JP2009109372A - Liquid level detecting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid level detecting device capable of reducing an impulsive force which acts on an arm when a wave collides with a float, by straining ingenuity in the shape of the float or the structure of the arm. <P>SOLUTION: The float 4 is formed into the shape of a spindle being on the same axis with a float holding part 5b. Consequently, when the wave W collides with the float 4, a fuel 10 flows along the surface of the float 4 smoothly, and the impulsive force F to be applied by the wave W to the float 4 is sharply reduced as compared with a conventional liquid level detecting device. Accordingly, it is possible to suppress faults such as deformation of the arm 5, or damages of a joining part of a housing holding part 5a to a magnet holder 2 and a joining part of the magnet holder 2 to a housing 3 caused by the impulsive force generated when the wave W by sway of the fuel 10 collides with the float 4. <P>COPYRIGHT: (C)2009,JPO&INPIT

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 is a configuration in which a magnetoelectric conversion element (for example, a Hall element) which is a magnetic detection element is disposed in a member (see Patent Document 1).

In this conventional liquid level detection device, the rotating member to which the arm is fixed is rotatably held by a housing that is a fixing member. The rotation of the arm corresponding to the fluctuation of the liquid level, that is, the rotation of the rotating member is detected by a detecting means composed of a magnet and a magnetoelectric conversion element.
Japanese Patent Laid-Open No. 2005-10047

  When the conventional liquid level detection device is arranged in the container, the float always floats on the liquid level. When the container vibrates and the liquid in the container swings, a wave is generated on the liquid surface, and this wave collides with the float of the liquid surface detection device, and an impact force may act on the float. This impact force is transmitted to the housing through the arm, and there is a risk that the arm is deformed, the arm is dropped from the rotating member, or the rotating member is dropped from the housing.

  The present invention has been made in view of such problems, and its purpose is to devise the float shape or the configuration of the arm, etc., and to reduce the impact force acting on the arm when a wave of the liquid level collides with the float. An object of the present invention is to provide a liquid level detection device that can be relaxed.

  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 a liquid level detection device comprising: a housing; an arm whose one end is rotatably supported by the housing; and a liquid attached to a float holding portion formed on the opposite side of the arm housing. A liquid level detection apparatus comprising: a float that floats; and a detection unit that converts a rotational movement of an arm due to a change in a float position in response to a change in a liquid level of the liquid contained in a housing into an electric signal, The float shape is formed so as not to have a surface orthogonal to the float holding portion of the arm.

  In the above configuration, when a wave of the liquid level collides with the float, for example, when the traveling direction of the wave is a direction along the axial direction of the float holding portion of the arm, the wave continues to collide with the axial end surface of the float. And flows along the side surface of the float. Here, the impact force acting on the float due to the wave collision is maximized when the end face of the float is in the wave traveling direction, in other words, along the axial direction of the float holding portion of the arm. In the liquid level detection device according to the first aspect of the present invention, the float shape is formed so as not to have a surface orthogonal to the float holding portion of the arm. Thereby, the impact force which acts on a float by the collision of a wave can be relieved. Therefore, it is possible to provide a liquid level detection device capable of reducing the impact force acting on the arm when the wave of the liquid level collides with the float.

  The liquid level detecting device according to claim 2 of the present invention is characterized in that the float shape is formed in a spindle shape coaxial with the float holding portion of the arm.

  According to the above-described configuration, when the wave of the liquid level collides with the float, for example, when the traveling direction of the wave is a direction along the axial direction of the float, the wave smoothly flows along the surface of the spindle-shaped float. . Thereby, the impact force acting on the float due to the collision of the waves is reduced as compared with the case of the conventional liquid level detection device. Therefore, it is possible to provide a liquid level detection device capable of reducing the impact force acting on the arm when the wave of the liquid level collides with the float.

  In the liquid level detection device according to the third aspect of the present invention, the float holding unit includes a regulating member that regulates the axial movement of the float holding unit of the float, and an elastic member is interposed between the regulating member and the float. It is characterized by that.

  According to such a configuration, when the wave of the liquid level collides with the float, an impact force acts on the float, and the float moves in the axial direction of the float holding portion of the arm, the float is an elastic member interposed between the regulating members. It moves while elastically deforming. As a result, the transmission of force from the float to the arm when the float receives an impact force due to the waves is not as shocking as the conventional liquid level detection device, but is transmitted while increasing gradually. Will be. Therefore, it is possible to provide a liquid level detection device capable of reducing the impact force acting on the arm when the wave of the liquid level collides with the float.

  In this case, as in the liquid level detection device according to claim 4 of the present invention, the elastic member may be formed by a coil spring disposed coaxially with the float holding portion. The coil spring can easily set its characteristics, in this case, characteristics for exhibiting a buffering effect. Therefore, it is possible to easily provide a liquid level detection device having an impact mitigation effect that is suitable for use conditions.

  The liquid level detection device according to claim 5 of the present invention includes a housing, an arm whose one end is rotatably supported by the housing, and a float that floats on a liquid attached to an end of the arm opposite to the housing; A liquid level detection device comprising: a detecting means that is accommodated in a housing and converts a rotational movement of the arm due to a change in a float position in response to a change in a liquid level of the liquid into an electric signal, the arm being a housing A housing holding part, a float holding part for holding the float, and an arm part formed between the housing holding part and the float holding part, and the float between the float holding part and the arm part. A buffer member having an elastic coefficient smaller than that of the holding part and the arm part is arranged.

  According to the above configuration, when a wave of the liquid level collides with the float and an impact force acts on the float, the impact force is first transmitted from the float to the buffer member, and then to the arm portion of the arm. At this time, the buffer member is elastically deformed by receiving the impact force, and a part of the impact force is consumed by this elastic deformation. Therefore, the magnitude of the force transmitted from the buffer member to the arm portion is detected by the conventional liquid level detection. It becomes smaller than the case of the device. As a result, the magnitude of the force transmitted to the arm portion of the arm when the float receives an impact force by the wave can be made smaller than in the case of the conventional liquid level detection device. When the liquid level is small and the wave is weak, the force received by the float is small, so the force transmitted to the buffer member is also small. Therefore, the elastic deformation of the buffer member is hardly deformed and the liquid level can be detected with high accuracy. As described above, it is possible to provide a liquid level detection device capable of reducing the impact force acting on the arm when a wave of the liquid level collides with the float.

  A liquid level detection device according to claim 6 of the present invention includes a housing, an arm whose one end is rotatably supported by the housing, a float that floats on a liquid attached to an end of the arm opposite to the housing, A liquid level detection device comprising: a detecting means that is accommodated in a housing and converts a rotational movement of the arm due to a change in a float position in response to a change in a liquid level of the liquid into an electric signal, the arm being a housing The housing holding portion held by the housing, the float holding portion for holding the float, and the arm portion formed between the housing holding portion and the float holding portion. Is characterized in that a buffer member having a small size is arranged.

  According to the above configuration, when the wave of the liquid level collides with the float and an impact force acts on the float, the impact force is transmitted from the float to the buffer member from the float side portion of the arm arm, and then the arm arm. Is transmitted to the housing side of the part. At this time, the buffer member is elastically deformed by receiving the impact force, and a part of the impact force is consumed by this elastic deformation. Therefore, the magnitude of the force transmitted from the buffer member to the housing side of the arm portion is It becomes smaller than the case of the liquid level detection device. When the liquid level is small and the wave is weak, the force received by the float is small, so the force transmitted to the buffer member is also small. Therefore, the elastic deformation of the buffer member is hardly deformed and the liquid level can be detected with high accuracy. As described above, the magnitude of the force transmitted to the housing side of the arm portion of the arm when the float receives an impact force by the wave can be made smaller than in the case of the conventional liquid level detection device. Therefore, it is possible to provide a liquid level detection device capable of reducing the impact force acting on the arm when the wave of the liquid level collides with the float.

  In this case, as in the liquid level detection device according to claim 7 of the present invention, the buffer member may be constituted by a coil spring. The coil spring can easily set its characteristic, that is, a characteristic for exhibiting a buffering effect. Therefore, it is possible to easily provide a liquid level detection device having an impact mitigation effect that is suitable for use conditions.

  According to an eighth aspect of the present invention, in the liquid level detection device, the detection means includes a resistance element fixed in the housing, and slides while conducting on the resistance element in synchronization with the rotation of the arm housed in the housing. It is comprised from the contactor which does.

  According to the above configuration, the liquid level is detected as an electric resistance value between the resistance element and the contact, and the liquid level can be detected with high accuracy. Therefore, it is possible to easily realize a liquid level detection device that can alleviate the impact force acting on the arm when a liquid level wave collides with the float.

  According to a ninth aspect of the present invention, in the liquid level detection device according to the present invention, the detection means includes: a magnet that rotates integrally with the shaft portion; and a magnetic detection element that is fixed so as to intersect the magnetic flux generated by the magnet in the housing. It is characterized by being composed.

  According to the above configuration, the liquid level is detected as an output signal level from the magnetic detection element, and the liquid level can be detected with high accuracy. Therefore, it is possible to easily realize a liquid level detection device that can alleviate the impact force acting on the arm when a liquid level wave collides with the float.

  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.

(First embodiment)
The fuel level gauge 1 is installed and fixed in the fuel tank 11 as shown in FIG. For example, the fuel tank 11 is installed and fixed in the same manner, and is integrally fixed to a fuel pump module (not shown) for sending the fuel 10 to the outside of the fuel tank 11, for example, an engine (not shown). FIG. 1 shows the liquid level 10a in a state where the amount of fuel in the fuel tank 11 is small by a solid line. In addition, the liquid level 10a, the arm 5, and the float 4 when the fuel amount in the fuel tank 11 is the maximum, that is, when the tank is full is indicated by broken lines.

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

  The fuel level gauge 1 generally includes a magnet holder 2 containing a magnet 6 rotatably held in a housing 3 containing a Hall IC 7 serving as a magnetic detection element, and is attached to the tip of an arm 5 fixed to the magnet holder 2. The float 4 floating on the liquid level 10a of the fuel 10 is held. When the float 4 moves up and down in response to fluctuations in the position of the liquid level 10a, the movement of the float 4 is transmitted to the magnet holder 2 via the arm 5, and the magnet holder 2 rotates relative to the housing 3. When the magnet holder 2 rotates with respect to the housing 3, the magnetic flux density of the magnet 6 that crosses the Hall IC 7 changes, and the electric signal level from the Hall IC 7 changes. Based on the electric signal from the Hall IC 7, the liquid level 10a is changed. The position is detected. Thus, in the fuel level gauge 1 according to the first embodiment of the present invention, the magnet 6 and the Hall IC 7 constitute detection means for converting the rotational movement of the arm 5 due to the fluctuation of the float 4 position into an electrical signal.

  The magnet holder 2 is made of, for example, a resin material. As shown in FIG. 2, a magnet 6 is fixed to the magnet holder 2 as detection means for converting the rotational motion of the arm 5 due to the fluctuation of the float 4 position into an electrical signal. 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 one is used and is arranged concentrically with the hole 2a as shown in FIG. . Furthermore, 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. 5, and the magnetic flux on the inner peripheral side of the magnet 6 flows in the radial direction of the hole 2a. In the fuel level gauge 1 according to the embodiment of the present invention, the magnet 6 is integrally insert-molded in the magnet holder 2 when the magnet holder 2 is resin-molded. The magnet holder 2 is rotatably held in a housing 3 described later. Accordingly, when the magnet holder 2 rotates with respect to the housing 3, the magnet 6 also rotates integrally with the magnet holder 2. 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 the housing 3 described later. As shown in FIG. 2, the magnet holder 2 is provided with a fixing hole 2 b for holding the arm 5 and a locking portion 2 c. As shown in FIGS. 1 and 2, two locking portions 2 c are arranged on the end surface of the magnet holder 2 opposite to the housing 3. As shown in FIG. 1, the two locking portions 2 c are arranged with a central axis C that is a rotation axis of the magnet holder 2 interposed therebetween. The two fixing portions 2d are arranged so that the central axis of the housing holding portion 5a intersects the central axis C of the magnet holder 2 when the housing holding portion 5a of the arm 5 is held and fixed to the locking portion 2c. Yes.

  The housing 3 is made of a resin material. As shown in FIG. 2, the housing 3 includes a shaft portion 3a, and the magnet holder 2 is rotatably held by fitting the hole 2a of the magnet holder 2 to the outer periphery of the shaft portion 3a. . The shaft portion 3a protrudes from the hole portion 2a as shown in FIG. 2 in a state where the hole portion 2a of the magnet holder 2 and the shaft portion 3a are fitted, and a portion protruding from the hole portion 2a is illustrated in FIG. As shown in FIG. 2, a groove portion 3b coaxial with the shaft portion 3a is provided. As shown in FIG. 2, a snap ring 12 is attached to the groove 3b. The snap ring 12 prevents the magnet holder 2 from moving away from the housing 3 (moving toward the left side in FIG. 2) and coming off. As shown in FIG. 1, the housing 3 includes a pair of stoppers 3 c for restricting the rotation angle range of the magnet holder 2.

  In the shaft portion 3a of the housing 3, as shown in FIG. 2, a Hall IC 7 is incorporated as a magnetic detection element which is a detection means for converting the rotational movement of the arm 5 due to the fluctuation of the float 4 position into an electric signal. . The Hall IC 7 is held and fixed in the shaft portion 3a by insert molding the housing 3 during resin molding. As shown in FIG. 2, the Hall IC 7 is disposed so that the overlapping length with the magnet 6 is as long as possible in 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 10a detection accuracy can be increased. As shown in FIG. 2, the Hall IC 7 includes a lead 7a as an electrode. The Hall IC 7 used in the fuel level gauge 1 according to one embodiment of the present invention includes three leads 7a as shown in FIG. The three leads 7a of the Hall IC 7 are electrically connected to the terminals 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 protrudes out of the housing 3 and forms a connector portion 3 d together with the housing 3. When external electrical wiring is joined to the connector portion 3d, the Hall IC 7 is connected to an external electrical circuit (not shown) via the terminal 8.

  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 10a, 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, 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.

  As shown in FIG. 3, the Hall IC 7 is insert-molded in the housing 3 in a state where the terminals 8 are conductively joined to the respective leads 7a.

  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. As shown in FIG. 1, the arm 5 is held by the housing 3. Specifically, the arm 5 is fixed to the magnet holder 2, and is held by the housing 3. The float 5 holds the float 4. The holding part 5b is comprised from the arm part 5c which connects the housing holding part 5a and the float holding part 5b.

  As shown in FIG. 2, the housing holding portion 5a of the arm 5 is formed in a substantially L shape, and the L-shaped tip side is the first holding portion 5a1, and the other L-shaped side is the second holding portion. 5a2. The first holding portion 5a1 is formed in parallel with the rotation axis of the magnet holder 2, that is, the central axis of the hole 2a described later, and is fitted in the fixed hole 2b of the magnet holder 2 as shown in FIG. On the other hand, the 2nd holding | maintenance part 5a2 is latched by the latching | locking part 2c of the magnet holder 2, as shown in FIG. Specifically, when the arm 5 is locked to the locking portion 2c, as shown in FIG. 4, the locking portion 2c is elastically deformed by expanding its inner diameter from D2 to D1 by the arm 5, and this elastic force Thus, the arm 5 is held. Further, when the magnet holder 2 rotates, the first holding portion 5a1 contacts the pair of stoppers 3c formed in the housing 3 as shown in FIG. That is, the magnet holder 2 can rotate within an angle range from the position where the first holding portion 5a1 is in contact with the one stopper 3c until the first holding portion 5a1 is in contact with the other stopper 3c. As described above, the pair of stoppers 3 c regulate the rotatable angle of the magnet holder 2.

  As shown in FIG. 2, the float holding part 5b of the arm 5 is provided so as to be substantially perpendicular to the arm part 5c. The float holding part 5 b holds the float 4 by fitting with the through hole of the float 4. A retainer 9 that is a restricting member that restricts axial movement of the float holding part 5b of the float 4 is fixed to the tip of the float holding part 5b. In the fuel level gauge 1 according to the first embodiment of the present invention, the retainer 9 is made of a metal flat washer and is press-fitted and fixed to the arm 5. As a restricting member on the side opposite to the retainer 9, the arm portion 5 c of the arm 5 plays the role.

  The float 4 is made of, for example, a resin material. The float 4 is set to float on the fuel 10 that is a liquid. Specifically, in the completed state of the fuel level gauge 1, even when the fuel level gauge 1 is immersed in the fuel 10, it is set so as to always float on the liquid level 10a. When the position of the liquid level 10a varies in the vertical direction, the position of the float 4 also varies at the same time. When the float 4 moves up and down following the liquid level 10 a, this movement is transmitted to the magnet holder 2 via the arm 5, and the magnet holder 2 rotates with respect to the housing 3. That is, the arm 5 functions to convert the vertical movement of the float 4 caused by the vertical movement of the liquid surface 10 a into the rotational movement of the magnet holder 2.

  As shown in FIG. 2, the float 4 has a spindle shape coaxial with the float holding portion 5 b of the arm 5. That is, the float 4 is formed so that the diameter of the float 4 is maximized in the central portion in the axial direction of the float 4 and gradually decreases toward both ends.

  Next, the function and effect of the fuel level gauge 1 according to the first embodiment of the present invention configured as described above, that is, the function and effect obtained by making the float shape a spindle shape will be described.

  When the fuel tank 11 vibrates due to vibrations during vehicle travel, the liquid level 10a of the fuel 10 swings and a wave is generated. Since the float 4 is always floating on the liquid level 10 a, this wave may collide with the float 4.

  Here, the case where the wave W collides from the axial direction of the float 4 is considered. First, in the conventional liquid level detection device, the float 44 is formed in a cylindrical shape. Since the end surface 44a of the float 44 is orthogonal to the traveling direction of the wave W as shown in FIG. 6A, the impact force F generated when the wave W collides with the end surface 44a of the float 44 is large. . This impact force F is transmitted to the housing holding portion 5a via the arm portion 5c of the arm 5, and further transmitted to the coupling portion between the housing holding portion 5a and the magnet holder 2 or the coupling portion between the magnet holder 2 and the housing 3. As a result, there is a possibility that problems such as damage to these connecting portions or deformation of the arm 5 may occur. On the other hand, in the fuel level gauge 1 according to the first embodiment of the present invention, when the wave W collides with the float 4, the float 4 is formed in a spindle shape. ), The impact force F exerted on the float 4 by the wave W flowing smoothly along the surface of the float 4 is greatly reduced as compared with the conventional liquid level detection device shown in FIG. To do. Thereby, the impact force transmitted to the coupling portion between the housing holding portion 5 a and the magnet holder 2 or the coupling portion between the magnet holder 2 and the housing 3 through the arm portion 5 c of the arm 5 can be reduced. Therefore, the coupling portion between the housing holding portion 5a and the magnet holder 2 and the coupling portion between the magnet holder 2 and the housing 3 are damaged by the impact force when the wave W generated by the oscillation of the fuel 10 collides with the float 4. Alternatively, the occurrence of problems such as deformation of the arm 5 can be suppressed.

(Second Embodiment)
The fuel level gauge 1 according to the second embodiment of the present invention is obtained by changing the mounting structure of the float 4 to the arm 5 with respect to the fuel level gauge 1 according to the first embodiment of the present invention. Except for the configuration of the attachment portion to 5, the other portions are the same as the fuel level gauge 1 according to the first embodiment of the present invention. Below, the attachment structure to the arm 5 of the float 4 is demonstrated.

  In the fuel level gauge 1 according to the second embodiment of the present invention, as shown in FIG. 7, in the axial direction of the float 4, between the float 4 and the retainer 9 and between the float 4 and the arm portion 5 c of the arm 5. The coil springs 13a and 13b, which are elastic members, are interposed.

  Consider the movement of the float 4 when a wave W collides with the float 4 and an impact force acts on the float 4. The float 4 moves in the axial direction of the float holding part 5b by the impact force received from the wave W. At this time, the float 4 moves to the right in FIG. 7 while pressing and contracting the coil spring 13b. As a result, the state of transmission of the impact force F generated in the float 4 to the arm 5 does not become shocking as in the conventional liquid level detection device, but is transmitted while gradually increasing. The impact force transmitted to the arm 5 is alleviated. Therefore, even with the fuel level gauge 1 according to the second embodiment of the present invention, the coupling between the housing holding portion 5a and the magnet holder 2 due to the impact force when the wave W generated by the oscillation of the fuel 10 collides with the float 4. It is possible to suppress the occurrence of problems such as damage to the joint portion between the magnet portion 2 and the magnet holder 2 and the housing 3, or deformation of the arm 5.

(Third embodiment)
The fuel level gauge 1 according to the third embodiment of the present invention is obtained by changing the structure of the arm 5 with respect to the fuel level gauge 1 according to the first embodiment of the present invention. The part is the same as the fuel level gauge 1 according to the first embodiment of the present invention. Below, the structure of the arm 5 is demonstrated.

  In the fuel level gauge 1 according to the third embodiment of the present invention, as shown in FIG. 8, a coil that is a buffer member having a smaller elastic coefficient than the arm 5 is provided between the float holding portion 5 b and the arm portion 5 c of the arm 5. A spring 14 is arranged. The coil spring 14 is formed of a tightly wound spring, and the float holding portion 5b and the arm portion 5c are fitted and fixed to both ends thereof. That is, in the fuel level gauge 1 according to the third embodiment of the present invention, the arm 5 is formed as a separate part with the float holding part 5b being disconnected from the arm part 5c, and both are connected via the coil spring 14. Both end portions of the coil spring 14 are fitted with the float holding portion 5b and the arm portion 5c, but the middle portion thereof is only the coil spring 14.

  When the wave W collides with the float 4 and an impact force acts on the float 4, the coil spring 14 is bent as shown in FIG. 9 while being elastically deformed. Since the impact force is consumed by this elastic deformation, the force transmitted from the coil spring 14 to the arm portion 5c is relieved. Therefore, also with the fuel level gauge 1 according to the third embodiment of the present invention, the coupling between the housing holding portion 5a and the magnet holder 2 due to the impact force when the wave W generated by the oscillation of the fuel 10 collides with the float 4 is achieved. It is possible to suppress the occurrence of problems such as damage to the joint portion between the magnet portion 2 and the magnet holder 2 and the housing 3, or deformation of the arm 5.

  When the oscillation of the liquid surface 10a is small and the wave W is small, that is, the wave height is low, the force that the float 4 receives from the wave W is also small, the coil spring 14 hardly undergoes elastic deformation, and the arm 5 is a single rigid body. Function as. That is, the coil spring 14 is set so as to reduce the impact force when the wave is large and hardly deform when the wave is small.

  In the fuel level gauge 1 according to the third embodiment of the present invention, the coil spring 14 is disposed between the float holding part 5b and the arm part 5c of the arm 5, but in the middle of the arm part 5c of the arm 5. You may arrange. That is, the arm portion 5 c may be cut in the middle, and the cut portion may be connected by the coil spring 14. Also in this case, as in the case of the fuel level gauge 1 according to the third embodiment of the present invention, the impact force when the wave W generated by the oscillation of the fuel 10 collides with the float 4 is alleviated, and the housing holding portion Generation | occurrence | production of malfunctions, such as damage to the coupling | bond part of 5a and the magnet holder 2, and the coupling | bond part of the magnet holder 2 and the housing 3, or the deformation | transformation of the arm 5, can be suppressed.

  Further, the shape of the float 4 may be a shape having a large chamfer with the planar area of a portion in contact with the retainer 9 being minimized, or a spheroid shape. Further, even when a cylindrical portion extending in the axial direction of the arm holding portion 5b is provided at the maximum diameter portion of the spheroid or spindle-shaped float 4, the wave W generated by the oscillation of the fuel 10 collides with the float 4. Due to this impact force, it is possible to suppress the occurrence of problems such as damage to the coupling portion between the housing holding portion 5a and the magnet holder 2 and the coupling portion between the magnet holder 2 and the housing 3, or deformation of the arm 5.

  In the first to third embodiments of the present invention described above and the modifications thereof, the magnet 6 and a hole that is a magnetic detection element are used as detection means for converting the rotational movement of the arm 5 due to the fluctuation of the float 4 position into an electrical signal. Although the IC 7 is used, another type of magnetic detection element detection element, such as an MRE element (magnetoresistance element), may be used instead of the Hall IC.

  In the first to third embodiments of the present invention described above and the modifications thereof, a magnet and a magnetic detection element are used as detection means for converting the rotational movement of the arm 5 due to the fluctuation of the float 4 position into an electric signal. Although used, other types of detection means, for example, resistive elements and contacts may be used. That is, a configuration may be adopted in which a resistance element is disposed in the housing 3, a contact made of a conductive metal is rotated in synchronization with the rotation of the arm 5, and the contact is slid while conducting on the resistance element. In this case, the rotational movement of the arm 5 due to the change in the position of the float 4 is detected as a change in electrical resistance between one end of the resistor and the contact.

  Further, in each of the embodiments of the present invention described above, the case where the liquid level detection 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.

1 is a front view of a fuel level gauge 1 according to a first 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 the IV-IV sectional view taken on the line in FIG. It is a schematic diagram explaining the magnetization state of the magnet 6 and magnetic flux distribution in the fuel level gauge 1 by 1st Embodiment of this invention. (A) shows the state when the wave W collides with the float 44 of the conventional liquid level detection device, and (b) shows the wave W collides with the float 4 of the fuel level gauge 1 according to the first embodiment of the present invention. It is a schematic diagram explaining the state when it did. It is an external view of the float 4 attachment part in the fuel level gauge 1 by 2nd Embodiment of this invention. It is an external view of the float 4 attachment part in the fuel level gauge 1 by 3rd Embodiment of this invention. In the fuel level gauge 1 by 3rd Embodiment of this invention, it is an external view explaining the condition when a wave collides with the float 4. FIG.

Explanation of symbols

1 Fuel level gauge (Liquid level detector)
2 Magnet holder 2a Hole portion 2b Fixing hole 2c Locking portion 3 Housing 3a Shaft portion 3b Groove portion 3c Stopper 3d Connector portion 4 Float 5 Arm 5a Housing holding portion 5a1 First holding portion 5a2 Second holding portion 5b Float holding portion 5c Arm portion 6 Magnet (detection means)
7 Hall element (detection means, magnetic detection element)
7a Lead 8 Terminal 9 Retainer (Regulator)
10 Fuel (liquid)
10a Liquid level 11 Fuel tank 12 Snap ring 13 Coil spring 14 Coil spring C Center axis D1, D2 Diameter dimension F Impact force M Magnetic flux W wave

Claims (9)

A housing;
An arm whose one end is rotatably supported by the housing;
A float floating on a liquid attached to a float holding part formed on the opposite side of the housing to the arm;
A liquid level detection device comprising: a detecting unit that is accommodated in the housing and converts a rotational movement of the arm due to a change in the float position in response to a change in a liquid level of the liquid into an electric signal;
The liquid level detection apparatus according to claim 1, wherein the float shape is formed so as not to have a surface orthogonal to the float holding portion of the arm.   The liquid level detection device according to claim 1, wherein the float shape is formed in a spindle shape coaxial with the float holding portion of the arm. The float holding unit includes a regulating member that regulates axial movement of the float holding unit of the float,
The liquid level detection device according to claim 1, wherein an elastic member is interposed between the regulating member and the float.   The liquid level detection device according to claim 3, wherein the elastic member is a coil spring disposed coaxially with the float holding portion. A housing;
An arm whose one end is rotatably supported by the housing;
A float floating in a liquid attached to the end of the arm opposite the housing;
A liquid level detection device comprising: a detecting unit that is accommodated in the housing and converts a rotational movement of the arm due to a change in the float position in response to a change in a liquid level of the liquid into an electric signal;
The arm is composed of a housing holding part held by the housing, a float holding part for holding the float, and an arm part formed between the housing holding part and the float holding part,
A liquid level detection device, wherein a buffer member having an elastic coefficient smaller than that of the float holding part and the arm part is arranged between the float holding part and the arm part. A housing;
An arm whose one end is rotatably supported by the housing;
A float floating in a liquid attached to the end of the arm opposite the housing;
A liquid level detection device comprising: a detecting unit that is accommodated in the housing and converts a rotational movement of the arm due to a change in the float position in response to a change in a liquid level of the liquid into an electric signal;
The arm is composed of a housing holding part held by the housing, a float holding part for holding the float, and an arm part formed between the housing holding part and the float holding part,
A liquid level detecting device, wherein a buffer member having an elastic coefficient smaller than that of the arm portion is disposed in the middle of the arm portion.   The liquid level detection device according to claim 5, wherein the buffer member is a coil spring.   The detection means includes a resistance element fixed in the housing and a contact that is accommodated in the housing and slides while conducting on the resistance element in synchronization with the rotation of the arm. The liquid level detection apparatus according to claim 1, wherein the liquid level detection apparatus is a liquid level detection apparatus.   2. The detection means includes a magnet that rotates integrally with the shaft portion, and a magnetic detection element that is fixed in the housing so as to intersect a magnetic flux generated by the magnet. The liquid level detection apparatus as described in any one of thru | or 7.

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