level detector

Abstract

A liquid level detector (3) includes a magnetic detection element (60) provided to a shaft (21) of a frame (11b) and detecting a rotation angle of a holder (40), and a magnet (65) provided in the holder and applying a magnetic field to the magnetic detection element (60). The holder includes a pair of flanges (43) protruding in directions opposite to each other along an extension direction of an arm (51) in an arm holding portion (46). The frame includes a lock groove (22) having two side walls (22a) facing each other in a direction along a central axis (AX) of the shaft and enabling the flanges (43) to be rotationally locked, and an arm facing portion (11c) provided at a position facing a track of the arm. A first space (G1) between the arm facing portion and the track of the arm is smaller than a second space (G2) between the side walls of the lock groove and the flanges.

Description

Technical Field

[0001] This invention relates to a liquid level detector. Background Technology

[0002] Traditionally, there exists a liquid level detector that detects the liquid level based on the displacement of an arm following the up-and-down movement of a float floating in the liquid. Patent Document 1 discloses a liquid level detector technique that is installed in a fuel tank in a vehicle such as an automobile and is capable of detecting the level of fuel stored in the fuel tank.

[0003] Reference List

[0004] Patent documents

[0005] Patent Document 1: JP2018-205136A Summary of the Invention

[0006] In the liquid level detector disclosed in Patent Document 1, a Hall element, serving as a magnetic detection element, is embedded in a shaft located in the device body. When a magnetic field is applied from the outside while a voltage is applied, the Hall element generates a Hall voltage. Simultaneously, a magnet is disposed inside a retainer, which is rotatably supported on the shaft and rotates via a retaining arm. With this configuration, when the retainer rotates due to changes in the liquid level, the magnet also rotates and shifts, and the cross angle between the magnetic flux of the Hall element and the magnet changes, thus changing the Hall voltage. Therefore, the liquid level detector detects the rotation angle of the retainer based on the measured Hall voltage, thereby enabling the detection of the fuel level. However, in the liquid level detector disclosed in Patent Document 1, gaps are provided between various components to account for dimensional variations during manufacturing, temperature variations during use, aging, etc. Therefore, for example, if an undesirable external force is applied to the arm supporting the float, the retainer of the retaining arm may tilt relative to the shaft positioned in the device body. In this case, when the tilt of the retainer is large, the magnetic flux density applied to the Hall element changes compared to the normal state, thus increasing the risk of output errors.

[0007] The purpose of this invention is to provide a liquid level detector that can suppress output errors.

[0008] The liquid level detector according to the invention comprises: a float that floats on a liquid; an arm that supports the float at its end; a retainer that holds the base end of the arm and converts the displacement of the arm, which moves up and down with the float as the liquid level changes, into rotational motion; a frame having an axis that serves as a rotation reference for the retainer; a magnetic detection element disposed on the axis and detecting the rotation angle of the retainer; and a magnet disposed in the retainer and applying a magnetic field to the magnetic detection element, wherein the retainer comprises: a shaft recess that is rotatably and slidably coupled to the... The shaft engagement; an arm retainer that holds the arm with the arm's extension direction perpendicular to the central axis of the shaft recess; and a pair of flanges that project in opposite directions along the arm's extension direction in the arm retainer, wherein the frame includes: a locking groove having two sidewalls facing each other in a direction along the central axis of the shaft and capable of rotatably locking the flanges; and an arm facing portion disposed at a position facing the track of the arm, wherein a first space between the arm facing portion and the track of the arm is smaller than a second space between the sidewalls of the locking groove and the flanges. Attached Figure Description

[0009] Figure 1 This is a perspective view of the liquid level detector according to the first embodiment.

[0010] Figure 2 This is an exploded perspective view of the main part of the liquid level detector according to the first embodiment.

[0011] Figure 3 This is a cross-sectional view of the main part of the liquid level detector according to the first embodiment.

[0012] Figure 4 This is a perspective view of the main parts of the liquid level detector, viewed from the front at an angle downwards.

[0013] Figure 5 This is a perspective view showing the conductive part of the arm at the intermediate detection position of the liquid level.

[0014] Figure 6 This is a perspective view showing the conductive part of the arm at the minimum detection position of the liquid level.

[0015] Figure 7 This is a perspective view of another example of a conductive part that can be used in a liquid level detector.

[0016] Figure 8 This is a cross-sectional view of another example of a conductive part that can be used in a liquid level detector.

[0017] Figure 9 This is a perspective view of the level detector according to the second embodiment.

[0018] Figure 10 This is a plan view of the level detector according to the second embodiment.

[0019] Figure 11 It is a conceptual diagram used to illustrate how to set the lead length.

[0020] Figure 12 This is a conceptual diagram used to illustrate the tensile load applied to the lead wire.

[0021] Figure 13 This is a perspective view of the level detector according to the third embodiment.

[0022] Figure 14 This is a cross-sectional view of the main part of the level detector according to the third embodiment.

[0023] Figure 15 It is an enlarged cross-sectional view used to illustrate the relationship between the first space and the second space.

[0024] Symbol Explanation

[0025] 3 liquid level detectors

[0026] 11b framework

[0027] 11c Arm Face

[0028] 21 axis

[0029] 22a Sidewall

[0030] 40 Retaining parts

[0031] 42 Shaft recess

[0032] 43 Flange

[0033] 46 Arm Holding Section

[0034] 50 floats

[0035] 51 arms

[0036] 60 Magnetic Detection Element

[0037] 65 Magnets Detailed Implementation

[0038] The liquid level detectors according to various embodiments will now be described in detail with reference to the accompanying drawings.

[0039] (First Embodiment)

[0040] Figure 1 This is a perspective view of the liquid level detector 1 according to the first embodiment. Figure 2 This is an exploded perspective view of the main part of the liquid level detector 1. Figure 3 This is a cross-sectional view of the main part of the liquid level detector 1 taken in a plane extending vertically, including the central axis of shaft 21. In the following text, the term "upper" or "lower" in the liquid level detector 1 refers to the upper or lower side in the vertical direction.

[0041] The liquid level detector 1 detects the liquid level (liquid surface position) based on the displacement of the arm 51 following the up-and-down movement of the float 50 floating in the liquid. As an example, the liquid level detector 1 is installed in a fuel tank in a vehicle such as an automobile, and detects the level of fuel stored in the fuel tank. The liquid level detector 1 includes a device body 10, a lead wire 30, a connector 37, a retainer 40, a float 50, and an arm 51.

[0042] The device body 10 is the main body portion of the level detector 1. The device body 10 includes a frame 11, a lead frame 12, and a retaining member 13. Hereinafter, the term "front and rear" in the device body 10 refers to the front or rear side in the horizontal direction. In this case, the front side is the side in which the retaining member 40 is supported in the device body 10, and the rear side is the side where inserts such as the lead frame 12 are formed.

[0043] The frame 11 is a structure made of, for example, resin, and rotatably supports the retainer 40. The frame 11 has a rotatable recess 20, a shaft 21, a locking groove 22, a pair of insertion holes 23, a guide protrusion 24, a first stop surface 25a, and a second stop surface 25b.

[0044] The rotating recess 20 is circular in plan view at the front of the frame 11 and rotatably accommodates a portion of the retainer 40. The shaft 21 is the rotation reference of the retainer 40, which is coaxially disposed at the center of the rotating recess 20, and engages with the shaft recess 42 formed in the retainer 40.

[0045] A locking groove 22 is circumferentially disposed in the inner periphery of the rotating recess 20, and rotatably locks the flange 43 of the retainer 40. A pair of insertion holes 23 are disposed at the edge of the rotating recess 20, facing each other in the horizontal direction, and communicate with the locking groove 22. A guide protrusion 24 is disposed at the bottom of the rotating recess 20 in a manner that surrounds the shaft 21, and guides the rotation of the retainer 40.

[0046] The first stop surface 25a and the second stop surface 25b are a pair of first stops that limit the swing of the arm 51 by contacting it, thereby limiting the rotation of the retainer 40. The pair of first stops are located on the front side of the frame 11 and below the center of the rotation recess 20, facing each other at a distance along the outer periphery of the rotation recess 20. When the retainer 40 rotates, the arm 51 contacts one of the pair of first stops at its end relative to the position facing the shaft 21. As a result, the rotation range of the retainer 40 is limited to an angle range θ. The first stop surface 25a contacts the arm 51 at the maximum detection position of the liquid level that the level detector 1 can detect. That is, the first stop surface 25a is at the position where the arm 51 contacts when the remaining fuel capacity in the fuel tank is almost full. The second stop surface 25b contacts the arm 51 at the minimum detection position of the liquid level that the level detector 1 can detect. That is, the second stop surface 25b is in contact with the arm 51 when the remaining fuel capacity in the fuel tank is almost empty.

[0047] The frame 11 may also have a rotating groove 26, a first auxiliary stop surface 27a, and a second auxiliary stop surface 27b. The rotating groove 26 is located at the upper edge of the rotating recess 20 between the two insertion holes 23, and becomes the track for the locking end 51a of the arm 51 when the retainer 40 rotates.

[0048] The first auxiliary stop surface 27a and the second auxiliary stop surface 27b are a pair of second stops that restrict the swing of the arm 51 by contacting the locking end 51a of the arm 51, thereby restricting the rotation of the retainer 40. The pair of second stops are located at both ends of the rotation groove 26 and face each other at a distance along the edge of the rotation recess 20. Therefore, when the retainer 40 rotates, the arm 51 contacts one of the pair of second stops at the locking end 51a, which is located on the base end side compared to the position facing the shaft 21. Here, the rotation range of the retainer 40 restricted by the pair of second stops can be set to a larger rotation angle than the angular range θ restricted by the pair of first stops. The first auxiliary stop surface 27a is positioned where the locking end 51a of the arm 51 contacts when the remaining fuel capacity in the fuel tank is almost full. The second auxiliary stop surface 27b is positioned where the locking end 51a of the arm 51 contacts when the remaining fuel capacity in the fuel tank is almost empty. When an overload is applied to arm 51, due to the large load, arm 51 bends by contacting one of the pair of first stops, and the locking end 51a of arm 51 also contacts one of the pair of second stops. As a result, the overload acting on arm 51 can be applied not only to the first stops but also to the second stops, thereby dispersing the overload.

[0049] Furthermore, the frame 11 has an insert molding section 28 and a lead arrangement section 29. The insert molding section 28 is the area in which inserts such as a part of the lead frame 12, the Hall element 60, and a part of the conductive section 70 are molded into the frame 11. In the lead arrangement section 29, the portion of the lead frame 12 connected to the lead 30 is exposed on the outside of the frame 11, and the end portion of the lead 30 connected to the lead frame 12 is arranged there.

[0050] The lead frame 12 is a conductor portion partially insert-molded into the frame 11. Depending on the type of lead 30 based on the detection method of the detection unit, the lead frame 12 includes multiple terminals, each serving as an independent plate. In this embodiment, the lead frame 12 includes an input terminal 34, a ground (GND) terminal 35, and an output terminal 36. The input terminal 34, ground terminal 35, and output terminal 36 are electrically connected to leads 62 extending from the Hall element 60 according to their respective functions.

[0051] The retaining member 13 is attached to the lead arrangement portion 29 provided in the frame 11 to retain the lead 30. For example, the retaining member 13 may have a groove 13a corresponding to the diameter of each lead 30. In the retaining member 13, the lead 30 is held in the lead arrangement portion 29 in the state where the lead 30 is engaged with the groove 13a, and therefore the lead 30 is unlikely to detach from the lead frame 12.

[0052] In addition, the device body 10 includes a Hall element 60 and a lead wire 62, the Hall element 60 being used as a detection part to detect the rotation angle of the retaining member 40.

[0053] The Hall element 60 is a magnetic detection element embedded in the shaft 21 of the frame 11. When a magnetic field is applied from the outside while a voltage is applied, a Hall voltage proportional to the magnetic flux density passing through the Hall element 60 is generated. Meanwhile, a magnet 65, which will be described later, is disposed inside the holder 40. When the holder 40 rotates due to a change in liquid level, the magnet 65 also rotates and shifts, and the cross angle between the magnetic flux of the Hall element 60 and the magnet 65 changes, thereby changing the Hall voltage. That is, the rotation angle of the holder 40 can be detected based on the measured Hall voltage, thereby enabling the detection of the fuel level. As described above, a lead 62 extends from the Hall element 60 and is electrically connected to terminals included in the lead frame 12.

[0054] Furthermore, the Hall element 60, lead 62, and a portion of the lead frame 12 can be mounted inside the frame 11 through multiple insert molding processes. For example, the Hall element 60 and lead 62 can be mounted in the frame 11 together with the resin body 63 through insert molding in a first step. Subsequently, the lead frame 12 can be mounted in the frame 11 through insert molding in a second step. The resin body 63 has an inner shaft 63a coaxially embedded inside the shaft 21 of the frame 11. The Hall element 60 is further disposed inside the inner shaft 63a. The Hall element 60 and lead 62 can be pre-embedded in the resin body 63 using a resin component 64. Although not shown, the resin component 64 may include other electronic components related to the operation of the Hall element 60.

[0055] Furthermore, the device body 10 includes a conductive portion 70, which is at least partially embedded in the frame 11. The conductive portion 70 will be described in detail below.

[0056] Multiple leads 30 are provided based on the detection method of the detection unit, and the multiple leads 30 electrically connect the liquid level detector 1 to an external device such as a measuring instrument. In this embodiment, the leads 30 include a power input line 31, a ground (GND) line 32, and a signal output line 33, which are independent of each other. One end of the input line 31 is connected to the input terminal 34 in the lead arrangement section 29. One end of the ground line 32 is connected to the ground terminal 35 in the lead arrangement section 29. One end of the output line 33 is connected to the output terminal 36 in the lead arrangement section 29.

[0057] Connector 37 connects the other ends of input line 31, ground line 32 and output line 33 without touching each other, and connects to a connector for electrical connection to an external device.

[0058] The retainer 40 is, for example, a component made of resin, and retains the base end side of the arm 51, converting the displacement of the arm 51, which moves up and down with the float 50 as the fuel level changes, into rotational motion. In the following text, the term "front and rear" in the retainer 40 refers to the front or rear side in the horizontal direction. Here, the front side is the side of the retaining arm 51, and the rear side is the side of the retainer 40 supported by the device body 10. The retainer 40 has a retainer body 41 and an arm retaining portion 46.

[0059] The retainer body 41 is a cylindrical component having a shaft recess 42, a pair of flanges 43 and a guide recess 44.

[0060] A shaft recess 42 is provided on the rear surface side of the retainer body 41 and is coaxially arranged with the central axis of the shaft 21. It is rotatably and slidably engaged with the shaft 21, which is provided in the frame 11, as a rotation axis. In this embodiment, the central axis of the shaft recess 42, unlike the central axis of the shaft 21, is referred to as the "rotation axis". Each flange 43 is configured to project radially outward from the rear edge of the retainer body 41. A pair of flanges 43 project in opposite directions along the extension direction of the arm 51 when the arm is held by the arm retainer 46. A guide recess 44 is provided on the rear surface side of the retainer body 41 and on the outer periphery of the magnet 65 provided in the retainer body 41, and accommodates a guide protrusion 24 provided in the frame 11.

[0061] When the retainer 40 is attached to the frame 11, the operator engages the retainer 40 into the rotating recess 20 with the pair of flanges 43 positioned to match the positions of the pair of insertion holes 23 in the frame 11. As the flanges 43 pass through the insertion holes 23, the shaft 21 of the frame 11 inserts into the shaft recess 42 of the retainer 40. Furthermore, the guide protrusion 24 of the frame 11 enters the guide recess 44 of the retainer 40. Next, when the operator rotates the retainer 40, which is engaged in the rotating recess 20, with the locking hole 47 (described later) positioned above, the flanges 43 enter the locking groove 22 of the frame 11, preventing the retainer 40 from disengaging from the rotating recess 20. With the retainer 40 holding arm 51 in the position, the rotation range of the retainer 40 is limited by a first stop or the like, preventing the retainer 40 from disengaging from the rotating recess 20 due to the flanges 43 moving to the position of the insertion holes 23.

[0062] The arm retaining portion 46 holds the arm 51 in such a way that the extension direction of the arm 51 is perpendicular to the rotation axis of the retainer 40. The arm retaining portion 46 has a locking hole 47. The locking hole 47 is provided at a portion of the periphery of the retainer body 41 in a manner that extends through the front-rear direction of the retainer 40, and locks the locking end 51a located at the base end side of the arm 51.

[0063] The retainer 40 is also provided with an annular magnet 65. The magnet 65 is disposed inside the retainer body 41 in such a way that it is arranged on the inner circumferential side of the shaft recess 42, and is a displacement member for detecting the rotation angle of the retainer 40 using a Hall element 60. In this case, the Hall element 60 is located on the inner diameter side of the magnet 65, which rotates and shifts with the rotation of the retainer 40.

[0064] Float 50 floats on the liquid fuel. That is, float 50 moves up and down as the liquid level of the fuel in the fuel tank changes.

[0065] Arm 51 is a rod-shaped component that connects retainer 40 and float 50 to each other. Arm 51 supports float 50 at its end side. Simultaneously, arm 51 is held at its base end side, opposite to the end side, by arm retainer portion 46 of retainer 40. Arm 51 may have more than one curved portion. The end of arm 51 at its base end side is a locking end 51a bent at a right angle. When arm retainer portion 46 holds arm 51, locking end 51a is inserted into locking hole 47. Locking end 51a inserted into locking hole 47 is arranged in rotation groove 26 provided in frame 11.

[0066] Next, the conductive part 70 will be described in detail. Figure 4 This is a perspective view of the main parts of the liquid level detector 1, including the device body 10 and the retaining member 40, viewed from the front at an angle downwards. Figure 4 This shows the state in which the arm 51 is in contact with the second stop surface 25b of the frame 11. Figure 5 This is a perspective view showing the conductive portion 70 of the arm 51 at the intermediate detection position of the liquid level, with the frame 11 removed from the device body 10. Figure 6 It is shown that... Figure 5 A perspective view of the conductive portion 70 of arm 51 at the minimum detection position of the liquid level is shown accordingly. Figure 5 and Figure 6 In the diagram, arm 51 is drawn with a double-dotted line, assuming that arm 51 is held by retainer 40.

[0067] The conductive portion 70 is a conductive member having an extension 71, a first end 72, and a second end 73. The extension 71 is the body of the conductive portion 70. The first end 72 is one end of the extension 71 and is connected to the grounding terminal 35 included in the lead frame 12. The second end 73 is the other end of the extension 71 and is positioned to contact the arm 51. In the conductive portion 70, the extension 71, the first end 72, and the second end 73 are all formed of a sheet material, for example, made of metal.

[0068] Here, the Hall element 60 and the lead frame 12 can be installed inside the frame 11 by multiple insert molding processes. Therefore, the conductive part 70 can also be installed inside the frame 11 by insert molding. In this case, the first end 72 can be pre-joined to the ground terminal 35 by welding or the like before insert molding.

[0069] In this embodiment, there are two conductive portions 70 with symmetrical shapes to each other. For example... Figure 4 As shown, the second end 73 of a conductive portion 70 protrudes from the first stop surface 25a of a pair of first stops toward the track of the arm 51. Furthermore, as... Figure 4As shown, the second end 73 of another conductive portion 70 protrudes from the second stop surface 25b of a pair of first stops toward the track of the arm 51. Each extension 71 is embedded in the frame 11 in a manner that does not interfere with other components and does not protrude from the outside of the frame 11, extending from the first end 72 to the second end 73. That is, the shape of the extension 71 is determined based on the internal structure or shape of the frame 11.

[0070] In the aforementioned conductive part 70, such as Figure 5 As shown, when the fuel level is at the intermediate detection position, arm 51 does not contact either the second end 73 exposed from the first stop surface 25a or the second end 73 exposed from the second stop surface 25b. Here, the intermediate detection position of the fuel level refers to a position approximately at the middle level among the fuel levels that the level detector 1 can detect. The intermediate level corresponds, for example, to the level shown when the remaining fuel capacity in the fuel tank is approximately half of what it would be when the fuel tank is full. Note that when the fuel level detection position is at the intermediate detection position and not at the maximum or minimum detection position, arm 51 does not contact either of the second ends 73.

[0071] At the same time, such as Figure 6 As shown, when the fuel level is at the minimum detection position, arm 51 contacts the second end 73 exposed from the second stop surface 25b. Similarly, when the fuel level is at the maximum detection position (not shown), arm 51 contacts the second end 73 exposed from the first stop surface 25a.

[0072] Next, the operation of level detector 1 will be described.

[0073] First, in the level detector 1, as a basic operation, the arm 51 swings up and down following the movement of the float 50 as the fuel level changes, and the retainer 40 connected to the arm 51 rotates relative to the device body 10. The Hall element 60 in the device body 10 detects changes in the magnetic flux of the magnet 65 in the retainer 40, and the detection result is transmitted via the output line 33 to a measuring unit or similar external device. For example, the measuring unit measures the liquid level based on the output signal transmitted from the level detector 1, and, if necessary, issues warnings such as fuel depletion in the fuel tank.

[0074] Here, when the level detector 1 is installed in the fuel tank of a vehicle, static electricity may be generated due to fuel oscillation caused by the vibration of the vehicle during operation, or the vibration of the various resin components, and the arm 51 may become charged. Conversely, when the remaining fuel capacity is full or empty, or even when the remaining fuel capacity is not full or empty, if the vibration amplitude of the arm 51 increases due to the large vibration of the vehicle during operation, the arm 51 comes into contact with one of the pair of first stop members. That is, the arm 51 comes into contact with the second end 73 of the conductive part 70 exposed from the first stop surface 25a or the second stop surface 25b. Since the conductive part 70 is connected to the grounding terminal 35 through the first end 72, the static electricity remaining in the arm 51 is released to the grounding wire 32 through the conductive part 70 due to the contact between the arm 51 and the second end 73.

[0075] Next, the effect of level detector 1 will be described.

[0076] The liquid level detector 1 includes: a float 50 that floats on a liquid; an arm 51 that supports the float 50 at its end; and a retainer 40 that holds the base end of the arm 51 and converts the displacement of the arm 51, which moves up and down with the float 50 as the liquid level changes, into rotational motion. Furthermore, the liquid level detector 1 includes: a frame 11 having a shaft 21 serving as a rotation reference for the retainer 40; a detection unit disposed within the frame 11 and detecting the rotation angle of the retainer 40; and a grounding terminal 35 connected to the detection unit. Additionally, the liquid level detector 1 includes a conductive portion 70 having a first end 72 connected to the grounding terminal 35 and a second end 73 positioned in a manner accessible to the arm 51, and the conductive portion 70 is at least partially embedded in the frame 11.

[0077] In the example above, the detection unit corresponds to the Hall element 60. However, the detection method used by the level detector 1 is not limited to the method using the Hall element 60, and other detection methods can be used, as long as the method can detect the rotation angle of the holding member 40.

[0078] In the level detector 1, the frame 11 may have a pair of first stops that contact the end side of the arm 51 relative to the position facing the shaft 21, thereby limiting the range of rotation of the retainer 40. In this case, the second end 73 may protrude from each of the first stop surfaces 25a and 25b constituting the pair of first stops toward the track of the arm 51.

[0079] According to the level detector 1, the conductive part 70 has a first end 72 connected to the grounding terminal 35 and a second end 73 positioned in a manner accessible to the arm 51. Therefore, even when the arm 51 is energized, when the arm 51 comes into contact with the second end 73, the static electricity remaining in the arm 51 can be released to the grounding wire 32 through the conductive part 70. Thus, the generation of sparks around the level detector 1 caused by the arm 51 being energized and the resulting static electricity attempting to flow from the arm 51 to a low potential position can be suppressed in advance.

[0080] According to the level detector 1, the conductive part 70 is at least partially embedded in the frame 11. Therefore, even though the level detector 1 is provided with the conductive part 70, there is no significant difference in appearance compared to the case where the conductive part 70 is not provided. Therefore, for example, when an operator installs the level detector 1 in a fuel tank, the operability of installing the level detector 1 is not reduced due to the increase in the size and complexity of the level detector 1.

[0081] Furthermore, by exposing the second end 73 of the conductive part 70 from the first stop surface 25a and the like toward the track of the arm 51, the aforementioned effect can be achieved with a simple structure. Moreover, even regarding the shape of the level detector 1, the position or structure of the first stop surface 25a and the like in the frame 11 is equivalent to the position or structure of existing level detectors. Therefore, even when the conductive part 70 is newly installed in the frame 11, the shape of the frame 11 does not need to be significantly changed from the existing shape. Furthermore, the second end 73 is positioned to match the first stop surface 25a and the like, so the conductive part 70 does not obstruct the swing of the arm 51. Therefore, the presence of the conductive part 70 does not affect the detection result of the level detector 1.

[0082] As described above, this embodiment enables the provision of a liquid level detector 1 with a compact form factor, which can suppress the generation of sparks around the device 1.

[0083] In the level detector 1, the conductive part 70 can be a conductive plate.

[0084] According to the level detector 1, the conductive portion 70 can be easily formed in terms of ease of processing. Furthermore, when the conductive portion 70 is embedded in the frame 11 by insert molding, the conductive portion 70 can be easily held in the desired shape in advance, and is therefore advantageous in terms of improving the efficiency of processability during insert molding.

[0085] In the level detector 1, the frame 11 may have a pair of first stops that contact the end side of the arm 51 relative to the facing axis 21, thereby limiting the rotation range of the retainer 40. The frame 11 may also have a pair of second stops that contact the base end side of the arm 51 relative to the facing axis 21, thereby limiting the rotation range of the retainer 40. The rotation range limited by the pair of second stops is greater than the rotation range limited by the pair of first stops. In this case, the second end 73 may protrude from each of the first auxiliary stop surface 27a and the second auxiliary stop surface 27b constituting the pair of second stops toward the track of the arm 51.

[0086] In the above description, one example has been described where the second end 73 of the conductive portion 70 is positioned to align with the positions of the first stop surface 25a and the second stop surface 25b, which are a pair of first stops. In contrast, in addition to the pair of first stops, the level detector 1, as described above, also has a pair of second stops, comprising a first auxiliary stop surface 27a and a second auxiliary stop surface 27b, with the locking end 51a of the arm 51 capable of contacting these second stops. Therefore, instead of the first stop surface 25a and the second stop surface 25b, the second end of the conductive portion can be positioned to align with the positions of the first auxiliary stop surface 27a and the second auxiliary stop surface 27b.

[0087] Figure 7 This is a perspective view showing two other examples of conductive parts 74 and 80 that can be used as conductive parts in the level detector 1, corresponding to... Figure 5 To distinguish conductive part 74 from conductive part 80, conductive part 80 is drawn with a double-dotted line. The structure other than conductive part 74 and conductive part 80 is similar to... Figure 5 The constructions shown are identical, and their descriptions will be omitted.

[0088] Similar to conductive portion 70, conductive portion 74 is a conductive member having an extension 75, a first end portion 76, and a second end portion 77. However, the second end portion 77 protrudes from the first auxiliary stop surface 27a and the second auxiliary stop surface 27b toward the track of the locking end 51a of the arm 51. Depending on the protrusion position of the second end portion 77, for example, the extension 75 may be shorter than the extension 71 of conductive portion 70. Since the locking end 51a contacts the first auxiliary stop surface 27a or the second auxiliary stop surface 27b when an overload is applied to the arm 51, the contact frequency is less than the contact frequency when the second end portion 73 of conductive portion 70 contacts one of the pair of first stops. However, by ensuring that the locking end 51a has the opportunity to contact one of the second ends 77 provided in the pair of second stops, and therefore the level detector 1 with its compact shape can also suppress the generation of sparks around the device 1.

[0089] Meanwhile, the conductive portion 80 can replace the aforementioned conductive portion 70 or conductive portion 74, and is a conductive structure having an extension 81, a first end portion 82, and a second end portion. For example, the extension 81 is a metal wiring. Here, the first end portion 82 is the end of the extension 81 connected to the grounding terminal 35, which is the same as the conductive portion 70. In contrast, the second end portion 80 is not the other end of the extension 81 itself, but a part of a block 84 connected to the other end 83 of the extension 81. The block 84 is a conductive component.

[0090] Even in this case, there are two symmetrical conductive portions 80. A portion of the block 84 of one conductive portion 80 can be exposed from the first stop surface 25a of the pair of first stops toward the track of the arm 51. A portion of the block 84 of the other conductive portion 80 can be exposed from the second stop surface 25b of the pair of first stops toward the track of the arm 51. Furthermore, a portion of the block 84 can be exposed from the first auxiliary stop surface 27a and the second auxiliary stop surface 27b constituting the pair of second stops in the same manner as the conductive portion 74.

[0091] Therefore, in the level detector 1, the conductive part 80 can be a combination of a conductive component at the second end and wiring.

[0092] According to the above-described liquid level detector 1, even if the conductive part 70 is not necessarily formed of a plate, a liquid level detector 1 with a simple structure that can suppress the generation of sparks around the device 1 can be provided.

[0093] Figure 8 This is a schematic cross-sectional view showing two other examples of conductive parts 85 and 85a that can be used as conductive parts in the level detector 1, corresponding to Figure 3 The structure, except for conductive parts 85 and 85a, is the same as... Figure 3The constructions shown are identical, and their descriptions will be omitted.

[0094] The conductive portion 85 can replace the conductive portion 70 described above, and is a conductive structure having an extension 86, a first end, and a second end. The extension 86 can be a sheet metal or metal wiring. Figure 8 In the diagram, the extension 86 and the first end are schematically shown with dashed lines. The route taken by the extension 86 inside the frame 11 can be arranged in various ways, for example, without interfering with other components and without being exposed outside the frame 11.

[0095] The second end of the conductive part 85 may be a protrusion 87 protruding from the frame 11 toward the track of the arm 51 to contact the arm 51 at the intermediate detection position of the liquid level. In this case, the protrusion 87 may be provided on the arm face portion 11c, which is a plane exposed toward the track of the arm 51 between the first stop surface 25a and the second stop surface 25b.

[0096] Meanwhile, the conductive portion 85a can replace the aforementioned conductive portion 85, and is a conductive structure having an extension portion 86a, a first end, and a second end. The extension portion 86a is equivalent to the extension portion 86 of the conductive portion 85.

[0097] The second end of the conductive part 85a may be a protrusion 87a protruding from the frame 11 toward the track of the arm 51 to contact the arm 51 at the intermediate detection position of the liquid level. In this case, the protrusion 87a may be provided in the rotation groove 26 exposed between the first auxiliary stop surface 27a and the second auxiliary stop surface 27b toward the track of the locking end 51a located at the base end side of the arm 51.

[0098] According to the level detector 1, even if the conductive part 70 and the like are not necessarily provided in the first stop or the second stop, it is possible to provide a level detector 1 with a compact shape that can suppress the generation of sparks around the device 1 with a simple structure. Furthermore, since the protrusion 87 and the like, which are at the second end, are arranged to contact the arm 51 at the middle detection position of the liquid level, the contact frequency is greater than the contact frequency when it is provided in the first stop or the like corresponding to the maximum or minimum detection position of the liquid level. Therefore, it is advantageous to more easily suppress the generation of sparks around the level detector 1.

[0099] (Second Embodiment)

[0100] Figure 9 This is a perspective view of the level detector 2 according to the second embodiment. Figure 10 This is a plan view of the level detector 2 with part of the float 50 and arm 51 removed. In the following text, the term "upper" in the level detector 2 refers to the upper or lower side in the vertical direction.

[0101] The liquid level detector 2 detects the liquid level (liquid surface position) based on the displacement of the arm 51 following the up-and-down movement of the float 50 floating on the liquid. As an example, the liquid level detector 2 is installed in a fuel tank in a vehicle, such as an automobile, and detects the level of fuel stored in the tank. The liquid level detector 2 includes a device body 10a, a lead wire 30a, a connector 37, a retainer 40, a float 50, and an arm 51.

[0102] The device body 10a is the main body of the level detector 2. The device body 10a includes a frame 11a, a lead frame 12, a retaining member 13, and a Hall element 60. Hereinafter, the term "front and rear" in the device body 10a refers to the front or rear side in the horizontal direction. In this case, the front side is the side in which the retaining member 40 is supported in the device body 10a, and the rear side is the side where inserts such as the lead frame 12 are formed.

[0103] The frame 11a is, for example, a structure made of resin, and rotatably supports the retainer 40. The frame 11a has a lead wire arrangement portion 29 on its upper part. In the lead wire arrangement portion 29, the portion of the lead frame 12 that connects to the lead wire 30a is exposed outside the frame 11a, and the end portion of the lead wire 30a connected to the lead frame 12 is arranged there.

[0104] The lead frame 12 is a conductor portion partially embedded into the frame 11a. The lead frame 12 includes at least three terminals, each terminal being an independent plate, depending on the type of the lead 30a used in the detection method based on the detection unit. In this embodiment, the lead frame 12 includes an input terminal 34, a ground (GND) terminal 35, and an output terminal 36. The input terminal 34, ground terminal 35, and output terminal 36 are electrically connected to the Hall element 60, which serves as the detection unit, according to their respective functions. That is, one end of the lead 30a is connected to the device body 10a to communicate with the Hall element 60.

[0105] The retaining member 13 is attached to the lead arrangement portion 29 provided in the frame 11a to retain the lead 30a. For example, the retaining member 13 may have a groove 13a corresponding to the diameter of each lead 30a. In the retaining member 13, the lead 30a is held in the lead arrangement portion 29 in the state where the lead 30a is engaged with the groove 13a, and therefore the lead 30a is unlikely to detach from the lead frame 12.

[0106] The Hall element 60 is a magnetic sensing element that detects the rotation angle of the retaining member 40, and is an example of a sensing unit that detects the amount of displacement to derive the fuel level.

[0107] At least three leads 30a are provided based on the detection method of the detection unit, and these three leads 30a electrically connect the liquid level detector 2 to an external device such as a measuring instrument. In this embodiment, the leads 30a include a power input line 31a, a ground (GND) line 32a, and a signal output line 33a, which are independent of each other. One end of the input line 31a is connected to the input terminal 34 in the lead arrangement section 29. One end of the ground line 32a is connected to the ground terminal 35 in the lead arrangement section 29. One end of the output line 33a is connected to the output terminal 36 in the lead arrangement section 29.

[0108] Here, in this embodiment, the lengths of at least three leads 30a are as follows: Figure 10 The locations shown are different, which will be described in detail below.

[0109] Connector 37 connects the other ends of input line 31a, ground line 32a and output line 33a without contacting each other, and connects to a receiving connector for electrical connection to an external device.

[0110] The retainer 40 is, for example, a component made of resin, and retains the base end of the arm 51, converting the displacement of the arm 51, which moves up and down with the float 50 as the fuel level changes, into rotational motion. The rotation range of the retainer 40 is limited to an angle range θ by a stop such as the first stop surface 25a provided on the frame 11. An annular magnet is provided inside the retainer 40. The magnet is a displacement component used to detect the rotation angle of the retainer 40 by a Hall element 60 provided in the frame 11a. The float 50 floats on the liquid fuel. That is, the float 50 moves up and down with the change in the fuel level in the fuel tank. The arm 51 is a rod-shaped component connecting the retainer 40 and the float 50 to each other. The arm 51 supports the float 50 at its end.

[0111] Next, the length of the lead 30a will be described in detail. In this embodiment, there are three leads 30a: an input line 31a, a ground line 32a, and an output line 33a. The arrangement of the three leads 30a is defined by three slots 13a provided in the holding member 13. The input line 31a, the ground line 32a, and the output line 33a are arranged parallel to each other at equal intervals, wherein the parallel direction is perpendicular to both the vertical direction and the front-back direction of the device body 10a.

[0112] Of the three leads 30a, the length of the first lead at each end in the parallel direction is longer than the length of the second lead positioned between the other two leads. In this embodiment, both the input line 31a and the output line 33a correspond to the first lead. Meanwhile, the ground line 32a, positioned between the input line 31a and the output line 33a, corresponds to the second lead. Therefore, as... Figure 10As shown, when connector 37 separates from device body 10a in the upward direction, ground wire 32a is taut with length L, and input wire 31a and output wire 33a are slack.

[0113] Figure 11 This is a conceptual diagram used to illustrate how to set the length of lead 30a, which corresponds to Figure 10 . Figure 11 The diagram shows the output line 33a, which serves as the first lead, tilting towards the ground line 32a, while the ground line 32b, which serves as the second lead, is taut.

[0114] Here, the length of the second lead, i.e., the length of the grounding wire 32a, is defined as L. The width between the first lead, i.e., the output wire 33a, located at one end in the parallel direction, and the grounding wire 32b located next to the output wire 33b, is defined as W. Furthermore, the tilt angle relative to the parallel direction obtained when the output wire 33a tilts towards the grounding wire 32a is defined as θ. A In this case, the length of output line 33a is longer than the length L of ground line 32a by Wcosθ. A The extension length LE is represented by (L+Wcosθ) A This indicates that the tilt angle θ is... A Set at 25° < θ A Within a range of <65°. Or, the tilt angle θ. A It can be set to 45°.

[0115] Although the length of the output line 33a, which is one of the first leads, has been described here, the length of the input line 31a, which is the other first lead, can be constructed similarly.

[0116] Next, the operation of level detector 2 will be described.

[0117] Figure 12 This is a conceptual diagram used to illustrate the tensile load applied to lead 30a, which corresponds to Figure 10 . Figure 12 A receiver connector 100 is shown. When the level detector 2 is installed in the fuel tank, the receiver connector 100 is the mating target of the connector 37, and the receiver connector 100 is indicated by a double-dotted line.

[0118] For example, when the operator installs the level detector 2 in the fuel tank, such as Figure 12 As shown, it is assumed that the operator connects connector 37 to the receiving connector 100, which is located obliquely above the device body 10a, while holding connector 37 in place. In particular, the receiving connector 100 is positioned closer to the input line 31a from directly above the device body 10a along the parallel direction of the lead 30a.

[0119] First, as a comparative example, assuming all leads 30a are of the same length, when an operator attempts to connect connector 37 to receiver connector 100, the input line 31a, positioned closer to receiver connector 100, may slack. However, the output line 33a, located further from receiver connector 100, may be pulled towards receiver connector 100 on the opposite side in the parallel direction. Therefore, the tensile load F applied to all three leads 30a may be concentrated on the output line 33a at one end in the parallel direction of the leads 30a.

[0120] In contrast, in this embodiment, the length of the output line 33a located at one end in the parallel direction of the lead 30a is preset to be longer than the length of the grounding line 32a located next to the output line 33b. Therefore, even if the output line 33a, which is away from the receiving connector 100, is pulled towards the receiving connector 100, such as Figure 12 As shown, the degree of tension is also approximately the same in the output line 33a and the ground line 32a. Therefore, the tensile load F applied to the three leads 30a as a whole is distributed between the output line 33a and the ground line 32a.

[0121] As an example, assume the tensile strength of each lead 30a is 70N. In the comparative example above, since the tensile load F is applied almost exclusively to the output line 33a, the overall tensile strength of lead 30a is also approximately 70N. In contrast, in this embodiment, since the tensile load F is distributed across both the output line 33a and the ground line 32a, the tensile strength of lead 30a is approximately twice that, approximately 140N.

[0122] In the description, an example has been described where the receiver connector 100 is positioned closer to the input line 31a from directly above the device body 10a along the parallel direction of the lead 30a. In contrast, in this embodiment, the length of the input line 31a, positioned parallel to the output line 33a on the opposite side, is also set to be longer than the length of the ground line 32a. Therefore, when the receiver connector 100 is positioned closer to the output line 33a from directly above the device body 10a along the parallel direction of the lead 30a, the overall tensile strength of the lead 30a is also improved.

[0123] The level detector 2 is installed on the inner wall of the fuel tank such that the rear surface of the device body 10a faces the inner wall surface of the fuel tank. At this time, the operator moves the lead wire 30a along the inner wall of the fuel tank while connecting the connector 37 to the receiving connector 100. Therefore, since the lead wire 30a typically moves in a parallel direction when installing the level detector 2, the aforementioned length setting of the lead wire 30a is effective.

[0124] Next, the effect of level detector 2 will be described.

[0125] The liquid level detector 2 is provided with a device body 10a, which includes a detection section for detecting the amount of displacement of the liquid level for discharging liquid. The liquid level detector 2 includes: at least three leads 30a, one end of which is connected to the device body 10a to communicate with at least the detection section and arranged parallel to each other; and a connector 37 connected to the other end of each lead 30a. Of the at least three leads 30a, the length of the first lead located at its parallel end is longer than the length of the second lead positioned between the other two leads.

[0126] In the above example, the detection unit corresponds to the Hall element 60. However, the detection system used by the level detector 2 is not limited to the system utilizing the Hall element 60, and other detection systems can be used, as long as the rotation angle of the holding member 40 can be detected in that system. Furthermore, in the above example, the first lead corresponds to the input line 31a and the output line 33a, and the second lead corresponds to the ground line 32a.

[0127] In the level detector 2, among the at least three leads 30a, the length of the first lead at its parallel-direction end is set to be longer than the length of the second lead positioned between the other two leads. Therefore, according to the level detector 2, even if the leads 30a are pulled obliquely upwards, it is difficult to concentrate the tensile load on the first lead at its parallel-direction end. Thus, since the tensile load F applied to the at least three leads 30a can be distributed among the multiple leads 30a, including the first lead, the overall tensile strength of the three leads can be improved.

[0128] As described above, according to this embodiment, a liquid level detector 2 can be provided for improving the tensile strength of the lead 30a.

[0129] Although the case of setting three leads 30a has been described above, depending on the conditions, such as differences in the detection method of the detection unit and the addition of electronic components for other functions, four or more leads 30a may be set. For example, when setting four leads 30a, two second leads that are adjacent to each other are set.

[0130] In the level detector 2, the length of the second lead is L, and the width between the first lead at its parallel end and the second lead located next to the first lead is W. Furthermore, when the first lead tilts towards the second lead, the tilt angle relative to the parallel direction is θ. A At this point, the length of the first lead can be expressed as (L + Wcosθ). A This indicates that the tilt angle can be less than θ. A Within the range of <65°.

[0131] According to the liquid level detector 2, the above-mentioned effect can be achieved by the setting position of the receiving connector 100 in the internal structure of the fuel tank, which is usually installed in a vehicle such as an automobile, relative to the mounting position of the device body 10a.

[0132] In level detector 2, the tilt angle can be 45°.

[0133] According to the liquid level detector 2, given the setting position of the receiving connector 100 in the internal structure of the fuel tank, which is typically installed in a vehicle such as an automobile, relative to the mounting position of the device body 10a, the above-mentioned effects can be achieved more reliably.

[0134] (Third Embodiment)

[0135] Figure 13 This is a perspective view of the level detector 3 according to the third embodiment. Figure 14 This is a cross-sectional view of the main part of the liquid level detector 1, which is taken in a plane extending in the vertical direction and includes the central axis of axis 21. In the following text, the term "upper" or "lower" in the liquid level detector 3 refers to the upper or lower side in the vertical direction.

[0136] The liquid level detector 3 detects the liquid level (liquid surface position) based on the displacement of the arm 51 following the up-and-down movement of the float 50 floating on the liquid. As an example, the liquid level detector 3 is installed in a fuel tank in a vehicle, such as an automobile, and detects the level of fuel stored in the tank. The liquid level detector 3 includes a device body 10b, a lead wire 30, a connector 37, a retainer 40, a float 50, and an arm 51.

[0137] The device body 10b is the main body portion of the level detector 3. The device body 10b includes a frame 11b, a lead frame 12, and a retaining member 13. Hereinafter, the term "front and rear" in the device body 10b refers to the front or rear side in the horizontal direction. In this case, the front side is the side in which the retaining member 40 is supported within the device body 10b, and the rear side is the side where inserts such as the lead frame 12 are formed.

[0138] The frame 11b is, for example, a structure made of resin and rotatably supports the retainer 40. The frame 11b has a rotating recess 20, a shaft 21, a locking groove 22, a pair of insertion holes 23, a guide protrusion 24, a first stop surface 25a, a second stop surface 25b, and an arm face portion 11c.

[0139] The rotating recess 20 is circular in plan view at the front of the frame 11b and rotatably accommodates a portion of the retainer 40. The shaft 21 is the rotation reference of the retainer 40, which is coaxially disposed at the center of the rotating recess 20, and engages with the shaft recess 42 formed in the retainer 40.

[0140] A locking groove 22 is circumferentially disposed within the inner periphery of the rotating recess 20, and rotatably locks the flange 43 of the retainer 40. The locking groove 22 has two sidewalls 22a facing each other in the direction along the central axis AX of the shaft 21. A pair of insertion holes 23 are disposed at the edge of the rotating recess 20, facing each other in the horizontal direction, and communicate with the locking groove 22. A guide protrusion 24 is disposed at the bottom of the rotating recess 20 in a manner that surrounds the circumference of the shaft 21, and guides the rotation of the retainer 40.

[0141] The first stop surface 25a and the second stop surface 25b are a pair of stoppers that limit the swing of the arm 51 by contacting it, thereby limiting the rotation of the retainer 40. The pair of stoppers are located on the front side of the frame 11b and below the center of the rotation recess 20, and face each other at a certain distance along the outer periphery of the rotation recess 20. When the retainer 40 rotates, the arm 51 contacts one of the stoppers at its end relative to the position facing the shaft 21. As a result, the rotation range of the retainer 40 is limited to an angle range θ. The first stop surface 25a contacts the arm 51 at the maximum detection position of the liquid level that the level detector 3 can detect. That is, the first stop surface 25a is at the position where the arm 51 contacts when the remaining fuel capacity in the fuel tank is almost full. The second stop surface 25b contacts the arm 51 at the minimum detection position of the liquid level that the level detector 3 can detect. That is, the second stop surface 25b is in contact with the arm 51 when the remaining fuel capacity in the fuel tank is almost empty.

[0142] The arm-facing portion 11c is a part of the outer peripheral surface of the frame 11b positioned facing the track of the arm 51. Here, the track of the arm 51 refers to the area where the arm 51 can be positioned when it moves within an angle range θ (the range of movement of the arm 51), where θ is the range of rotation of the retainer 40. Figure 13 As shown. Furthermore, the position facing the track of arm 51 refers to the position where the arm 51 can face the track in the direction along the central axis AX of shaft 21. In this embodiment, the arm facing portion 11c corresponds to a plane perpendicular to the central axis AX of shaft 21 and exposed towards the track of arm 51 between the first stop surface 25a and the second stop surface 25b. The first space G1, etc., regarding the arm facing portion 11c will be described in detail below.

[0143] Furthermore, the frame 11b has an insert molding portion 28 and a lead wire arrangement portion 29. The insert molding portion 28 is the area in which inserts such as a part of the lead frame 12 and a part of the Hall element 60 are molded into the frame 11b. In the lead wire arrangement portion 29, the portion of the lead frame 12 connected to the lead wire 30 is exposed outside the frame 11b, and the end portion of the lead wire 30 connected to the lead frame 12 is arranged there.

[0144] The lead frame 12 is a conductor portion partially insert-molded into the frame 11b. Depending on the type of the lead 30 based on the detection method of the detection unit, the lead frame 12 includes multiple terminals, each serving as an independent plate. In this embodiment, the lead frame 12 includes an input terminal, a ground (GND) terminal 35, and an output terminal. The input terminal, ground terminal 35, and output terminal are electrically connected to leads 62 extending from the Hall element 60 according to their respective functions. Note that the input and output terminals are not shown.

[0145] The retaining member 13 is attached to the lead arrangement portion 29 provided in the frame 11b to retain the lead 30. For example, the retaining member 13 may have a groove 13a corresponding to the diameter of each lead 30. In the retaining member 13, the lead 30 is held in the lead arrangement portion 29 with the lead 30 engaged with the groove 13a, and therefore the lead 30 is unlikely to detach from the lead frame 12.

[0146] In addition, the device body 10b includes a Hall element 60 and a lead wire 62, the Hall element 60 being used as a detection part to detect the rotation angle of the retainer 40.

[0147] The Hall element 60 is a magnetic detection element embedded in the shaft 21 of the frame 11b. When a magnetic field is applied from the outside while a voltage is applied, it generates a Hall voltage proportional to the magnetic flux density passing through the Hall element 60. Meanwhile, a magnet 65, described later, is disposed inside the retainer 40. When the retainer 40 rotates due to a change in liquid level, the magnet 65 also rotates and shifts, and the cross angle between the magnetic flux of the Hall element 60 and the magnet 65 changes, thereby changing the Hall voltage. That is, the rotation angle of the retainer 40 can be detected based on the measured Hall voltage, thereby enabling the detection of the fuel level. As described above, a lead 62 extends from the Hall element 60 and is electrically connected to terminals included in the lead frame 12.

[0148] Furthermore, the Hall element 60, lead 62, and a portion of the lead frame 12 can be mounted inside the frame 11b through multiple insert molding processes. For example, the Hall element 60 and lead 62 can be mounted in the frame 11b together with the resin body 63 through insert molding in a first step. Subsequently, the lead frame 12 can be mounted in the frame 11b through insert molding in a second step. The resin body 63 has an inner shaft 63a coaxially embedded inside the shaft 21 of the frame 11b. The Hall element 60 is further disposed inside the inner shaft 63a. The Hall element 60 and lead 62 can be pre-embedded in the resin body 63 using a resin component 64. Although not shown, the resin component 64 may include other electronic components related to the operation of the Hall element 60.

[0149] Multiple leads 30 are provided based on the detection method of the detection unit, and the multiple leads 30 electrically connect the liquid level detector 3 to an external device such as a measuring instrument. In this embodiment, the leads 30 include a power input line 31, a ground (GND) line 32, and a signal output line 33, which are independent of each other. One end of the input line 31 is connected to the input terminal in the lead arrangement section 29. One end of the ground line 32 is connected to the ground terminal 35 in the lead arrangement section 29. One end of the output line 33 is connected to the output terminal in the lead arrangement section 29.

[0150] Connector 37 connects the other ends of input line 31, ground line 32 and output line 33 without touching each other, and connects to a receiving connector for electrical connection to an external device.

[0151] The retainer 40 is, for example, a component made of resin, and retains the base end side of the arm 51, converting the displacement of the arm 51, which moves up and down with the float 50 as the fuel level changes, into rotational motion. In the following text, the term "front and rear" in the retainer 40 refers to the front or rear side in the horizontal direction. Here, the front side is the side of the retainer arm 51, and the rear side is the side of the retainer 40 supported by the device body 10b. The retainer 40 has a retainer body 41 and an arm retaining portion 46.

[0152] The retainer body 41 is a cylindrical component having a shaft recess 42, a pair of flanges 43 and a guide recess 44.

[0153] A shaft recess 42 is provided on the rear surface side of the retainer body 41 and is coaxially disposed with the central axis of the shaft 21. It is rotatably and slidably engaged with the shaft 21, which is disposed in the frame 11b, as a rotation axis. In this embodiment, the central axis of the shaft recess 42 is referred to as the "rotation axis," unlike the central axis AX of the shaft 21. Each flange 43 is configured to project radially outward from the rear edge of the retainer body 41. A pair of flanges 43 project in opposite directions along the extension direction of the arm 51 when the arm is held by the arm retainer 46. A guide recess 44 is provided on the rear surface side of the retainer body 41 and on the outer periphery side of the magnet 65 disposed in the retainer body 41, and accommodates a guide protrusion 24 disposed in the frame 11b.

[0154] When the retainer 40 is attached to the frame 11b, the operator engages the retainer 40 into the rotating recess 20 with the pair of flanges 43 aligned with the positions of the pair of insertion holes 23 in the frame 11b. As the flanges 43 pass through the insertion holes 23, the shaft 21 of the frame 11b is inserted into the shaft recess 42 of the retainer 40. Furthermore, the guide protrusion 24 of the frame 11b enters the guide recess 44 of the retainer 40. Next, when the operator rotates the retainer 40 into the rotating recess 20 with the locking hole 47 (described later) positioned above, the flanges 43 enter the locking groove 22 of the frame 11b, preventing the retainer 40 from disengaging from the rotating recess 20. With the retainer 40 holding arm 51 in its position, the rotation range of the retainer 40 is limited by the first stop 25a, thereby preventing the retainer 40 from disengaging from the rotating recess 20 due to the flanges 43 moving to the position of the insertion holes 23.

[0155] The arm retainer 46 holds the arm 51 in such a way that the extension direction of the arm 51 is perpendicular to the rotation axis of the retainer 40. The arm retainer 46 has a locking hole 47. The locking hole 47 is provided at a portion of the periphery of the retainer body 41 in a manner that extends through the front-rear direction of the retainer 40, and locks the locking end 51a located at the base end side of the arm 51.

[0156] The retainer 40 is also provided with an annular magnet 65. The magnet 65 is disposed inside the retainer body 41 in such a way that it is arranged on the inner circumferential side of the shaft recess 42, and is a displacement member for detecting the rotation angle of the retainer 40 by means of a Hall element 60. In this case, the Hall element 60 is located on the inner diameter side of the magnet 65, which rotates and shifts with the rotation of the retainer 40.

[0157] Float 50 floats on the liquid fuel. That is, float 50 moves up and down as the liquid level of the fuel in the fuel tank changes.

[0158] Arm 51 is a rod-shaped component that connects retainer 40 and float 50 to each other. Arm 51 supports float 50 at its end side. Simultaneously, arm 51 is held at its base end side, opposite to the end side, by arm retainer portion 46 of retainer 40. Arm 51 may have more than one curved portion. The end of arm 51 at its base end side is a locking end 51a bent at a right angle. When arm retainer portion 46 holds arm 51, locking end 51a is inserted into locking hole 47.

[0159] Next, the arm face portion 11c provided in the frame 11b will be described in detail. Under normal circumstances, the extension direction of the arm 51 is approximately perpendicular to the central axis AX of the shaft 21. At this time, a gap as a first space G1 is formed between the arm face portion 11c and the track of the arm 51 in the direction along the central axis AX of the shaft 21. That is, under normal circumstances, the arm 51 does not contact the arm face portion 11c. Here, the term "normal circumstances" means that no undesirable external force is applied to the arm 51 except for the up-and-down movement of the float 50.

[0160] Meanwhile, under normal conditions, the flange 43 of the retainer 40 is approximately parallel to the sidewall 22a of the locking groove 22 provided in the frame 11b. At this time, a gap as a second space G2 is formed between the sidewall 22a of the locking groove 22 and the flange 43 in the direction along the central axis AX of the shaft 21. The size of this gap is determined in advance, taking into account dimensional changes during manufacturing, temperature changes during use, aging, etc. As an example, when the level detector 3 is installed in the fuel tank of a common automobile, the gap represented by the second space G2 in this embodiment is approximately 0.3 mm.

[0161] Figure 15 It is used to illustrate the relationship between the first space G1 and the second space G2. Figure 14 An enlarged cross-sectional view of the main parts. In this embodiment, the first space G1, which relates to the gap between the frame 11b and the arm 51, is smaller than the second space G2, which relates to the gap between the frame 11a and the retainer 40.

[0162] Here, as a first assumption, it is assumed that arm 51 receives an external force F in the direction from the outside toward the front of the level detector 3. A In the case of tilting, when the distance from the central axis AX of shaft 21 to the first contact point P1 that contacts the arm face 11c when the arm 51 is tilted is set as L1, the arm 51 receives an external force F. A The first maximum angle θ1 when tilted satisfies the relationship tanθ1=G1 / L1.

[0163] At the same time, when arm 51 receives external force F AWhen tilted, the retainer 40 of the retaining arm 51 also tilts; that is, the flange 43, which serves as part of the retainer 40, also tilts relative to the sidewall 22a of the locking groove 22. Here, as a second assumption, it is assumed that the first space G1 is set to be relatively large, and even when the arm 51 receives an external force F... A When tilted, arm 51 does not contact arm face 11c. In this case, one flange 43 contacts one sidewall 22a of locking groove 22 at the second contact point P2, and retainer 40 tilts at the second contact point P2 as the base point, and therefore the other flange 43 contacts the other sidewall 22a of locking groove 22. When the distance from the outermost end of one flange 43 to the outermost end of the other flange 43 is set as L2, the second maximum angle θ2 of retainer 40, that is, the second maximum angle θ2 of flange 43, satisfies the relationship tanθ2=G2 / L2.

[0164] Considering the first and second assumptions mentioned above, in this embodiment, in the relationship between the first space G1 and the second space G2, the first maximum angle θ1 is less than the second maximum angle θ2. For example, when the liquid level detection device 3 is installed in the fuel tank of a regular car, the second maximum angle θ2 is approximately 1.5°.

[0165] Next, the operation of the liquid level detection device 3 will be described.

[0166] First, in the level detector 3, as a basic operation, the arm 51 swings up and down following the movement of the float 50 as the fuel level changes, and the retainer 40 connected to the arm 51 rotates relative to the device body 10b. The Hall element 60 in the device body 10b detects changes in the magnetic flux of the magnet 65 in the retainer 40, and the detection result is transmitted via the output line 33 to a measuring unit or similar external device. For example, the measuring unit measures the liquid level based on the output signal transmitted from the level detector 3, and, if necessary, issues warnings such as fuel depletion in the fuel tank.

[0167] Meanwhile, when using the liquid level detector 3, as described above in the relationship between the first space G1 and the second space G2, in some cases, an undesirable external force F... A An external force F is applied to arm 51. When arm 51 receives an external force F... A When tilted, the retainer 40 of the retaining arm 51 also tilts. Here, since the Hall element 60 is disposed in the shaft 21 of the frame 11b and the magnet 65 is disposed in the retainer 40, the arrangement relationship between the Hall element 60 and the magnet 65 changes when the retainer 40 tilts relative to the shaft 21, which serves as the rotation reference for the retainer 40. Therefore, as the tilt of the retainer 40 increases, the magnetic flux density applied to the Hall element 60 changes compared to the normal state, thereby increasing the risk of output error.

[0168] For example, in the engagement structure between the frame 11b and the retainer 40, the retainer 40 is held in the frame 11b by engaging a pair of flanges 43 provided in the retainer 40 with locking grooves 22 provided in the frame 11b. Therefore, as a comparative example, when the first space G1, as shown in the second assumption above, is set to be relatively large, even if the arm 51 receives an external force F... A When tilted, arm 51 will not contact the arm face portion 11c. As a result, retainer 40 is tilted such that one flange 43 contacts one sidewall 22a of locking groove 22 at the second contact point P2 and the other flange 43 contacts the other sidewall 22a of locking groove 22. As for the output error caused by the tilted posture of retainer 40, it can be considered that the output error that can be generated becomes the largest when retainer 40 is in this tilted posture.

[0169] In contrast, in this embodiment, the position of the arm face portion 11c is set such that the first space G1 related to the gap between the frame 11b and the arm 51 is smaller than the second space G2 related to the gap between the frame 11a and the retainer 40. Therefore, when the arm 51 receives an external force F... A When tilted, the arm 51 contacts the arm face portion 11c before the tilting posture of the retainer 40 becomes the tilting posture that maximizes the output error that can be generated. In other words, the retainer 40 of the retaining arm 51 becomes difficult to tilt to the posture that maximizes the output error that can be generated, thereby suppressing the output error caused by the tilting posture of the retainer 40 as much as possible.

[0170] Next, the effect of the level detector 3 will be described.

[0171] The liquid level detector 3 includes: a float 50 that floats on the liquid; an arm 51 that supports the float 50 at its end; and a retainer 40 that holds the base end of the arm 51 and converts the displacement of the arm 51, which moves up and down with the float 50 as the liquid level changes, into rotational motion. Furthermore, the liquid level detector 3 includes a frame 11b having a shaft 21 serving as a rotation reference for the retainer 40. Additionally, the liquid level detector 3 includes a magnetic detection element and a magnet 65. The magnetic detection element is disposed on the shaft 21 and detects the rotation angle of the retainer 40, while the magnet 65 is disposed in the retainer 40 and applies a magnetic field to the magnetic detection element. The retainer 40 has: a shaft recess 42 that rotatably and slidably engages with the shaft 21; and an arm retainer 46 that holds the arm 51 such that the extension direction of the arm 51 is perpendicular to the central axis of the shaft recess 42. Furthermore, the retainer 40 has a pair of flanges 43 that project in opposite directions along the extension direction of the arm 51 in the arm retainer 46. The frame 11b has a locking groove 22 and an arm face 11c. The locking groove 22 includes two sidewalls 22a facing each other in a direction along the central axis of the shaft 21 and rotatably locks the flanges 43. The arm face 11c is positioned facing the track of the arm 51. The first space G1 between the arm face 11c and the track of the arm 51 is smaller than the second space G2 between the sidewalls 22a of the locking groove 22 and the flanges 43.

[0172] In the example above, the magnetic detection element corresponds to Hall element 60.

[0173] According to the liquid level detector 3, the first space G1 between the arm face portion 11c and the track of the arm 51 is set to be smaller than the second space G2 between the side wall 22a of the locking groove 22 and the flange 43. Therefore, as described above, even when the arm 51 is subjected to external force F A When tilted, due to the engagement between the frame 11b and the retainer 40, the retainer 40 contacts the arm face 11c before its tilting posture becomes the one that maximizes the output error. Therefore, the retainer 40 of the retaining arm 51 becomes less likely to tilt to the point of maximizing the output error, thereby minimizing the output error caused by the tilting posture of the retainer 40.

[0174] As described above, this embodiment enables the provision of a level detector 3 capable of suppressing output errors.

[0175] Furthermore, in the level detector 3, the first space is identified by G1, and the distance from the central axis AX of shaft 21 to the first contact point P1 that contacts the arm face portion 11c when the arm 51 is tilted is identified by L1. At this time, it is assumed that when the arm 51 receives an external force F...A The first maximum angle θ1 when tilted satisfies the relationship tanθ1 = G1 / L1. Furthermore, the second space is identified by G2, and the distance from the outermost end of one flange 43 to the outermost end of the other flange 43 is identified by L2. Now, assuming one flange 43 is in contact with one sidewall 22a of the locking groove 22 and the other flange 43 is in contact with the other sidewall 22a of the locking groove 22, the second maximum angle θ2 satisfies the relationship tanθ2 = G2 / L2. In this case, the first maximum angle θ1 can be smaller than the second maximum angle θ2.

[0176] Based on the liquid level detector 3, taking into account the dimensions of the frame 11b and the retainer 40, the first space G1 and the second space G2 can be derived from the relationship between the first maximum angle θ1 and the second maximum angle θ2. Therefore, the liquid level detector 3 can more reliably achieve the aforementioned effect of suppressing the output error caused by the tilting posture of the retainer 40.

[0177] The entire contents of Japanese Patent Application No. 2021-200149 (filed on December 9, 2021) are incorporated herein by reference.

[0178] While specific embodiments have been described, these embodiments are presented by way of example only and are not intended to limit the scope of the invention. In fact, the novel embodiments described herein can be implemented in various other forms; furthermore, various omissions, substitutions, and changes can be made in the forms of the embodiments described herein without departing from the spirit of the invention. The appended claims and their equivalents are intended to cover such forms or modifications that fall within the scope and spirit of the invention.

Claims

1. A liquid level detector, the liquid level detector comprising: A float that floats on the liquid; An arm that supports the float at its end; A retainer that holds the base end of the arm and converts the displacement of the arm, which moves up and down with the float as the liquid level changes, into rotational motion. A frame having an axis that serves as a rotational reference for the retainer; A magnetic detection element is disposed on the shaft and detects the rotation angle of the retaining member; as well as A magnet, disposed within the retaining member, applies a magnetic field to the magnetic detection element, wherein... The retaining element includes: A shaft recess that engages with the shaft in a rotatable and slidable manner; An arm retainer that holds the arm such that the arm's extending direction is perpendicular to the central axis of the shaft recess; and A pair of flanges that project in opposite directions along the extension direction of the arm in the arm holder. The framework includes: A locking groove having two sidewalls facing each other in a direction along the central axis of the shaft, and capable of rotatably locking the flange; and An arm face portion is positioned facing the track of the arm, and The first space between the arm face and the arm track is smaller than the second space between the sidewall of the locking groove and the flange.

2. The liquid level detector according to claim 1, wherein, The first space is identified by G1, and the distance from the central axis of the shaft to the first contact point that contacts the face of the arm when it is tilted is identified by L1. Furthermore, when the arm tilts due to an external force, the first maximum angle θ1 satisfies the relationship tanθ1 = G1 / L1. The second space is identified by G2, and the distance from the outermost end of one flange to the outermost end of the other flange is identified by L2. Furthermore, the second maximum angle θ2, when one flange contacts one sidewall of the locking groove and the other flange contacts the other sidewall of the locking groove, satisfies the relationship tanθ2=G2 / L2. The first maximum angle θ1 is less than the second maximum angle θ2.

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