Detection device

Abstract

To provide a detection device capable of suppressing a rise in cost.SOLUTION: A detection device comprises a rotary member 20 which rotates on an axis AX as a detection object is displaced, magnets 21a, 21b which are provided at hollow parts G1, G2 provided at the rotary member 20, a magnetic detection element 30 which detects a magnetic field changing as the rotary member 20 rotates, a case 40 which supports the rotary member 20 rotatably, and a non-magnetic member 50 which is arranged covering the magnets 21a, 21b at least in part. The case 40 has a shaft part 42 which is provided along the axis AX, and the magnetic detection element 30 is arranged at a space part 42b provided on the shaft part 42.SELECTED DRAWING: Figure 2

Description

[Technical Field]

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

[0002] A conventional detection device of this type is disclosed, for example, in Patent Document 1. The detection device described in Patent Document 1 includes a resin magnet holder (rotating member) that houses a magnet inside and rotates in response to the displacement of a float floating on the surface of the liquid, 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] JP 2014-71042 A 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 injecting resin (molten resin), and to mold the magnet holder, case, and resin cover (i.e., three injection-molded products), a separate mold (i.e., three molds) is required for each component, which increases the cost of parts for manufacturing the detection device and causes an increase in costs. SUMMARY OF THE INVENTION In order to address the above-mentioned problems, an object of the present invention is to provide a detection device that can suppress increases in costs. [Means for solving the problem]

[0005] The present invention provides a magnetic detection device comprising: a rotating member that rotates around an axis in response to displacement of a detection target; a magnet disposed in a recess provided in the rotating member; a magnetic detection element that detects changes in a magnetic field accompanying the rotation of the rotating member; a support member that rotatably supports the rotating member; and a non-magnetic member that is disposed so as to cover at least a portion of the magnet. The support member has a shaft portion provided along the axis, the magnetic detection element is disposed in a space provided in the shaft portion, the rotating member is provided with a through-hole through which the shaft portion can pass, and the non-magnetic member has an open-ended ring portion surrounding a protruding portion of the shaft portion protruding from the through-hole, and a plurality of fitting portions that fit into grooves provided in the protruding portion. It is characterized by:

[0008] The present invention is also characterized in that the ring portion is arranged along a virtual circumference centered on the axis, and the rotating member has a raised portion formed on the virtual circumference in a manner corresponding to the missing portion where the ring portion is missing, and a portion of the raised portion is fitted into the groove portion.

[0009] The present invention is also characterized in that the fitting portion is a fitting protrusion partially provided on the inside of the ring portion, and is provided at both end portions of the ring portion and at a middle portion of the ring portion.

[0010] In the present invention, the inner edge portion of the magnet is covered by the ring portion, and the outer edge portion of the magnet is covered by a locking portion formed on the rotating member.

[0011] In the invention, the non-magnetic member rotates in conjunction with the rotation of the rotary member.

[0012] The present invention is also characterized by comprising a float that floats on the liquid to be detected and displaces along with the liquid surface, and an arm that connects the float to the rotating member and rotates the rotating member in accordance with the displacement of the float. [Effects of the Invention]

[0013] According to the present invention, it is possible to provide a detection device that can achieve the intended purpose and suppress an increase in costs. [Brief explanation of the drawings]

[0014] [Figure 1] FIG. 2 is a front view of the detection device according to the present embodiment. [Figure 2] FIG. 2 is an exploded perspective view of the detection device according to the embodiment. [Figure 3] Cross section AA of Figure 1. [Figure 4] Cross section B-B of Figure 1. [Figure 5] 2 is a diagram showing the rotating member and the supporting member as viewed from the direction of arrow C in FIG. 1. FIG. [Figure 6] FIG. 10 is a front view of the detection device when the position of the float arm is changed according to the embodiment. [Figure 7] DD cross section of Figure 5. [Figure 8] FIG. 8 is a diagram showing a state in which the first rib in FIG. 7 has been cut off. DETAILED DESCRIPTION OF THE INVENTION

[0015] An embodiment of the present invention will be described with reference to the drawings.

[0016] The detection device F shown in Fig. 1 is configured as a liquid level detection device that detects the position (liquid level) of the liquid level La of the liquid L contained in a tank (not shown). The liquid level La displaces vertically in response to an increase or decrease in the amount of the liquid L. For example, the detection device F is attached to a fuel tank of a vehicle and detects the liquid level corresponding to the amount of gasoline as the liquid L.

[0017] In the following, the components of the detection device F may be described using the mutually orthogonal X, Y, and Z axes as appropriate. The Y axis is along the vertical direction in FIG. 1. The Z axis is parallel to the axis line 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.

[0018] As shown in appropriate views of Figures 1 to 7, the detection device F includes a float 10, an arm 11, a rotating member 20 that rotates around an axis AX, a magnetic detection element 30, a case 40 as a support member, a non-magnetic member 50, a PCB (Printed Circuit Board) 60, a wiring portion 70, a grommet 80, and a molding material 90.

[0019] 1, the float 10 floats on the liquid L to be detected and displaces with the liquid surface La. The float 10 is made of, for example, synthetic rubber.

[0020] The arm 11 connects the float 10 and the rotating member 20, and rotates the rotating member 20 around the axis AX in response to the displacement of the float 10. The arm 11 is made of a non-magnetic metal, and holds the float 10 at one end and is attached to the rotating member 20 at the other end.

[0021] The arm 11 has a first portion 11a that is inserted into the float 10 and that is locked to a first arm locking portion (described later) that is provided on the rotating member 20, a second portion 11b that is bent at a substantially right angle from one end of the first portion 11a and that is locked to a second arm locking portion (described later) that is provided on the rotating member 20, and a third portion 11c that is bent at a substantially right angle from the other end of the first portion 11a that is opposite to the one end and that is connected to the float 10. Note that the float 10 and the arm 11 are not shown in Figure 2.

[0022] The rotating member 20 rotates around the axis AX in response to the displacement of the detection target, and has two magnets 21a and 21b and a magnet holder 22 that holds the magnets 21a and 21b (see FIGS. 2 and 4). The rotating member 20 generates a magnetic field by the magnets 21a and 21b that can be detected by the magnetic detection element 30. This magnetic field changes as the rotating member 20 rotates.

[0023] Magnets 21a and 21b are made of known materials such as neodymium or ferrite, and are respectively placed in recesses, which will be described later. Magnets 21a and 21b are, for example, 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.

[0024] Magnet holder 22 is an injection-molded product made of, for example, a synthetic resin material, and is formed in a generally circular shape. Magnet holder 22 includes main body 22a, first and second arm locking portions 22b, 22c, raised portion 22d, flexible locking portions 22e, 22f, and a plurality of ribs 22g.

[0025] The main body portion 22a is a part that constitutes the main part of the magnet holder 22, and has recessed portions G1 and G2, a recessed portion H1 provided on the bottom surface facing the case 40 (the surface facing the -Z direction), and a through portion R.

[0026] The recesses G1 and G2 are provided to accommodate the magnets 21a and 21b, and are formed by being recessed in the -Z direction as shown in Figures 2 and 4. The magnet 21a is accommodated (e.g., press-fitted) in the recess G1, and the magnet 21b is accommodated (e.g., press-fitted) in the recess G2.

[0027] As shown in Figures 3 and 4, the recessed portion H1 is recessed in a direction away from the case 40. As shown in Figures 3 and 7, the recessed portion H1 has an annular shape centered on the axis AX. The function of the recessed portion H1 will be described later. The through portion R is a portion through which a shaft portion (described later) provided on the case 40 can pass, and is provided along the axis AX and configured as a circular through-hole that penetrates the front and back of the main body portion 22a.

[0028] 1 and 2, the first arm locking portion 22b and the second arm locking portion 22c are provided on the outer periphery of the main body portion 22a. In this embodiment, the first arm locking portion 22b is configured as a portion that can lock the first portion 11a of the arm 11, and the second arm locking portion 22c is configured as a portion that can lock the second portion 11b of the arm 11. The first and second arm locking portions 22b, 22c are located on the side facing the +Z direction from first and second restriction portions (described later) that are provided on the case 40. Note that a groove J1 is formed in the first arm locking portion 22b on the side facing the -Z direction, and the first portion 11a is fitted into this groove J1 to be locked to the first arm locking portion 22b. On the other hand, a groove J2 is formed in the second arm locking portion 22c on the side facing the +Z direction, and the second portion 11b is fitted into this groove J2, thereby being locked to the second arm locking portion 22c.

[0029] In this embodiment, the swing direction of the arm 11 is configured to be changeable in accordance with the displacement of the liquid level La and the float 10, taking into account the shape of the tank that contains the liquid L. Specifically, for example, as shown in FIG. 6, the first portion 11a is engaged with the second arm locking portion 22c, and the second portion 11b is engaged with the first arm locking portion 22b, thereby making it possible to change the swing direction of the arm 11 in consideration of the shape of the tank. Note that by making the formation width K1 of the first arm locking portion 22b along the direction of the arm 11 shorter than the formation width K2 of the second arm locking portion 22c along the direction of the arm 11, it becomes easy to visually check for misassembly of the arm 11 (see FIGS. 1 and 6).

[0030] The raised portion 22d is a protruding rib provided on the side facing the +Z direction from the main body portion 221, and is formed in a substantially arc shape so as to cover a missing portion provided in the non-magnetic member 50, which will be described later.

[0031] The locking portions 22e and 22f are provided on portions of the outer periphery of the recesses G1 and G2, respectively, provided in the rotating member 20. The locking portion 22e is a portion that covers and locks the outer edge portion W3 of the magnet 21a housed in the recessed portion G1, and includes a locking claw E1 that locks the outer edge portion W3 and a flexible elastic piece E2 that is located outside the magnet 21a (see FIGS. 2 and 4). Similarly, the locking portion 22f is a portion that covers and locks the outer edge portion W4 of the magnet 21b housed in the recessed portion G2, and includes a locking claw E3 that locks the outer edge portion W4 and a flexible elastic piece E4 that is located outside the magnet 21b. The locking portion 22e is spaced from the recessed portion G1 by a slit M1 formed around the periphery. The locking portion 22f is spaced from the recessed portion G2 by a slit M2 formed around the periphery. By configuring in this manner, the locking portions 22e, 22f formed integrally with the rotating member 20 are capable of flexibly deforming, and the magnets 21a, 21b can be accommodated in the recesses G1, G2 with the locking portions 22e, 22f (elastic pieces E2, E4) bent outward. After accommodation, the outer edge portions W3, W4 of the magnets 21a, 21b can be locked by the elastic restoring force of the locking portions 22e, 22f.

[0032] A plurality of ribs 22g are provided between the first and second restricting portions provided on the case 40. For example, as shown in FIG. 5, five ribs 22g are provided at equal intervals between the first and second restricting portions and generally aligned along the X direction. In this embodiment, the ribs are referred to as the first rib R1, the second rib R2, the third rib R3, the fourth rib R4, and the fifth rib R5 from left to right in FIG. 5. The ribs R are configured to be able to come into contact with either the first or second restricting portion when the rotating member 20 rotates, and have the function of determining the rotation angle of the arm 11.

[0033] For example, when the first rib R1, the second rib R2, the third rib R3, the fourth rib R4, and the fifth rib R5 are all present, if the rotating member 20 rotates in the clockwise direction N1 shown in FIGS. 2 and 7, the first rib R1 comes into contact with the first restricting portion, thereby restricting the rotation of the rotating member 20. The rotation angle of the arm 11 at this time is angle P1 shown in FIG. 7. On the other hand, if the rotating member 20 rotates in the counterclockwise direction N2, which is the opposite direction to the clockwise direction N1, when the first rib R1, the second rib R2, the third rib R3, the fourth rib R4, and the fifth rib R5 are all present, the fifth rib R5 comes into contact with the second restricting portion, thereby restricting the rotation of the rotating member 20. The rotation angle of the arm 11 at this time is angle P2 shown in FIG. 7.

[0034] In this embodiment, the rotation angle of arm 11 is configured to be changeable. For example, in a situation where the first rib R1 of the first rib R1, the second rib R2, the third rib R3, the fourth rib R4, and the fifth rib R5 is cut and rib 22g is configured with the second rib R2, the third rib R3, the fourth rib R4, and the fifth rib R5, when the rotating member 20 rotates in the clockwise direction N1 shown in FIGS. 2 and 7, the second rib R2 comes into contact with the first restricting portion, thereby restricting the rotation of the rotating member 20. In this case, the rotation angle of arm 11 becomes angle P3, which is larger than the above-mentioned angle P1. In this way, in this embodiment, the rotation angle of arm 11 can be changed by using rib 22g.

[0035] The magnetic detection element 30 shown in FIG. 2 detects changes in the magnetic field that accompany the rotation of the rotating member 20. The magnetic detection element 30 may be, for example, a Hall IC (Integrated Circuit) including a Hall element, an operational amplifier, etc. 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 PCB 60. Because the magnetic field generated by the magnets 21a and 21b changes with the rotation of the rotating member 20, the detection signal indicates a value corresponding to the position of the float 10 that rotates the rotating member 20, i.e., the position of the liquid level La. The magnetic detection element 30 may also be another known magnetic detection element that uses an MR (Magneto-Resistive Sensor) element, etc.

[0036] The case 40 is an injection-molded product made of, for example, a synthetic resin material, and rotatably supports the rotating member 20 and houses the magnetic detection element 30. The case 40 has a base portion 41, a shaft portion 42, and first and second restriction portions 43a and 43b.

[0037] 2, the base 41 is substantially rectangular, and is located on the side of the bottom surface (surface facing the -Z direction) of the rotating member 20, as shown in Fig. 3. The base 41 has a protrusion 41a provided on the side of the mounting surface on which the rotating member 20 is placed, and a board accommodating portion 41b and a wiring lead-out portion 41c formed on the side of the bottom surface.

[0038] The protrusion 41a protrudes in the +Z direction from the mounting surface of the base 41 and is inserted into the recess H1 provided in the rotating member 20. The protrusion 41a has an annular shape centered on the axis AX, as shown in FIGS.

[0039] When the rotating member 20 rotates in the clockwise direction N1 or counterclockwise direction N2, the recessed portion H1 slides against the protruding portion 41a of the case 40, guiding the rotational movement of the rotating member 20. The protruding portion 41a has a trapezoidal cross section in the radial direction centered on the axis AX. This cross-sectional shape reduces contact resistance when the recessed portion H1 slides over the protruding portion 41a. The rotating member 20 rotates with the protruding portion 41a provided on the case 40 inserted into the recessed portion H1, thereby preventing the rotating member 20 from shifting in a direction perpendicular to the axis AX (radial direction). Rotation of the rotating member 20 at an angle relative to the axis AX can also be prevented. As a result, wear on the components and a decrease in detection accuracy can be prevented. Furthermore, the rotating member 20 and case 40 with this structure are highly durable even when subjected to external forces via the arm 11.

[0040] The board accommodating portion 41b is a portion recessed in the +Z direction from the bottom surface of the case 40, and accommodates a PCB 60 or the like. The board accommodating portion 41b is filled with a molding material 90. Note that the molding material 90 is not shown in FIG.

[0041] The wiring pull-out portion 41c is a portion from which the wiring portion 70 is pulled out from the case 40, and is formed in communication with the board accommodating portion 41b. The wiring pull-out portion 41c is located at the end of the case 40 in the +Y direction. A grommet 80 that holds a portion of the wiring portion 70 is fixed to the wiring pull-out portion 41c as described below.

[0042] The shaft 42 protrudes from the base 41 in the +Z direction and is arranged along the axis AX. The shaft 42 here is formed in a substantially cylindrical shape, is inserted (thrusts through) a through-hole R provided in the main body 22a (rotating member 20), and has a protruding portion 42a protruding from the through-hole R. The rotating member 20 rotates around the shaft 42. The magnetic detection element 30 is arranged (press-fitted and held) in a space 42b as a void provided inside the shaft 42. The space 42b is a closed space whose end in the -Z direction is open and communicates with the substrate accommodating portion 41b, and whose end in the +Z direction is closed.

[0043] The first and second restricting portions 43a, 43b are portions for restricting the rotation angle of the arm 11, and are provided on the outer periphery of the base portion 41 (see FIG. 2). The first and second restricting portions 43a, 43b are located in the -Z direction of the rotating member 20 (arm 11) as shown in FIGS. 5 and 7, with the first restricting portion 43a being provided near the first rib R1 and the second restricting portion 43b being provided near the fifth rib R5.

[0044] As shown in FIG. 4, the non-magnetic member 50 is disposed so as to cover inner edge portions W1 and W2 of the magnets 21a and 21b, which are portions of the magnets 21a and 21b. These inner edge portions W1 and W2 are configured as portions of the magnets 21a and 21b located close to the shaft portion 42. The non-magnetic member 50 includes a ring portion 51 with ends surrounding the protruding portion 42a of the shaft portion 42 protruding from the through-hole R, and a plurality of fitting portions 52 that fit into annular groove portions 42c provided in the protruding portion 42a. In this embodiment, both the fitting portions 52 and a raised fitting portion S of the raised portion 22d located on the shaft portion 42 side are configured to fit into the groove portion 42c (see FIG. 3). The raised fitting portion S corresponds to a portion of the raised portion 22d described in the claims below.

[0045] In this case, the ring portion 51 may be a generally C-shaped ring having a missing portion T that is interrupted midway, and is provided along an imaginary circumference V (see FIG. 1) centered on the axis line AX. The raised portion 22d of the rotating member 20 is located at this missing portion T. That is, in this embodiment, as shown in FIG. 2, the raised portion 22d is a portion on the imaginary circumference V that is formed as a raised portion corresponding to the missing portion T where the ring portion 51 is missing.

[0046] The fitting portions 52 are fitting protrusions partially provided on the inside of the ring portion 51, and have a raised shape that protrudes toward the inside of the ring portion 51. The fitting portions 52 are provided at both end portions of the ring portion 51 and at the center portion of the ring portion 51. When the rotating member 20 rotates, the fitting portions 52 and the raised fitting portions S rotate while being fitted into the groove portions 42c. In other words, the non-magnetic member 50 rotates in conjunction with (synchronized with) the rotation of the rotating member 20.

[0047] In this case, ring portion 51 of non-magnetic member 50 covers inner edge portions W1, W2 of magnets 21a, 21b in the Z direction. Furthermore, locking claws E1, E3 (locking portions 22e, 22f) cover outer edge portions W3, W4 of magnets 21a, 21b in the Z direction. That is, in this embodiment, magnets 21a, 21b are configured such that inner edge portions W1, W2 are covered by ring portion 51, and outer edge portions W3, W4 are covered by locking claws E1, E3 (locking portions 22e, 22f) integrally formed with rotating member 20. As a result, non-magnetic member 50 regulates the positions of magnets 21a, 21b in the direction along axis AX, and has a retaining function that prevents magnets 21a, 21b from coming off rotating member 20.

[0048] 2 and 3, a circuit that electrically connects the magnetic detection element 30 and the wiring portion 70 is mounted on the PCB 60, and the PCB 60 is accommodated in the board accommodation portion 41b of the case 40. The magnetic detection element 30 is electrically connected to the PCB 60 via a substantially L-shaped terminal 31 that extends from the magnetic detection element 30 toward the PCB 60. The PCB 60 has a connection portion 61 to which the wiring portion 70 is connected, at a position spaced apart from the terminal 31 in the radial direction centered on the axis AX. The wiring portion 70 is connected to the connection portion 61 by soldering or the like.

[0049] The wiring unit 70 is configured to transmit a detection signal from the magnetic detection element 30 to the outside. One end of the wiring unit 70 is electrically connected to the PCB 60, and the other end is electrically connected to a control unit (not shown) located outside the detection device F. The wiring unit 70 is configured by bundling together multiple cords made of a conductive metal such as copper coated with an insulating material.

[0050] The wiring unit 70 includes a signal line for transmitting a detection signal. The control unit is made up of a microcomputer, and acquires the detection signal output from the magnetic detection element 30 and transmitted via the terminal 31, PCB 60, and wiring unit 70. Then, based on the acquired detection signal, the control unit calculates the position of the liquid level La of the liquid L and the amount of the liquid L corresponding to that position using a known method. The control unit may be configured to be included in the detection device F.

[0051] The grommet 80 is made of a known elastic material such as nitrile rubber and is attached to the wiring lead-out portion 41c of the case 40. The grommet 80 has insertion holes through which each of the multiple cords of the wiring portion 70 passes. The grommet 80 acts as a buffer against bending of the wiring portion 70 at the lead-out portion. As shown in FIG. 4 , the grommet 80 has recesses corresponding to the protrusions formed on the wiring lead-out portion 41c, and is fitted into the wiring lead-out portion 41c using these recessed and protruding shapes. Note that the relationship of the protrusions and recesses may be reversed. That is, the grommet 80 may have protrusions and the wiring lead-out portion 41c may have recesses. The fitting mechanism between the grommet 80 and the wiring lead-out portion 41c facilitates positioning of the grommet 80 relative to the case 40, preventing the grommet 80 from falling off the case 40.

[0052] The molding material 90 shown in FIG. 4 is made of a known material such as epoxy, covers the PCB 60 (see FIG. 2), and fills the board accommodating portion 41b. The molding material 90 is, for example, black. To make it easier to determine the amount and degree of filling of the molding material 90 in the board accommodating portion 41b, the color of the case 40 is set to a color (for example, white) different from that of the molding material 90. Note that the colors of the molding material 90 and the case 40 are not limited to this example, and may be any color as long as they are different enough to be distinguishable from each other.

[0053] As described above, this embodiment includes a rotating member 20 that rotates around the axis AX in response to the displacement of the detection target, magnets 21a and 21b disposed in recesses G1 and G2 formed in the rotating member 20, a magnetic detection element 30 that detects changes in the magnetic field associated with the rotation of the rotating member 20, and a non-magnetic member 50 disposed to cover a portion of the magnets 21a and 21b. Therefore, by using the non-magnetic member 50, which is not an injection-molded product, instead of the injection-molded resin cover that has been used in the past, the number of injection-molded products can be reduced compared to the past. This reduces the number of molds required to obtain the injection-molded products (reducing the number of steps required for injection molding), lowering the cost of parts required to manufacture the detection device and suppressing cost increases.

[0054] In addition, in this embodiment, the non-magnetic member 50 is provided with an open-ended ring portion 51 that surrounds the protruding portion 42a of the shaft portion 42 that protrudes from the through-hole R, and a plurality of fitting portions 52 that fit into groove portions 42c provided in the protruding portion 42a, thereby reducing the contact area between the non-magnetic member 50 and the shaft portion 42, which has the advantage of improving the durability of the non-magnetic member 50 that rotates in synchronization with the rotation of the rotating member 20.

[0055] Furthermore, in this embodiment, the rotating member 20 has a raised portion 22d formed on the virtual circumference V in a manner corresponding to the missing portion T where the ring portion 51 is missing, and the raised portion 22d has a part thereof, the raised fitting portion S, fitted into the groove portion 42c, so that the non-magnetic member 50 (plurality of fitting portions 52) slides stably within the groove portion 42c, which has the advantage of further improving the durability of the non-magnetic member 50.

[0056] 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.

[0057] In the above description, the magnets 21a, 21b are configured such that their inner edge portions W1, W2 are covered by the ring portion 51 and their outer edge portions W3, W4 are covered by the locking claws E1, E3 (locking portions 22e, 22f) formed on the rotating member 20. However, for example, the locking claws E1, E3 may be omitted, and the entire magnets 21a, 21b or most of the magnets 21a, 21b may be covered by the ring portion 51 (non-magnetic member 50). The key is that the non-magnetic member 50 needs to be positioned so as to cover at least a portion of the magnets 21a, 21b. When the locking claws E1, E3 are omitted, it is preferable to press-fit and fix the magnets 21a, 21b using the elastic pieces E2, E4.

[0058] In the above, an example has been shown in which the protrusion 41a provided on the case 40 has an annular shape centered on the axis line AX, but the shape is not limited to this. For example, the protrusion 41a may have a plurality of portions arranged intermittently along the circumferential direction centered on the axis line AX. It is preferable that the plurality of portions be arranged at equal intervals in the circumferential direction centered on the axis line AX to stably guide the rotational movement of the rotating member 20.

[0059] In the above, an example has been described in which magnet holder 22 holds two magnets 21a and 21b, but 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.

[0060] 3 shows an example in which 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 detection device F can properly detect the position of the detection target. For example, the magnetic detection element 30 may be positioned off the axis AX.

[0061] In the above description, in order to facilitate understanding of the present invention, descriptions of well-known technical matters have been omitted as appropriate. [Explanation of symbols]

[0062] 10 Float 11 Arm 20 Rotating member 21a, 21b Magnet 22 Magnet holder 22a Main body 22b First arm locking portion 22c Second arm locking portion 22d ridge 22e, 22f Locking part 22g rib 30 Magnetic detection element 40 Case (supporting member) 41 Daibu 42 Shaft 42a Projecting part 42b Space part 42c Groove 50 Non-magnetic materials 51 Ring section 52 Fitting part 60 PCB 70 Wiring section 80 Grommets 90 Molding material AX axis G1, G2 recessed parts H1 recess R penetration part T missing part V Virtual circumference

Claims

1. a rotating member that rotates around an axis in response to the displacement of the detection target; a magnet disposed in a recess provided in 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 that rotatably supports the rotary member; a non-magnetic member disposed so as to cover at least a portion of the magnet; the support member has a shaft portion provided along the axis line, the magnetic detection element is disposed in a space provided in the shaft portion, The rotary member is provided with a through-hole through which the shaft portion can pass, The non-magnetic member is characterized in that it has an end-shaped ring portion surrounding the protruding portion of the shaft portion that protrudes from the through portion, and a plurality of fitting portions that fit into grooves provided in the protruding portion.

2. the ring portion is provided along a virtual circumference having the axis as its center, the rotating member includes a raised portion formed on the virtual circumference in a manner corresponding to a missing portion of the ring portion, 2. The detection device according to claim 1, wherein a portion of the raised portion is fitted into the groove portion.

3. 2. The detection device according to claim 1, wherein the fitting portion is a fitting protrusion partially provided on the inside of the ring portion, and is provided at both end portions of the ring portion and at a middle portion of the ring portion.

4. 3. The detection device according to claim 1, wherein the magnet has an inner edge portion covered by the ring portion and an outer edge portion covered by a locking portion formed on the rotating member.

5. 5. The detection device according to claim 1, wherein the non-magnetic member rotates in conjunction with the rotation of the rotary member.

6. a float that floats on the liquid to be detected and displaces together with the liquid surface; 6. The detection device according to claim 1, further comprising an arm that connects the float and the rotary member and rotates the rotary member in response to displacement of the float.

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