Liquid level detection device

Abstract

To provide a liquid level detection device facilitating setting of a rotatable range of a rotating part while avoiding interference between the rotating part and a case.SOLUTION: A liquid level detection device comprises a rotating part 20 including an annular holder 22 for holding a magnet and being rotatable about a shaft part 41, a case 40 including a holder arrangement part 42 where the holder 22 is arranged, and an arm for rotating the rotating part 20 in response to displacement of a float. The holder 22 includes a hook 221a for hooking the magnet, and a protrusion 222. The holder arrangement part 42 includes a hook relief surface 421 that does not come into contact with the hook 221a even when the rotating part 20 rotates within the rotatable range, and a pair of stoppers S1 that are spaced apart from each other with the protrusion 222 interposed therebetween in a circumferential direction centered on an axis AX, to restrict the rotatable range.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present disclosure relates to a liquid level detection device. [Background technology]

[0002] For example, the liquid level detection device described in Patent Document 1 comprises a float arm with a float that moves with fluctuations in the liquid level, and an arm holder (rotating part) that holds the float arm and rotates relative to a frame (case), and detects the position of the liquid level based on the rotation of the arm holder. In this device, the range in which the arm holder can rotate is restricted by a protrusion formed on the outer periphery of the arm holder that can come into contact with the frame. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2010-38550 Summary of the Invention [Problem to be solved by the invention]

[0004] In the structure described in Patent Document 1, depending on the shapes of the rotating part and the case, the rotating part and the case may interfere with each other, and the rotatable range of the rotating part may not be set to a desired range.

[0005] The present disclosure has been made in consideration of the above-mentioned situation, and aims to provide a liquid level detection device that makes it easy to set the rotatable range of the rotating part while avoiding interference between the rotating part and the case. [Means for solving the problem]

[0006] In order to achieve the above object, the liquid level detection device according to the present disclosure comprises: a float that floats on the liquid and displaces according to the position of the liquid surface; a rotating part having an annular holder for holding a magnet and into which a shaft part formed around an axis line is inserted, the rotating part being rotatable with respect to the shaft part; a case including the shaft portion and a holder placement portion located behind the holder into which the shaft portion is inserted and in which the holder is placed; a magnetic detection element located inside the shaft portion and detecting a change in a magnetic field caused by rotation of the rotating portion; an arm that connects the float and the rotating part and rotates the rotating part in response to displacement of the float, The holder is a recessed portion recessed from the rear surface of the holder and configured to accommodate the magnet; a hook that forms a part of the outer peripheral wall of the holder and that hooks the magnet housed in the recess; a protruding portion protruding rearward beyond the rear surface of the holder, The holder arrangement portion includes: a hook relief surface that does not come into contact with the hook even when the rotating portion rotates within a rotatable range; The hook includes a portion located rearward of the hook relief surface, and is provided with a pair of stoppers located at a distance from each other on either side of the protrusion in the circumferential direction centered on the axis, thereby restricting the rotatable range. [Effects of the Invention]

[0007] According to the present disclosure, it is easy to set the rotatable range of the rotating part while avoiding interference between the rotating part and the case. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a perspective view of a liquid level detection device according to an embodiment of the present disclosure; [Figure 2] FIG. [Figure 3] FIG. 2 is a rear perspective view showing a part of the liquid level detection device according to the embodiment; [Figure 4] 4 is a cross-sectional view of the case, the circuit board, and the magnetic detection element taken along line II in FIG. 3 according to the embodiment. [Figure 5] FIG. [Figure 6]FIG. 2 is a perspective view of a case and a rotating part according to the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] An embodiment of the present disclosure will be described with reference to the drawings.

[0010] 1 detects the position (liquid level) of the liquid surface of a liquid contained in a tank (not shown). For example, the liquid level detection device 1 is attached to a fuel tank of a vehicle and detects the liquid level according to the amount of gasoline as the liquid.

[0011] In the following, the components of the liquid level detection device 1 may be described using the mutually orthogonal X, Y, and Z axes as appropriate. The Y axis extends vertically in FIG. 1. The Z axis is parallel to the axis AX, which will be described later. The direction in which the arrows indicating each of the X, Y, and Z axes point is the + (plus) direction of each axis, and the opposite direction is the - (minus) direction. For each component of the liquid level detection device 1, the +Z direction is the front, and the -Z direction is the rear. The rear surface of each component is also referred to as the back surface.

[0012] As shown in appropriate figures in Figures 1 to 6, the liquid level detection device 1 comprises a float 10, an arm 11, a rotating part 20, a magnetic detection element 30, a case 40, a retainer 50, a circuit board 60, a wiring part 70, and a grommet 80.

[0013] The float 10 floats on the liquid whose level is to be detected and displaces with the liquid surface. The float 10 is made of, for example, synthetic rubber.

[0014] The arm 11 connects the float 10 and the rotating part 20, and rotates the rotating part 20 in response to the displacement of the float 10. The arm 11 is made of, for example, a non-magnetic metal.

[0015] Rotating unit 20 is rotatable with respect to shaft 41 of case 40, that is, configured to be rotatable around axis line AX. As shown in FIG. 2, rotating unit 20 has two magnets 21a and 21b, a holder 22 that holds magnets 21a and 21b, and an arm support unit 23 that supports arm 11. Rotating unit 20 generates a magnetic field by magnets 21a and 21b that can be detected by magnetic detection element 30. This magnetic field changes as rotating unit 20 rotates.

[0016] Magnets 21a and 21b are made of known materials such as neodymium or ferrite and are disposed in recesses 220a and 220b, respectively, which will be described later. Magnets 21a and 21b are each magnetized with two poles in the radial direction about axis AX so as to generate a magnetic field between them. Magnets 21a and 21b are each formed along an arc centered on axis AX and face each other in the radial direction about axis AX.

[0017] The holder 22 is formed in an annular shape with a through-hole 22H provided in its center. A shaft 41 (described later) of the case 40 is inserted into the through-hole 22H. The arm support 23 is provided connected to an outer wall of the holder 22. For example, the holder 22 and the arm support 23 are integrally formed from, for example, a synthetic resin material.

[0018] The holder 22 includes recesses 220a and 220b, hooks 221a and 221b, and a protrusion 222.

[0019] The recesses 220a and 220b are recessed from the rear surface 22B of the holder 22 and accommodate the magnets 21a and 21b. The magnet 21a is press-fitted into the recess 220a and accommodated therein. The magnet 21b is press-fitted into the recess 220b and accommodated therein.

[0020] Hooks 221a and 221b each form part of the outer peripheral wall of holder 22. Hook 221a hooks magnet 21a housed in recess 220a while covering the outer edge of magnet 21a. Hook 221b hooks magnet 21b housed in recess 220b while covering the outer edge of magnet 21b. Slits are formed on both sides of each of hooks 221a and 221b, allowing hooks 221a and 221b to be elastically deformed. Magnets 21a and 21b are housed in recesses 220a and 220b with hooks 221a and 221b bent outward. The outer edge of magnets 21a and 21b housed in recesses 220a and 220b is hooked by the elastic restoring force of hooks 221a and 221b. The rear ends of the hooks 221a and 221b protrude rearward beyond the rear surface 22B of the holder 22.

[0021] The protrusion 222 protrudes rearward beyond the back surface 22B of the holder 22. The rear end of the protrusion 222 is located further rearward than the rear ends of the hooks 221a and 221b. The protrusion 222 is provided on the arm support portion 23 side of the holder 22. The protrusion 222 is located at one end in a circumferential direction centered on the axis line AX and has a first side portion 222a that can come into contact with a stopper S1 (described later), and a second side portion 222b that is located at the other end in the circumferential direction and can come into contact with a stopper S2 (described later). The function of the protrusion 222 will be described later.

[0022] The magnetic detection element 30 shown in FIG. 3 detects changes in the magnetic field that accompany the rotation of the rotating part 20. For example, a Hall IC (Integrated Circuit) including a Hall element, an operational amplifier, etc. can be used as the magnetic detection element 30. The magnetic detection element 30 outputs a detection signal (e.g., a voltage signal) corresponding to the strength of the detected magnetic field (magnetic flux density) to the circuit board 60. Because the magnetic field formed by the magnets 21a and 21b changes with the rotation of the rotating part 20, this detection signal indicates a value corresponding to the position of the float 10 that rotates the rotating part 20, i.e., the position of the liquid surface. Note that the magnetic detection element 30 may also be another known magnetic detection element that uses an MR (Magneto-Resistive Sensor) element, etc.

[0023] As will be described later, the magnetic detection element 30 is located inside the shaft portion 41 and includes a substantially rectangular parallelepiped element body 31 and a substantially L-shaped terminal 32 extending from the element body 31 toward the circuit board 60.

[0024] 5, the case 40 is made of, for example, a synthetic resin material and includes an axis portion 41 formed around the axis line AX, a holder placement portion 42, and a front outer wall portion 43. The holder placement portion 42 is recessed rearward from the front outer wall portion 43, and is the portion where the holder 22 is placed.

[0025] The shaft portion 41 is formed in a cylindrical shape centered on the axis AX. The shaft portion 41 has an exposed portion 41a that is exposed forward of the holder 22 when the shaft portion 41 is inserted into the through-hole 22H of the holder 22. An annular groove 41b into which the retaining member 50 is fitted is formed on the outer periphery of the exposed portion 41a.

[0026] 1 is a member made of a non-magnetic metal that prevents the holder 22 from coming off the shaft portion 41. The stopper 50 has a generally C-shaped, ring-like shape with ends.

[0027] The holder placement portion 42 is located behind the holder 22 inserted into the shaft portion 41, and is a portion where the holder 22 is placed. As shown in Fig. 5, the holder placement portion 42 includes a bottom surface 420, a hook relief surface 421, a base 422, a receiving portion 423, and a pair of stoppers S1 and S2.

[0028] 6, the bottom surface 420 is a surface that does not come into contact with the protruding portion 222 of the holder 22. A slight clearance is provided between the bottom surface 420 and the rear end of the protruding portion 222.

[0029] 5 and 6, the hook flank surface 421 is a surface formed by stepping up and forward from the bottom surface 420. The hook flank surface 421 is positioned rearward and lower than the receiving portion 423, and is a surface that does not come into contact with the hooks 221a and 221b even when the rotating portion 20 rotates within a rotatable range described below.

[0030] 5, the base 422 is connected to the rear end of the shaft portion 41 and has a larger diameter than the shaft portion 41. In this embodiment, the front surface of the base 422 is located rearward of the front surface of the receiving portion 423, and when the rotating portion 20 rotates relative to the shaft portion 41, the base 422 does not come into contact with the back surface 22B of the holder 22. The base 422 is formed across the bottom surface 420 and the hook relief surface 421.

[0031] The receiving portion 423 is a portion that can receive the back surface 22B of the holder 22. The receiving portion 423 is formed to rise forward from the hook flank 421, and is therefore provided closer to the back surface 22B of the holder 22 than the hook flank 421. In this embodiment, the receiving portion 423 comes into contact with the back surface 22B of the holder 22 when the rotating portion 20 rotates relative to the shaft portion 41.

[0032] Note that the holder arrangement section 42 may have a configuration in which the front surface of the receiving portion 423 is positioned slightly rearward of the front surface of the base 422. In this configuration, the base 422 mainly receives the back surface 22B of the holder 22, and when the holder 22 is slightly tilted with respect to the shaft section 41, the receiving portion 423 comes into contact with the back surface 22B of the holder 22 and receives the back surface 22B. In other words, the manner in which the receiving portion 423 can receive the back surface 22B of the holder 22 is not limited to the manner in which the receiving portion 423 is always in contact with the back surface 22B of the holder 22, but may also be the manner in which the receiving portion 423 comes into contact with the back surface 22B of the holder 22 at some point while the rotating section 20 is rotating with respect to the shaft section 41. Furthermore, the front surface of the receiving portion 423 may be at the same height as the front surface of the base 422.

[0033] 5, the pair of stoppers S1, S2 are wall portions rising from the bottom surface 420 toward the hook flank surface 421. In other words, the pair of stoppers S1, S2 are formed to include a portion located rearward of the hook flank surface 421.

[0034] The pair of stoppers S1, S2 are positioned at an interval in the circumferential direction centered on the axis line AX and regulate the rotatable range of the rotating part 20. In this embodiment, the stoppers S1 and S2 are positioned at an interval of 180° about the axis line AX.

[0035] 6 shows a state in which the first side portion 222a of the protruding portion 222 abuts against the stopper S1 in the circumferential direction about the axis line AX. When the rotating unit 20 rotates from this state in a direction in which the protruding portion 222 approaches the other stopper S2, the second side portion 222b of the protruding portion 222 abuts against the stopper S2. As a result, the range in which the protruding portion 222 can move in the circumferential direction about the axis line AX is restricted by the stoppers S1 and S2. In other words, the pair of stoppers S1, S2 are positioned at a distance from each other across the protruding portion 222 in the circumferential direction about the axis line AX, restricting the rotatable range of the rotating unit 20.

[0036] In this embodiment, as shown in FIG. 2, the first side portion 222a is a side surface (hereinafter referred to as the first side surface) facing in the circumferential direction centered on the axis line AX. The second side portion 222b is a side surface (hereinafter referred to as the second side surface) located on the opposite side of the protrusion 222 from the first side surface in the circumferential direction. The angle formed between the first side surface and the second side surface is set to an angle α about the axis line AX. In this embodiment, α = 60°. As described above, the stoppers S1 and S2 are positioned at an angle of 180° about the axis line AX, and therefore the rotatable range of the rotating portion 20 is 180° - 60° = 120°.

[0037] Note that the first side portion 222a and the second side portion 222b are not limited to the above-described planar shape and may have any shape. Here, a line connecting a point of the first side portion 222a that contacts the stopper S1 and the axis AX (a line extending radially from the axis AX) is defined as a first line, and a line connecting a point of the second side portion 222b that contacts the stopper S2 and the axis AX (a line extending radially from the axis AX) is defined as a second line. By setting the angle between the first line and the second line to a value equivalent to the aforementioned α, the rotatable range of the rotating portion 20 can be determined, and therefore the shapes of the first side portion 222a and the second side portion 222b can be changed arbitrarily.

[0038] As described above, the case 40 is provided with the hook relief surface 421 that does not come into contact with the hooks 221a, 221b, thereby preventing interference between the rotating part 20 and the case 40. Furthermore, the rotatable range of the rotating part 20 can be determined by the relationship between the protrusion 222 of the holder 22 and the stoppers S1, S2 of the case 40, so the liquid level detection device 1 makes it easy to set the rotatable range of the rotating part 20.

[0039] Furthermore, receiving portion 423 is provided at a position where it does not come into contact with hooks 221a, 221b even when rotating portion 20 rotates within the rotatable range. Receiving portion 423 can receive back surface 22B of holder 22 without interfering with rotation of rotating portion 20 within the rotatable range.

[0040] As shown in FIGS. 3 and 4, the case 40 further includes a board accommodating section 44 on the rear side of the holder placement section 42, which accommodates the circuit board 60. The board accommodating section 44 is a section formed by recessing forward (in the +Z direction) from the rear surface of the case 40. The board accommodating section 44 is provided with a plurality of pins that are integral with the case 40, and the position of the circuit board 60 relative to the board accommodating section 44 is determined by inserting the plurality of pins into through holes or notches formed in the circuit board 60. A molding material (not shown) is filled in the board accommodating section 44, covering the circuit board 60. The molding material is made of a known material such as epoxy.

[0041] 3 and 4, the shaft portion 41 is formed with an insertion hole H1 that is recessed forward (in the +Z direction) from the substrate housing portion 44 and into which the element body 31 of the magnetic detection element 30 is inserted, and a fitting hole H2 that communicates with the insertion hole H1 and into which the element body 31 fits. The fitting hole H2 is recessed further from the bottom of the insertion hole H1 and has a smaller diameter than the insertion hole H1.

[0042] The element body 31 of the magnetic detection element 30 is inserted through the insertion hole H1 using a jig (not shown), and the element body 31 is press-fit into the fitting hole H2, thereby fitting the element body 31 into the fitting hole H2. The insertion hole H1, which has a larger diameter than the fitting hole H2, facilitates the insertion of the element body 31. When the element body 31 is fully fitted into the fitting hole H2, the portion of the element body 31 that protrudes from the fitting hole H2 is positioned within the insertion hole H1, and the terminals 32 come into contact with or close to the circuit board 60. This facilitates visual confirmation of whether the element body 31 is properly fitted into the fitting hole H2 before filling the board accommodating portion 44 with a molding material. This also facilitates the electrical connection of the terminals 32 to the circuit board 60 with solder or the like. Note that the term "close proximity of the terminals 32 to the circuit board 60" refers to a close enough proximity between the terminals 32 and the circuit board 60 that they can be electrically connected using only a conductive material such as solder.

[0043] 3, a grommet 80 that holds a portion of the wiring portion 70 is fitted into the portion of the case 40 that surrounds the board housing portion 44. The grommet 80 is made of a known elastic material such as nitrile rubber. The grommet 80 has insertion holes formed therein through which each of the multiple cords of the wiring portion 70 passes.

[0044] The circuit board 60 is made of a PCB (Printed Circuit Board) provided with a circuit that electrically connects the magnetic detection element 30 and the wiring portion 70. The wiring portion 70 is connected to an end region of the circuit board 60 on the opposite side to the terminal 32 by means of soldering or the like.

[0045] The wiring unit 70 is configured to transmit the detection signal from the magnetic detection element 30 to the outside. One end of the wiring unit 70 is electrically connected to the circuit board 60, and the other end is electrically connected to a control unit (not shown) located outside the liquid level detection device 1. The wiring unit 70 is configured by bundling together multiple cords made of a conductive metal such as copper coated with an insulating material. The wiring unit 70 includes a signal line for transmitting the detection signal. The control unit is made up of a microcontroller and acquires the detection signal output from the magnetic detection element 30 and transmitted via the terminal 32, the circuit board 60, and the wiring unit 70. Then, based on the acquired detection signal, the control unit calculates the position of the liquid level and the amount of liquid corresponding to that position using a known method. The control unit may be configured to be included in the liquid level detection device 1.

[0046] The present invention is not limited to the above-described embodiments and drawings, and modifications (including the omission of components) can be made as appropriate within the scope of the present invention.

[0047] In the above, an example has been shown in which the protrusion 222 is provided on the arm support portion 23 side of the holder 22, but the position of the protrusion 222 on the holder 22 can be changed as desired. For example, the position of the protrusion 222 on the holder 22 may be set to a position rotated 180° about the axis line AX from the position shown in Fig. 2. In this case, the arrangement of the bottom surface 420, hook relief surface 421, and receiving portion 423 in the holder arrangement portion 42 may be symmetrical about the x-axis with the arrangement shown in Fig. 5.

[0048] As described above, when the configuration is adopted in which the base 422 receives the rear surface 22B of the holder 22, the receiving portion 423 may be omitted from the holder placement portion .

[0049] In the above, an example has been shown in which the rotation range of the rotating part 20 relative to the case 40 is 120°, but this rotation range can be set arbitrarily by changing the relationship between the pair of stoppers S1, S2 and the protrusion 222.

[0050] Although the above description has been given of an example in which holder 22 holds two magnets 21a and 21b, as long as a magnetic field can be formed in magnetic detection element 30, the shape, number, and magnetization direction of the magnets are arbitrary.

[0051] The present invention allows various embodiments and modifications without departing from the broad spirit and scope of the present invention. Furthermore, the above-described embodiments are intended to illustrate the present invention and do not limit the scope of the present invention. That is, the scope of the present invention is defined by the claims, not by the embodiments. Various modifications made within the scope of the claims and the meaning of the invention equivalent thereto are considered to be within the scope of the present invention. [Explanation of symbols]

[0052] 1...Liquid level detection device 10...float, 11...arm 20...Rotating part 21a, 21b...Magnet 22...holder, 22H...through hole, 22B...back surface 220a, 220b...recessed portion 221a, 221b…Hook 222...protrusion, 222a...first side portion, 222b...second side portion 23...Arm support part 30...magnetic detection element, 31...element body, 32...terminal 40…case 41...Axis portion, AX...Axis line, H1...Insertion hole, H2...Fitting hole 41a... exposed portion, 41b... annular groove 42...Holder placement section 420...Bottom surface, 421...Hook relief surface, 422...Base, 423...Receiving portion S1, S2...Stopper 43…Front outer wall part 44...Substrate housing section 50: retainer, 60: circuit board, 70: wiring section, 80: grommet

Claims

1. a float that floats on the liquid and displaces according to the position of the liquid surface; a rotating part having an annular holder for holding a magnet and into which a shaft part formed around an axis line is inserted, the rotating part being rotatable with respect to the shaft part; a case including the shaft portion and a holder placement portion located behind the holder into which the shaft portion is inserted and in which the holder is placed; a magnetic detection element located inside the shaft portion and detecting a change in a magnetic field caused by rotation of the rotating portion; an arm that connects the float and the rotating part and rotates the rotating part in response to displacement of the float, The holder is a recessed portion recessed from the rear surface of the holder and configured to accommodate the magnet; a hook that forms a part of the outer peripheral wall of the holder and that hooks the magnet housed in the recess; a protruding portion protruding rearward beyond the rear surface of the holder, The holder arrangement portion includes: a hook relief surface that does not come into contact with the hook even when the rotating portion rotates within a rotatable range; a pair of stoppers including a portion located rearward of the hook flank surface, the stoppers being positioned at an interval on either side of the protruding portion in the circumferential direction about the axis line and restricting the rotatable range, Liquid level detection device.

2. the holder placement portion further includes a receiving portion capable of receiving a back surface of the holder, the receiving portion is provided closer to the back surface of the holder than the hook relief surface, and is provided at a position where it does not come into contact with the hook even when the rotating portion rotates within the rotatable range. The liquid level detection device according to claim 1 .

3. the case includes a board accommodating portion on the rear side of the holder arrangement portion for accommodating a circuit board electrically connected to the magnetic detection element, the magnetic detection element includes an element body and a terminal extending from the element body; The shaft portion has an insertion hole recessed from the substrate accommodating portion and into which the element main body is inserted; a fitting hole that communicates with the insertion hole, has a smaller diameter than the insertion hole, and into which the element body is fitted, is formed; When the element body is fitted all the way to the end of the fitting hole, the portion of the element body that protrudes from the fitting hole is positioned within the insertion hole, and the terminals come into contact with or are close to the circuit board. The liquid level detection device according to claim 1 or 2.

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