rotating member;
Provided on the shaft portion and coaxially and annularly in said stationary member, and a second restricting portion which is abuttable against the made form in the axial direction of the shaft portion to the first restricting portion,
In a state where the rotating member is assembled to the fixing member, a gap between the first restricting portion and the second restricting portion in the axial direction of the shaft portion is within a range in which the rotating member can smoothly rotate. It is set smaller than the displacement generated on the outer peripheral surface of the rotating member due to the fitting gap between the shaft portion and the through hole of the rotating member ,
One of the first restricting portion and the second restricting portion is formed in an annular shape continuous over the entire circumference,
The other of the first restricting portion and the second restricting portion is formed in a partially interrupted annular shape .

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