Detection device

Abstract

To provide a detection device that facilitates attachment of a fixing member to a shaft portion of a resin-made support member.SOLUTION: A detection device 1 comprises: a rotating member 10 that rotates about an axis AX in accordance with displacement of a detection target and has a through-hole 112 penetrating in a direction in which the axis AX extends; one or more magnets 20a, 20b which are held by the rotating member 10; a magnetic detection element 30 that detects a change in a magnetic field involved in the rotation of the rotating member 10; a support member 40 that has a shaft portion 42 extending along the axis AX and supports the rotating member 10 rotatably about the axis AX by inserting the shaft portion 42 through the through-hole 112; and a nonmagnetic fixing member 50 that is attached to a protruding portion 421 protruding from the through-hole 112 in the axis AX. The rotating member 10 includes one or more guide portions 113a, 113b that guide the fixing member 50 to the protruding portion 421 when the fixing member 50 is attached to the protruding portion 421.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a detection device, for example, a detection device for detecting the level of a liquid. [Background technology]

[0002] A known conventional detection device for detecting displacement of an object is, for example, a detection device for detecting the liquid level disclosed in Patent Document 1. The detection device described in Patent Document 1 includes a resin magnet holder that houses a magnet inside and rotates in response to displacement of a float floating on the liquid surface, a magnetic detection element that detects changes in the magnetic field that accompany the rotation of the magnet holder, a resin case that rotatably supports the magnet holder and houses the magnetic detection element, and a resin cover that is arranged to cover the magnet holder, and the resin cover is welded and fixed to the case by melting four welding projections provided at the four corners of a base that constitutes the main part of the case. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-71042 Summary of the Invention [Problem to be solved by the invention]

[0004] In the case of the detection device described in Patent Document 1, the magnet holder, case, and resin cover are all injection-molded products obtained by injection molding resin (molten resin), and a mold was required for each component to mold the magnet holder, case, and resin cover. This resulted in increased parts costs for manufacturing the detection device, which was a cause of increased costs. In addition, the resin cover needed to be welded to the case, so a detection device that could be easily assembled was desired.

[0005] SUMMARY OF THE INVENTION An object of the present invention is to provide a detection device that is easy to assemble. [Means for solving the problem]

[0006] In order to solve the above problem, the present invention provides a detection device for detecting a displacement of a detection object, comprising: The detection device a rotating member that rotates around an axis in response to displacement of the detection target and has a through hole that penetrates in a direction in which the axis extends; one or more magnets held by the rotating member; a magnetic detection element that detects a change in a magnetic field caused by rotation of the rotary member; a support member including a shaft portion extending along the axis, the shaft portion being inserted into the through hole to support the rotating member so as to be rotatable around the axis; a non-magnetic fixing member attached to a protruding portion of the shaft portion protruding from the through hole; Equipped with The detection device further includes one or more guide portions, in which the rotating member is provided with one or more guide portions that guide the fixing member to the protruding portion when the fixing member is attached to the protruding portion. [Effects of the Invention]

[0007] According to the present invention, a detection device is provided that is easy to assemble. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a front view showing a detection device according to one embodiment of the present invention. [Figure 2] FIG. 2 is an exploded perspective view of the detection device of FIG. [Figure 3] FIG. 3 is a cross-sectional view taken along line AA in FIG. [Figure 4] FIG. 4 is a cross-sectional view taken along line BB in FIG. [Figure 5] FIG. 5 is a cross-sectional view taken along line CC in FIG. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0010] Fig. 1 is a front view showing a liquid level detection device 1 according to one embodiment of the present invention, Fig. 2 is an exploded perspective view of the liquid level detection device 1 shown in Fig. 1, and Figs. 3 to 5 are cross-sectional views taken along lines AA, BB, and CC in Fig. 1, respectively.

[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 x axis extends in the left-right direction in FIG. 1, the y axis extends in the up-down direction in FIG. 1, and the z axis is parallel to the axis line AX described below. 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 example, the + direction along the z axis is referred to as the +z direction.

[0012] 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.

[0013] 1 and 2, the liquid level detection device 1 includes a rotating member 10, magnets 20a and 20b, a magnetic detection element 30, a support member 40, a fixed member 50, a float 60, an arm 70, a PCB (Printed Circuit Board) 80, and a wiring section 90. Each of these members will be described below.

[0014] <Rotating parts> The rotary member 10 rotates about an axis AX parallel to the z-axis direction in response to the displacement of the float 60 caused by the displacement of the detection target.

[0015] The rotating member 10 includes an annular portion 110 configured in a generally circular ring shape, and an arm support portion 120 that supports the arm 70. The annular portion 110 and the arm support portion 120 are preferably formed integrally, but the rotating member 10 may be formed after each is formed separately. The rotating member 10 is formed, for example, by injection molding or 3D printing using a synthetic resin material.

[0016] The annular portion 110 includes a thin-walled flat plate portion 111 having a main surface that is approximately parallel to the xy plane, a through hole 112 located in the central portion of the annular portion 110 and penetrating in the direction in which the axis AX extends (axial direction), guide portions 113a, 113b located on the main surface (main surface (+z)) on the +z direction side of the flat plate portion 111 and guiding the fixing member 50 when attaching the fixing member 50 to the shaft portion 42, a convex portion 114 located between the guide portions 113a, 113b, and recessed portions 115a, 115b located on the -z direction side of the flat plate portion 111 and holding the magnets 20a, 20b.

[0017] The flat plate portion 111 is a thin-walled annular portion having a main surface that is approximately parallel to the xy plane. A through-hole 112 penetrates the center of the flat plate portion 111. Guide portions 113a and 113b and a protrusion 114 are provided on the main surface (+z) of the flat plate portion 111, and recesses 115a and 115b are provided on the -z direction side of the flat plate portion 111.

[0018] The through hole 112 is located in the center of the annular portion 110 and is a hole that penetrates the rotating member 10 in the direction in which the axis line AX extends (axial direction). The cross section of the through hole 112 in the direction perpendicular to the axis line AX (radial direction) is circular. A shaft portion 42 of the support member 40, which will be described later, is inserted into the through hole 112. This supports the rotating member 10 so that it can rotate around the axis line AX. The inner peripheral surface of the through hole 112 may abut against the outer peripheral surface of the shaft portion 42.

[0019] 3 and 4, the length of through-hole 112 in the z-axis direction is shorter than the length of shaft portion 42 in the z-axis direction, and shaft portion 42 protrudes from the opening in the +z direction of through-hole 112. The protruding portion of shaft portion 42 is called protruding portion 421.

[0020] The guide portions 113a and 113b are provided as a pair of protruding portions on the main surface (+z) of the flat plate portion 111, and when the fixing member 50 is attached to the protruding portion 421, they restrict the movement of the fixing member 50 on the main surface (+z) of the flat plate portion 111, thereby guiding the fixing member 50 to the protruding portion 421. The guide portions 113a and 113b are preferably formed integrally with the annular portion 110 (or the rotating member 10) when the annular portion 110 (or the rotating member 10) is molded, but may also be provided on the flat plate portion 111 after being molded as separate bodies.

[0021] The minimum distance between the guide portions 113a and 113b is not limited as long as it is wider than the maximum width of the fixed member 50 in the x-axis direction and allows the fixed member 50 to be guided to the protruding portion 421. If the minimum distance between the guide portions 113a and 113b is not sufficiently wider than the maximum width of the fixed member 50 in the x-axis direction, contact between the fixed member 50 and the guide portions 113a and 113b increases, preventing the fixed member 50 from being smoothly guided to the protruding portion 421. In addition, friction between the fixed member 50 and the guide portions 113a and 113b may increase the generation of trace amounts of resin powder (shavings) derived from the synthetic resin that makes up the guide portions 113a and 113b. If the minimum distance between the guide portions 113a and 113b is excessively wider than the maximum width of the fixed member 50 in the x-axis direction, movement of the fixed member 50 on the main surface (+z) of the flat portion 111 is not sufficiently restricted. Therefore, it is preferable that the minimum distance between guide portions 113a and 113b be set slightly wider than the maximum width in the X-axis direction of fixed member 50. Here, "the minimum distance between guide portions 113a and 113b" refers to the smallest distance from any point on one guide portion 112a to any point on the other guide portion 112a.

[0022] The guide portions 113a and 113b may be arranged substantially parallel to each other, or may be arranged so that the distance therebetween gradually narrows toward the shaft portion 42, and are preferably arranged parallel to each other.

[0023] The height (length in the z-axis direction) of guide portions 113a and 113b is not limited as long as it is a height that can guide fixing member 50 to protruding portion 421. If the height of guide portions 113a and 113b is excessively low compared to the height of fixing member 50 from the main surface (+z) of flat plate portion 111, fixing member 50 may easily climb over guide portions 113a and 113b when fixing member 50 is attached, and the guide function may not be fully performed. If the height of guide portions 113a and 113b is excessively high compared to the height of fixing member 50 from the main surface (+z) of flat plate portion 111, guide portions 113a and 113b become bulky, which may reduce the workability, for example, when fixing member 50 is attached to protruding portion 421.

[0024] 1 and 2, each of the guide portions 113a, 113b is preferably formed as a continuous raised portion, but may be formed from a plurality of raised portions. In addition, in this embodiment, the guide portions 113a, 113b are a pair of raised portions, but the shape and number of the guide portions are not limited as long as they can guide the fixing member 50 to the protruding portion 421.

[0025] As shown in FIGS. 1, 2, and 5, the annular portion 110 may have a protrusion 114 between the guide portions 113a and 113b that protrudes in the +z direction from the main surface (+z) of the flat portion 111. The protrusion 114 prevents the fixing member 50 from directly contacting the main surface (+z) of the flat portion 111, thereby reducing the contact area between the fixing member 50 and the annular portion 110. This reduces frictional resistance between the fixing member 50 and the annular portion 110 when attaching the fixing member 50 to the protruding portion 421, improving workability and reducing the generation of trace resin powder (shavings) derived from the synthetic resin that constitutes the annular portion 110 due to friction between the fixing member 50 and the annular portion 110. The height of the protrusion 114 may determine the position of the fixing member 50 in the z-axis direction during and after attachment to the protruding portion 421. The protrusions 114 are preferably formed integrally with the annular portion 110 (rotating member 10) when the annular portion 110 is molded, but may be formed separately and then provided on the flat plate portion 111.

[0026] The height (length in the z-axis direction) of the protrusions 114 is set lower than the height of the guide portions 113a and 113b. If the height of the protrusions 114 is higher than the height of the guide portions 113a and 113b, the fixing member 50 will climb over the guide portions 113a and 113b when the fixing member 50 is attached, impairing the guide function of the guide portions 113a and 113b. Furthermore, the height and shape of the protrusions 114 are set so that the fixing member 50 does not become unbalanced on the protrusions 114 when the fixing member 50 is attached to the protruding portion 421. There are no particular limitations on the height, shape, or number of the protrusions 114 as long as the contact area with the fixing member 50 is not too large and the fixing member 50 does not climb over the guide portions 113a and 113b. The number of the protrusions 114 is preferably two or more, for example, three.

[0027] The magnets 20a and 20b are housed (press-fitted) in the recesses 115a and 115b, respectively. There are no particular limitations on the shape of the recesses 115a and 115b, as long as they can hold the magnets 20a and 20b. The recesses 115a and 115b are preferably formed integrally with the annular portion 110 (rotating member 10) when the annular portion 110 is molded, but may also be formed separately and then provided in the flat plate portion 111. The recesses 115a and 115b are preferably molded integrally with at least the flat plate portion 111.

[0028] The recesses 115a and 115b are provided on the −z direction side of the flat plate portion 111. In this embodiment, as shown in Figures 3 and 5, the recesses 115a and 115b that hold the magnets 20a and 20b are recessed in a direction (+z direction) from the base side of the shaft portion 42 toward the protruding portion 421, and are open in a direction (−z direction) from the protruding portion 421 of the shaft portion 42 toward the base side of the shaft portion. The bottoms (opposite the openings) of the recesses 115a and 115b and the −z direction side of the flat plate portion 111 are formed integrally, and the bottoms of the recesses 115a and 115b are formed as part of the flat plate portion 111. As shown in Figures 3 and 5, from the -z direction side to the +z direction side, the openings of the recesses 115a and 115b, the magnets 20a and 20b, the bottoms of the recesses 115a and 115b (formed as part of the flat plate portion 111), and the fixing member 50 are located in that order.

[0029] The arm support part 120 supports one end of the arm 70 on the rotating member 10. Displacement of the float 60 connected to the other end of the arm 70 is converted into rotation of the rotating member 10. The shape of the arm support part 120 is not particularly limited as long as it can support one end of the arm 70.

[0030] <Magnet> The magnets 20a and 20b are made of known materials such as neodymium and ferrite, and are disposed in the recesses 115a and 115b, respectively, of the rotating member 10. The magnets 20a and 20b generate a magnetic field that can be detected by the magnetic detection element 30. This magnetic field changes as the rotating member 10 rotates.

[0031] The magnets 20a and 20b are each magnetized with two poles in the radial direction about the axis AX so as to generate a magnetic field between them. The magnets 20a and 20b are each arranged along an arc about the axis AX and face each other in the radial direction about the axis AX.

[0032] In this embodiment, the two magnets 20a and 20b are held by the rotating member 10 as described above, but the shape, number, and magnetization direction of the magnets are arbitrary as long as they can generate a magnetic field that can be detected by the magnetic detection element 30.

[0033] <Magnetic detection element> The magnetic detection element 30 detects the magnetic field formed by the magnets 20a and 20b. The magnetic field formed by the magnets 20a and 20b changes with the rotation of the rotating member 10, and therefore the strength of the detected magnetic field (magnetic flux density) changes depending on the position of the float 60 that rotates the rotating member 10, i.e., the position of the liquid surface.

[0034] The magnetic detection element 30 is electrically connected to the PCB 80 via a substantially L-shaped terminal 31 extending from the magnetic detection element 30 toward the PCB 80. The magnetic detection element 30 outputs a detection signal (e.g., a voltage signal) to the PCB 80 according to the strength of the detected magnetic field.

[0035] For example, a Hall IC (Integrated Circuit) including a Hall element, an operational amplifier, etc. can be applied as the magnetic detection element 30. Alternatively, the magnetic detection element 30 may be another known magnetic detection element that uses a magnetoresistive effect element (MR element: Magneto Resistive Sensor), etc.

[0036] 2, the magnetic detection element 30 is positioned on the axis AX, but the arrangement of the magnetic detection element 30 is arbitrary as long as the magnetic detection element 30 can effectively detect changes in the magnetic field. For example, the magnetic detection element 30 may be positioned off the axis AX.

[0037] <Supporting member> The support member 40 rotatably supports the rotating member 10 and houses the magnetic detection element 30, the PCB 80, etc. The support member 40 is formed, for example, by injection molding or 3D printing using a synthetic resin material. The support member 40 has a base portion 41 and a shaft portion 42.

[0038] The base 41 has a structure with a predetermined thickness, and is located opposite the -z side of the annular portion 110 of the rotating member 10, as shown in Figures 2 and 3. The +z side of the base 41 has a structure corresponding to the bottom of the rotating member 10. The structure on the -z side of the base 41 is recessed toward the +z side, and accommodates the PCB 80, etc. For example, the -z side of the base 41 is filled with a molding material M with the PCB 80, etc. accommodated therein, to cover the PCB 80, etc.

[0039] 2 to 4, the shaft portion 42 protrudes in the +z direction from the base portion 41 and is formed in a substantially cylindrical shape centered on the axis line AX. The shaft portion 42 is inserted into the through-hole 112 of the rotating member 10 and has a protruding portion 421 protruding from the through-hole 112.

[0040] 3 and 4, a space for accommodating the magnetic detection element 30 is formed inside the shaft portion 42. This space is open on the -z direction side and closed on the +z direction side. The magnetic detection element 30 is disposed (press-fitted and held) in the space provided inside the shaft portion 42. As with the -z direction side of the base portion 41, the space is filled with the molding material M with the magnetic detection element 30 and the like accommodated therein.

[0041] 2 to 4, it is preferable that shaft 42 has, on the outer periphery of protruding portion 421, groove 4211 recessed in a direction toward the center of the diameter centered on axis AX. Groove 4211 is a groove recessed in a circular or arc-like shape, preferably an arc-like shape, along the outer periphery of shaft 42. Groove 4211 improves the ease of attaching fixing member 50 to shaft 42, determines the axial position of fixing member 50, and ensures that fixing member 50 is firmly attached to shaft 42.

[0042] <Fixing material> In order to restrict the axial movement of the rotating member 10 and fix the axial position, a non-magnetic fixing member 50 is attached to the protruding portion 421 of the shaft portion 42. As shown in Figures 3 and 5, the flat portion 111 of the rotating member 10 (and the bottoms of the recesses 115a and 115b) is interposed between the fixing member 50 and the magnets 20a and 20b.

[0043] The fixing member 50 may be any member that can prevent the rotating member 10 from coming off or shifting in the axial direction and can fix the axial position of the rotating member 10, and may be configured, for example, in a generally ring-like shape with ends (roughly C-shaped), and preferably has a ring-shaped portion 51 with ends that surrounds the protruding portion 421 of the shaft portion 42 of the support member 40. In an embodiment in which the protruding portion 421 has a groove portion 4211, the fixing member 50 preferably has one or more fitting portions 52 that fit into the groove portion 4211 of the protruding portion 421. The number of fitting portions 52 is preferably two or more, and more preferably three.

[0044] The fixing member 50 is, for example, a snap ring (also called a retaining ring), preferably an E-ring (also called an E-type ring or an E-type retaining ring) or a C-ring (also called a C-type ring or a C-type retaining ring), more preferably an E-ring.

[0045] The fixing member 50 is a non-magnetic material, and is preferably made of a non-magnetic metal, for example, non-magnetic stainless steel.

[0046] <float> The float 60 floats on the liquid whose level is to be detected and displaces with the liquid surface. The float 60 is made of, for example, synthetic rubber.

[0047] <Arm> The arm 70 connects the float 60 and the rotating member 10 and rotates the rotating member 10 in accordance with the displacement of the float 60. As described above, the magnets 20a and 20b are held on the rotating member 10, and the magnetic field changes due to the magnets 20a and 20b rotating as the rotating member 10 rotates. The arm 70 is formed of, for example, a non-magnetic metal.

[0048] <pcb> The PCB 80 mounts a circuit that electrically connects the magnetic detection element 30 and the wiring portion 90. As described above, the PCB 80 is electrically connected to the magnetic detection element 30 via the substantially L-shaped terminal 31 extending from the magnetic detection element 30. The wiring portion 90 is connected to the end region of the PCB 80 on the opposite side from the terminal 31 by means of soldering or the like.

[0049] <Wiring section> The wiring section 90 transmits a detection signal from the magnetic detection element 30 to the outside. One end of the wiring section 90 is electrically connected to the PCB 80, and the other end is electrically connected to a control section (not shown). The control section is located outside the support member 40, and a grommet G is attached to the wiring lead-out section from the support member 40. The grommet G is made of a known elastic material such as nitrile rubber, and acts as a buffer against bending of the wiring section 90 at the wiring lead-out section.

[0050] The wiring unit 90 is configured by bundling together multiple cords each made of a conductive metal (e.g., copper) coated with an insulating material. The wiring unit 90 includes a signal line for transmitting a detection signal. The control unit is configured by a microcomputer. The control unit acquires the detection signal output from the magnetic detection element 30 and transmitted to the control unit via the terminal 31, PCB 80, and wiring unit 90, and then calculates the position of the liquid level and the amount of liquid corresponding to that position based on the acquired detection signal using a known method. The control unit may be located outside the liquid level detection device 1, or may be included in the liquid level detection device 1.

[0051] 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.

[0052] In the above description, in order to facilitate understanding of the present invention, descriptions of well-known technical matters have been omitted as appropriate.

[0053] The present invention includes the following embodiments. [1] A detection device for detecting a displacement of a detection object, The detection device a rotating member that rotates around an axis in response to displacement of the detection target and has a through hole that penetrates in a direction in which the axis extends; one or more magnets held by the rotating member; a magnetic detection element that detects a change in a magnetic field caused by rotation of the rotary member; a support member including a shaft portion extending along the axis, the shaft portion being inserted into the through hole to support the rotating member so as to be rotatable around the axis; a non-magnetic fixing member attached to a protruding portion of the shaft portion protruding from the through hole; Equipped with A detection device, wherein the rotating member has one or more guide portions that guide the fixing member to the protruding portion when the fixing member is attached to the protruding portion. [2] The detection device described in [1], wherein the shaft portion is cylindrical with a closed portion on one side, and the protruding portion has a circular or arc-shaped groove along the outer periphery of the shaft portion. [3] The detection device described in [2], wherein the fixing member comprises a ring-shaped portion with ends surrounding the protruding portion and a plurality of fitting portions that fit into the groove portion. [4] The detection device according to [3], wherein the fixing member is an E-ring. [5] The detection device according to any one of [1] to [4], wherein the one or more guide portions are a pair of raised portions. [6] The detection device described in [5], wherein the rotating member has one or more convex portions between the pair of raised portions. [7] A detection device according to any one of [1] to [6], wherein the rotating member has one or more recesses, and the one or more magnets are each held in the one or more recesses. [8] The detection device described in [7], wherein the one or more recesses are recessed in a direction from the base side of the shaft portion toward the protruding portion and open in a direction from the protruding portion of the shaft portion toward the base side. [Explanation of symbols]

[0054] 1. Liquid level detection device 10. Rotating member 110... Annular part 111...Flat plate part 112...Through hole 113a,113b...ridges 114···Convex part 115a, 115b...recessed portion 120 Arm support 20a, 20b: Magnet 30 Magnetic detection element 31 Terminal 40 Support member 41...base 42 Shaft 421...Protruding part 4211 Groove 50 Fixing member 51 Ring-shaped portion 52 Fitting part 60···float 70···Arm 80···PCB 90...Wiring section M···Molding material G···Grommet< / pcb>

Claims

1. A detection device for detecting a displacement of a detection object, The detection device a rotating member that rotates around an axis in response to displacement of the detection target and has a through hole that penetrates in a direction in which the axis extends; one or more magnets held by the rotating member; a magnetic detection element that detects a change in a magnetic field caused by rotation of the rotary member; a support member including a shaft portion extending along the axis, the shaft portion being inserted into the through hole to support the rotating member so as to be rotatable around the axis; a non-magnetic fixing member attached to a protruding portion of the shaft portion protruding from the through hole; Equipped with A detection device, wherein the rotating member has one or more guide portions that guide the fixing member to the protruding portion when the fixing member is attached to the protruding portion.

2. The detection device according to claim 1 , wherein the shaft portion is cylindrical with a closed end on one side, and the protruding portion has a circular or arcuate groove along the outer periphery of the shaft portion.

3. The detection device according to claim 2 , wherein the fixing member comprises a ring-shaped portion surrounding the protruding portion and one or more fitting portions that fit into the groove portion.

4. The detection device according to claim 3 , wherein the fixing member is an E-ring.

5. The detection device according to claim 1 , wherein the one or more guide portions are a pair of raised portions.

6. The detection device according to claim 5 , wherein the rotating member has one or more protrusions between the pair of raised portions.

7. The detection device according to claim 1 , wherein the rotating member has one or more recesses, and the one or more magnets are held in the one or more recesses, respectively.

8. 8. The detection device according to claim 7, wherein the one or more recesses are recessed in a direction from a base side of the shaft portion toward the protruding portion and open in a direction from the protruding portion of the shaft portion toward the base side.

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